Effects of organic insecticides on the performance of soybean (Glycine Max L.) varieties in Thai Nguyen, Viet Nam condition

Beato This research was conducted in Vietnam from June to October 2014 to determine the growth and yield performance of three varieties of soybeans using different sources of insecticide

EFFECTS OF ORGANIC INSECTICIDES ON THE PERFORMANCE

OF SOYBEAN (Glycine Max L.) VARIETIES IN THAI NGUYEN,

VIETNAM CONDITION

A Thesis presented toThe Faculty of the Graduate Studies and Applied Research LAGUNA STATE POLYTECHNIC UNIVERSITY

Siniloan, Laguna Philippines

ACKNOWLEDGEMENT

The author would like to express her heartfelt and warmest gratitude to the following persons who gave their valuable suggestions, immeasurable support, and for the strength and inspiration to finish this study

Dr Nestor M De Vera, University President, for his valuable ideas, comments, and suggestions for the improvement of this study

Dr Lolita L Beato, Dean of College of Agriculture and Adviser, for her guidance, motivation, valuable ideas and suggestions to make this study complete

Dr Robert C Agatep, Statistician, for the encouragement, patience and for helping her on the analysis and interpretation of data

Dr Carlos J Andam, Subject Specialist, for his brilliant ideas, comments and suggestions for the improvement of this study

Prof Lydia R Chavez, Technical Editor, for her comments and suggestions on the technical aspect of this study

Thanks to the farmers for lending his land area for the conduct of this study

Lastly, the author would like to thank his parents who always love, comfort, encourage and support in everything he needs to complete this study

THANH TRUNG DAM

ABSTRACT

DAM THANH TRUNG, Laguna State Polytechnic University, Siniloan, Laguna NOVEMBER 2014 “EFFECTS OF ORGANIC INSECTICIDES ON

GROWTH AND YIELD OF SOYBEAN (Glycine Max L.) VARIETIES IN THAI

NGUYEN CONDITION, VIETNAM” Adviser: Dr Lolita L Beato

This research was conducted in Vietnam from June to October 2014 to determine the growth and yield performance of three varieties of soybeans using different sources of insecticides under Thai Nguyen condition in Vietnam Specifically, the study sought answers to the following questions: what are the significant differences among the performance of three varieties of soybeans?; which variety and insecticide sources or their combination will give better growth performance of soybeans in terms of plant height at maturity, number of days from transplanting to flowering, fruiting and harvesting and number of branches?; which variety and insecticide sources will give better yield performance of soybeans in terms of number of pods per plant, length and weight of pods per plant; weight of soybean seeds and yield per hectare?; which variety and insecticide sources will give lower number and percentage of infestation of soybean plants in terms of kinds of insects at different stages of plant and percentage of infestation a different stages of soybean plant?; are there significant interaction effects between and or among soybean varieties and sources of insecticides?; which variety of soybean and insecticide sources or their combination will be most suitable and economical to use in Thai Nguyen

A 3x5 factorial experiment in a Randomized Complete Block design (RCBD) was used in the study with three finger pepper varieties ( A1- DT22, A2- DT26 and A3- DT51 variety) and five sources of insecticides B1- control, B2- 50L hoban 30EC /ha, B3- 50L hocsinh/ha, B4- 50L thaomo/ha and B5- 50L hattao/ha Each treatment was replicated four times Duncans’ Multiple Range Test (DMRT) was used to determine the significant differences between variety and fertilizer means

Result showed that the growth and yield performance of soybean plants were affected by varieties in terms of plant height, number of days from transplanting to flowering to fruiting, number of branches, length and weight of pods Among the three varieties of soybean plants, DT 22 showed better growth and yield performance

Insect infestation of soybean plant is affected by the insecticides applied

at fruiting stage The yield and economic performance of soybean plants were affected by varieties and insecticides in terms of number of pods, weight of soybean seeds, yield per hectare, net income and return on expenses

Interaction effect was present in insect infestation at vegetative and flowering stage of soybean plants Insect infestation is lower at the application of organic insecticide

Total sale, net income and return on expense of soybeans increased at the application of insecticide with the rate of 50L hocsinh/ha

Since the growth, yield and economic performance of soybeans were significantly affected by varieties and fertilizer in terms of plant height, number of days from transplanting to flowering to fruiting, number of branches, length and weight of pods, number of pods per plant, weight of soybean seeds, yield per hectare, net income and return on expenses, the use of DT 22 variety and application of organic insecticide Hocsinc (chilli, garlic, corn bran and egg shell)

at the rate of 50L/ha is being recommended

Replication of the same study in other areas and field is also recommended

Vegetable soybean is rich in phytochemicals beneficial to the human being and is therefore considered a neutraceutical or a functional food crop Edamame (vegetable soy bean) is well established legume in the human diet in Asia The positive health benefits of soy have greatly increased consumer awareness of soy products and created a market potential for soy products (Beckman, 1997)

