Insecticide Treatments Research Articles

Multifunctional coreid bug pheromones for efficient bioprotection against legume pests and enhanced food productivity

BackgroundIn Africa, food legumes such as cowpeas and beans constitute important sources of proteins for millions of rural and urban populations. However, attacks by multiple pest species can reduce yields by up to 80%. Small-holder farmers protect their crops against pests using conventional insecticides, thereby contributing to insecticide resistance and jeopardizing food safety. To date, no alternative sustainable practices are available to reduce insecticide use in the management of legume pests. This study aimed to provide a sustainable alternative to insecticide use based on semiochemicals to manage multiple legume pest species and enhance food productivity.ResultsUsing coupled gas chromatography-mass spectrometry (GC–MS) and coupled GC-electroantennographic detection (EAD) analyses, we identified 2-methylbutyl 2-methylbutanoate as the male-produced aggregation pheromone of the legume pest, Clavigralla elongata, a coreid bug species specific to East Africa. In multi-site field trials conducted in West Africa and East Africa, 2-methylbutyl 2-methylbutanoate and its analogue, isopentyl butanoate, previously identified from the pan-tropical coreid bug, C. tomentosicollis, both lured multiple legume insect pest species including from the Clavigralla genus, the legume pod-borer Maruca vitrata, flower thrips Megalurothrips sjostedti, and whitefly Bemisia tabaci into traps. Additionally, both pheromones lured the Clavigralla natural enemy parasitoid Gryon fulviventris into traps. The whitefly was only captured in pheromone-baited traps in East Africa. Deployment of an optimized pheromone trapping system significantly reduced legume pests and increased natural enemy density by up to sixfold compared to farmer practice (insecticide-treatment) and control. Legume yields for pheromone and insecticide treatments were comparable, ~ 320–590% higher than untreated controls.ConclusionThese findings establish coreid bug pheromones as effective novel multifunctional semiochemical-based tools for sustainable legume pest management and production without insecticide use.Graphical abstract

Field Bio Efficiency of Insect Growth Regulators and Insecticides against Pod Fly, Melanagromyza obtusa in Pigeonpea (Cajanus cajan, L.)

The present study on the bio efficacy of insect growth regulators and insecticides on pod fly was carried out during kharif 2021 in pigeonpea using Co 7 variety. An experiment was laid out using a randomized block design (RBD) with seven treatments and three replications. Insecticidal treatments consisted of four insect growth regulators and two insecticides along with untreated check and applications were made twice. Among the seven treatments tested, T4: Flubendiamide 480 SC @ 30 g a.i. ha-1 proved to be effective in reducing pod fly population (3.67 No/25 pods). The other treatments tested were found to be on par except T1: Buprofezin 25 SC @ 200 g a.i. ha-1 treated plots (6.33 Nos), whereas untreated check reported with 14.67 Nos at 14 DAS. At the same time, pod damage was also calculated and the lowest pod damage was recorded in T4: Flubendiamide 480 SC @ 30 g a.i. ha-1 and T5: Lufenuron 5.4 EC @ 30 g a.i. ha-1 treated plots and were significantly superior over other treatments and found to be on par with each other with 10.00 and 11.33 per cent, respectively. At two applications of treatments also, T4: Flubendiamide 480 SC @ 30 g a.i. ha-1 treated plots was superior over other treatments and recorded 3.15 Nos per 25 pods with 3.72 and 11.88 per cent pod and seed damage, respectively. After two applications of T4: Flubendiamide 480 SC @ 30 g a.i. ha-1 the pod fly damage reduction was upto 80.1 per cent and other treatments reported the damage between 42.2 – 78.0 per cent over untreated check. The highest yield was reported in plots treated with T4: Flubendiamide 480 SC @ 30 g a.i. ha-1 for its highest grain yield of 757.7 kg ha-1 with 43.2 per cent increase over untreated check. The other treated plots reported between 478.3 - 680.0 kg of grain yield ha-1 with 10.82-75.56 per cent increase over untreated check. The highest Benefit: Cost ratio was obtained in the plots treated with T4: Flubendiamide 480 SC @ 30 g a.i. ha-1 (1:1.6) and other treatments reported between 1:1.0 – 1:1.4 whereas untreated plots reported with lowest benefit cost ratio of 1:0.9.

