Natural Enemy Populations Research Articles

Bioefficacy of Thiocyclam Hydrogen Oxalate 50 SP against Major Pests of Rice

Bioefficacy of thiocyclam hydrogen oxalate 50 SP, a new molecule of nereistoxin group, was evaluated against three major pests of rice viz. stem borer, leaf folder and whorl maggot during Sali (Kharif) and Ahu (Rabi) seasons, 2016–2017 at Instructional Cum Research (ICR) farm of Assam Agricultural University, Jorhat. Cartap hydrochloride 50 EC and trizophos 40 EC were used as standard check along with three doses of thiocyclam hydrogen oxalate 50 SP viz., 200, 350 and 500 g ai ha−1. The result showed that thiocyclam hydrogen oxalate 50 SP @ 200 and 500 g ai ha−1 recorded the lowest dead heart (2.3 and 2.0%), white ear head (1.4 and 1.3%) and leaf folder infestation (3.0 and 2.8%) with highest yield (5069 and 5097 kg ha−1) in Sali (Kharif) season 2016. Similarly, in Ahu (Rabi) season of 2017, the thiocyclam hydrogen oxalate 50 SP @ 200 and 500 g ai ha−1 recorded the lowest dead heart (1.9 and 1.8%), white ear head (1.0 and 0.5%) and leaf damage by whorl maggot (2.2 and 2.1%) with highest yield (4691 and 4861 kg ha−1), respectively. Moreover, thiocyclam hydrogen oxalate did not show any deleterious effect on natural enemies population of rice ecosystem.

KEY GENERAL ASPECTS TO BE CONSIDERED IN HABITAT MANAGEMENT: A REVIEW

The aim of this work is to analyse the most important components that involve habitat management considerations to understand how it could be an alternative to reduce pest pressure in crops to avoid the use of pesticides in agricultural ecosystems. To accomplish this objective, a literature review of several research papers related to the topic was done. It was found that a high percentage of studies showed favourable results for natural enemy populations and pest pressure. However, these practices show more positive results for natural enemy populations than for pest suppression. The success of habitat management practices to reduce pest pressure depends mainly on the selection of non-crop plant species at crop field scale, landscape complexity and the targeted natural enemy species. Nevertheless, among these factors, the landscape complexity in the surrounding semi natural habitat is the most important aspect, since it could determine the abundance of natural enemies in the crop. Understanding the complexity of semi natural habitats could help farmers to take better coordinated decisions to manage semi natural areas and improve the biological control service in their farms. Finally, the adoption of habitat management measures is not broadly accepted by farmers and more research is needed to show them the benefits of these practices.

Ground cover vegetation promotes biological control and yield in pear orchards

AbstractThe use of ground cover vegetation is becoming a prominent way of promoting biodiversity and associated ecosystem services in Chinese orchards. Despite the large number of studies that have addressed the effects of ground cover vegetation on promoting natural enemy populations and related pest control, it is still unclear whether enhanced natural pest control can increase yield and reduce the use of pesticide. We performed an experiment comparing three cover vegetation practices (ryegrass, clover and hairy vetch) versus a bare ground control in commercial pear orchards in the Yangtze River Delta of East China (YRDEC), China. Natural enemy density (predator and parasitoid abundance), invertebrate herbivore performance (piercing‐sucking herbivore abundance and branch‐boring and fruit‐boring percentage), pesticide input, and pear fruit yield were recorded. The results indicated that cover vegetation decreased herbivore abundance and boring percentage by 50% and 64%, respectively, thus decreasing pesticide use by 26%. We also found that cover vegetation increased the abundance of natural enemies by 621%, and increased pear fruit yield by 7%. Piecewise structural equation modelling confirmed that increased natural enemy densities, decreased herbivore performance by 102%, pesticide use by 51% and increased fruit yield by 10%. This study suggests that the use of ground cover vegetations, especially with clover and hairy vetch, is an effective way of promoting biocontrol services and associated ecosystem services in pear orchards.