Imports of soybeans in 2011 rose significantly due to the increased demand from the food processing, livestock, and aquaculture feed industries, and the vegetable oil industry combined with a zero percent import tariff Vietnam’s soybean imports reached a record in 2011, surpassing one million metric tons (MMT) This represents a 350 percent increase over the previous year; 22 percent of the total imported volume was sourced from the United

States Post expects imports of full-fat soybeans to steadily increase in the next three to five years Soybean meal imports increased to a record 3.0 MMT to meet the growing demand from the livestock, and aquaculture feed sectors (Nguyen, 2012)

Demand for imported soybean meal is forecast to fall as new processing facilities come on-line in Vietnam Already, we have seen a sharp increase in soybean imports in preparation for the opening of the first of two processing plants Meal production is expected to grow through the latter-half of 2011 and attain peakproduction the following year The full impact on meal imports will be felt in 2012 with an anticipated reduction in trade around 20 percent This figure would be lower if not for continued growth in meal demand driven by expansion

in the pork, poultry and aquaculture sectors Although initial soybean sales have comepredominately from South America, there remains opportunity for future growth in U.S sales to the region (United States Department of Agricuture, 2011)

In 2012, U.S soybean exports to Vietnam reached a record of 461 thousand metric tons (TMT), double the 2011 level due to high demand from the two commercial oilseed crushing facilities, and from the food industry In 2013, U.S soybean exports are expected to reach about 500 TMT In 2012, Vietnam’s soybean meal (SBM) imports were 2.5 million metric tons (MMT) Post forecasts

2013 and 2014 SBM imports to gradually decrease due, to 2.4 and 2.37 MMT, respectively, due to local production Local soy oil production and exports have

been increasing in recent years as results of larger crush and greater oil availability Soy oil exports are projected at 110 TMT and 120 TMT in 2013 and

2014, accordingly (Nguyen, 2012)

Productivity of soybeans in Asia, and particularly Vietnam, is low compared with elsewhere in the world Vietnam’s average yields are 1t/ha

compared with 1.3 t/ha in Thailand, 1.75 t/ha in Brazil and 2.25 t/ha in the USA

This low productivity is a problem because Vietnam needs more soybeans to

satisfy a growing demand for stock feed and to improve the nutrition of the

human population The reasons for poor production in Vietnam have been clearly

identified One of the most significant is the fact that the varieties grown in

summer have a growing period too short to produce the maximum yield possible

for the season Moreover, soybean is invariably treated as secondary to rice, and

so receives less research attention, less fertilizer input, and less effort at insect

control (James, 2006)

With the various problems brought about by the increased use of chemical inputs, high quality seed production, especially on a commercial scale, should be through an alternative system, such as organic and biodynamic farming This means reduced or zero use of chemical fertilizers and pesticides, use of alternative nutrient sources like green manure crops, animal manure, compost, and the likes and more natural ways of pest and disease control, and an overall ecological approach to farming (Fernandez,2002)

The researcher was encouraged to study on how to increase yield of soybeans by controlling insect infestation through the use of organic insecticide under Thai Nguyen condition in Vietnam to help farmers increase their income

Background of the Study

The demand in the production, consumption and processing of soybean in Vietnam is increasing In order to increase soybean production to meet this demand, Vietnamese farmers are using high amount of chemical fertilizers and pesticides and intensive cropping practices However, high-input practices such

as heavy use of chemicals have created a variety of economic, environmental, ecological and social problems Furthermore, the increasing costs of chemical inputs have left farmers helpless, resulting to decreasing seed quality of certain crops and resulting in the fall of commodity prices and consequently reducing farm incomes In addition, in Vietnam, organic/sustainable agriculture is mistakenly equated with primitive, traditional, or subsistence agriculture and their low yields Therefore, most Vietnamese farmers resist adopting sustainable agriculture for their crop production (Fernandez, 2002)

Soybean is a crop of one plant species, however, differences caused by variety selection, planting date, cultural techniques, site, and season makes the crop highly variable in it's attractiveness to insect pests In other words, all soybean fields are not alike, as far as attracting and building-up pest insects is concerned If the organic soybean farmer recognizes these differences, he can

actually plan to manage the crop for reduced insect pest numbers or, when this is not possible, he can predict which of his fields are attractive and may need more attention to prevent yield loss The organic soybean grower can normally rely upon reducing soybean attractiveness to pests, as well as beneficial insects to reduce pest numbers, and the soybean plant’s natural ability to compensate for insect damage (tolerance) In instances where caterpillar pests are not avoidable, organically approved Entrust insecticide may be successfully used (Reisig, 2000)

Vietnam began using pesticides as early as the 1950s, when agricultural production was limited to cooperatives, collective farms, and state farm enterprises Under this regime, little knowledge existed of the hazards of pesticides, and with no regulation system Application was centrally-run by brigades of 4-5 farmers who worked in conjunction with the Plant Protection Department (PPD) The PPD supplied pesticides at subsidized prices and recommended spraying on a calendar basis, with little or no attention to field conditions Brigade interventions generally resulted in high costs but had little effect on pests and diseases (Chung and Dung, 2002)