Nanoformulation of imidacloprid insecticide with biocompatible materials and its ecological and physiological effects on wheat green aphid, Schizaphis graminum Rondani

Nanoformulation of imidacloprid was prepared using the biocompatible polymer of polyethylene glycol (PEG). TEM image showed that the spherical nanoparticles were 50–150 nm. The lethal concntrationof 30 percent (LC30) and 50 percent (LC50) of the insecticide and its nanoformulation studied on adult female aphids were 21.46 and 58.56 mg a.i./L for pure insecticide, and 3.79 and 4.94 mg a.i./L for nanoformulated insecticide, respectively. The results of the sublethal effect test (LC30) of this insecticide showed that nymphal developmental in nanoimidacloprid (5.55 days) was higher than control (4.22 days). The results showed that the insecticide treatments significantly reduced the demographic characteristics of Schizaphis graminum. The intrinsic rates of increase (r) values of aphids in control, insecticide treatment and its nanoformulation were 0.421, 0.315 and 0.29, respectively. The results of evaluating the effect of the studied insecticide on the specific activity of beta-esterase and glutathione S-transferase showed that there was no significant difference in the activity of this enzymes between the control and the insecticide treatment and its nanoformulation. Based on the obtained results, it can be concluded that after conducting additional tests, the insecticide nanoformulation can be used due to its effectiveness in lower concentrations in the management of sucking pests such as aphids.

Managing Emerald ash borer in urban Forests: Integrating biocontrol and insecticide treatments

Ash trees (Fraxinus spp.) were commonly planted street trees in urban environments prior to the arrival of emerald ash borer (EAB), Agrilus planipennis Fairmaire, in the 1990 s and its subsequent impacts. Insecticide treatments can provide consistent control of EAB and are used to protect high-value trees; however, control only lasts a few years before reapplication is needed. An EAB biological control program seeks to provide long-term control and several parasitoids have been released to that end, including the larval parasitoids Tetrastichus planipennisi Yang (Eulophidae) and Spathius galinae Belokobylskij (Braconidae). In 2015, we released parasitoids in three cities (Syracuse NY, Naperville IL, Boulder CO) while city arborists were simultaneously treating high-value street trees with insecticides. We hypothesized parasitoids would be able to establish on EAB in untreated trees and spread throughout the cities while treated trees remained healthy. We also hypothesized EAB densities would fall as non-treated ash died and would not subsequently rebound as insecticide treatments were removed from street trees due to the parasitism of biocontrol agents. Three-hundred trees were selected for monitoring in each city: 100 untreated, 100 treated, and 100 temporarily treated. Tetrastichus planipennisi successfully established in all three cities, while S. galinae established in Syracuse and Boulder. Untreated trees rapidly declined as expected while treated trees remained healthy. During the study subsets of trees were removed from the treatment cycle as EAB densities fell (≤ 10 larvae/m2). Minor canopy decline was present in 2021–2023 in trees from which treatment was removed, with median crown classes declining from 1 to 2. Despite this shift, most of these trees remained un-infested (∼ 75 %) and retained healthy canopies. Trees that did become infested had high apparent parasitism and low EAB densities. Due to the high value of urban trees, we recommend managers continue monitoring trees and consider selectively reinstating insecticide treatments on trees that start to decline and/or are subject to additional urban stressors.

