Life table study of the effects of sublethal concentrations of thiamethoxam on Bradysia odoriphaga Yang and Zhang

Bradysia odoriphaga Yang and Zhang (chive gnat) is the major insect pest affecting Chinese chive in Northern China. In order to explore the integrated control of B. odoriphaga, sublethal effects of the neonicotinoid insecticide thiamethoxam were studied. The standard contact and stomach bioassay method was used to assess the effects of sublethal (LC5 and LC20) concentrations of thiamethoxam on the demographic parameters of B. odoriphaga, and data were interpreted based on the age-stage, two-sex life table theory. After thiamethoxam treatment, the intrinsic and finite rates of increase, net reproduction rate, survival rate, and reproductive value were all markedly decreased, while the mean generation time, total preovipositional period, and larval and pupal duration were prolonged, compared with controls. The intrinsic rates of increase dropped from 0.1775/day to 0.1502-0.1136/day. Following LC5 and LC20 treatments, net reproduction rate dropped from 61.75 offspring/individual (control) to 43.36 and 20.75 offspring/individual, respectively. Sublethal concentrations of thiamethoxam decreased the developmental rate of laboratory populations of B. odoriphaga, suggesting that such doses may be useful in integrated pest management strategies.

An investigation of the impact of triclosan adaptation on Proteus mirabilis clinical isolates from an Egyptian university hospital

Antibiotic resistance is a main threat to the public health. It is established that the overuse and misuse of antibiotics are highly contributing to antibiotic resistance. However, the impact of nonantibiotic antimicrobial agents like biocides on antibiotic resistance is currently investigated and studied. Triclosan (TCS) is a broad-spectrum antibacterial agent widely used as antiseptic and disinfectant. In this study, we aimed to evaluate the effect of exposure of Proteus mirabilis clinical isolates to sublethal concentrations of TCS on their antibiotic susceptibility, membrane characteristics, efflux activity, morphology, and lipid profile. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of TCS were determined for 31 P. mirabilis clinical isolates. The tested isolates were adapted to increasing sublethal concentrations of TCS. The MICs of 16 antibiotics were determined before and after adaptation. Membrane characteristics, efflux activity, ultrastructure, and lipid profile of the tested isolates were examined before and after adaptation. Most adapted P. mirabilis isolates showed increased antibiotic resistance, lower membrane integrity, lower outer and inner membrane permeability, and higher membrane depolarization. Nonsignificant change in membrane potential and lipid profile was found in adapted cells. Various morphological changes and enhanced efflux activity was noticed after adaptation. The findings of the current study suggest that the extensive usage of TCS at sublethal concentrations could contribute to the emergence of antibiotic resistance in P. mirabilis clinical isolates. TCS could induce changes in the bacterial membrane properties and increase the efflux activity and in turn decrease its susceptibility to antibiotics which would represent a public health risk.

Toxicity and sublethal effects of sulfoxaflor on the red imported fire ant, Solenopsis invicta

To understand whether sulfoxaflor, a novel neonicotinoid, poses unacceptable risks to the environment, it is important to assess its effects on nontarget insects. Therefore, the effects of short-term exposure (28 days) of free-feeding sublethal concentrations (1-2μg/ml) of sulfoxaflor to the red imported fire ant, Solenopsis invicta, were investigated. The following parameters were evaluated to determine the impact of exposure: colony growth, food consumption (sugar water and locusts), and interspecific interactions. Sulfoxaflor exposure produced significant negative effects on S. invicta colony growth, with cumulative colony weight losses of 83.36% and 100.00% after treatment with 1μg/ml and 2μg/ml, respectively. The consumption of sugar water (containing sulfoxaflor) of surviving colonies decreased with increasing sulfoxaflor concentration. Moreover, the consumption of locusts decreased after treatment with 2μg/ml, but not 1μg/ml, sulfoxaflor. Sulfoxaflor treatment for 14 days led to reduced aggressiveness of S. invicta workers in interspecific confrontations (S. invicta vs. unexposed Pheidole fervida), and their probability of survival of aggressive encounters was reduced significantly to 48% of that of control ants. Our results indicate that sublethal concentrations of sulfoxaflor are likely to have a negative impact on ants.