Pesticide use has been on the rise in Vietnam, notably over the past decade with a near doubling of consumption from 1990-1998 Field evidence has suggested that farmers are also misusing and overusing pesticides in order

to maintain crop yields and production As a consequence of this growing

dependence and hap-hazard use of pesticides, the prevalence of health impairments and environmental damage are mounting (Meisner, 2003)

In addition to the alarming increase in pesticide use, there is also significant evidence suggesting that the substances being used are harmful to human health and the environment In a nation-wide survey conducted by the PPD in 2000, 2,500 kg of banned pesticides were found (methamidophos, DDT and other chemicals), along with 4,753 liters and 5,645 kg of illegally imported or counterfeit pesticides (Plant Protection Department, 2000)

In regards to the health impacts of pesticide use, hospital admission records in Vietnam trace nearly 11% of all poisonings to pesticide misuse: or approximately 840 poisonings in 53 cities and provinces in 1999 (Vietnam Ministry of Health, 2000)

As an alternative to pesticide use, other pest management methods are possible and appear to be gaining traction in Vietnam The main appeal to alternative methods is that the farmer decreases his/her use of pesticides and it

is therefore considered a more “safer” alternative Examples of other methods include Integrated Pest Management (IPM: an ecologically-based approach to control of harmful insects and weeds), biological control (use of natural or modified organisms, genes, or gene products to reduce the effects of pests and diseases), or organic methods (farming that avoids the use of synthetic chemicals and genetically modified organisms (Meisner, 2000)

In the mid 1990s there were a number of food safety scares resulting from inappropriate pesticide use and the Vietnamese Government were forced to act

In April 1998 the Ministry of Agriculture and Rural Development (MARD) issued the 1“Temporary Regulations for the Production of Safe Vegetables”1 These regulations specify the required quality for safe vegetables and contain a number

of tables showing the Maximum Residual Levels (MRLs) for permitted pesticides, nitrate content, heavy metal content and bacterial pathogens and intestinal parasites that are allowed in harvested vegetables Vegetable farmers across Vietnam, particularly those around the major cities of Hanoi and Ho Chi Minh City received training on safe vegetable production and integrated pest management (IPM) in an attempt to reduce pesticide residues in vegetables and improve food safety The protection of human health appears o be the primary driver behind safe vegetable production (Phan et al., 2005)

Thus, this study will be conducted to determine the effect of organic insecticide that will give better growth and yield performance of soybeans under Thai Nguyen condition in Vietnam

Theoretical Framework of the Study

Numerous kinds of insects occur in soybeans field Some are beneficial or harmless, but some can cause damage by reducing yield and even total crop failure if can’t be managed properly Soybean is very much susceptible to insect attack from seedling to mature stage Scanty information is available about the

insects associated with multipurpose trees and shrubs that are gaining economic importance as components of agroforestry systems Many factors govern insect pest intensity in agroforestry and each factor may have a different effect on pests

at different times under different situation such as, vegetation diversity, host range of pest, biological control potential, microclimate, exotic plants and pests, domestication of plants, tree-crop competition for nutrition and management

practices (Chakma et al., 2008)

A new study reveals some organic pesticides can have a higher environmental impact than conventional pesticides Researchers investigated the effectiveness and environmental impact of organic pesticides to those of conventional and novel reduced-risk synthetic products on soybean crops The researchers found the organic pesticides required larger doses and were more harmful to pests that help protect the crop compared to the synthetic pesticides (Bahai et al., 2010)

Productivity of crops grown for human consumption is at risk due to the incidence of pests, especially weeds, pathogens and animal pests Crop losses due to these harmful organisms can be substantial and may be prevented, or reduced, by crop protection measures An overview is given on different types of crop losses as well as on various methods of pest control developed during the last century The concept of integrated pest/crop management includes a threshold concept for the application of pest control measures and reduction in the amount/frequency of pesticides applied to an economically and ecologically

acceptable level Often minor crop losses are economically acceptable; however,

an increase in crop productivity without adequate crop protection does not make sense, because an increase in attainable yields is often associated with an increased vulnerability to damage inflicted by pests (Oerke, 2006)

The farm level impacts of such crop on insecticides used, yield and net return vary with crop and technology Adoption of herbicide-tolerant led to significant increase in yield and return but was not associated with significant changes in insecticide use (Fernandez, 2002)

Conceptual Framework of the Study

The conceptual paradigm of the study is shown in figure 1 The first box presents the independent variables which include varieties of soybeans and different sources of insecticides which may directly or indirectly affected the dependent variables which include the growth characterizations, yield, insect infestation and economic components of soybeans

