Sublethal effects of anthranilic diamide insecticides on the demographic fitness and consumption rates of the Coccinella septempunctata (Coleoptera: Coccinellidae) fed on Aphis craccivora

Sublethal Effects of Chlorantraniliprole on the Mobility Patterns of Sitophilus spp.: Implications for Pest Management

Chlorantraniliprole, an anthranilic diamide insecticide, has emerged as a promising solution for controlling agricultural pests because of its low mammalian toxicity and selectivity towards non-target organisms. This study investigated the sublethal effects of chlorantraniliprole on the mobility behavior of two significant stored-product pests, Sitophilus oryzae (L.) and Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae). Contact toxicity assays revealed varying susceptibility levels between the two species, with S. zeamais showing higher sensitivity. Subsequent analysis of mobility behavior, both in the presence and absence of food, indicated significant differences between chlorantraniliprole-exposed and control groups. While S. oryzae exhibited altered locomotion patterns and a decreased number of food approaches at sublethal concentrations, S. zeamais displayed increased walking time and reduced immobility periods. These findings highlight the importance of considering sublethal effects in understanding the overall impact of chlorantraniliprole on stored-product pests. Further research into the long-term consequences of sublethal exposure is warranted to inform more effective pest management strategies in storage.

Sublethal acetamiprid affects reproduction, development and disrupts gene expression in Binodoxys communis

At present, understanding of neonicotinoid toxicity in arthropods remains limited. We here evaluated the lethal and sublethal effects of acetamiprid in F0 and F1 generations of Binodoxys communis using a range of sublethal concentrations. The 10% lethal concentration (LC10) and half lethal concentration (LC25) of ACE had negative effects on the B. communis survival rate, adult longevity, parasitism rate, and emergence rate, and significantly prolonged the duration of the developmental cycle. ACE also had intergenerational effects, with some biological indices affected in the F1 generation after pesticide exposure. Transcriptomic analysis demonstrated that differentially expressed genes were enriched in specific pathways including the amino acid metabolism, carbohydrate metabolism, energy metabolism, exogenous metabolism, signal transduction, and glutathione metabolism pathways. These results indicated strong contact toxicity of ACE to B. communis, which may inhibit their biological control capacity. These results improve our understanding of the toxicological mechanisms of parasitic natural enemies in response to insecticide exposure.

Impact of a glyphosate-based herbicide on the longevity, fertility, and transgenerational effects on Chrysopa pallens (Rambur) (Neuroptera: Chrysopidae)

Glyphosate-based herbicides (GBHs) are common herbicide formulations used in the field and are increasingly used worldwide with the widespread cultivation of herbicide-tolerant genetically modified crops. As a result, the risk of arthropod exposure to GBH is increasing rapidly. Chrysopa pallens (Rambur) (Neuroptera: Chrysopidae) is a common predatory natural enemy in agroecosystems, which is exposed to GBH (Roundup®) while preying on pests. To identify and characterize the potential effects of GBH on C. pallens, the life tables of C. pallens larvae and adults fed with GBH were constructed. Moreover, the effects of GBH treatment on the expression of genes involved in insulin signalling in adults were analyzed using qRT-PCR. The results showed that GBH treatment altered the pupal period and preadult stage of C. pallens larvae. However, it did no effect on longevity, fecundity, and population parameters and two insulin receptor genes (InR1, InR2), a serine/threonine kinase (Akt), an extracellular-signal-regulated kinase (erk), and vitellogenin (Vg1) expression of C. pallens. Adults feeding on GBH significantly altered development, longevity, and differences in the mean generation time of the F0 generation. However, GBH feeding only minimally influenced the growth and population parameters of the F1 generation. In addition, InR1, InR2, erk, and Vg1 expression in the F0 generation were downregulated on the fifth day of feeding on GBH. Furthermore, the expression levels of InR1, InR2, Akt, erk, and Vg1 in C. pallens decreased with the increase of GBH concentration, although the expression levels returned to control levels on the tenth day. Overall, the consumption of the GBH by larvae and adults of C. pallens had minimal effect on the growth and population parameters of C. pallens. The findings of this study can provide a reference for elucidating the environmental risks of GBH, guiding the optimal use of glyphosate in agricultural practices in the future.