Evaluating the agronomic and economic benefit of including spinosad with and without pyrethroid insecticides in bermudagrass stem maggot treatments

AbstractThe bermudagrass stem maggot (BSM; Atherigona reversura Villeneuve) is known to have a detrimental effect on bermudagrass (Cynodon spp.). Currently, two strategically timed pyrethroid applications are recommended for BSM suppression in each harvest cycle. However, producers are interested in applying spinosad because of its residual effects for other insects or reducing the number of pyrethroid applications to cut input costs. Therefore, the objective of this study was to determine the agronomic and economic implications of one or multiple pyrethroid (zeta‐cypermethrin) and/or spinosad applications on ‘Alicia’ and ‘Tifton 85’ bermudagrasses. Generally, zeta‐cypermethrin treatments resulted in a greater herbage accumulation compared to the untreated control in both cultivars. Regardless of cultivar, spinosad only treatments did not improve upon the herbage accumulation observed in the untreated control. Crude protein and total digestible nutrients were not affected by insecticide treatments in either cultivar. Finally, two zeta‐cypermethrin applications resulted in greater net profit compared to other insecticide treatments. These data illustrate that there is not yet an alternative for two pyrethroid applications for BSM suppression. Ongoing research and breeding efforts are focused on BSM tolerance and reduced pyrethroid usage to prevent resistance to the insecticide.

Direct and indirect effects of selective insecticides on 2 generalist predators of Bemisia tabaci (Hemiptera: Aleyrodidae).

Generalist arthropod predators have historically contributed to the suppression of arthropod pests in many agroecosystems. The successful implementation of integrated pest management (IPM) programs hinges on the incorporation of insecticides that are compatible with the biological attributes of natural enemies of pests. A potentially promising pathway is improving biological control by natural enemies through the timely application of selective insecticides. In our study, adult predators were exposed to commercially available insecticides (cyantraniliprole and pyriproxyfen) using a combined laboratory and field approach to assess their effects on survivorship and predation. We isolated 2 predators, Hippodamia convergens Guérin-Méneville and Geocoris punctipes (Say), in the laboratory to estimate the survivorship and consumption of whitefly nymphs, Bemisia tabaci (Gennadius). In the field, we deployed whitefly nymph-infested potted cotton plants in replicated cotton plots with both insecticide treatments. We enumerated whitefly nymph populations on enclosed (predator-exclusion) and open (predator-accessible) potted plants. While pyriproxyfen had a negligible effect on the predators, cyantraniliprole exposure directly affected H. convergence by reducing survivorship duration and indirectly influenced both predators by reducing prey consumption and altering the consumption of alternative prey. In field conditions, regardless of pesticide exposure, whitefly-infested potted plants that excluded predators had more whiteflies than predator-accessible potted plants. Overall, pyriproxyfen demonstrated minimal impact on the predators in the laboratory or field, while cyantraniliprole adversely influenced mortality and indirect foraging under controlled laboratory conditions but did not have a significant impact in the field.

Seroprevalence and associated risk factors for Trypanosoma evansi infection in equine in North of Egypt

This study determined the seroprevalence of Trypanosoma evansi infection and its associated risk factors in 200 equines across four Egyptian governorates based on CATT/T. evansi. Serological testing revealed T. evansi antibodies in 34.5% of the examined animals, exhibiting notable discrepancies among different governorates. Dakahlia exhibited the highest seroprevalence at 42.4%, while the lowest seroprevalence rate (12.5%) was reported in Gharbia. No significant differences were observed in seroprevalence among age groups or equine species. The multivariate regression analysis model identified pivotal risk factors, wherein the presence of flies increasing infection odds threefold and animals lacking routine insecticide treatment having four times higher odds of infection. Equines in poor health condition displayed double the odds of infection. Surprisingly, a history of venereal disease increased the odds of T. evansi infection. Notably, there were no substantial differences in infection rates based on the disposal of used syringes or prior mange history. These findings provide essential insights into the transmission patterns of T. evansi. Gaining a comprehensive understanding of these identified risk factors is crucial for developing effective methods to reduce the prevalence of T. evansi in populations of equids.