The second box presents the dependent variables which include the growth and yield performance of soybeans as affected by different varieties and sources of insecticides Growth performance was measured in terms of plant height, number of days from transplanting to flowering, number of days from flowering to fruiting, number of days from fruiting to harvesting and number of branches Yield performance was measured in terms of number of pods per

plant, length of pods per plant, weight of soybean seeds per harvest area and

yield per hectare Insect infestation was measured in terms of kind and

percentage of insect infestation at different stages of plant The economic

parameters were measured in terms of cost of production, gross income, net

income and return on expenses

The third box represents the mediating variables which include weather,

climate and temperature

Independent variables Dependent variables

1 Different varieties (Factor A) Growth performance

A1 – DT22 1 Height of plant

A2 – DT26 2 Number of days from planting to flowering

A3 - DT51 3 Number of days from flowering to fruiting

4 Number of days from fruiting to harvesting 2 Different insecticides (Factor B) 5 Number of branches

B1 - no insecticide Yield performance B2 – inorganic insecticide 1 Number of pods per plant hoban 30EC 2 Length of pods per pant

B3 - hocsinh 3 Weight of pods per plant

B4 - thaomoc 4 Weight of soybean seeds per harvest area

B5- hattao 5 Yield per hectare

Figure 1 Conceptual paradigm showing the relationship between independent

and dependent variables of the study.

Statement of the Problem

This study was conducted to determine the growth and yield performance

of three varieties of soybeans using different sources of insecticides under Thai

Nguyen condition in Vietnam

Specifically, the study sought answers to the following questions:

1 Are there significant differences among the performance of three

varieties of soybeans?

2 Which variety and insecticide sources or their combination will give better

growth performance of soybeans in terms of:

a plant height at maturity;

b number of days from transplanting to flowering;

c number of days from flowering to fruiting;

d number of days from fruiting to harvesting; and

e number of branches?

3 Which variety and insecticide sources will give better yield performance of soybeans in terms of:

a number of pods per plant;

b length of pods per plant ;

c weight of pods per plant;

d weight of soybean seeds

e yield per hectare;

4 Which variety and insecticide sources will give lower number and percentage of infestation of soybean plants in terms of:

a Kinds of insects at different stages of plant;

b Percentage of infestation a different stages of soybean plant

5 Are there significant interaction effects between and or among soybean varieties and sources of insecticides?

6 Which variety of soybean and insecticide sources or their combination will

be most suitable and economical to use in Thai Nguyen condition in Vietnam?

1 There are no significant differences on the performance of the three varieties of soybeans

2 There are no significant differences on the growth and yield performance

of different varieties of soybeans as affected by different insecticide sources under Thai Nguyen condition in Vietnam

3 There are no significant interaction effects between and among soybeans variety and insecticide sources (AxB)

Significance of the Study

This study was conducted to determine the effect of organic insecticide on growth and yield performance of different varieties of soybean under Thai Nguyen condition in Vietnam

Students The results of this study may serve as guide or reference for

other students who would like to conduct related studies

Farmers The outcomes of the study will serve as guide to farmers

particularly those who are engaged in soybean production in the selection of variety and kinds of insecticide to be applied that are safe, economical and appropriate to use under Thai Nguyen condition in Vietnam

Researchers The results of the study will serve as bases for other

researchers who may decide to conduct further investigation of soybeans using different varieties and insecticides under other conditions

Agricultural Extension Workers This study will serve as a basis of

recommendation to transfer technology to farmers who are interested to venture

on soybean production to increase crop productivity and income

Government The results of the study will provide some insights and

information for policy makers in the formulation of more effective and efficient programs that will encourage farmers and agriculturist to have a productive and attainable food security and sustainability

Scope and Limitations of the Study

The experiment of the study had three factors laid out in a split-plot design

in Thai Nguyen University of Agriculture and Forestry (TUAF) Thai Nguyen Vietnam from June to October 2014

The study focused on the effects of organic insecticide sources (Hocsinh, Thaomos and Hattao) on the growth and yield performance of different varieties

of soybeans (DT-22, DT-26 and DT51) under Thai Nguyen condition in Vietnam

Growth, yield performance and insect infestation of soybeans were measured in terms of plant height at maturity, number of days from transplanting

to flowering, number of days from flowering to fruiting, number of days from fruiting to harvesting, number of branches, number of pods per plant, length and weight of pods, weight of soybean seeds, yield per hectare, kinds and percentage of insect infestation

The economical and profitability of finger pepper were measured in terms

of cost of production, gross and net income, and return on expenses

Hocsinh, Haomoc and Hattao - are the organic insecticides to be

applied in soybeans to control insect pests in the experimental study

Thai Nguyen - is a place in Vietnam inside the Nguyen University of

Agriculture and Forestry where the researcher conducted his study

Composite soil sampling – Composite sampling can be performed by combining soil from several locations prior to soil analysis to determine nutrient and contaminated content, composition, and other characteristics such as the acidity or pH level

Land preparation – begins after the last harvest or during fallow period This is important for effective weed control and for enriching the soil Generally, it will take 3−4 weeks to prepare the field before planting

Planting – sowing or the process of casting of soybean seeds over prepared land

Weeding – is the botanical component of pest control to pull the weeds that may compete for the soybean plants in getting the nutrients

