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Background Fall armyworm (FAW), Spodoptera frugiperda (Smith), is an economically important pest worldwide. In this study, we selected a genotype of FAW resistant to chlorpyrifos from a field-collected population, characterized the genetic basis of resistance, evaluated cross-resistance and mechanisms of resistance using synergists. Results The LD50 values of chlorpyrifos for the resistant (Clorp-R) and susceptible (Sus) FAW genotypes were 24.26 and 0.023 μg larva-1 , respectively, representing a resistance ratio >1,050-fold. The LD50 values of chlorpyrifos against heterozygotes were 3.34 and 4.00 μg larva-1 , suggesting that resistance is autosomally inherited. The chlorpyrifos resistance in FAW was influenced by few genes, with the minimum numbers of segregations being 1.74 and 1.88. On chlorpyrifos-sprayed plants and leaves, Clorp-R and heterozygotes genotypes showed >95% and >52% survival, respectively, whereas the Sus genotype had no survival, indicating that the resistance is incompletely dominant at the field rate of chlorpyrifos. The Clorp-R genotype presented some cross-resistance to acephate, but low cross-resistance to thiodicarb, methomyl, chlorfenapyr, flubendiamide, methoxyfenozide, spinetoram, and teflubenzuron. The synergists piperonyl butoxide, diethyl maleate and S,S,S-tributyl phosphorotrithiotate did not have relevant effects on the Clorp-R genotype, suggesting a minor role for metabolic resistance. Conclusions The inheritance of chlorpyrifos resistance in FAW was characterized as autosomal, incompletely dominant and polygenic, with metabolic resistance playing a small role in the detoxification of chlorpyrifos. Low cross-resistance between chlorpyrifos and other Mode of Action (MoA) insecticides occurs in FAW, highlighting the importance of considering the rotation of MoA as a strategy to delay resistance. This article is protected by copyright. All rights reserved.

Background Integrating fungal biocontrol agents into crop protection programs dominated by synthetic pesticides is an important first step towards developing an IPM program, however their successful integration relies on an understanding of how their performance may be impacted by the remaining agrochemicals deployed for managing other pests and diseases. In this study we tested ten formulated pesticides used in macadamia production at different concentrations to determine their effects on the germination, mycelial growth and sporulation of Metarhizium anisopliae and Beauveria bassiana in vitro. Further tests with laboratory grade actives of the non‐compatible pesticides were conducted to determine whether any antagonistic effects were caused by the active constituent or by formulation additives. Results At their registered concentrations, formulated trichlorfon, acephate and indoxacarb were compatible with M. anisopliae, whereas B. bassiana showed compatibility with formulated trichlorfon, acephate, indoxacarb, sulfoxaflor and spinetoram. Bioassays using laboratory grade active constituents indicated that the adverse impact of formulated beta‐cyfluthrin on both fungal species and that of formulated methidathion on B. bassiana is probably due to components of the emulsifiable concentrate formulations rather than their active constituents. Diazinon was the only insecticidal active that showed high toxicity to both fungal species. The two fungicides, carbendazim and pyraclostrobin, were toxic to both fungal species at all tested concentrations. Conclusion Our results identify which pesticides used on macadamias in Australia are compatible and incompatible with entomopathogenic fungi. Future studies on pesticides degradation rates will help define the spray intervals required to eliminate these adverse effects.

Background Diagnosis of acute intoxication with organophosphate (OP) or carbamate (CM) pesticides in humans is achieved by measuring plasma butyrylcholinesterase (BuChE) activity. However, BuChE activity is not an ideal biomarker in experimental animal models. The aim of this study was to establish an experimental mouse model for evaluating exposure to OP and CM pesticides by monitoring BuChE activity using chimeric mice in which the liver was reconstituted with human hepatocytes. Results A single oral administration of acephate (300 mg/kg), chlorpyrifos (10 mg/kg), fenobucarb (300 mg/kg) or molinate (250 mg/kg) in chimeric mice led to inhibition of >95%, > 95%, 28% and 60% of plasma BuChE activity after 7, 0.5, 0.5 and 7 h, respectively. Dose-dependent decreases in plasma BuChE activity were also observed for acephate and chlorpyrifos. A 5-day repeated-dose study with 10 or 30 mg/kg acephate found a constitutive reduction in plasma BuChE activity to 80% and 70% of pre-dose levels, respectively. Conclusion Changes in plasma BuChE activity in chimeric mice with humanized liver clearly reflected the exposure levels of OP and CM pesticides. These results suggest that the humanized-liver mouse model may be suitable for estimating levels of exposure to these pesticides in humans. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