First report of Bihar hairy caterpillar, Spilarctia obliqua Walker (Lepidoptera: Erebidae), infesting sweet basil in India

The Bihar hairy caterpillar, Spilarctia obliqua, is a dreaded and sporadic pest on several cash crops in the Oriental region. The polyphagous feeding habit enables it to survive on a variety of crops. The group of hairy caterpillars of this study was found on young plants of the sweet basil. Young larvae feed gregariously on the under surface of the leaves later it feed solitary in nature. Damage symptoms, as skeletonization of the upper epidermis of the leaves, were observed. The identity of the pest species confirmed through morphological and molecular methods (No. MK491177). The phylogenetic analysis indicates the distribution of uniform populations of S. obliqua infesting soybean and sweet basil. The total life cycle was longest during winter (male, 68.67: female, 73.27 d) compared to Kharif season (male, 49.37; female, 53.74 d). The damage incidence ranged between 13.33–60% and 10–63.33% in 2018 and 2019, respectively. The natural enemy populations Glyptapanteles obliquae (11%) and Carcelia sp (17%) were recorded. This is the first report of S. obliqua on sweet basil, Ocimum basilicum, in India.

Effect of selected neonicotinoids on predatory coccinellids in Bt cotton ecosystem

With the introduction of Bt cotton in India during 2002, the production and productivity has increased considerably with the reduction in bollworm complex incidences. But, sucking insect pests became a menace that warranted spraying of chemical insecticides. These insecticides belonging different groups, adversely affected the population of natural enemies like coccinellids that played a vital role in naturally keeping the sucking insect pest population under control. Field studies were conducted in 2 villages viz., Mambattu and Salai in Tamilnadu during the years 2014 and 2015. Five neonicotinoids viz., imidacloprid 17.8 SL, acetamiprid 20 SP, thiacloprid 21.7 SC, thiamethoxam 25 WDG and clothianidin 50 WDG were tested alongside monocrotophos 36 SL and untreated control. At 1, 3, 7 and 14 days after treatment, monocrotophos recorded maximum population reduction of 78.8, 83.5, 70.4 and 62.6% respectively. Among neonicotinoids, clothionidin was found to be comparatively more toxic to coccinellids, followed by thiamethoxam and thiacloprid. Acetamiprid was found to be safest among chemical treatments with population reduction percentages of 45.6, 53.9, 36.5 and 24.7% respectively at 1, 3, 7 and 14 days after treatment followed by imidacloprid and thiacloprid. Two rounds of spray of neonicotinoids on Bt cotton had significant impact on the Coccinellids, when compared with untreated control plots. However, monocrotophos recorded relatively lowest population of coccinellids compared to untreated control and neonicotinoids. With significant population built-up after 7 days after acetamiprid and imidacloprid sprays, the 2 neonicotinoids may be suitable candidates for inclusion in integrated pest management of sucking insect pests in major Bt cotton growing areas as these insecticides are comparatively less toxic to predators as compared to broad spectrum neonicotinoids like thiacloprid, thiamethoxam and clothianidin and non-selective insecticide like monocrotophos.

Effect of flower identity and diversity on reducing aphid populations via natural enemy communities.

Floral plantings are often used in agriculture to attract pollinator communities, but they also play an important role in recruiting and establishing natural communities for natural pest control. Inconsistent effects of floral plantings for pest control may be a result of an absence of mechanistic insights and a reliance on the idea that simply increasing flower diversity will benefit these services. A more tailored set of flower species may be needed to benefit the natural enemies through provision of nectar and alternative prey. We used an outside pot experiment to investigate the effect of three flower plants (Fagopyrum esculentum, Vicia faba, and Trifolium pratense) on reducing aphid pests on four different plant cultivars of barley (Hordeum vulgare), over two years. We grew the four cultivars of barley alone, next to a single flower or next to a mixture of flowers, and observed aphid and natural enemy colonization across the growing season. Aphid population sizes were reduced on all barley cultivars grown next to a flower with stronger pest suppression when all flowers were present. Each flower species recruited a different community of non‐barley aphids that, in turn, varied in their ability to establish the natural enemy populations and subsequently the ability to reduce barley aphid populations. Overall, increased pest suppression in the mixed treatments was a result of numerous weaker interactions between different flower, aphid, and natural enemy species, rather than a few dominant interactions. Natural enemy communities could be enhanced by incorporating flower species that vary in their ability to attract and host alternative prey (i.e., non‐pest aphids) as well as suitable nectar provisioning. We can use our knowledge of ecological interactions to tailor floral plantings to increase the effectiveness of pest control services.