Ecotoxicological effects of the insecticide fipronil in Brazilian native stingless bees Melipona scutellaris (Apidae: Meliponini)

Melipona scutellaris Latreille, 1811 (Hymenoptera, Apidae) is a pollinator of various native and cultivated plants. Because of the expansion of agriculture and the need to ensure pest control, the use of insecticides such as fipronil (FP) has increased. This study aimed to evaluate the effects of sublethal doses of FP insecticide on M. scutellaris at different time intervals (6, 12, and 24 h) after exposure, via individually analyzed behavioral biomarkers (locomotor activity, behavioral change) as well as the effect of FP on different brain structures of bees (mushroom bodies, antennal cells, and optic cells), using sub-individual cell biomarkers (heterochromatin dispersion, total nuclear and heterochromatic volume). Forager bees were collected when they were returning to the nest and were exposed to three different concentrations of FP (0.40, 0.040, and 0.0040 ng a.i/bee) by topical application. The results revealed a reduction in the mean velocity, lethargy, motor difficulty, paralysis, and hyperexcitation in all groups of bees treated with FP. A modification of the heterochromatic dispersion pattern and changes in the total volume of the nucleus and heterochromatin were also observed in the mushroom bodies (6, 12, and 24 h of exposure) and antennal lobes (6 and 12 h) of bees exposed to 0.0040 ng a.i/bee (LD_50/100). FP is toxic to M. scutellaris and impairs the essential functions required for the foraging activity.

Sublethal effects of beta-cypermethrin modulate interspecific interactions between specialist and generalist aphid species on soybean

In agroecosystems, plant-pest interactions are at the basis of complex food webs, which can be affected by both biotic and abiotic factors. In the present study, we evaluated the impact of the insecticide beta-cypermethrin on interspecific interactions between the specialist aphid Aphis glycines and the generalist aphid Aulacorthum solani on soybean. Aphis glycines showed higher fecundity than A. solani on soybean and the aphids caused unbalanced reduction in population growth on each other. A sublethal concentration of beta-cypermethrin (LC5 for A. glycines) stimulated the reproduction of A. glycines but it did not impact the fecundity of A. solani. However, the LC5 of beta-cypermethrin enhanced the interspecific inhibition of fecundity between the two aphid species. Moreover, the two species showed different spatial distribution on soybean seedlings. Aphis glycines mainly aggregated on the stem of soybean plant while A. solani colonized soybean leaves. The LC5 of beta-cypermethrin drove A. solani migrating from soybean leaves to stems independently of interspecific competition. Aphis glycines facilitated A. solani colonization on soybean plant through impacting host susceptibility, and vice versa. Nevertheless, such facilitated colonization-induced susceptibility could be modulated through exposure to the LC5 of beta-cypermethrin. These findings hinted that the pyrethroid insecticide beta-cypermethrin has the potential to mediate the interspecific competition between specialist and generalist aphids (at the sublethal concentration of LC5), and that it could influence aphid population growth and community structure in soybean crops. This knowledge could contribute to rationalize application of insecticides and to optimize Integrated Pest Management in soybean.

Single and mixed exposure to cadmium and mercury in Drosophila melanogaster: Molecular responses and impact on post-embryonic development

Heavy metals, like many other chemical elements, are naturally present in the environment; however, the concentrations of these metals in various environmental matrices have increased through their intensive use in many human activities (such as industry, mining and agriculture). Among the heavy metals, cadmium (Cd) and mercury (Hg) induce a wide variety of defects in animals. While the effects of these heavy metals have been widely documented, a single exposure paradigm is typically used. Few studies have focused on evaluating combined exposure to these metals. However, in the environment, animals are confronted with a plethora of substances simultaneously; thus, the presence and origin of such substances must be determined to reduce the sources of contamination. Using the model of the fruit fly Drosophila melanogaster, for which many tools are readily available, we investigated how different concentrations of Cd and Hg in single and combined exposures impact post-embryonic development. In parallel, we evaluated the extended expression pattern of 38 molecular targets used as potential biomarkers of exposure through qPCR. Our results showed that both metals caused developmental delays and mortality in dose-dependent responses. Both metals were able to deregulate genes involved in hormonal control, general stress, and oxidative stress. Importantly, we confirmed synergistic interactions between Cd and Hg. Our results indicate the importance of assessing several biomarkers and their kinetics in mixtures. Drosophila represents a useful model for monitoring the toxicity of substances in polluted environments.