Impact of triflumezopyrim (insecticide) on blood and serum biochemistry of freshwater fish, subadult Labeo rohita (Hamilton, 1822)

The impact of insecticides on water bodies can be evaluated by studying the physiology and health of fish. These chemicals pose a significant and direct risk to aquatic ecosystems and hence aquatic animals like fish. Therefore, this study was designed to investigate the toxic effects of sub-lethal concentrations of triflumezopyrim, a novel synthetic insecticide commonly used in crop protection, on the biochemical and hematological parameters of freshwater sub-adult Labeo rohita L. Here, fish were subjected to sub-lethal doses of triflumezopyrim at various concentrations (1.41 ppm, 3.27 ppm, and 4.97 ppm) for 21 days. In addition, fish were grown in an insecticide-free control group to determine the toxic effects of the insecticides. The obtained data on various biochemical and hematological parameters of the fish were analyzed using state-of-the-art statistics. Our findings suggest that triflumezopyrim exposure has a significant effect on blood variables. However, variable response, such as mean corpuscular volume, hemoglobin concentration, neutrophils, and eosinophils were unaffected by insecticide treatment, regardless of the dose. Our interhematological parameter analysis revealed varying interrelationships at various insecticide doses. Similarly, triflumezopyrim exposure significantly affected the response of serum biomarker profiles i.e., the difference in mean treatment pairs (control and three doses of triflumezopyrim) had a significant effect on the response of most serum profile parameters.For example, cholesterol response was inversely related to serological markers, including total protein, alanine aminotransferase, and aspartate aminotransferase, under triflumezopyrim exposure. The relationship pattern and grouping dynamics of the blood and serum parameters changed drastically under various insecticide doses according to correlation and cluster analyses. Our results showed that repeated exposure of fish to various sub-lethal concentrations of triflumezopyrim negatively affected their physiology and serology, which is highly harmful to the organism.

Population Dynamic of Aphis gossypii, and Their Parasitoids, and Effect of Some Insecticides on Aphids, Chlorophyll Content, Non-Enzymatic and Antioxidant Enzymes Activity in Cantaloupe Leaves in Greenhouses

Under green house, the Population density of Aphis gossypii on cantaloupe plants recorded two peaks on May 9th and 23th with 1409 and 1561 individuals/ 10 leaves in season 2022, while one highest peak, on 16th May with 1650 individuals/ 10 leaves in season 2023. Parasitism status of Aphidius colemani and Lysiphlebus fabarum varied from 1.49% on 25 April to 35.79% on 9th of May with seasonal parasitism 2023 in 2022 and ranged between 0.73% on 25th of April and 30.06% on 16th of May with seasonal parasitism 16.57% in 2023. Acetamiprid, imidacloprid, imidacloprid + abamectin, jojoba oil, orange oil and thiamethoxam + abamectin compounds were tested to control aphids during two seasons. Imidacloprid recorded the highest reduction with all average 97.88 ±1.15 and 97.39 ±1.15 in the first and second season respectively. the highest mean reduction of emergence of the two-parasites caused by thiamethoxam + abamectin by 16.92% followed by Imidacloprid with 16.87%. While the least toxicity to emergence of the parasitoids recorded with jojoba oil 0.0% followed by orange oil 1.93% in season 2022, while in season 2023, the higher parasitoid reduction caused by acetamiprid 18.05% followed by Imidacloprid 17.69% and thiamethoxam + abamectin 17.53%. Chlorophyll content increased with treatment jojoba oil followed by Imidacloprid by 47.91 and 44.73 unit in the first season and Thiamethoxam with abamectin lead to the highest content by 44.05 unit in the leaves followed by jojoba oil with 43.65 unit. The least treatment was Imidacloprid + abamectin with 39.55 unit compared with control treatment 40.43 unit. Treatment Thiamethoxam + abamectin recorded the highest content of carbohydrates (48.43) compared with control (47.71). Treatments of insecticides led to increase of protein, fats and total lipid compared with control. Also, Antioxidant enzymes activity in cantaloupe leaves were found to be increased in the treatment of insecticides compared with control.

