Sublethal effects of growth-regulating insecticides of synthetic and botanical origins on the biological parameters of Spodoptera frugiperda (Lepidoptera: Noctuidae).

The objective of this study was to evaluate the effects of growth-regulating insecticides of synthetic (e.g., Certero 480 SC, Intrepid 240 SC, Match EC and Mimic 240 SC) and botanical origins (e.g., Azamax 1.2 EC, Agroneem 850 EC, Azact 2.4 EC and Fitoneem 850 EC) on the biological parameters and fertility life table of Spodoptera frugiperda (J.E. Smith) under laboratory conditions. Larvae were fed insecticides that were incorporated into artificial diets. To develop the fertility life table, the following biological parameters were evaluated: survival at 7 days after infestation (d.a.i) and survivorship at adult eclosion, duration of the neonate-to-adult eclosion period, larval and pupal weights and total fecundity (number of total eggs per female). The results indicated that S. frugiperda neonates surviving LC25 or LC50 concentrations of the evaluated insecticides showed longer larval and egg-to-adult periods, lower larval and pupal weights and reduced fecundity, when compared to the control treatment. Larvae exposed to Azamax at LC25 or LC50 concentrations showed the greatest increase in generation duration (75 d). In addition, S. frugiperda adults emerged from pupae when larvae reared on an artificial diet containing growth regulating insecticides of synthetic and botanical origins produced fewer females per female per generation (Ro). As well as, lower rates of natural population increase per day (rm) compared to insects fed the control diet. Our findings indicated that, neem-derived products and growth-regulating insecticides of synthetic origin may be employed within integrated management strategies that aim to keep populations of S. frugiperda below levels that cause economic damage. Similarly, they offer alternatives for insecticide resistance management programs.

Phosphonium-based deep eutectic solvent coupled with vortex-assisted liquid-liquid microextraction for the determination of benzoylurea insecticides in olive oil.

In this study, a novel method using a phosphonium-based deep eutectic solvent coupled with vortex-assisted liquid-liquid microextraction was investigated for the enrichment and separation of five benzoylurea insecticides in olive oil. The experimental factors affecting the extraction efficiency, including the extractant type, deep eutectic solvent volume, extraction time, and extraction mode, were optimized. Under optimal conditions, good linearity was observed for all target analytes, with correlation coefficients (r) ranging from 0.9971 to 0.9998; the limits of detection were in the range of 1.5 to 7.5 µg/L, and the recoveries of analytes using the proposed method ranged between 66.9 and 111.0%. The simple, rapid, and effective method was successfully applied for detecting target analytes in olive oil sample.

Resistance mutation conserved between insects and mites unravels the benzoylurea insecticide mode of action on chitin biosynthesis.

Despite the major role of chitin biosynthesis inhibitors such as benzoylureas (BPUs) in the control of pests in agricultural and public health for almost four decades, their molecular mode of action (MoA) has in most cases remained elusive. BPUs interfere with chitin biosynthesis and were thought to interact with sulfonylurea receptors that mediate chitin vesicle transport. Here, we uncover a mutation (I1042M) in the chitin synthase 1 (CHS1) gene of BPU-resistant Plutella xylostella at the same position as the I1017F mutation reported in spider mites that confers etoxazole resistance. Using a genome-editing CRISPR/Cas9 approach coupled with homology-directed repair (HDR) in Drosophila melanogaster, we introduced both substitutions (I1056M/F) in the corresponding fly CHS1 gene (kkv). Homozygous lines bearing either of these mutations were highly resistant to etoxazole and all tested BPUs, as well as buprofezin-an important hemipteran chitin biosynthesis inhibitor. This provides compelling evidence that BPUs, etoxazole, and buprofezin share in fact the same molecular MoA and directly interact with CHS. This finding has immediate effects on resistance management strategies of major agricultural pests but also on mosquito vectors of serious human diseases such as Dengue and Zika, as diflubenzuron, the standard BPU, is one of the few effective larvicides in use. The study elaborates on how genome editing can directly, rapidly, and convincingly elucidate the MoA of bioactive molecules, especially when target sites are complex and hard to reconstitute in vitro.

Dispersive liquid-liquid microextraction based on the solidification of deep eutectic solvent for the determination of benzoylureas in environmental water samples.

We present a novel dispersive liquid-liquid microextraction method based on the solidification of deep eutectic solvent coupled with high-performance liquid chromatography with a variable-wavelength detection for the detection of five benzoylureas in real water samples. In this work, a green solvent consisting of 1-octyl-3-methylimidazolium chloride and 1-dodecanol was used as an extraction solvent, yielding the advantages of material stability, low density, and a suitable freezing point near room temperature. Parameters that significantly affect extraction efficiency were optimized by the one-factor-at-a-time approach. Under optimal conditions, the recoveries of five target compounds were obtained ranging from 87.39 to 98.05% with correlation coefficients ranging from 0.9994 to 0.9997 for pure water. The limits of detection were in the range of 0.09-0.16 µg/L. The enrichment factors were in the range of 171-188. Linearities were achieved in the range of 0.5-500 µg/L. The proposed method was successfully applied to determine benzoylureas in environmental water samples with a satisfactory recovery of approximately 81.38-97.67%.

A core-shell structured magnetic sulfonated covalent organic framework for the extraction of benzoylureas insecticides from water, pear juice and honey samples.