Harvesting –is the process of gathering the matured pods of soybean Insect population - is the number of insects present in the experiment plot Percentage of insect infestation - is the percentage of plant infested in

the experimental plot / area

Gross income or gross farm income is the total of all income accruing to

the farm sector from both cash and non-cash sources

Net income refers to the return to farm operators for their labor, management and capital, after all production expenses have been paid

Return On Expenses (ROE) is an indicator, used in the formal discipline

of cost-benefit analysis, that attempts to summarize the overall value of money of

a project or proposal ROE = Total Revenue / Total Cost

Chapter 2

REVIEW OF RELATED LITERATURE AND STUDIES

Various references were reviewed by the researcher to determine theories, concepts, principles, methodologies, and findings that are relevant and helpful to the conduct of the study

Related Literature

Soybeans belong to the legume family and are native to East Asia They have been an important protein source in the Orient for over five thousand years Soybeans have only been introduced to the Western world since the 20th century.Soybeans grow on a variety of soils and a wide range of climates, ranging form tropical Brazil to the snowy island Hokkaido in the north of Japan

As soybeans mature in the pod, they ripen into hard, dry beans Although most soybeans are yellow, there are also rare varieties which are black, brown or green coloured A given area of land planted with soybeans can produce much more protein than land planted with other crops, or if the land were used to raise cattle (Encyclopedia of Life, 2012)

An insecticide is a substance used to kill insects (IUPAC, 2006).They include ovicides and arvicides against insect eggs and larvae respectively Insecticides are used in agriculture, medicine, industry and by consumers Insecticides are claimed to be a major factor behind the increase in agricultural

20th century's productivity Insecticides can be classified in different ways Systemic insecticides are incorporated by treated plants Insects ingest the insecticide while feeding on the plants Contact insecticides are toxic to insects when brought into direct contact Efficacy is often related to the quality

of pesticide application, with small droplets (such as aerosols) often improving performance.Natural insecticides, such as nicotine, pyrethrum and neem extracts are made by plants as defenses against insects Nicotine-based insecticides are

widely used in the US and Canada, but are barred in the European Union

Inorganic insecticides are contact insecticides that manufactured with metals and include arsenates, copper and fourine compounds, which are now seldom used, and sufur, which is commonly used.Organic insecticides are contact insecticides that comprise the largest numbers of pesticides available for use today (Peakall 1996)

Most synthetic organic insecticides penetrate by all three of these pathways, however, and hence are better distinguished from each other by their

compounds occurring naturally in plants are useful insecticides, as are some inorganic compounds Most insecticides are sprayed or dusted onto plants and other surfaces traversed or fed upon by insects (Encycopedia Britannica, 2014)

The soybean aphid, a pest originally from Asia, was first discovered in North America in 2000 and in Ontario in 2001 This insect has two hosts that it requires to complete its life cycle The soybean aphid survives as eggs on the

twigs of buckthorn species In the spring, nymphs hatch from these eggs, and the aphids undergo two generations as wingless females on the buckthorn The third generation develops into winged adults that migrate to soybean plants The aphids then continue to produce wingless generations until the soybean plants become crowded with aphids and the plants experience a reduction in quality Once crowded, winged forms are produced to disperse to less-crowded soybean plants There can be as many as 18 generations of aphids per year on soybeans Like most aphids, the soybean aphids are all female, born pregnant and give birth to live nymphs Males are only born in the fall so that the females and males can mate to produce the egg on buckthorn (OMAFRA, 2009)

Currently available varieties of soybeans differ in growth characteristics and the time required for maturity Variety characteristics can affect susceptibility

to insect injury For example, early maturating varieties are less likely to be seriously damaged by soybean loopers or velvet bean caterpillars because they often mature before late season generations of the pests occur Also, varieties with little pubescence (hairs) on the undersides of leaves are susceptible to potato leafhopper infestations Maturity differences can be used to manage some insect pests For example, planting about 5 percent of the soybean acreage in an area 10 –14 days earlier than the remainder of the crop will concentrate overwintering bean leaf beetles into these earlier plantings The early-planted soybeans serve as a trap crop for the adults, and a relatively small amount of insecticide can then be used to prevent their spread into later planted soybeans

If early maturing varieties are planted as the trap crop, they will also act as a trap crop for stink bugs during pod development Soybeans that do not have a closed canopy at the time of bloom, as often occurs in late-plantings and wider-row spacings, are more susceptible to bollworm infestations No-till soybeans are at greater risk to cutworm damage than conventionally tilled soybeans (Kalisch, 2012)

In 2000, a new insect, the soybean aphid, Aphis glycines Matsumura, was discovered in soybean fields in many areas of the Midwest, including Indiana The soybean aphid feeds using needle-like, sucking mouthparts to remove plant sap Plant damage occurs as a consequence of large numbers of aphids removing significant amounts of water and nutrients from leaves and stems during feeding This may cause leaf puckering, plant stunting, reduced pod and/or seed counts, and smaller seeds (Krupke, Obermeyer, and Bledsoe,2010)