Application of transcriptomic analysis to unveil the toxicity mechanisms of fall armyworm response after exposure to sublethal chlorantraniliprole

The anthranilic diamide insecticide chlorantraniliprole is highly effective against Lepidoptera pests, but the underlying mechanisms of toxic effects of chlorantraniliprole exposures for adapting to the chemical environment are poorly known in fall armyworm (FAW), Spodoptera frugiperda (J.E.Smith). FAW being one of the most pests of maize in Latin America, suddenly appeared in China in 2019 and spread rapidly. In this study, using bioassay and transcriptomic and biochemical analyses, we comprehensively investigated gene expression changes of third instar larvae in response to different sublethal concentrations (LC10 and LC30) of chlorantraniliprole in this insect. Exposure to LC10 chlorantraniliprole (0.73 mg/L) causes 1266 differentially expressed genes (DEGs), of which 578 are up-regulated and 688 down-regulated. Exposure to LC30 (2.49 mg/L) causes differential expression of 3637 DEGs (1545 up-, 2092 down-regulated). Interestingly, the LC30 treatment led to a significant increase in the number of DEGs compared to that of the LC10, indicating a concentration effect manner. Moreover, enrichment analysis identified important DEGs belonging to specific categories, such as amino acid, carbohydrate, lipid, energy, xenobiotics metabolisms, signal transduction, and posttranslational modification pathways, and enzymes activities in enriched pathways were significantly altered at the LC10 and LC30, which matched transcriptome analysis to mediate toxic mechanisms. The DEGs encoding detoxification-related genes were identified and validated by quantitative real-time PCR (qRT-PCR), which correlated with the RNA-sequencing (RNA-seq) data. To our knowledge, these findings provide the first toxicity mechanisms for a better understanding of chlorantraniliprole action and detoxification in FAW and other insect pests at molecular level.

Co3O4 nanoparticles at sublethal concentrations inhibit cell growth by impairing mitochondrial function

Co₃O₄ nanoparticles (NPs) are one kind of the important nanomaterials that have the application potential in catalyst, electrochromic devices, sensors, etc. However, their biological effect remains to be detailed. In this study, we investigated the effect of the as-synthesized Co₃O₄ NPs (15-30 nm) on the growth of mammalian cells, and found that the NPs severely inhibited cell growth at the sublethal concentrations from 12.5 to 200 mg/L. Interestingly, the NPs did not cause obvious cell death and ROS accumulation, indicating that their inhibitory effect was not attributed to both apoptosis- or necrosis-related cell death and ROS accumulation. Transcription profiling analysis revealed that the NPs caused remarkable down regulation of the genes involved in mitochondrial functions. Transmission electron microscopy (TEM) and biochemical analysis further showed that the NPs might interact with the mitochondria, impairing the mitochondrial membrane potential (MMP) and ATP production. This study uncovers a mitochondrial respiratory chain-related and ROS-independent toxicity mechanism of Co₃O₄ NPs in eukaryotic cells.

Direct and delayed effects of exposure to a sublethal concentration of the insecticide λ-cyhalothrin on food consumption and reproduction of a leaf beetle

Anthropogenic pollution such as the application of pesticides poses a major threat to many (non-target) organisms. However, little is known about the persistence of harmful effects or potential recovery in response to a period of exposure to a sublethal insecticide dose. Adults of the mustard leaf beetle, Phaedon cochleariae (Coleoptera: Chrysomelidae), were either exposed to a sublethal concentration of the pyrethroid λ-cyhalothrin for two weeks or kept unexposed as control. During, immediately after and at a delayed time after the exposure, consumption and reproduction, i.e., number of eggs laid and hatching success, were assessed. In addition, long-term effects on unexposed offspring were investigated. Exposure to λ-cyhalothrin reduced the consumption during the insecticide exposure, but led to compensatory feeding in females at a delayed time after exposure. The reproductive output of females was impaired during and directly after λ-cyhalothrin exposure. At the delayed time point there was no clear evidence for a recovery, as the reproduction of heavier females was still negatively affected, while lighter females showed an enhanced reproduction. Persistent negative effects on unexposed offspring had been found when collected from parents directly after a λ-cyhalothrin exposure period. In contrast, in the present experiment neither negative effects on life-history traits nor on consumption were observed in unexposed offspring derived from parents at the delayed time after λ-cyhalothrin exposure. Moreover, eggs of offspring from insecticide-exposed parents showed a higher hatching success than those of offspring of unexposed parents, which may indicate transgenerational hormesis. Our results highlight that λ-cyhalothrin exposure has persistent negative effects on fitness parameters of the exposed generation. However, offspring may not be harmed if their parents had sufficient time to recover after such an insecticide exposure. Taken together, our study emphasises that the time-course of exposure to this anthropogenic pollution is crucial when determining the consequences on life-history.