An entomopathogenic fungus and a natural extract benefit rice (Oryza sativa) by suppressing populations of insect pests while keeping high populations of their natural enemies

Sustainable and environmentally safe pest management often involves the use of natural enemies as an alternative to chemical means. For successful management of pests by natural enemies, a balanced population between insect pests and their natural enemies should be achieved. In this study, we compared such population balances in rice fields of Cambodia under the following conditions: no insecticide (NI), chemical pesticide-based conventional practice (CP), the use of a biopesticide (Beauveria bassiana, Bb), and the use of an orange oil extract (Oo). Treatment effects were evaluated by monitoring 17 species of insect pests and 15 species of natural enemies at two sites for two seasons. In the NI treatment, the level of natural enemies was the highest, however, the pest population density was also higher in this treatment than in the Bb and the Oo treatments, resulting in a low grain yield similar to that in the CP treatment notably in one trial. The Bb and the Oo treatments showed the lowest insect pest populations, although the Oo treatment had little impact on the populations of natural enemies. These results suggest that contributions of Bb and Oo treatments to decreasing pest populations were greater than those of the NI and the CP treatments, and that the Bb and the Oo treatments resulted in a favorable balance between populations of insect pests and their natural enemies. A high level of white earhead caused by stemborers resulted in significant yield losses in one trial. Among the four treatments in the trial, the Bb treatment resulted in the highest grain yield, and importantly, this treatment depressed the insect pest populations without much affecting the populations of their natural enemies. Overall, the results of this study suggest that the use of biopesticides in rice paddies is effective to keep the well-balanced population between insect pests and natural enemies by decreasing the serious pests such as stemborer and leaf folder that directly affect rice grain yields.

The Fitness of Mass Rearing Food on the Establishment of Chrysopa pallens in a Banker Plant System under Fluctuating Temperature Conditions.

Simple SummaryThe predatory lacewing, Chrysopa pallens, a generalist predator in the field, plays an important role in sustainable, integrated pest management strategies by allowing a reduction in the use of chemical pesticides. However, the effect of mass rearing food, i.e., eggs of the rice moth Corcyra cephalonica, on the establishment of C. pallens in a banker plant system in the field is unknown. Based on the age-stage, two-sex life table, and predation rate data of C. pallens ever cultured on the C. cephalonica eggs or the aphid Megoura japonica preying on Aphis craccivora under fluctuating temperature conditions in a greenhouse, we found that C. pallens could complete their development fed on A. craccivora regardless of the food used during culture. This suggests that rice moth eggs could be provided for the mass rearing of predatory lacewings without affecting their population development and biological performance in practical applications compared with lacewings cultured on aphids. This information can serve as a basis for the application of a banker plant system with the mass reared C. pallens in the field.Banker plant systems can be used to sustain a reproducing population of biological control agents (BCAs) within a crop, thus providing long-term pest suppression. The founder population of natural enemies in banker plant systems is usually mass-reared on factitious hosts. Thus, a better understanding of the population fitness and pest control performance of mass-reared BCAs in the field is crucial when developing integrated pest management (IPM) strategies. In this study, we determined the fitness of the generalist predator, Chrysopa pallens (Hemiptera: Chrysopidae) ever cultured on different food sources (i.e., mass rearing food, Corcyra cephalonica eggs, and aphid food, Megoura japonica) preying on Aphis craccivora in a banker plant system in a greenhouse based on Chi’s age-stage, two-sex life table analysis method. The life tables and predation rate parameters of C. pallens were not significantly different between both treatments under fluctuating temperature conditions. Corcyra cephalonica eggs did not significantly weaken the performances of C. pallens in a Vicia faba–A. craccivora banker plant system compared to aphids. In conclusion, C. cephalonica eggs can be used for the mass production of C. pallens as the founder population in a banker plant system. Moreover, linking the life table data with the predation rate is an effective strategy for evaluating mass rearing programs in establishing banker plant systems.

Pemantauan Keanekaragaman Hama dan Musuh Alami Tanaman Ubi Jalar dengan Pitfall Trap