Fitness effect and transcription profile reveal sublethal effect of nitenpyram on the predator Chrysopa pallens (Neuroptera: Chrysopidae)

Although neonicotinoids are widely used and important insecticide, there are growing concerns about their effect on nontarget insects and other organisms. Moreover, the effects of nitenpyram (NIT), a second generation of neonicotinoid insecticides, on Chrysopa pallens are still unclear. Therefore, this study purposed to investigate the acute toxicity of NIT to C. pallens using the spotting method. To examine the potential effects of a sublethal dose of NIT (LD30 , 1.85 ng of active ingredient per insect) on C. pallens, we constructed the life tables and analyzed the transcriptome data. The life table results showed that the period of second instar larvae, adult pre-oviposition period and total pre-oviposition period were significantly prolonged after exposure to sublethal dose of NIT, but had no significant effects on the other instars, longevity, oviposition days, and fecundity. The population parameters, including the preadult survival rate, gross reproduction rate, net reproductive rate, the intrinsic rate of increase, and finite rate of increase, were not significantly affected, and only the mean generation time was significantly prolonged by NIT. Transcriptome analysis showed that there were 68 differentially expressed genes (DEGs), including 50 upregulated genes and 18 downregulated genes. Moreover, 13 DEGs related to heat shock protein, nose resistant to fluoxetine protein 6, and prophenoloxidas were upregulated. This study showed the potential effects of sublethal doses of NIT on C. pallens and provided a theoretical reference for the comprehensive application of chemical and biological control in integrated pest management.

Assessment of the risk of imidaclothiz to the dominant aphid parasitoid Binodoxys communis (Hymenoptera: Braconidae)

The neonicotinoid of imidaclothiz insecticide with low resistance and high efficiency, has great potential for application in pest control in specifically cotton field. In this systematically evaluate the effects of sublethal doses of imidaclothiz (LC10: 11.48 mg/L; LC30: 28.03 mg/L) on the biology, transcriptome, and microbiome of Binodoxys communis, the predominant primary parasitic natural enemy of aphids. The findings indicated that imidaclothiz has significant deleterious effects on the survival rate, parasitic rate, and survival time of B. communis. Additionally, there was a marked reduction in the survival rate and survival time of the F1 generation, that is, the negative effect of imidaclothiz on B. communis was continuous and trans-generational. Transcriptome analysis revealed that imidaclothiz treatment elicited alterations in the expression of genes associated with energy and detoxification metabolism. In addition, 16S rRNA analysis revealed a significant increase in the relative abundance of Rhodococcus and Pantoea, which are associated with detoxification metabolism, due to imidaclothiz exposure. These findings provide evidence that B. communis may regulate gene expression in conjunction with symbiotic bacteria to enhance adaptation to imidaclothiz. Finally, this study precise evaluation of imidaclothiz's potential risk to B. communis and provides crucial theoretical support for increasing the assessment of imidaclothiz in integrated pest management.

Exposure to flupyradifurone affect health of biocontrol parasitoid Binodoxys communis (Hymenoptera: Braconidae) via disrupting detoxification metabolism and lipid synthesis

Assessing the potential effects of insecticides on beneficial biological control agents is key to facilitating the success of integrated pest management (IPM) approaches. Flupyradifurone (FPF) is a novel neonicotinoid insecticide that is replacing traditional neonicotinoids over a large geographical range to control pests. Binodoxys communis, is the dominant parasitic natural enemy of aphids. To date, no reports have addressed sublethal effects of FPF on B. communis. In this study, the lethal and sublethal effects of FPF on B. communis were investigated by indirect exposure to larvae and direct exposure to adults. Results showed that the sublethal LC₁₀ and LC₂₅ of FPF had negative effects on the biological parameters of B. communis, including significantly reducing survival rate, adult longevity, parasitism rate, and emergence rate, and significantly prolonging the developmental stages from egg to cocoons. In addition, we observed a transgenerational effect of FPF on the next generation (F1). RNA-Seq transcriptomic analysis identified a total of 1429 differentially expressed genes (DEGs) that were significantly changed between FPF-treated and control groups. These DEGs are mainly enriched in metabolic pathways such as peroxisomes, glutamate metabolism, carbon metabolism, fatty acid metabolism, and amino acid metabolism. This report is the first comprehensive evaluation of how FPF effects B. communis, which adds to the methods of assessing pesticide exposure in parasitic natural enemies. We speculate that the significant changes in pathways, especially those related to lipid synthesis, may be the reason for weakened parasitoid biocontrol ability. The present study provides new evidence for the toxic effects and environmental residue risk of FPF.