Sublethal and hormesis effects of beta-cypermethrin on the biology, life table parameters and reproductive potential of soybean aphid Aphis glycines

Beta-cypermethrin has long been recommended as an effective pesticide to control the soybean aphid, Aphis glycines Matsumura, a serious pest in soybean crops. Besides acute toxicity, it leads to changes in life history traits of A. glycines, notably its reproductive potential. This study has assessed the effects of five sublethal concentrations (0.625, 1.25, 2.5, 5 and 10 µg/L) of beta-cypermethrin on different life history traits of A. glycines. Exposure to these concentrations caused shorter oviposition period and reduced adult longevity. The strongest stimulatory effect on aphid reproduction was achieved when exposed to a higher sublethal beta-cypermethrin concentration (5 µg/L). Net reproduction rate (R 0 ), intrinsic rate of increase (r m ) and finite rate of increase (λ) were significantly higher than that of the control, increasing by 20.58, 4.89 and 2.06%, respectively. We found no significant difference in mean generation time (T) between the treatment of 5 µg/L beta-cypermethrin and the control. However, when the concentration increased to 10 µg/L, the reproduction behavior was restrained and the mean generation time (T) was shortened, resulting in significant decrease in R 0 and T by 16.58 and 3.83%, respectively. In conclusion, a sublethal concentration (5 µg/L) of beta-cypermethrin triggered the strongest hormesis on A.glycines, thus providing valuable knowledge on the sublethal effects of this insecticide on soybean aphids. Hormesis may be one of the mechanisms underlying pest resurgences, and better knowledge would enable a more effective use of insecticides in Integrated Pest Management programs.

Fate of silver nanoparticles in constructed wetlands and its influence on performance and microbiome in the ecosystems after a 450-day exposure

Great controversy still exists on the ecological effects of silver nanoparticles (AgNPs) especially at relatively low concentrations. The performance, fate of AgNPs and microbiome in CWs were evaluated under a long-term exposure to AgNPs (0, 50 and 200 µg/L) for 450 days. Results showed that AgNPs (50, 200 µg/L) caused no obviously negative effects on COD removal whereas nitrogen and phosphorus removals were slightly stimulated. AgNPs could be removed efficiently from wastewater attributed to the accumulations of soil and plant tissues. Mass balance of AgNPs was analysed and soil layer of CWs was the major sink of nanoparticles. High-throughput sequencing further revealed the impact of AgNPs on the ecological structure of CWs. Moreover, the presence of AgNPs altered the relative abundances of key functional bacteria. The ecological risks of persistent exposure to low concentrations AgNPs should not be ignored, even though it did not result in deterioration of the CWs' operating performance in our studies.

Transcriptomic identification and characterization of genes commonly responding to sublethal concentrations of six different insecticides in the common fruit fly, Drosophila melanogaster

Pretreatment with sublethal concentrations (LC₁₀) of six insecticides (chlorantraniliprole, cypermethrin, dinotefuran, indoxacarb, ivermectin, and spinosad) significantly elevated tolerance of the common fruit fly Drosophila melanogaster to lethal concentration of the respective insecticide. Commonly responding genes to sublethal treatments of the six insecticides were identified by transcriptome analysis based on a fold change >1.5 or < -1.5, and p < 0.05 as selection criteria. Following treatment with all the six insecticides, 26 transcripts were commonly over-transcribed, whereas 30 transcripts were commonly under-transcribed. Reliability of the transcriptome data was confirmed by quantitative PCR. A majority of the over-transcribed genes included those related to olfactory behavior, such as odorant-binding proteins, as well as immune-related genes, including attacin, diptericin, and immune-induced molecule 18. In contrast, genes belonging to the mitochondrial respiratory chain, such as mitochondrial NADH-ubiquinone oxidoreductase chain 1/3/4/5 and mitochondrial cytochrome b/c, were commonly under-transcribed. Furthermore, genes related to eggshell formation and motion were also under-transcribed, which may indicate a possible energy trade-off for xenobiotic stress. In summary, most of the differentially expressed genes were not directly related to well-known detoxification genes, suggesting that the roles of commonly expressed tolerance-related genes are not likely related to direct metabolic detoxification, but rather are associated with restoration of homeostasis.