The abundance of pest and natural enemy populations on a land can be given in the diversity and abundance of feeding sources and other available resources. The purpose of this study was to determine the diversity of pests and natural enemies of sweet potato plants. Research on land with three types of sweet potatoes, namely yellow sweet potatoes with narrow leaves, yellow sweet potatoes with broad leaves, and sweet potatoes with white leaves. Around the research area are long beans, papaya, guava, soursop, and durian. Sampling of pests and natural enemies by using a pitfall trap. The data analyzed was in the form of the Shannon-Weaver (H') diversity index. The index of pest diversity of the order Coleoptera on narrow-leaved yellow sweet potato, broad-leaved yellow sweet potato, and white sweet potato was 0,160; 0,1270; and 0,1300. The index of pest diversity of the order Orthoptera on narrow-leaved yellow sweet potato, broad-leaved yellow sweet potato, and white sweet potato was 0,3585; 0,3599; and 0,3632. The index of pest diversity of the order Hemiptera on narrow-leaved yellow sweet potato, broad-leaved yellow sweet potato, and white sweet potato was 0,0635; 0,0771; and 0,1300. Diversity index of natural enemies of the order Araneae on narrow-leaved yellow sweet potato, broad-leaved yellow sweet potato, and white sweet potato 0.2180; 0.3061; and 0.2705. The three sweet potato fields had a low diversity index.

Effect of Farming Systems on Diversity and Seasonal Abundance of Insect Pests and their Natural Enemiesin Cauliflower

A study was conducted on effect of two farming systems namely zero budget natural farming (ZBNF) and conventional farming (CF) on diversity and seasonal abundance of insect pests of cauliflower and their natural enemies during 2018-19 and 2019-20. Studies revealed that ZBNF system harboured less pest diversity and attracted more natural enemies as compared to the CF system. Natural enemy activity and % parasitisation were maximum in ZBNF system as compared to CF system. The results indicate that indigenous ZBNF formulations and intercropping have a positive effect on the population of natural enemies and repelled the insect pests much better as compared to CF system.

Control of cotton pests and diseases by intercropping: A review

Cotton (Gossypium hirsutum L.) is a globally important crop that is often damaged by pests and diseases. Current cotton pests and diseases management is dependent on chemical pesticides. Although chemical pesticides are usually effective, long-term application of these pesticides often leads to increased insecticide resistance in the pests, fewer natural enemies, reduced natural control, and a degraded environment. Because of increased environmental awareness and the need for sustainable cotton production, the control of cotton pests and diseases using biological means like intercropping is increasingly receiving attention. Intercropping of cotton with other crops can often boost the total yield and output of the intercropping system and provide significant economic benefits without sacrificing cotton quality. Intercropping also increases the number of natural enemies, and reduces the occurrence of cotton pests and diseases by altering the ecological structure and environmental conditions in the fields. Cotton-based intercropping is an effective strategy to reduce the competition between cotton and grain or other economic crops for arable land. It is also an important way to increase the populations of natural enemies in cotton fields for the management of pests and diseases. However, inappropriate intercropping can also increase labor requirements and even result in inadequate control of pests and diseases. This review focuses on the performance and the mechanisms of intercropping for reducing cotton pests and disease as well as on the effective management of intercropping systems. The risks and limitations, as well as the study approaches needed and the prospects of intercropping for the control of cotton pests and diseases, are also discussed. This information is intended to aid researchers and growers in designing economically viable and ecologically friendly pest and disease management strategies that will reduce the use of chemicals and the cost of cotton production.

Evaluation of biorational pesticides against Bemisia tabaci Gennadius and Amrasca biguttula biguttula Ishida and its impact on natural enemies population in cowpea ecosystem

The whitefly (Bemisia tabaci Gennadius) and leafhopper (Amrasca biguttula biguttula Ishida) are two major sucking pests causing considerable damage in cowpea production. Considering the negative impact of chemical pesticides on food safety, environment, and human welfare; an eco-friendly approach is aimed at utilizing naturally derived products for effective management of the aforesaid pests and maintain ecological balance. The present study was performed under field conditions to evaluate the performance of five naturally derived components [water plant extracts viz. chili (Capsicum annum), garlic (Allium sativum L.), and neem (Azadirachta indica A. Juss.) along with cow urine in three different combinations, two formulated entomopathogenic fungi (Metarrhizium anisopliae and Beauveria bassiana) along with one positive (Imidacloprid) and negative (water) control. The study was designed in RCBD with three replications for the years 2019 and 2020, respectively. Combined application of neem, chili, garlic, and cow urine extracts (NCGC) at 10% w/v had the highest population reduction of whitefly (0.09 & 0.10 per three leaves) and leafhopper (0.03 & 0.04 per three leaves) over both standard controls after two round of application in the year 2019 and 2020, respectively. Natural enemies (coccinellids) population was drastically reduced in positive control whereas the population build-up strengthened in all other treatments including negative control. Cowpea treated with NCGC produced a higher economic yield (1.54 Mg ha−1) than those of other treatments. The study suggests that NCGC is an effective biorational based technology for sustainable management of whitefly and leafhopper in cowpea cropping system with ensuring food safety and eco-friendly approach. This novel finding can be integrated with an integrated pest management program for diverse cropping systems.