Early-season aphid infestations tend to concentrate on the newly emerging leaves and upper trifoliates of the plant Later in the season, once into the reproductive stages of soybeans, the aphids tend to migrate down to the middle or lower canopy, possibly due to heat and predator abundance experienced at the top of the canopy Because of this movement within the canopy through the season, taking full plant counts is still the best method to estimate the number of aphids per plant and relate that to the threshold (OMAFRA, 2009)

Different biological parameters of the stink bugs, Nezara viridula L and Piezodorus guildinii Westwood (Hemiptera: Pentatomidae), are affected by the developmental stage of the soybean (Glycine max Merrill) pods they feed on These effects of the soybean on the stink bugs could represent a selection pressure leading to the ability of these species to discriminate the phenological stage of soybean pods, and, therefore, to exhibit feeding preferences Most phytophagous pentatomids, commonly referred to as "stink bugs," are polyphagous,and their wide host range includes both cultivated and wild plants (Coombs, 2000)

Stink bugs are major agricultural pests across the world and they are most often attracted to plants with growing shoots and developing seeds or fruits (Olson, 2011)

Despite their broad host-range, plant use bypentatomids changes with host maturity and phenology, with plants being most attractive during fruit and pod formation stages As the fruit/seeds mature, the plants become less attractive, and the stink bugs move to more succulent plants (McPherson and McPherson, 2000)

Variation in the quality of food resources has an important effect in the performance of phytophagous insects The intrinsic rate of increase of generalist herbivorous insects, particularly plant sucking ones, can vary significantly among host plant species (Speigh, 2008)

Developmental and reproductive rates provide important clues concerning the ability of the host to have an impact on fitness Optimal foraging theory predicts that phytophagous adults should prefer to feed on those host plants or plant organs that confer the highest fitness This prediction can be applied even

to novel plant-insect interactions, as herbivorous insects can evolve adaptations

to plants in periods as short as 50 years (Schoonhoven, Van Loon and Dicke,2005)

Related Studies

Janeiro (2009) on his studies used Anticarsia gemmatalis nucleopolyhedrovirus (AgMNPV) as a biological insecticide Host plant resistance of soybean to insects is been searched for he have mentioned the interference of plant chemistry in virus efficiency Interactions among soybean extracts of genotypes used as a source of resistance (PI 274454 and PI 227687) with different AgMNPV concentrations in populations of A geatalis susceptible (S) and resistant (R) to the virus were studied at laboratory condition Higher mortality was observed when larvae fed on diets with extracts

of the soybean genotypes compared with those fed on a plain diet (control) The mean lethal concentration (LC50) was reduced about 10 ties in the S-population fed on diets containing PI 274454 extracts and different concentrations of AgMNPV, compared to control diet

Bueno, Parra and Vieira (2008) studied the effects of different insecticides, herbicides and fungicides on eggs, larvae and pupae of Trichogramma

pretiosum The results showed that studied pesticides had different impact on T pretiosum Esfenvalerate 7.5 and spinosad 24.0 grams ha-1 were classified as harmfull (class 4) while clorfluazuron 10.0, methoxyfenozide 19.2, lactofen 165.0, fomesafen 250.0, fluazifop 125.0, glyphosate 960.0 (Gliz® and Roundup Transorb®), azoxistrobin + ciproconazol 60.0 + 24.0, azoxistrobin 50.0 and myclobutanil 125.0 grams ha-1 were chemicals classified as harmless to all imature T pretiosum stages All the other chemicals evaluated had different impact on T pretiosum being classified from harmless (class 1) to harmful (class 4) varying the impact accordingly to the different parasitoid stage Then, less noxious products should be chosen whenever possible to be used in a soybean IPM program

Riedell and Catangui (2006) studied on how to measure soybean growth, yield, and yield components affected by soybean aphid under controlled environments Greenhouse-grown plants were infested with aphids at the firstnode stage (V1), the third node stage (V3), the beginning bloom stage (R1), thefull pod stage (R4), and the beginning maturity stage (R7) Aphids remained onhe plants for a total of 6,000 aphid-d (e.g 600 aphids present for 10 days) afterwhich time the insects were removed with insecticide Increases in stemlength, as compared with uninfested controls, were observed in plants infestedat the V1 and V3 stages but not at the R7 development stage Aphid infestationhad no significant effect on seed yield, number of pods plant−1, or number ofseeds pod−1

Dubey (2012) investigated the effect of application of different Pesticides : Field scale experiment :These experiments were carried out in randomized block design with there replication in the selected field of Sidhi block of district Sidhi Soybean seeds (MACS 450 variety) were sown in the filed Pesticides used in this study for seed treatment included carbosulphan 25 DS, thiamethoxam 70

WS, imidaclopried 70 WS, Chlorpyriphos 20 EC For soil application phrate 10G and carbofuran 3G and for fire spray chorphriphos 20 Es, thiamethoxam 25 WG and imidaclopride 200 EC These pesticides were used as per All India Coordinated Entomology Experiment for control of seedling Soyaban insect pest