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.

Sublethal toxicity of sulfoxaflor to parasitoid Binodoxys communis Gahan

Integrated pest management is focused on combining biological and chemical controls. There is evidence of a negative impact of neonicotinoids on biological control, however, sulfoxaflor (SFX), a novel insecticide, its impact on parasitoid natural predator remain limited. Binodoxys communis is an important parasitic natural enemy of Aphis gossypii, which may have direct and indirect toxicity from the insecticides and aphids. Understanding the potential threat of SFX to B. communis is therefore essential to integrated pest management and the conservation of parasitoids. Here, the effects of sublethal doses of SFX on B. communis larvae and adults are presented for the first time. Sublethal SFX doses had a significant negative effect on the survival rate, adult life span, duration of development, and rate of parasitism. Moreover, exposure to sublethal SFX doses also had adverse effects on the biological performance of the next generation of B. communis. Based on the transcriptome analysis, the expression of genes involved in fatty acid metabolism, glycerolipid metabolism, glycerophospholipid metabolism, peroxidase, lysosomes, glutathione metabolism, drug metabolism, and CYP450 were significantly shifted by sublethal SFX exposure. These results indicate that sublethal SFX doses might adversely affect the biological performance of B. communis by altering gene expression related to the function of detoxification systems and energy metabolism. In conclusion, considering the beneficial ecological services of provided by parasitoids and the negative effects of sulfoxaflor across a greater usage scale, we emphasize the importance to optimize pesticide applications in IPM packages, in order to ensure the safety and survival of natural pest parasitoids.

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.

Life history and physiological responses of native and invasive brine shrimps exposed to zinc

Although a substantial amount of research exists on pollution and biological invasions, there is a paucity of understanding of how both factors interact. Most studies show that pollution favours the establishment of invasive species, but pollution may also promote local adaptation of native species and prevent the establishment of new incomers. However, evidence for this is extremely limited because most studies focus on successful invasions and very few on cases where an invasion has been resisted. Here we provide evidence of local adaptation of native species to pollution combining life history and physiological data. We focused on the invasion of the North American brine shrimp Artemia franciscana, which is causing a dramatic biodiversity loss in hypersaline ecosystems worldwide, and one of the last native Artemia populations in SW Europe (A. parthenogenetica from the historically polluted Odiel estuary, SW Spain). Life table response experiments were carried out in the laboratory to compare the demographic responses of A. parthenogenetica and a nearby A. franciscana population to long-term Zn exposure (0.2 mg L^-1). We also evaluated oxidative stress by measuring antioxidant defences (catalase, glutathione reductase and superoxide dismutase) and lipid peroxidation (thiobarbituric acid reactive substances). A high concentration of Zn induced strong mortality in A. franciscana, which also showed high levels of lipid peroxidation, suggesting relatively poor physiological resistance to pollution compared with A. parthenogenetica. The age at maturity was shorter in A. parthenogenetica, which may be an adaptation to the naturally high mortality rate observed in the Odiel population. Exposure to Zn accelerated age at first reproduction in A. franciscana but not in A. parthenogenetica. In contrast, Zn had a stimulatory effect on offspring production in A. parthenogenetica,which also showed higher reproductive parameters (number of broods, total offspring and offspring per brood) than A. franciscana. Overall, the results of this study strongly suggest that native Artemia from Odiel estuary is locally adapted (at both, reproductive and physiological levels) to Zn contamination and that A. franciscana is highly sensitive. This is a good example of how pollution may play a role in the persistence of the last native Artemia populations in the Mediterranean.

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.

