Degree of insecticide exposure and access to nectar impact survival of Trissolcus japonicus , a hymenopteran parasitoid, in flowering border strips

Impact of insecticide drift on aphids and their parasitoids: residual toxicity, persistence and recolonisation

Studies on resistance to insecticides in Tribolium castaneum (Herbst)—III. Selection of a strain resistant to lindane and its biological characteristics

Biological control of Halymorpha halys (Stål) (Hemiptera: Pentatomidae) in apple orchards versus corn fields and their adjacent woody habitats: High versus low pesticide-input agroecosystems

Conventional and alternative pre-harvest treatments affect the quality of ‘Golden delicious’ and ‘York’ apple fruit

Walking activity and dispersal on deltamethrin- and spinosad-treated grains by the maize weevil Sitophilus zeamais

The modified Mpp51Aa2 (previously Cry51Aa2.834_16) insecticidal crystal protein derived from Bacillus thuringiensis (Bt) protects against feeding damage caused by targeted hemipteran and thysanopteran pests, and was transformed in cotton to produce the MON 88702 cotton event. As part of an ecological risk assessment, we evaluated the relative impact of MON 88702 on the abundance of predatory Hemiptera, compared to a conventional control. Field trials were established in 2018 at six sites within cotton production regions of the U.S. Specific arthropod populations in MON 88702 and its conventional control (DP393), grown under different insecticide regimes within a randomized complete block design, were assessed at each field site. Arthropod samples were collected 10 times, starting at early squaring and weekly thereafter, over the course of the season at each site, using vertical beat sheets, sweep nets and visual counts. Across the sites, no significant differences were detected in abundance of predatory Hemiptera (Orius spp., Geocoris spp., Nabis spp., and Zelus spp.) between unsprayed MON 88702 and the unsprayed conventional control. In contrast, a broad-spectrum insecticide treatment significantly reduced the abundance of these and other taxa. Consistent with laboratory studies, the lack of differences between unsprayed MON 88702 and the unsprayed control indicates that the cultivation of MON 88702 is unlikely to adversely impact the predatory function associated with these beneficial Hemiptera in the cotton agro ecosystem.

Insecticide drift and its effect on Kampimodromus aberrans (Oudemans) in an Italian vineyard-hedgerow system

Insecticides can have consequences for beneficial arthropods. Insect parasitoids can contact insecticides through direct exposure spray droplets or residues on crop foliage. Here, we focus on better understand the response of Meteorus pulchricornis (Wesmael), a parasitoid wasp of lepidopteran pests, and its detoxification mechanisms on stress caused by phoxim and cypermethrin. Hence, we determined the dose–mortality curves and estimating the sublethal concentrations (LC30 and LC50). Then, we applied the sublethal concentrations against adult parasitoids to assess its survival, parasitism efficacy, and also developmental and morphometric parameters of their offspring. Simultaneously, we check the activities of glutathione S-transferase (GST), acetylcholinesterase (AChE), and peroxidase (POD) after sublethal exposure of both insecticides, which has measured until 48 h after treatment. Overall, phoxim and cypermethrin exhibited acute lethal activity toward the parasitoid with LC50 values 4.608 and 8.570 mg/liter, respectively. Also, we detect that LC30 was able to trigger the enzymatic activity of GST, AChE, and POD, suggesting a potential detoxification mechanism. However, even when subjected to sublethal exposure, our results indicate strong negatives effects, in particular for phoxim, which has affected the parasitism efficacy and also the developmental and morphometric parameters of M. pulchricornis offspring. Therefore, it can be concluded that both phoxim and cypermethrin have negative impacts on M. pulchricornis and we suggest cautioning their use and the need for semifield and field assessments to confirm such an impact.

Studies were conducted between 1993 and 1996 using 3 natural grape vine populations, 1 susceptible laboratory strain, and 1 resistant selected strain of Drosophila melanogaster L. In vitro monooxygenase activity (ethoxycoumarine-O-deethylation) (ECOD) was recorded from microsomal fractions of all strains. Results varied over a 6-fold range between susceptible laboratory Canton and resistant selected RDDT strains and over a 2-fold range between the Canton strain and natural populations of flies. Few significant variations of ECOD activity were detected among the natural populations despite many insecticide treatments, but activities were significantly correlated with toxicological tolerance to 5 of the 15 insecticides (deltamethrin, fipronil, chlorpyriphos ethyl, DDT, and diazinon). Moreover, immunoblotting responses of microsomal protein encoded by Cyp6A2 showed that the levels of expression were quantitatively correlated with toxicological tolerance to almost the same group of insecticides (deltamethrin, fipronil, chlorpyriphos ethyl, DDT, fenvalerate, and fenthion). However, the level of CYP6A2 expression in some natural strains (still weakly resistant) was almost comparable with one of the resistant strains. In vivo monooxygenase activity recorded in individual abdomens of flies showed that frequency distributions of ECOD activity in natural populations overlapped those of the resistant and laboratory strains, which were much narrower. Substantial and fast frequency changes (of the narrowness) that obtained in laboratory were related to either the time of rearing of 1 of the natural populations or selecting this population with an insecticide that has a toxicology correlated with both of the monooxygenase signs measured. Perspectives on using the CYP6A2 expression and ECOD activity for detecting a resistance mechanism by cytochrome P450 in field populations are discussed.