Incremental Cost Benefit Ratio (ICBR) of Poly House and Open Field Conditions in Cabbage (Brassica oleracea var. capitata) after Chemical Intervention

This study evaluates the Incremental Cost Benefit Ratio (ICBR) between Poly house and Open field conditions in cabbage cultivation chemical intervention. The research aimed to compare the economic feasibility of adopting poly house technology over traditional open field methods, considering costs and benefits associated with chemical inputs. A comparative cost analysis was conducted to assess production expenses like costs for insecticidal treatments and labor charges. Yield data from both environments were collected to determine output differences and subsequent economic returns. Results indicate that Incremental cost benefit ratio of cabbage heads yields to the cost of treatments in poly house and open field presented as there was a significant superior difference in ICBR ratio of poly house with 1: 0.946 as compared to open field with 1: 0.639 of cabbage heads. The economic analysis revealed that the higher yields and quality achieved in poly house conditions due to less dissipation and undisturbed environmental factors on insecticide applied. Resulting in a favorable incremental Cost benefit ratio compared to open field cultivation.

Enhancing pest management - Utilizing supplementary food spray to harness predatory insects against fall armyworm in maize crop of Vinh Phuc Province, Vietnam

The effect of supplementary food spray on the fall armyworm (Spodoptera frugiperda) and beneficial insects (predominantly predatory insects) was studied in commercial maize field experiments from 2020 to 2022. The food spray formulation was developed from local ingredients in Vietnam, both with and without neem extract. The sugar-based rice dough product attracted and sustained beneficial insects, significantly reducing fall armyworm populations. Compared to conventional insecticide treatments, the net margin achieved in plots treated with food spray was higher ($3,467) to $3,394 in the conventional insecticide-treated plots demonstrating its economic viability (1 AUD=17.28 VND). Our study observed an average predator-to-prey ratio of 9.2:1 per plant in the food-spray-treated plots, and that was effective in managing the fall armyworm throughout the season. We propose that this ratio can serve as a valuable parameter and decisionmaking tool in food spray-based Integrated Pest Management (IPM) programs against fall armyworm in maize fields. Therefore, we suggest that food sprays can be incorporated into IPM strategies to successfully manage fall armyworm infestation in maize crop.

Comparative Study of the Efficacy of Two Biological Insecticides (Azadirachta indica and Bacillus thuringiensis) and a Chemical insecticide (Diflubenzuron WP) against Fall Armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae) in Maize Crop, Western Bur

Aims: This study aimed at comparing the biological efficacy of Diflubenzuron WP, a chemical insecticide, and two biopesticides, one based on neem oil (Azadirachta indica) and an entomopathogen (Bacillus thuringiensis) against the fall armyworm on maize. Place and Duration of Study: The work was carried out on the irrigated scheme of Bama, western Burkina Faso during the 2022 and 2023 wet seasons. Methodology: The experimental design was a Fisher block with 4 treatments: T0: untreated or control; T1: Bacillus thuringiensis; T2: neem oil; T3: Diflubenzuron WP, in 4 replications. Entomological observations focused on the score and severity of attacks, as well as the pest's infestations rate. Results: The results showed that the different insecticides tested over the two wet seasons of 2022 and 2023 induced better control of S. frugiperda populations, with larval density being kept lower with the treatment of Diflubenzuron WP (4.25±1.2%), neem oil (14.28±1.6%) and Bacillus thuringiensis (24.5±3.2%). The insect damage severity rates and scores of damaged ears were also low for the three treatments respectively (1.09±0.2, 0.9±0.26 and 0.27±0.71) over the two cropping seasons. Diflubenzuron WP insecticide treatment not only reduced pest pressure, but also significantly improved maize yield. No surprisingly the highest yield (5.14 t/ha) was recorded with Diflubenzuron WP, followed by neem oil (4.62kg/ha) and finally Bacillus thuringiensis (3.92kg/ha). Conclusion: Further studies are needed to determine the optimal doses of neem oil and Bt for the control of Fall Armyworm. Neem oil can be considered as a good alternative to a chemical insecticide like Diflubenzuron WP.