Bahlai et al (2010) reported the results of a study examining the

environmental impact of several new synthetic and certified organic insecticides

under consideration as reduced-risk insecticides for soybean aphid (Aphis

glycines) control, using established and novel methodologies to directly quantify

pesticide impact in terms of biocontrol services We found that in addition to

reduced efficacy against aphids compared to novel synthetic insecticides,

organic approved insecticides had a similar or even greater negative impact on

several natural enemy species in lab studies, were more detrimental to biological

control organisms in field experiments, and had higher Environmental Impact

Quotients at field use rates

Sarnaik et al (2006) studied that pesticide residues contributing to the contamination of soil may influence microbial population of the soil and in turn fertility of soil The present paper reports the effect of pesticides applied to

soybean i.e phorate, carbofuran, carbosulfan, thiomethoxam, imidacloprid, chlorpyriphos and monocrotophos on soil microflora The viable count of rhizobia and phosphate solubilizing bacteria from rhizospheric soil of soybean ranged between 107-108 cfu/g soil which was comparable to the count of bacteria from untreated (control) soil No significant change in the total viable count of any kind

of bacteria due to application of pesticides has been found showing their ability to degrade these pesticides

Kim et al (2006) estimated the economic losses resulting from soybean aphid infestation by using a dynamic equilibrium model Results indicate that, first, the reduction of soybean production resulting from soybean aphid infestation is largely absorbed by reducing soybean exports, due to the higher price elasticity of export demand compared to the domestic demand Second, the economic losses to U.S soybean producers would grow on average annually between $12.8 million and $23.4 million during the first five years of infestation

In the longer-run, soybean producers would suffer greater economic losses as the dispersion rate of infested soybean acreage with soybean aphids rises However, the successful discovery of the soybean aphid gene (TF04048) Rag-1 (which confers resistance) does not at this time warrant soybean growers and policy-makers becoming too seriously alarmed Even so, time is an important factor in the eventual control of the soybean aphid

Bahlai et al (2010) reported the results of a study examining the environmental impact of several new synthetic and certified organic insecticides

under consideration as reduced-risk insecticides for soybean aphid (Aphis

glycines) control, using established and novel methodologies to directly quantify

pesticide impact in terms of biocontrol services We found that in addition to

reduced efficacy against aphids compared to novel synthetic insecticides,

organic approved insecticides had a similar or even greater negative impact on

several natural enemy species in lab studies, were more detrimental to biological

control organisms in field experiments, and had higher Environmental Impact

Quotients at field use rates

Kim et al (2008) estimated the economic benefits resulting from controlling

soybean aphid infestation by using a multi-regional competitive dynamic

equilibrium model Results indicate that the re- duction of soybean production

resulting from a soybean aphid infestation is largely absorbed by reducing

soybean exports, due to the higher price elasticity of export demand compared to

domestic demand Producer benefits resulting from controlling soybean aphids

would increase by between $949 million and $1.623 billion in ten years under

various scenarios Results also suggest that it is economically more efficient to

control soybean aphids when the rate of intrin- sic growth is relatively lower, the

supply price elasticity of soybean acreage is relatively more elastic, and

insecticide treatment costs per acre are lower However, if the discovery of the

gene Rag-1 (TF04048) leads to new cultivars that withstand the soybean aphid,

our estimates will overestimate the actual damages Even so, our analysis

demonstrates that it is critical to control soybean aphids early in their infestation

cycle to avoid a rapid increase in damages

Johnson(2014)investigatedthatseveral “biological insecticides” are labeled

for use on soybean pests The action of these insecticides differs from the

traditional concepts in that they do not poison the pest Rather these compounds

kill by causing a disease, in the case of Bacillus thuringiensis, or a physiological

dysfunction as with Dimilin These products are particularly suited to use with

pest management operations because they have no effect on the natural

enemies of the pest However, because of their mode of action, use of these

compounds does not result in a quick kill It may take from one to three days

after application before the insect is killed However, little or no feeding by the

pest will occur during this period

Mueler and Wiggs (2014) were able to evaluate fungicides under drier weather conditions While individual products affected yields at certain locations,

in general, all products had minimal significant effects on yield There were very few diseases (and insects) at all seven locations, so benefits from pest management were not part of the equation Fungicides are effective for management of diseases However, in years with very little pest pressure – most likely from lack of moisture in 2012 – positive yield responses to fungicides are not consistent

Kurle (2011) conducted trial at the University of Minnesota Southwest research and Outreach Center, Lamberton, MN, Headline fungicide was applied

at three rates at V5, at two rates at R2 and at one rate at V5 and R2 At R4, Headline, Quadris Tilt ad Bravo were applied at a single rate each Additionally

at R4 Warrior was applied alone and in combination with Headline and Quadris, Lorsban was applied with Headline and Quadris and Mustang Max was applied with headline Differences in soybean lower leaf loss and to a lesser extent brown stem rot were observed With the exception of Mustang Max, treatments with an insecticide had less aphids than those without These treatment differences did not translate into yield as all treatments yielded equivalently Differences in soybean growth were not observed Although other diseases were present in the trial, treatment differences were not observed With the exception

of a brief yellowing in some Bravo treated plots, crop injury was not observed for any of the treatments