BACKGROUND Detection of neonicotinoid resistance in populations of tobacco thrips, Frankliniella fusca Hinds, throughout the southeastern USA has motivated an examination of alternative insecticides to control problematic infestations on seedling cotton. The objective of this study was to refine understanding of stage-specific mortality and reduced oviposition of several common insecticides (acephate, abamectin, cyantraniliprole, spinetoram, imidacloprid, imidacloprid+thiodicarb, thiamethoxam) on neonicotinoid resistant and susceptible F. fusca populations under laboratory and field conditions. RESULTS Laboratory studies revealed that the average number of eggs per female and larval or adult survivorship responses differed by insecticide and were dependent on the resistance status of the population. In the presence of neonicotinoids, the resistant F. fusca populations exhibited lower mortality and higher egg counts than the susceptible population. In the field study, similar patterns of oviposition suppression were observed, indicating that some insecticides may impact reproductive rate. CONCLUSION This study shows that insecticides have different effects on F. fusca oviposition events, larval and adult mortality that are dependent on neonicotinoid resistance status. Because insecticides tested in this study have varied activity on specific F. fusca life stages (e.g. oviposition suppression, larvicidal activity, adulticidal activity), knowledge of stage-specific activity can be used to improve control and enhance long-term product stewardship. © 2017 Society of Chemical Industry.

BACKGROUND Diagnosis of acute intoxication with organophosphate (OP) or carbamate (CM) pesticides in humans is achieved by measuring plasma butyrylcholinesterase (BuChE) activity. However, BuChE activity is not an ideal biomarker in experimental animal models. The aim of this study was to establish an experimental mouse model for evaluating exposure to OP and CM pesticides by monitoring BuChE activity using chimeric mice in which the liver was reconstituted with human hepatocytes. RESULTS A single oral administration of acephate (300 mg/kg), chlorpyrifos (10 mg/kg), fenobucarb (300 mg/kg) or molinate (250 mg/kg) in chimeric mice led to inhibition of >95%, > 95%, 28% and 60% of plasma BuChE activity after 7, 0.5, 0.5 and 7 h, respectively. Dose‐dependent decreases in plasma BuChE activity were also observed for acephate and chlorpyrifos. A 5‐day repeated‐dose study with 10 or 30 mg/kg acephate found a constitutive reduction in plasma BuChE activity to 80% and 70% of pre‐dose levels, respectively. CONCLUSION Changes in plasma BuChE activity in chimeric mice with humanized liver clearly reflected the exposure levels of OP and CM pesticides. These results suggest that the humanized‐liver mouse model may be suitable for estimating levels of exposure to these pesticides in humans. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

BACKGROUND The diamondback moth (DBM), Plutella xylostella, is one of the most harmful insect pests on crucifer crops worldwide. In this study, 19 cDNAs encoding glutathione S-transferases (GSTs) were identified from the genomic and transcriptomic database for DBM (KONAGAbase) and further characterized. RESULTS Phylogenetic analysis showed that the 19 GSTs were classified into six different cytosolic classes, including four in delta, six in epsilon, three in omega, two in sigma, one in theta and one in zeta. Two GSTs were unclassified. RT-PCR analysis revealed that most GST genes were expressed in all developmental stages, with higher expression in the larval stages. Six DBM GSTs were expressed at the highest levels in the midgut tissue. Twelve purified recombinant GSTs showed varied enzymatic properties towards 1-chloro-2,4-dinitrobenzene and glutathione, whereas rPxGSTo2, rPxGSTz1 and rPxGSTu2 had no activity. Real-time quantitative PCR revealed that expression levels of the 19 DBM GST genes were varied and changed after exposure to acephate, indoxacarb, beta-cypermethrin and spinosad. PxGSTd3 was significantly overexpressed, while PxGSTe3 and PxGSTs2 were significantly downregulated by all four insecticide exposures. CONCLUSION The changes in DBM GST gene expression levels exposed to different insecticides indicate that they may play individual roles in tolerance to insecticides and xenobiotics. © 2014 Society of Chemical Industry