Efficacy of selected insecticide sprays against Indian meal moth (Lepidoptera: Pyralidae) wandering larvae on various surfaces

The Indian meal moth, Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae), is a worldwide pest found in food product warehouses. Presence of P. interpunctella wandering larvae causes customer complaints and product rejection from customers. Its prepupal stage is susceptible to insecticide treatment due to their wandering behavior. We evaluated the efficacy of three insecticide sprays, ExciteR (0.017% pyrethrins, 0.174% piperonyl butoxide), Suspend SC (0.053% deltamethrin), and Transport Mikron (0.047% acetamiprid, 0.056% bifenthrin) against P. interpunctella wandering larvae by forced exposure to porous (vinyl tile, unpainted pinewood, concrete, and paper) and non-porous (steel, glazed ceramic) surfaces, and exposure to treated harborages made of two pieces of vinyl tiles, unpainted pinewood, and concrete. Under continuous exposure conditions, both ExciteR and Suspend SC caused significantly higher mortality (90–96%) than Transport Mikron (73–75%) on non-porous surfaces after 4 days (P < 0.05). But on porous surfaces, the three insecticides caused ≤63% mortality with Suspend SC being the most effective. When using 2× amount of insecticides as that in the previous test (2.1 gallon/1000 ft2, which is 4.33, 1.20, and 2.33 mg a.i./m2 of ExciteR, Suspend SC, and Transport Mikron, respectively), Suspend SC was the only insecticide causing high mortality (≥99%) through both forced exposure to concrete surface and exposure to treated concrete harborage. Whereas other treatments caused <12% mortality. Among the porous surfaces, residual efficacy of Suspend SC on concrete was significantly higher than that on vinyl tiles. Application of an effective liquid insecticide (such as 0.053% deltamethrin) into harborages or directly to the possible pupation sites, such as corners, cracks, and crevices could be an effective strategy for managing P. interpunctella wandering larvae in warehouse environment.

Thrips (Thysanoptera: Thripidae) in citrus nursery: Seasonal incidence, damage and insecticide treatments to reduce infestation

Thrips (Thysanoptera: Thripidae) in citrus nursery: Seasonal incidence, damage and insecticide treatments to reduce infestation

Impact of insecticides on natural enemies of planthoppers in direct seeded rice

In the kharif season of 2020, a field experiment was conducted at the Agricultural College Farm, Bapatla to evaluate the impact of some insecticides in combination with the neem products on natural enemies of planthoppers such as green miridbug, Cyrtorhinus lividipennis (Reuter) and spider Lycosa pseudoannulata (Boesenberg and Strand) and Tetragnatha maxillosa (Thorell) in direct seeded rice (DSR). The results concerning the influence of insecticidal treatments, on natural predators such as miridbugs and spiders revealed that neem formulation 1500ppm @ 5ml l-1 with 6.13 miridbugs/hill and 8.83 spiders/10 hills h were at par with the untreated control showing no adverse effects on the predators of rice planthoppers. Among the other treatments, dinotefuran 20SG @ 40g a.i. ha-1 has recorded lowest number of natural predators with 2.77 miridbugs/hill and 5.17 spiders/10 hills, followed by triflumezopyrim 10.6SC @ 25g a.i. ha-1 with 2.93 miridbugs/hill and 5.27 spiders/10 hills; Pymetrozine 50WG @ 150g a.i. ha-1 with 3.07 miridbugs/hill and 5.50 spiders/10 hills which differed significantly from the untreated control.