Toxicity and Sublethal Effects of Diamide Insecticides on Key Non-Target Natural Predators, the Larvae of Coccinella septempunctata L. (Coleoptera: Coccinellidae)

Coccinella septempunctata (ladybird) is an extremely important natural predator that feeds on aphids. An assessment of the toxicity of pesticides on environmental organisms is an essential component of Integrated Pest Management (IPM) strategies. This study evaluated diamide insecticides' toxicity at lethal and 30% lethal doses (LR₃₀) against C. septempunctata larvae. The pre-imaginal median lethal doses (LR₅₀) of chlorantraniliprole 10% SC, tetrachlorantraniliprole 10% SC, and broflanilide 10% SC were calculated to be 42.078, 289.516, and 0.0943 g active ingredient (a.i.)/ha, respectively. The mortality tests demonstrated that chlorantraniliprole and tetrachlorantraniliprole are comparatively less toxic to C. septempunctata than broflanilide, which were detected to be highly toxic to C. septempunctata. The mortality rates of the groups treated with the three diamide insecticides tended to stabilize after 96 h, extending to the pre-imaginal stage. Furthermore, when compared to broflanilide, which had a much higher potential risk, the hazard quotient (HQ) values indicated that chlorantraniliprole and tetrachlorantraniliprole have a lower risk potential for C. septempunctata in farmland and off farmland. The LR₃₀ dose induces abnormalities in the development phase 4th-instar larvae weight, pupal weight, and adult weight of treated C. septempunctata. The study emphasizes the importance of assessing the adverse effects of diamide insecticides on natural predator species that serve as biological control agents in agricultural IPM strategies.

Multiple factors mediate insecticide toxicity to a key predator for cotton insect pest management

Mortality of agricultural pests caused by arthropod predators is a valuable ecosystem service for crop production. The earwig, Euborellia annulipes (Lucas), attacks different pest species in various crop ecosystems, including larvae and pupae of the boll weevil, Anthonomus grandis grandis (Boh.). In this study, multiple factors were assessed to measure the selectivity of insecticides used against sap-sucking and chewing cotton pests for two E. annulipes populations. Nymphs and adults of E. annulipes were exposed to the insecticides in two ways: ingestion of contaminated prey, and contact with dried residues on either inert surfaces or treated plants bearing prey. Pymetrozine, chlorantraniliprole, and spinetoram had little effect on the predator regardless the tested earwig population, life stage with developmental time and survival, or the route of exposure (ingestion and residual). Cyantraniliprole dried-residue impeded nymph to complete development and only 27% of adults survived until 20 days after exposure. Pyriproxyfen was harmless through acute toxicity to nymphs and adult earwigs (70-100% survival 72 h after exposure), but prevented normal development of nymphs to adults causing chronic toxicity. Chlorfenapyr, indoxacarb, lambda-cyhalothrin, chlorpyrifos, dimethoate, and malathion were harmful to the predator regardless life stage or method of exposure. The negative impact of thiamethoxam, lambda-cyhalothrin and indoxacarb was diminished when exposure occurred on plants with predator allowed to shelter in the soil. The results indicate that insecticide selectivity outcome varies by the insecticide, predator life stage and the predator's behavior. Therefore, testing different predator life stages via several routes of exposure, without denying the insect the opportunity to engage in its normal behavior can provide better estimates of insecticide selectivity.