Effects of sublethal fipronil exposure on cross-generational functional responses and gene expression in Binodoxys communis

The effective systemic insecticide fipronil is widely used on a variety of crops and in public spaces to control insect pests. Binodoxys communis (Gahan) (Hymenoptera: Braconidae) is the dominant natural enemy of Aphis gossypii Glover (Homoptera: Aphididae), an important cotton pest, and has good efficiency in inhibiting aphid populations. The direct effects of environmental residues of sublethal fipronil doses on adult B. communis have not previously been reported. This study therefore aimed to evaluate the side effects and transcriptomic impacts of sublethal fipronil doses on B. communis. The results showed that exposure to the LC10 dose of fipronil significantly reduced the survival rate and parasitism rate of the F0 generation, but did not affect these indicators in the F1 generation. The LC25 dose did not affect the survival or parasitic rates of the F0 generation, but did significantly reduce the survival rate of F1 generation parasitoids. These results indicated that sublethal doses of fipronil affected B. communis population growth. Transcriptome analysis showed that differentially expressed genes (DEGs) in B. communis at 1 h after treatment were primarily enriched in pathways associated with fatty acid elongation, biosynthesis of fatty acids, and fatty acid metabolism. DEGs at 3 days after treatment were mainly enriched in ribosomal functions, glycolysis/gluconeogenesis, and tyrosine metabolism. Six DEGs (PY, ELOVL, VLCOAR, MRJP1, ELOVL AAEL008004-like, and RPL13) were selected for validation with real-time fluorescent quantitative PCR. This is the first report of sublethal, trans-generational, and transcriptomic side effects of fipronil on the dominant parasitoid of A. gossypii. The results of this study show that adaptation of parasitoids to high concentrations of pesticides may be at the expense of their offspring. These findings broaden our overall understanding of the intergenerational adjustments used by insects to respond to pesticide stress and call for risk assessments of the long-term impacts and intergenerational effects of other pesticides.

Sublethal Impacts of a Commercial Botanical Pesticide (Salpipest®) Containing Nanoencapsulated Essential oil of Wild Pistachio on Demographic Parameters of the Predatory Mite Amblyseius swirskii Feed on Greenhouse Whitefly

The greenhouse whitefly Trialeurodes vaporariorum Westwood is one of the most important economic pests of greenhouse products around the world. The use of pesticides is one of the most common methods to control this pest. The wide distribution of the host, the large number of generations, and the polyphagous nature of T. vaporariorum have created the basis for its resistance to pesticides. The predatory mite Amblyseius swirskii Athias-Henriot is one of the effective natural enemies to control whiteflies in greenhouses. This study investigated the sublethal effects of the botanical pesticide Salpipest® derived from wild pistachio (Pistacia atlantica Desf. (Anacardiaceae)) essential oil on the biological parameters of A. swirskii on bell pepper plant under laboratory conditions. After conducting bioassays by leaf-dipping method and determining LC50 (121.599 mg a.i. L-1), the predator was exposed to the sublethal concentrations of LC10, LC20, and LC30 and its demographic parameters were determined. The results showed that the application of sublethal concentrations of Salpipest® had no significant effect on the duration of the different life stages and fecundity of A. swirskii. Population growth parameters of this predator were also not affected by sublethal concentrations of Salpipest®. Our results showed that Salpipest® had no negative effects on the biological performance of A. swirskii; therefore, the sublethal concentrations of this pesticide can be used in combination with A. swirskii in the integrated management of T. vaporariorum.

Reduced avoidance behaviour in Daphnia magna due to agrochemical-induced vulnerability

The continuous discharge of agrochemicals used in intensive agriculture contaminates aquatic systems, harming aquatic biota and their processes. Although mobile organisms can avoid continuous exposure by moving to less-affected habitats, their capacity can be altered by pollutant exposure. Populations with a previous disturbance history, which show a lower ability to respond to subsequent stressors, are defined as vulnerable. Therefore, this study investigated the so far unknown escape capacity of a vulnerable zooplankton population previously exposed to a contaminated environment. To this end, agrochemically driven vulnerability was induced in populations of Daphnia magna by exposure to sublethal concentrations of glyphosate. Vulnerability was verified using a starvation test in which significant differences were observed between the control populations and populations with a disturbance history. Both the Control and Vulnerable populations were assessed for their avoidance capacity by exposing them to a glyphosate gradient using a Heterogeneous Multiple-Habitat Assay System (HeMHAS). The control populations showed a rapid reaction from the beginning of the assay, with avoidance rates increasing over 24 h, while vulnerable populations were unable to avoid contaminated habitats for up to 24 h. Therefore, we concluded that vulnerable populations have a lower capacity to avoid contaminated habitats. In heterogeneously contaminated habitats, a lower avoidance capacity is responsible for the differential spatial distribution of the affected species, which impacts the ecosystem structure. Additionally, agrochemically induced vulnerability and its effect on avoidance behaviour may affect ecosystem functioning through the altered spatial distribution of zooplankton populations.