Irrigated trap crops impact key hemipteran pests in organic pistachio orchard

Using sown groundcovers as trap crops to protect a cash crop is a traditional pest management tool. Pistachio is a major crop in California’s Central Valley, where high summer temperatures and little to no precipitation between May and November lead to summer dry-down of annual groundcover. Hemipteran pests that consist of ‘small bugs’ and ‘large bugs’ are a major contributor to nut damage, especially in organic production. In this 2-year field study, we tested the use of irrigated trap crop mixtures, sown between tree rows, to reduce those hemipteran pests’ abundance or damage. Biweekly beat samples of the tree canopy and sweep samples of the sown groundcovers in trap crop plots and resident weedy vegetation in control plots were taken over two consecutive growing seasons. Arthropod richness and abundance were highest in the groundcover and tree canopy in the trap crop plots. Small and large bug pest populations were higher and lower, respectively, in the tree canopy in trap crop plots, indicating a mixed response of these hemipterans to the presence of the trap crops. Additionally, natural enemy populations were more abundant in the tree canopy in trap crop plots than in control plots. There was no difference in nut damage between plots with and without the trap crop. These findings suggest that populations of hemipteran pests and beneficials can be manipulated successfully with irrigated trap crops, but future studies will need to focus on doing so in a way that decreases hemipteran pistachio damage.

Population Fluctuations of Diaphorina citri and Its Natural Enemies in Response to Various Management Practices in Florida

The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), is a serious threat to citrus production because it transmits the bacterium, Candidatus Liberibacter asiaticus Jagoueix (Hyphomicrobiales: Rhizobiaceae), that causes huanglongbing. Currently, there is no cure for huanglongbing, and vector management is implemented to reduce the spread of pathogen. In Florida, calendar-based insecticide application had been used widely for D. citri management, but the evolution of insecticide resistance in D. citri and associated reductions of natural enemy populations mandate more sustainable approaches. The objective of our study was to compare the effects of organic management versus intermittent use of conventional insecticides on population suppression of D. citri by natural enemies in Florida. We conducted a survey of natural enemies in citrus groves that were managed organically versus intermittently treated with conventional insecticides from Mar to Dec 2019. We also compared mortality of D. citri in those groves by deploying sentinel psyllids on leaf flush with or without exclusion cages. The abundance of natural enemies was recorded by visual observations made on tree branches for 2 min intervals. Finally, we estimated tree flush density and monitored adult D. citri populations. Survival of sentinel D. citri was significantly lower on uncaged flush when natural enemies had access to eggs and nymphs during spring, summer, and fall in organic groves; however, such a difference was not observed between caged and uncaged D. citri in intermittently sprayed groves, particularly during summer and fall. Similarly, organic sites had lower numbers of adult D. citri compared to intermittently sprayed sites throughout most of the sampling period, suggesting that natural enemies contributed to regulation of D. citri populations in organic groves more so than in the intermittently treated conventional groves. The most common natural enemies found were Coccinellidae, Chrysopidae, Formicidae, Eulophidae, Syrphidae, Dolichopodidae, and Arachnida. Among these groups, formicids were most abundant in organic groves, whereas dolichopodids and coccinellids were most abundant in intermittently managed groves. Our results suggest that intermittent spraying for D. citri with conventional insecticides could affect activity of natural enemies even though such practices did not entirely eliminate their populations.

Validation of IPM strategy in Bt cotton in whitefly (Bemisia tabaci) hot spot of North-West India