BACKGROUND Laboratory selection is often employed in resistance mechanism studies because field-derived populations commonly do not have high enough resistance for such studies. In the present study, a field-collected Laodelphax striatellus population from eastern China was laboratory selected for chlorpyrifos resistance and susceptibility, and the developed strains, along with a field population, were studied for cross-resistance and resistance mechanisms at biochemical and molecular levels. RESULTS A 158.58-fold chlorpyrifos-resistant strain (JH-chl) and a chlorpyrifos-susceptible strain (JHS) were established after laboratory selection of 25 generations. Cross-resistance to deltamethrin, diazinon, methomyl, carbosulfan, acephate and imidacloprid were detected in JH-chl and a field-collected strain (JHF). Synergism and enzyme activity data suggested potential involvement of P450s and esterases in JH-chl as well as AChE alteration. Furthermore, CYP6AY3v2, CYP306A2v2, CYP353D1v2 and LSCE36 genes were significantly overexpressed in JH-chl (6.87–12.14-fold). Feeding of dsRNAs reduced the expression of the four target genes (35.6–56.8%) and caused significant adult mortality (75.21–88.45%), implying resistance reduction. However, mechanism(s) conferring chlorpyrifos resistance in JHF were unclear. CONCLUSION In contrast to previous reports, multiple overexpressed detoxification genes were potentially associated with chlorpyrifos resistance, as confirmed by RNAi feeding tests. Chlorpyrifos resistance exhibits cross-resistance with insecticides in the same and different classes. © 2013 Society of Chemical Industry

Mole crickets (Neoscapteriscus spp.) consume turfgrasses and pasture grasses and uproot plants by their tunneling, which is detrimental to turf aesthetics and decreases forage quantity and quality. Insecticides are frequently used to prevent damage. In typical field trials, damage symptoms, not percent mortality or achieved level of control, are used to assess treatment efficacy. Here, however, laboratory tests assessed the direct effect of key insecticides on Neoscapteriscus mole cricket behavior.Mole crickets, Neoscapteriscus spp., were able to detect and avoid areas treated with fipronil [formulated product (FP)] and imidacloprid (FP). They tunneled less in sand treated with fipronil and avoided sand treated with fipronil and imidacloprid if given a choice. Mole crickets escaped areas treated with acephate, bifenthrin and fipronil. Bifenthrin and acephate caused increased tunneling during the first 90 min of observation. Fipronil and imidacloprid significantly reduced overall tunneling on treated areas.Tested insecticides elicited two types of behavioral changes in Neoscapteriscus mole crickets: increased locomotory activity and tunneling [acephate (organophosphate) and bifenthrin (pyrethroid)] and reduced spatial movement [fipronil (phenylpyrazole) and imidacloprid (neonicotinoid)]. These behavioral responses resulted mainly from contact chemoreception and inherent neurotoxicity of the chemicals on Neoscapteriscus mole crickets. © 2017 Society of Chemical Industry.