Henry (2011) determined the influence of a fungicide and insecticide on soybean yield and growth when disease and insect pressure is minimal Soybean was planted at three locations across Indiana, USA, in 2009 and 2010 and treated with various combinations of glyphosate, pyraclostrobin, and lambda-

application of pyraclostrobin alone and by lambda-cyhalothrin alone, respectively

increased 5% by lambda-cyhalothrin No other yield component was influenced

by the fungicide or insecticide Economic analysis using Simulation and Econometrics to Analyze Risk (SIMETAR) demonstrated a single, post

application of glyphosate to be the most efficient treatment option across a range

of risk attitudes This study indicates that yield increases are possible using below threshold applications of fungicides and insecticides However, growers may not benefit from such applications if input costs are higher than the economic returns of the increased yield

Siddiqui and Ahmed (2006) combined effects of pesticides on soybean growth and nutritive composition of seeds were observed Pesticide treated soil had significant effects on leaf growth components such as leaf area ratio, leaf area index, specific leaf area, net assimilation rate, leaf weight ratio and leaf area duration Low concentration of pesticide enhanced leaf growth components at all the growth stages studied The plants grown at the site treated with 0.25g L-1 pesticide, displayed maximum relative growth rate (RGR) and crop growth rate (CGR) compared to control However, significant reduction in CGR and RGR were recorded at the sites treated with 0.5 and 0.75g L-1 concentration Total phenols in leaf, shoot and fruit were used as a stress indicator to ascertain the possibility of chemical stress caused by systemic pesticide 114 and 220% increase in total phenol at vegetative stage and 50, 166 and 163% at late fruiting stage were recorded in the sites treated with high pesticide concentration Significant differences in nutritive values of seeds between treated and control plants were also observed At the site treated with low pesticide concentration, lipid content was very high (28.9%) compared to the control With increasing concentration, protein and lipids contents started to decline Present study

showed the combined effects of pesticides concentration on plant growth and

Chapter 3 METHODOLOGY

This chapter presents the research materials, research design, determination of sample, experimental crops, research procedures, data gathering procedures and statistical treatment of data

Research Materials

The research materials used in this study were seeds, insecticide sources and measuring instruments and these are as follows:

Research Materials :

1 Soybean Varieties

The three Soybeans Varieties are:

DT22 (Đậu tương 22) : this is potential soybean variety in Vietnam

and is quite pest resistant

DT26 (Đậu tương 26) : this is quite resistant to rust, brown spots,

especially the ability to recover after stem maggot

DT51 (Đậu tương 51) : this is potential soybean that is quite pest

20 pieces egg shells

1 liter of water

10 grams of chili and 5 grams of garlic were chopped into small pieces, added to 1 liter of water and stored overnight Mix Corn bran was watered until it became paste and cooked for 15 minutes All of them were combined and added

the crushed egg shells The mixture was purified and loaded in a sprayer

Thaomoc (B4) This spray solution was composed of;

ginger 15 grams

garlic 8 grams

alcohol 2 liter

red sugar 40 grams

Each type of material was chopped and segregated and placed in each barrel Wine poured to each barrel with the rate of 1kg/1liter wine After 12 hours, red sugar was poured with rate of 1 kg /0,3 liter wine and after 5 days ,more wine

were added with the rate of 1 kg / 5 liter wine and kept after 15 days Liquids and

sediments were segregated and kept the liquid portion in sealed bottles ( reject rats , butterfly with a cost of 30 Pesos / 360 m2 )

Hattao (B5)

1 kilogram apple seeds were grinded without shells until pulverized and mixed it with 5 liters of rice wine and ferment it for 5 days After fermenting, take

it out and put it in a sprayer

There were two factors used in this study These were factor A, varieties

of soybean; and factor B, different sources of insecticides The effect of different sources of insecticides on the growth, yield, infestation and economic performance of three varieties of soybeans were determined using the split-plot method in randomized complete block design (RCBD)

According to Gomez and Gomez (1984), Randomized Complete Block Design (RCBD) is characterized by the presence of equally sized blocks, each containing all of the treatments The randomized block design for P treatments with r replications has rp plots arranged into r blocks with p plots in each block Each of the p treatments is assigned at random to one plot in each block The allocation of a treatment in a block is done independently of other blocks

Split-plot experiments on the other hand are factorial experiments in which the levels of one factor are assigned at random to large plots The large plots are then divided into small plots known as "sub-plots" or "split plots", and the levels of the second factor are assigned at random to small plots within the large plots

The experimental treatments are as follows:

Main plot factor

Factor A- varieties of soybean

Factor A1- DT22

Factor A2- DT26