Multigenerational hormetic effects of different insecticides on Spodoptera frugiperda (J.E. smith) (Lepidoptera: Noctuidae)

To protect crops from pest insects, farmers continuously use insecticides, which eventually degrade into residue due to abiotic or biotic factors. These residual effects of pesticides may cause low lethal and/or sublethal impacts on the exposed pest insect populations, leading to the induction of pest resurgence through hormesis and ultimately the development of resistance. Hormesis is a beneficial bi-phasic effect generally characterized by low-dose reproductive stimulation and high-dose inhibition. In the present study, we investigated the impact of low lethal and sublethal concentrations (LC10, LC20, and LC30) of spinetoram, chlorantraniliprole, and thiodicarb on the F0 generation as well as their multigenerational hormesis effects on the F1 and F2 generations of Fall Armyworm (FAW), Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae). The study focused on reproductive parameters, fecundity, fertility, and life index parameters such as net reproductive rate (R0), intrinsic rate of increase (rm), finite rate of increase (λ), mean length of generation (Tc), and gross reproductive rate (GRR). Fecundity of S. frugiperda increased by 4.82%, 4.63% and 4.58%, while eggs fertility improved by 7.77%, 6.78% and 6.52% at LC10 of thiodicarb, chlorantraniliprole and spinetoram, respectively, from the F1 to F2 generation. Further, interaction analysis (Concentration × Insecticidal treatments) revealed that important vital parameters like pre-oviposition period (POP), oviposition period (OP), post-oviposition period (PtOP), R0,rm,λ, Tc and GRR of F0 were negatively impacted by LC30 of all the tested insecticides and LC20 of only spinetoram. However, LC10 of any of the tested insecticides did not affect these parameters when compared with control. Furthermore, interactive analysis in multigenerational exposure experiments (Concentration × Insecticidal treatments × Generation(s)) showed hermetic effects of LC10 of all tested insecticides which is more positive in F2 as compared to F1 generation. These unwanted positive hermetic effects of low lethal concentrations (LC10) of tested insecticides in offspring of exposed parental population of S. frugiperda indicated its resistance and/or resurgence. Furthernore, present study emphasizes the necessity for additional research to elucidate the underlying mechanisms responsible for these effects.

Insecticide and low food quality treatments reduce health and pollination services of two key pollinator taxa

Abstract Pesticides and the lack of floral resources are key drivers of insect decline in agricultural areas. Both land‐use stressors can have a variety of synergistic and sublethal effects on pollinators, affecting their health and foraging behaviour. Pollinating insects include species with vastly different life histories, giving them potentially different vulnerability and resilience to stressors. However, most research has generally focused on bees. Here, we contrast synergistic effects of nutritional stress and pesticide use on social bumblebees and solitary hoverflies. We experimentally tested the effects of the neonicotinoid acetamiprid and low‐quality food on health traits of Bombus terrestris workers and Episyrphus balteatus adults (ovarian development, body size and colony development or survival). The foraging behaviour of treated pollinators was recorded in a semi‐field setup and, for B. terrestris, we measured the pollen amount on the body surface and the pollen deposited on stigmata after a single floral visit. Both stressors affected bumblebee health. Additionally, insecticide‐treated workers showed increased flower handling times and flight durations, while low‐quality food reduced the amount of pollen on the surface of bumblebees and the pollen deposited on stigmata. Syrphids were mostly affected by low‐quality food, which decreased their survival probability and changed their foraging behaviour. Furthermore, we found an interactive effect between the two stressors, reducing E. balteatus ovary development. Synthesis and applications. Insecticide and food stress affected fitness traits of both bumblebees and syrphid flies, possibly reducing pollinator populations under natural conditions. Especially for bumblebees, long‐term exposure led to a reduction in the provision of pollination services, both by changing their behaviour and reducing pollen transfer. We found differences between the two pollinator groups, showing that results gained from single groups like bees should not be extrapolated to all pollinators. Interactive effects indicate potential buffering effects of high‐quality food against other stressors and highlight the importance of considering synergies between multiple stressors in risk assessments. This further emphasizes the relevance of floral resources such as wild flower strips in agricultural areas to conserve pollinators and pollination services.