Survival, development and reproduction of Harmonia axyridis (Pallas, 1773) (Coleoptera: Coccinellidae) under effects of insecticides used in tomato plants

Agriculture depends on the correct use of different methods for pest control, however the cultivation methods adopted for Solanaceae demands numerous pesticide applications. These products can be either harmful or selective to beneficial organisms, such as Coccinellidae predators. The aim of this study was to assess the physiological selectivity of insecticides, registered for tomato pest control, on Harmonia axyridis (Pallas, 1773) (Coleoptera: Coccinellidae). The maximum recommended field dosage of the insecticides spinetoram, spiromesifen, methoxyfenozide, metaflumizone, tebufenozide and methomyl was used. They were sprayed on eggs, third instar larvae, pupae and adults of H. axyridis using Potter´s tower; control treatment consisted of water. Methoxyfenozide didn't reduce any biological feature of the predator. Spiromesifen only reduced survival over time when sprayed on third instar larvae. Spinetoram shortened larval period and reduced survival of adults. When sprayed on larvae, metaflumizone reduced larval survival. Tebufenozide reduced egg viability, pupal period and larval survival over time. It is concluded that methoxyfenozide, spiromesifen and spinetoram are the least toxic to H. axyridis, and their usage should be prioritized in integrated pest management (IPM) programs; both tebufenozide and metaflumizone are harmful to some important biological features of the predator. Methomyl is highly toxic in controlled conditions, so its toxicity to H. axyridis should be confirmed in field and greenhouse tests, we also suggest further studies with the other compounds in different concentration and route of exposure.

Transcriptomics and enzymology combined five gene expressions to reveal the responses of earthworms (Eisenia fetida) to the long-term exposure of cyantraniliprole in soil

Cyantraniliprole is a novel diamide insecticide that acts upon the ryanodine receptor (RyR) and has broad application prospects. Accordingly, it is very important to evaluate the toxicity of cyantraniliprole to earthworms (Eisenia fetida) because of their vital role in maintaining a healthy soil ecosystem. In this study, an experiment was set up, using four concentrations (0.1, 1, 5, and 10 mg/kg) and solvent control group (0 mg/kg), to investigate the ecotoxicity of cyantraniliprole to earthworms. Our results showed that, after 28 days of exposure to cyantraniliprole, both cocoon production and the number of juvenile earthworms had decreased significantly at concentrations of either 5 or 10 mg/kg. On day 14, we measured the activities of digestive enzymes and ion pumps in the intestinal tissues of earthworms. These results revealed that cyantraniliprole exposure caused intestinal damage in earthworm, specifically changes to its intestinal enzyme activity and calcium ion content. Cyantraniliprole could lead to proteins' carbonylation under the high-dose treatments (i.e., 5 mg/kg, 10 mg/kg). At the same time, we also found that cyantraniliprole can cause the abnormal expression of key functional genes (including HSP70, CAT, RYR, ANN, and CAM genes). Moreover, the transcriptomics data showed that exposure to cyantraniliprole would affect the synthesis of carbohydrates, proteins and lipids, as well as their absorption and transformation, while cyantraniliprole would also affect signal transduction. In general, high-dose exposure to cyantraniliprole causes reproductive toxicity, genotoxicity, and intestinal damage to earthworms.

Drivers of pesticide resistance in freshwater amphipods

Aquatic invertebrates exposed to pesticides may develop pesticide resistance. Based on a meta-analysis we revealed environmental factors driving the magnitude of resistance in the freshwater amphipod Gammarus pulex in the field. We showed that (i) insecticide tolerance of G. pulex increased with pesticide contamination in agricultural streams generally by a factor of up to 4. Tolerance increased even at concentrations lower than what is considered safe in regulatory risk assessment (ii) The increase in insecticide tolerance was pronounced at high test concentrations; comparing the LC50 of populations therefore potentially underestimates the development of resistance. (iii) Insecticide resistance in agricultural streams diminished during the spraying season, suggesting that adverse effects of sublethal concentrations in the short term contrast long-term adaptation to insecticide exposure. (iv) We found that resistance was especially high in populations characterized not only by high pesticide exposure, but also by large distance (>3.3 km) from non-polluted stream sections and by low species diversity within the invertebrate community. We conclude that the test concentration, the timing of measurement, distance to refuge areas and species diversity mediate the observed response of aquatic communities to pesticide pollution and need to be considered for the sustainable management of agricultural practices.