Bt cotton has witnessed the increasing infestation of sucking pests especially whitefly during last one decade. During 2015, whitefly (Bemisia tabaci Ishii) emerged as a serious pest in North India destroyed 2/3 of the cotton crop in Punjab. There was an urgent need to validate integrated pest management (IPM) strategy for management of whitefly in Bt cotton in hot spot area with farmer's participatory mode. To overcome the problem, ICAR-NCIPM initiated a trial on validation of IPM in cotton at Fazilka, Punjab in 2.5 ha during 2016, which was extended to 12 ha and 40 ha area in the year 2017 and 2018 respectively. The validated IPM strategy included timely sowing of recommended cotton hybrid, removal of weed as alternate host, proper plant nutrition along with foliar spray of 2% potassium nitrate, use of neem based pesticides, conservation of natural enemies by avoidance of insecticides which are harmful to natural enemies, and judicious use of safer pesticides. IPM implementation resulted in successful management of whitefly and other pests with significant increase in population of natural enemies predators along with significant reduction in the number of insecticides spray (>68%) and amount of active ingredients (>84%) in IPM fields as compared to FP (Farmer's practice) fields. IPM implementation also brought > 18% increase in yield, > 17% reduction in input cost and >90% increase in net profit compared to FP. The benefit-cost ratio in IPM was 2.55 against 1.88 in FP.

Effect of planting dates and recommended insecticides application on Earias insulana (Boisd.) and its associated predators in cotton field in Egypt.

Cotton crops are an important agricultural product in Egypt. However, the bollworm Earias insulana is a significant pest of cotton. Field experiment was carried out during the 2018 and 2019 seasons at Qaha Experimental Station, Qalyoubia governorate to determine the best dates for sowing cotton crops, to minimize E. insulana infestation and maintain high populations of the predators of spiny bollworm. The latest sowing date had a significantly lower infestation of squares, flowers and green bolls than the other two sowing dates. After spraying the three planting date plots with profenofos, lambda-cyhalothrin and methomyl insecticides, infestation of cotton bolls by spiny bollworm was significantly reduced in treated compared with untreated plots. A significant positive correlation (r = 0.829* and 0.827*) was found between the average temperature and E. insulana infestation of squares and flowers, respectively, for the first planting date and (r = 0.819*) in squares for the second planting date of untreated plots of season 2018. The explained variance percentages of multiple regression analysis showed that the effects of mean temperature and relative humidity (RH) on the third sowing date had a significantly lower infestation of squares, flowers and green bolls by spiny bollworm as compared to the first and second sowing dates. The populations of common natural enemies of E. insulana on cotton plants, i.e., Chrysoperla carnea, Coccinella undecimpunctata and spiders were counted during the two seasons. The correlation between the RH percentage and populations of the three predators was insignificantly positive during the 2018 season, while it was negatively or positively insignificant during the 2019 season. The correlation between the mean temperature and the populations of the three predators was insignificantly negative for C. carnea and positive for spiders during the 2018 season, whereas a positive correlation was found between temperature and C. carnea and spiders and a negative correlation between temperature and C. undecimpunctata during the 2019 season.

Efektivitas Pengendalian Penyakit Tungro secara Terpadu dengan Pendekatan Pengendalian Biointensif

<p>Tungro disease is one of the obstacles to increase the national rice production program. In some areas, this important disease is endemic. On the one hand, some farmers in controlling plant pests and diseases still use pesticides, which negatively impact health and the environment. On the other hand, environmentally friendly tungro disease control technology is available. This study aims to determine an environmentally friendly integrated control technique for tungro disease consisting of resistant varieties, biopesticides, and conservation of natural enemies with flowering plants in suppressing green leafhopper populations and the incidence of tungro transmission in infection-sensitive plant stage. The test area is located in Lanrang,Sidrap at the Experimental field of Tungro Disease Research Station, Lanrang Sidrap, South Sulawesi, Indonesia from April to September 2017, using a split-plot design. Main plots are: 1) Biointensive control plots, using flowering plants (refugia) and pest control with andrometa which is a mixture of the entomopathogenic fungus Metharizium anisopliae and sambiloto extract; 2) Conventional plots, without flowering plants and pest control using pesticides. As sub-plots are rice varieties: 1) TN1, 2) IR64, and 3) Inpari-9 Elo which differ in resistance to tungro. Observations were made at 2, 4, 6, and 8 weeks after planting (MST). The results showed that the population of green leafhoppers in the TN1, both in the bio-intensive control plot and in the conventional control plot, was higher than the other two varieties. The population of natural enemies in bio-intensive control consists of 10 predator families and the conventional control consists of 9 predator families. The effectiveness of bio-intensive control has an effect on decreasing the population of green leafhoppers and the diversity of natural enemies, and has no significant effect on the incidence of tungro transmission, and has no effect on grain yield. Therefore, biointensive control needs to be developed to create a pesticide-free agricultural environment.</p>

Indirect Effect of Pesticides on Insects and Other Arthropods.