The alfalfa leafcutting bee, Megachile rotundata F. (Hymenoptera: Megachilidae), is one of the most intensively managed solitary bees and greatly contributes to alfalfa production in both the United States and Canada. Although production of certain commodities, especially alfalfa seed, has become increasingly dependent on this species' pollination proficiency, little information is known about how M. rotundata is affected by insecticide exposure. To better understand the risk posed to M. rotundata by the increasing use of insecticides to manage mosquitoes, we conducted field experiments that directly exposed M. rotundata nests, adults, and larvae to a pyrethroid insecticide via a ground-based ultra-low-volume (ULV) aerosol generator. We directly targeted nest shelters with Zenivex® E20 (etofenprox) at a half-maximum rate of 0.0032 kg/ha at dusk and then observed larval mortality, adult mortality, and the total number of completed nests for both the treated and control groups. There was no significant difference in the proportion of dead (P = 0.99) and alive (P = 0.23) larvae when the control group was compared with the treated group. We also did not observe a significant difference in the number of emerged adults reared from the treated shelters (P = 0.22 and 0.50 for females and males, respectively), and the number of completed cells after exposure to the insecticides continued to increase throughout the summer, indicating that provisioning adults were not affected by the insecticide treatment. The results from this study suggest that the amount of insecticide reaching nest shelters may not be sufficient to cause significant mortality.

Spodoptera frugiperda (fall armyworm) poses a substantial risk to crops worldwide, resulting in considerable economic damage. The gut microbiota of insects plays crucial roles in digestion, nutrition, immunity, growth and, sometimes, the degradation of insecticides. The current study examines the effect of synthetic insecticides on the gut microbiome of third instar S. frugiperda larvae using both culture-dependent techniques and 16S rRNA gene sequencing for bacterial community profiling and diversity analysis. In untreated larvae, the sequencing approach revealed a diverse microbiome dominated by the phyla Firmicutes, Proteobacteria and Bacteroidota, with key genera including Bacteroides, Faecalibacterium and Pelomonas. In parallel, 323 bacterial strains were isolated and assigned to the orders Bacillales, Burkholderiales, Enterobacterales, Flavobacteriales, Lactobacillales, Micrococcales, Neisseriaies, Pseudomonadales, Sphingobacteriales and Xanthomonadales. The prevailing culturable species included Serratia marcescens, Klebsiella variicola and Enterobacter quasiroggenkampii. Treatment with sublethal concentrations of three insecticides (broflanilide, spinosad and indoxacarb) caused significant changes in gut microbiome diversity and composition. Treated larvae showed a shift towards increased Proteobacteria abundance and decreased Firmicutes. Specifically, Acinetobacter and Rhodococcus were dominant in treated samples. Functional predictions highlighted significant metabolic versatility involving nutrient processing, immune response, detoxification, xenobiotic metabolism, and stress response, suggesting microbial adaptation to insecticide exposure. Network correlation analysis highlighted disrupted microbial interactions and altered community structures under insecticide treatment. These findings enhance our understanding of how insecticides impact the gut microbiota in S. frugiperda and may inform future strategies for managing pest resistance through microbiome-based approaches.