Species Sensitivity Distribution (SSD) profiles towards λ-cyhalothrin for key ecosystem service provider (ESP) species across five European countries representing different pedoclimatic zones

Although our understanding of the dramatic worldwide loss of biodiversity in recent decades is far from adequate, one of the main factors in areas dominated by agriculture is undoubtedly the widespread use of synthetic pesticides. Unfortunately, the ecological risk assessment (EcoRA) for pesticides is based on a few single-species bioassays which do not allow for the evaluation of risks to whole communities. Here we present the results of an experimental assessment of the risk to the ecosystem service provider (ESP) communities – pest control agents – from exposure to the commonly used pyrethroid insecticide, λ-cyhalothrin. The study was performed in five European countries (Germany, Poland, Portugal, Spain, United Kingdom) representing different pedoclimatic zones. Representatives of the most common species of the ESP communities in each country were exposed in a standardized insecticide-coated glass vials bioassay to five doses of λ-cyhalothrin: 0.8 %, 4 %, 20 %, 100 %, and 200 % of the recommended field dose (RFD) plus an untreated control. Based on the calculated LD50s, species sensitivity distributions (SSDs) were estimated for each country and on combined data. In all five countries, the estimated hazardous concentration for 5 % of the species (HD5) was between 0.23 % and 1.67 % RFD, with HD5 = 0.44 % RFD based on combined data. At the RFD = 7.5 g a.i./ha (active ingredient per hectare), the predicted affected fraction of the ESP communities was between 96.4 % and 99.9 % of the species (98.5 % for combined data). The results indicate an extremely high risk to ESP communities across Europe associated with the use of λ-cyhalothrin at the recommended doses when these species are exposed to insecticide treatment. We recommend that EcoRA should include multi-species approaches, such as SSD, to better protect entire ESP communities from the negative impacts of pesticides.

Flupyradifurone application: A promising approach to curtail tomato leaf curl New Delhi virus (ToLCNDV) transmission vectored by Bemisia tabaci in potato farming

The whitefly, Bemisia tabaci, serves as a carrier and transmitter of the tomato leaf curl New Delhi virus (ToLCNDV) in potatoes, leading to the emergence of potato apical leaf curl disease. Among the six insecticides tested against B. tabaci, flupyradifurone resulted in the highest mortality of nymphs and adults. Three effective insecticides were then further evaluated for their ability to prevent the acquisition and transmission of ToLCNDV by B. tabaci. Utilizing qPCR techniques, we determined the amount of virus acquired by B. tabaci from virus-positive plants that had undergone prior insecticide treatment. The results revealed a significant reduction in virus levels in the whitefly's body, flupyradifurone was found to be most effective among the tested insecticides in reducing ToLCNDV acquisition. Flupyradifurone also exhibited the highest efficacy in reducing ToLCNDV transmission by B. tabaci. Experiments conducted in the glasshouse 24 h post insecticide application demonstrated the complete prevention of ToLCNDV transmission in all plants treated with flupyradifurone. In the field experiment also, flupyradifurone effectively suppressed whitefly-mediated ToLCNDV transmission for up to 14 days following insecticide application. The findings indicate that the use of flupyradifurone has the potential to manage the vector population and control associated viral disease, which is known to cause significant losses in potato crops.

Field Efficacy of Insecticides for Management of Lepidopteran Pests in Cashew

Efficacy of different insecticides against lepidopteran pests of cashew were tested at Dr. YSRHU- Cashew Research Station, Bapatla, AICRP on Cashew during 2015-16 to 2021-22. Among the insecticides lamda-cyhalothrin 5 EC @ 0.6 ml/l was found effective in managing the foliage and floral pests such as, leaf and blossom webber, leaf miner, shoot tip caterpillar, apple and nut borer followed by Dr. YSR Horticultural University package of practices (POP) i.e. monocrotophos 36 SL @ 1.6 ml/l during the flushing stage, chlorpyrifos 20 EC @ 2.0 ml/l during the flowering stage and profenophos 50 EC @ 1.0 ml/l during the apple and nut development stage. Further, the spider population was observed to be highest in untreated check and Beauveria bassiana treatments compared to insecticidal treatments.