Pesticides released to the environment can indirectly affect target and non-target species in ways that are often contrary to their intended use. Such indirect effects are mediated through direct impacts on other species or the physical environment and depend on ecological mechanisms and species interactions. Typical mechanisms are the release of herbivores from predation and release from competition among species with similar niches. Application of insecticides to agriculture often results in subsequent pest outbreaks due to the elimination of natural enemies. The loss of floristic diversity and food resources that result from herbicide applications can reduce populations of pollinators and natural enemies of crop pests. In aquatic ecosystems, insecticides and fungicides often induce algae blooms as the chemicals reduce grazing by zooplankton and benthic herbivores. Increases in periphyton biomass typically result in the replacement of arthropods with more tolerant species such as snails, worms and tadpoles. Fungicides and systemic insecticides also reduce nutrient recycling by impairing the ability of detritivorous arthropods. Residues of herbicides can reduce the biomass of macrophytes in ponds and wetlands, indirectly affecting the protection and breeding of predatory insects in that environment. The direct impacts of pesticides in the environment are therefore either amplified or compensated by their indirect effects.

​Effects of Genotypic Diversity on Insect-pests of Soybean

Background: Intercropping and mixed cropping based on two or more different crops have been widely used in Insect Pest Management to manage the population density of insect pests in various crops like maize with soybean, sorghum with soybean and sunflower with soybean. Genotypic diversity is the mixture or combination of various varieties/lines/genotypes of a crop. It decreases the insect-pests population by unfitness of crop to them due to intraspecific diversity such as mixture of susceptible and resistant varieties. Also, it increases the natural enemy population more due to longer period of flowering, availability of wide diverse food, more movement of herbivores etc. This concept has also been used successfully to manage insect-pests in maize, wheat and potato. In India, this connect is used in very small scale in crop. The objective of this study was to determine effects of genotypic diversity by comparing the population densities of major insect pests between monoculture of single variety and mixture of varieties. Methods: To test the effects of genotypic diversity on soybean insect-pest and their natural enemy population an experiment was laid in kharif 2018 and 2019 at the ICAR-Indian Institute of Soybean Research, Indore. All recommended agronomic package of practices were followed for raising of crop. Randomized block design with three replication having plot size of 9 rows of 5 meter row length was used. Totally 20 treatments were chosen for this experiment and out of 20 four treatments namely, T1, T6, T11 and T16 were the treatments of four varietal mixture treatments of almost similar maturity duration and agronomic traits and rest of treatments were of sole varietal treatments. Observations were made on insect-pests from 10 selected plants in each plot on three leaves selected at top, middle and lower portion of plant. Result: Effects of genotypic diversity in soybean revealed that for whitefly management T11 (NRC-86, JS-335, JS-2098 and RKS-45) was found most effective treatment. In case of mite, thrips and treehoppers management T1 (JS-9560, JS-20-34, MAUS-47 and MAUS-1460) was found most effective treatment. For leafhopper and mealy bug T6 (JS-9305, JS-2029, RVS-2001-4 and Dsb-28-3) was found most effective treatment. While for spittlebug T16 (NRC-37, JS-9752, RSC-1046 and RKS-113) was found most effective treatment. So, genotypic diverse treatments were found more effective than their respective sole varietal treatments.

Beneficial insects are associated with botanically rich margins with trees on small farms

Beneficial insect communities on farms are influenced by site- and landscape-level factors, with pollinator and natural enemy populations often associated with semi-natural habitat remnants. They provide ecosystem services essential for all agroecosystems. For smallholders, natural pest regulation may be the only affordable and available option to manage pests. We evaluated the beneficial insect community on smallholder bean farms (Phaseolus vulgaris L.) and its relationship with the plant communities in field margins, including margin trees that are not associated with forest fragments. Using traps, botanical surveys and transect walks, we analysed the relationship between the floral diversity/composition of naturally regenerating field margins, and the beneficial insect abundance/diversity on smallholder farms, and the relationship with crop yield. More flower visits by potential pollinators and increased natural enemy abundance measures in fields with higher plant, and particularly tree, species richness, and these fields also saw improved crop yields. Many of the flower visitors to beans and potential natural enemy guilds also made use of non-crop plants, including pesticidal and medicinal plant species. Selective encouragement of plants delivering multiple benefits to farms can contribute to an ecological intensification approach. However, caution must be employed, as many plants in these systems are introduced species.