BACKGROUND: Trunk injections of systemic insecticides were evaluated for the management of avocado thrips. Insecticide residues were quantified in leaves to determine when after treatment, and for how long, toxic concentrations of the insecticides were present. Residues in fruit were quantified to determine whether trunk injection of insecticides might present a greater risk than traditional application methods for contaminating fruit. RESULTS: Residues of imidacloprid and dinotefuran were at least tenfold higher in leaves when trees were treated via trunk injection compared with soil application. Dinotefuran uptake was more rapid than imidacloprid, and no residues were detected within fruit. Acephate was also mobilized very rapidly and gave good control of thrips in bioassays; however, residues of acephate and its insecticidal metabolite methamidophos were detected in the fruit for up to 4 weeks after injection. Avermectin uptake was very slow, and it was ineffective against avocado thrips. CONCLUSIONS: Trunk injections of acephate and dinotefuran permitted rapid uptake into avocados, and they are strong candidates as control methods for avocado thrips. However, residues of organophosphates in fruit could necessitate increased preharvest intervals. Residues of neonicotinoids were below detection limits in fruit, suggesting that neonicotinoids may be the more suitable control option of the two chemical classes. Copyright © 2012 Society of Chemical Industry

BACKGROUND: High amounts of insecticides are often used in intensive tropical vegetable production systems. Their persistence and residues in vegetables and soils need to be studied to ensure food safety and environmental stability. The dissipation of acephate, chlorpyrifos, cypermethrin and their metabolites was studied in green mustard [Brassica juncea (L.) Coss.] and soils. Two treatments, Impact 75 (acephate) and Agent 505 (cypermethrin plus chlorpyrifos), were applied 4 times at weekly intervals. RESULTS: Dissipation of acephate, chlorpyrifos and cypermethrin in green mustard and topsoils followed first-order kinetics, with half-lives of between 1.1 and 3.1 days in green mustard and between 1.4 and 9.4 days in topsoils (26 °C). Higher vapour pressure of insecticides and higher rainfall appeared to stimulate dissipation from the vegetable, with least effect of rainfall on chlorpyrifos. Dissipation rates in the vegetable were faster or similar (cypermethrin) to rates observed for temperate areas. Preharvest intervals of 13, 4 and 3 days were required for acephate, chlorpyrifos, cypermethrin and their metabolites to comply with the tolerance levels. The pesticide dissipation rates in soils varied by less than a factor of 3 between sites. The metabolites methamidophos and TCP derived from acephate and chlorpyrifos amounted to less than 10 and 25% by mass of the parent compounds in soils. Vegetable shading possibly retarded pesticide degradation in soil. CONCLUSION: The dissipation of pesticides and their metabolites in the vegetable was rapid and faster than the dissipation in temperate climates. The degradation rates of pesticides in the soil were equal to or slightly faster than the degradation rates in temperate soils. Copyright © 2008 Society of Chemical Industry

Efficient chemical control is achieved when insecticides are active against insect pests and safe to natural enemies. In this study, the toxicity of 17 insecticides to the sweetpotato whitefly, Bemisia tabaci (Gennadius), and the selectivity of seven insecticides to natural enemies of this insect pest were evaluated. To determine the insecticide toxicity, B. tabaci adults were exposed to abamectin, acephate, acetamiprid, cartap, imidacloprid, malathion, methamidophos, bifenthrin, cypermethrin, deltamethrin, esfenvalerate, fenitrothion, fenpropathrin, fenthion, phenthoate, permethrin and trichlorphon at 50 and 100% of the field rate (FR), and to water (untreated control). To determine the insecticide selectivity, adults of Encarsia sp., Acanthinus sp., Discodon sp. and Lasiochilus sp. were exposed to abamectin, acephate, acetamiprid, cartap, imidacloprid, malathion and methamidophos at 50 and 100% FR, and to water. Groups of each insect species were exposed to kale leaves preimmersed in each treatment under laboratory conditions. Mortality of exposed individuals was recorded 24 h after treatment. Cartap and imidacloprid at 50 and 100% FR and abamectin and acetamiprid at 100% FR showed insecticidal activity to B. tabaci adults. Abamectin at 50 and 100% FR was the least insecticidal compound to the natural enemies Acanthinus sp., Discodon sp. and Lasiochilus sp. The present results suggest that abamectin at 100% FR may decrease B. tabaci field populations but can still be harmless to predators. Implications of these results within an integrated pest management context are discussed.