Three magnetic covalent organic frameworks (named M-TpPa-SO3Na, M-TpPa-SO3H and M-TpPa) were prepared by the solvothermal synthesis method with 1,3,5-trimethylphenol (TP) and either 2-sulfo-1,4-phenylenediamine (Pa-SO3H) or p-phenylenediamine (Pa) as monomers. Among them, the M-TpPa-SO3Na possessed relatively high hydrophilicity, good magnetic responsiveness, and high affinity for the benzoylureas (BUs) insecticides. It was then explored as the magnetic solid-phase extraction adsorbent for the extraction of six BUs (diflubenzuron, triflumuron, hexaflumuron, teflubenzuron, flufenoxuron and chlorfluazuron) from water, pear juice and honey samples prior to high-performance liquid chromatography with ultraviolet detection. Under the optimized experimental conditions, a good linearity was achieved within the concentration range of 0.27-40.0 ng mL-1 for water sample, 0.47-30.0 ng mL-1 for pear juice sample, and 2.70-200.0 ng g-1 for honey sample. The limits of detection for the analytes were 0.08-0.11 ng mL-1 for water sample, 0.14-0.19 ng mL-1 for pear juice sample and 0.80-1.00 ng g-1 for honey sample. The method recoveries for spiked samples were in the range of 85.0%-111.0% with the relative standard deviations less than 8.8%. The developed method was successfully used for the determination of the BUs in water, pear juice and honey samples.

Facile synthesis of magnetic hypercrosslinked polymer for the magnetic solid-phase extraction of benzoylurea insecticides from honey and apple juice samples.

In this work, a novel knitting aromatic polymer (KAP) was fabricated for the first time by knitting ferrocene with 1,3,5-tris(bromomethyl)-2,4,6-trimethylbenzene via Friedel-Crafts reaction, and then the KAP was magnetically functionalized with Fe3O4 nanoparticles to produce a magnetic KAP (M-KAP). Combining M-KAP based magnetic solid-phase extraction with high performance liquid chromatography-ultraviolet detection, a simple and sensitive method was developed for simultaneous determination of six benzoylurea insecticides (BUs) in honey and apple juice samples. In the optimized conditions, a good linearity for the BUs existed in the range of 1.67-1000 ng g-1 for honey sample and 0.500-100.0 ng mL-1 for apple juice sample. The limits of detection were 0.500-1.50 ng g-1 and 0.150-0.400 ng mL-1 for honey and apple juice sample, respectively. Satisfactory recoveries were in the range of 85.5-105.5% with RSDs ≤ 8.3%. The developed method demonstrated an excellent practicability for sensitive analysis of the BUs.

Ecotoxicological assessment of Fluazuron: effects on Folsomia candida and Eisenia andrei.

The cattle production in Brazil has increased considerably in the last years, mainly due to the control of parasite infestation of the animals, which cause loss of productivity to the sector. Fluazuron is an active ingredient (a.i.) of the benzoylurea class used to control ticks in cattle. As this a.i. has been found unchanged in animal feces, which may present a risk to edaphic organisms, this study aimed to assess the effects of fluazuron on survival, reproduction, and behavior of the soil invertebrates Folsomia candida and Eisenia andrei, through ecotoxicological assays. We carried out bioassays in a tropical artificial soil (TAS) spiked with increasing doses of the insecticide. Earthworm mortality was found only at the highest tested fluazuron concentration (LOEC = 160 mg a.i. kg-1 dry soil and NOEC = 80 mg kg-1), while the reproduction of F. candida and E. andrei was reduced at lower fluazuron concentrations (EC50 = 4.48 mg kg-1 and EC50 = 20.8 mg kg-1, respectively). Avoidance behavior was detected for both species at lower concentrations than those that caused impacts on reproduction, indicating that the substance may affect the soil habitat function. Since the possible adverse effects of fluazuron on edaphic fauna are still unknown or neglected, this study also warns about the possible harmful effect of veterinary pharmaceutical products on edaphic fauna.

Fitness costs and life table parameters of highly insecticide-resistant strains of Plutella xylostella (L.) (Lepidoptera: Plutellidae) at different temperatures.

BACKGROUND: In many cases, resistance alleles have been associated with fitness costs and are often dependent on environmental factors such as temperature. Here, we studied the effects of temperature on the overall fitness, including development, survival and reproduction, of three insecticide-resistant and one susceptible strain of diamondback moth (DBM), Plutella xylostella (L.). RESULTS: The broader cross-resistance profile of the resistant strains previously selected by diamide and benzoylurea insecticides was tested. Cohort studies were conducted in the laboratory at three different temperatures (20 ± 1 °C, 25 ± 1 °C and 30 ± 1 °C), and involved fitness costs were estimated. We observed significant differences in the development time, with the susceptible strain showing a shorter developmental period from egg stage to adult stage compared with the resistant strains. Moreover, the resistant strains differed significantly between one another. Additionally, the population growth parameters varied among the strains, with the benzoylurea-resistant strain showing the highest costs affecting the overall fitness of this strain. A temperature of 30 °C was unfavourable for DBM development, resulting in a reduced fitness in all strains. CONCLUSION: Benzoylurea selection pressure on a diamide-resistant P. xylostella strain resulted in lowest reproduction parameters and the longest generation time, as well as doubling the time among all strains tested. This suggests significant effects on the overall fitness and population growth parameters for diamide-resistant populations pressured by benzoylureas under applied conditions. © 2017 Society of Chemical Industry.