This study aims to investigate the toxicity effects of plant-based insecticides containing eugenol and azadirachtin on the immune system of Common Carp (Cyprinus carpio L.). Several immunological parameters, including white blood cell count, red blood cell count, stress response, and macroscopic clinical symptoms, were examined [1]. The study was conducted from September to October 2022 at the Ciparanje Inland Fisheries Hatchery, Faculty of Fisheries and Marine Sciences, Universitas Padjadjaran. This study employed a completely randomized design with six treatments and three replications. The observation period encompassed the measurement of red and white blood cell counts, stress response, and macroscopic clinical symptoms for the initial 14 days. Leukocyte and erythrocyte counts were assessed before and after insecticide exposure on days 3, 7, 10, and 14. Data analysis involved the utilization of quantitative descriptive analysis for red and white blood cell counts. Exposure to plant-based insecticides containing eugenol and azadirachtin resulted in a suppression of the immune system in common carp fry. However, the insecticide treatment with a concentration of 64 ppm (Treatment F) remained safe for common carp. The highest count of white blood cells was observed in Treatment F (64 ppm) on day 3, while the lowest count was recorded in Treatment A (control). Treatment A (control) also exhibited the highest count of red blood cells, whereas Treatment F (64 ppm) displayed the lowest count. Thus, plant-based insecticides with a concentration of 64 ppm can still be safely utilized in common carp.

Insects that infest postharvest commodities cause significant damage or destruction, costing billions of dollars in lost products yearly. Insecticide treatments applied as contact insecticides are effective in managing insect populations. However, recovery of the insects after exposure to these insecticides is increased if food is present, reducing the efficacy of surface treatments and leading to continued infestations. In addition, variation in temperature and humidity could play a significant role in recovery. Here, we assess the role of food, temperature, and humidity on the recovery of Tribolium castaneum Herbst, red flour beetle, after exposure to a contact insecticide. We found food is an important factor in recovery under different temperature and humidity conditions. While recovery was higher at warmer temperatures and higher humidities, recovery increased further when food was present versus absent. Moreover, we found that any amount of flour, even a dusting, resulted in over 90% of beetles recovering after insecticide exposure, but when sand was substituted for flour, recovery was 25% lower compared to a no food treatment. These results highlight the importance of how environmental factors and the availability of food influence efficacy of insecticide treatments. Sanitation in food facilities is critically important as even the smallest amount of food present can cause substantial recovery, allowing beetles to escape treated areas and move throughout facilities. Further work pinpointing variation in underlying recovery between different populations and among different insect species is needed to understand local adaptation potential.

Insecticide sprays and dusts are used for controlling bed bugs, Cimex lectularius L. In natural environments, bed bugs have daily access to hosts after they are exposed to insecticides. The established laboratory insecticide bioassay protocols do not provide feeding after insecticide treatments, which can result in inflated mortality compared with what would be encountered in the field. We evaluated the effect of posttreatment feeding on mortality of bed bugs treated with different insecticides. None of the insecticides tested had a significant effect on the amount of blood consumed and percent feeding. The effect of posttreatment feeding on bed bug mortality varied among different insecticides. Feeding significantly reduced mortality in bed bugs exposed to deltamethrin spray, an essential oil mixture (Bed Bug Fix) spray, and diatomaceous earth dust. Feeding increased the mean survival time for bed bugs treated with chlorfenapyr spray and a spray containing an essential oil mixture (Ecoraider), but did not affect the final mortality. First instars hatched from eggs treated with chlorfenapyr liquid spray had reduced feeding compared with nymphs hatched from nontreated eggs. Those nymphs hatched from eggs treated with chlorfenapyr liquid spray and successfully fed had reduced mortality and a higher mean survival time than those without feeding. We conclude that the availability of a bloodmeal after insecticide exposure has a significant effect on bed bug mortality. Protocols for insecticide efficacy testing should consider offering a bloodmeal to the treated bed bugs within 1 to 3 d after treatment.

Bemisia tabaci (Gennadius) is one of the most important invasive species in China, with strong insecticide resistance and thermotolerance. In this study, we investigated the effects of elevated temperature on the tolerance of B. tabaci MEMA1 to abamectin (AB) and thianethixam (TH) insecticides. We firstly cloned two new CYP450 genes from B. tabaci MEAM1, including one CYP6 family gene (BtCYP6k1) and one CYP305 family gene (BtCYP305a1). The expression patterns of the two BtCYP450 genes were compared in response to high-temperature stress and insecticide exposure, and RNAi was then used to demonstrate the role that these two genes play in insecticide tolerance. The results showed that expression of the two BtCYP450 genes could be induced by exposure to elevated temperature or insecticide, but this gene expression could be inhibited to a certain extent when insects were exposed to the combined effects of high temperature and insecticide treatment. For AB treatment, the expression of the two BtCYP450 genes reached the lowest level when insects were exposed to a temperature of 41 °C and treated with AB (combined effects of temperature and insecticide). In contrast, TH treatment showed a general decrease in the expression of the two BtCYP450 genes with exposure to elevated temperatures. These findings suggest that insecticide tolerance in B. tabaci MEAM1 could be mediated by high temperatures. This study provides a prospective method for the more effective application of insecticides for the control of B. tabaci in the field.