A susceptible strain of diamondback moth, Plutella xylostella (L.), was used to select for resistance to tebufenozide in the laboratory. After continuous selection with tebufenozide 17 times during 35 generations, a resistant strain was achieved with high resistance to tebufenozide (RR 93.8). Bioassay revealed that this strain showed high cross-resistance to abamectin (RR 35.7), methoxyfenozide (29.1) and JS118 (16.5), and a little to deltamethrin (3.9), but no obvious cross-resistance was found to cypermethrin (1.3), fipronil (1.3), trichlorfon (1.1), chlorfenapyr (1.0), phoxim (0.9) and acephate (0.8). The resistant and susceptible insects had similar development rates, but life table tests indicated that the resistant strain showed reproductive disadvantages, including decreased copulation rate, reproductivity and hatchability. When compared with the susceptible strain, the resistant insects had a relative fitness of only 0.3. This indicated that tebufenozide resistance selected under laboratory conditions had considerable fitness costs in this pest, and therefore rotational use of insecticides without cross-resistance is recommended to delay development of resistance.

BACKGROUND:Uraba lugens Walker (Lepidoptera: Nolidae) has the potential to become a serious pest of susceptible forestry and urban trees in New Zealand. Stem injection of insecticides provides a method for the control of U. lugens in public locations where foliar applications are not suitable. Field and laboratory studies were conducted in 2009 and 2010 to determine a dose response profile of U. lugens larvae to acephate injected at 0.0, 0.25, 0.50 and 1.00 g cm−1 tree diameter measured at breast height (dbh). The concentration of the injected solution varied across years. RESULTS: The highest mortality (85–100%) of U. lugens larvae occurred at 1.00 g acephate injected cm−1 dbh. The lower rates (0.25 and 0.50 g acephate cm−1) were more effective in 2010 than in 2009, a factor attributed to the change in volume of injected solution. CONCLUSION: Systemic injections of acephate at rates above 0.50 g cm−1 dbh provide a tool for the management of U. lugens in public places. It is recommended that stem injection operations for control of U. lugens larvae be timed to coincide with the emergence of first instars so that larvae are exposed to lethal insecticide doses. Copyright © 2011 Society of Chemical Industry

BACKGROUND: Japanese beetles, Popillia japonica Newman, are a quarantine challenge for nursery shipments from infested to non-infested states. Marathon (imidacloprid) and Discus (imidacloprid + cyfluthrin) are approved preharvest nursery treatments (US Domestic Japanese Beetle Harmonization Plan; DJHP). This study evaluated approved and non-approved (acephate, carbaryl, clothianidin, dinotefuran, halofenozide, thiamethoxam, trichlorfon) preharvest treatments, optimal rates (labeled 1×, 0.3–0.75× or 2–3×) and optimal timings (June, July, August and September) to control early-instar (grubs) P. japonica in field nurseries. RESULTS: Most insecticides effectively reduced grub densities, except for acephate, carbaryl and trichlorfon. Clothianidin, thiamethoxam and halofenozide provided grub control equivalent to DJHP standards during most years. Across all test years and timings, percentage grub reductions were: Marathon (1×: 59.2–100; 3×: 78.9–100), Discus (1×: 60.7–100), clothianidin (1×: 96.1–100; 3×: 97.4–100), thiamethoxam (1×: 75.0–100; 3×: 80.0–100), halofenozide (1×: 70.0–100; 3×: 90.0–100) and dinotefuran (1×: 13.2–88.2; 3×: 71.1–93.4). CONCLUSIONS: July application was more consistent and effective than other timings, and higher rates (2× and 3×) did not generally improve grub control. Overall, clothianidin, thiamethoxam and halofenozide (and dinotefuran applied in August) were equivalent to current DJHP standards. These insecticides may be suitable for DJHP Category 2 states, potentially lowering grower costs. Copyright © 2009 Society of Chemical Industry