Search Results (73)

Megalurothrips usitatus is a global pest damaged legume crops, particularly cowpea (Vigna unguiculata). This study aimed to determine the chemical composition of lemongrass essential oil (LEO) and its insecticidal activity against the insect pest M. usitatus. The composition of lemongrass essential oil was analyzed using Gas Chromatography Mass Spectrometry (GC-MS). D-limonene, Neral, and Citral were found to constitute over 30% of the essential oil. LEO exhibited higher insecticidal toxicity than the individual pure components. Based on our results, the optimal formulation of LEO emulsifiable concentrates (ECs) was identified, and their insecticidal activity was further investigated. The mortality rate induced by the LEO did not significantly differ from that of the emamectin benzoate (EB) formulation but was lower than that of spinosad (SP). Additionally, LEO was shown to act as a synergist when combined with EB for controlling M. usitatus. This research offers an alternative strategy for controlling M. usitatus and reducing the reliance on synthetic pesticides. Full article

Spalangia endius Walker, a pupal parasitoid of the alien invasive pest Zeugodacus cucurbitae (Coquillett), causes 33% host mortality. This study assessed whether combining S. endius with insecticides (abamectin, thiamethoxam, nitenpyram, emamectin benzoate, or beta-cypermethrin)—all effective against Z. cucurbitae—could enhance control efficacy. Among these, abamectin was the least toxic to adult S. endius. Surface contact treatments with 12 and 15 mg a.i./kg of abamectin did not significantly increase S. endius mortality. However, mixing 12 mg a.i./kg of abamectin into a honey solution to encourage ingestion decreased the survival, parasitism, and fecundity of S. endius. In olfactometer assays, S. endius adults avoided abamectin-treated host pupae, though prior exposure to abamectin mitigated this avoidance. The timing of abamectin soil application relative to host pupation and S. endius release affects host mortality. The most effective timing is spraying abamectin before host pupation (to expose Z. cucurbitae larvae) and then releasing S. endius. Field trials confirmed that combining abamectin (12 mg a.i./kg) with S. endius increased host mortality more than either treatment alone. In conclusion, abamectin (12 mg a.i./kg) is a suitable insecticide for combination with S. endius to control Z. cucurbitae. The application sequence should be spraying abamectin before hosts pupate and, only after that, releasing the parasitoid. Full article

Corymbia citriodora is a eucalypt tree of significant economic value due to its essential oils (EOs), rich in citronellal, citronellol, and other oxygenated monoterpenes with diverse biological activities. Its EOs show potential for the formulation of biopesticides with a lower impact on the environment and human health. This study evaluated the in vitro nematicidal activity of C. citriodora EOs, obtained from in vivo and in vitro grown plants, and their main volatile compounds against the pinewood nematode (PWN, Bursaphelenchus xylophilus), a major phytosanitary threat. The impact of their main compounds on the environment and human health was assessed using available experimental data and predictions from specialized software. Citronellal and citronellol were the most active EO compounds and exhibited EC₅₀ values comparable to the pesticide emamectin benzoate (0.364 ± 0.009 mg/mL). They also displayed superior safety profiles, with reduced environmental persistence and toxicity to non-target organisms. Furthermore, C. citriodora shoots were efficiently propagated through an in vitro system and their volatile profile was characterized by a dominance of citronellal (64%), and citronellol (10%), which highlights their potential as a scalable and sustainable source of nematicidal compounds. Remarkably, the EO of C. citriodora in vitro shoots was strongly active against the PWN, exhibiting the lowest EC₅₀ (0.239 ± 0.002 mg/mL) obtained. These findings underline the viability of C. citriodora EOs as a promising alternative for sustainable pest management, addressing the urgent need for environmentally friendly and health-conscious biopesticides while providing a renewable approach to nematode control. Full article

Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is a super pest that seriously endangers the development of the agricultural economy worldwide. To prevent and control B. tabaci, insecticides have been used for many years, which has inevitably led to increased tolerance to chemical agents. To elucidate the development of field resistance and more scientifically and efficiently control B. tabaci, in December 2024, we conducted bioassays on B. tabaci on soybeans in Suzhou, Anhui Province, using 14 insecticides. These fourteen insecticides, namely, abamectin, spinetoram, thiamethoxam, flupyradifurone, imidacloprid, dinotefuran, acetamiprid, thiacloprid, nitenpyram, bifenthrin, deltamethrin, pyridaben, flonicamid, and emamectin benzoate, have multiple action sites and have all shown good control effects on B. tabaci. The results revealed that B. tabaci has developed high resistance to many insecticides and that some insecticides have even tended to fail, but B. tabaci is still sensitive to a small number of insecticides. Different biotypes of B. tabaci differ significantly in terms of insecticide resistance. We determined that the population of B. tabaci on soybean in Suzhou was the MED (Q) biotype. It carried the TYLCV virus, with a virus carrying rate of 60%, but did not carry ToCV or CCYV. Full article

In southern China, cowpea production is severely threatened by Megalurothrips usitatus due to its fast-evolving resistance to insecticides. The toxicity monitoring of commonly used insecticides against field populations provides key information for the resistance management of pests. In this study, field populations of Megalurothrips usitatus were collected from three locations (QY, YF, MM) in Guangdong, and the sensitivity of these populations against insecticides was determined by using a thrips insecticides bioassay system (TIBS) method. The bioassay results indicated there were sensitivity variances to insecticides between these three field populations. Among these 10 insecticides, spinetoram and spinosad both showed high toxicity against all three field populations. In addition, broflanilide for QY, emamectin benzoate for YF, and emamectin benzoate and cyantraniliprole for MM were suggested as alternate insecticides to alleviate selective pressure from insecticides on field populations. In field experiments, the corrected control efficacy of cyantraniliprole and spinetoram against M. usitatus was over 75% at 7 dpa, which proved to be ideal insecticides for field application. These field-based results provide guidance for chemical control against thrips and can be valuable in proposing appropriate strategies for thrips resistance management. Full article

The fall armyworm, Spodoptera frugiperda, a lepidopteran pest from the family Noctuidae, has become a major invasive pest since 2016. Using RNAi methods to control S. frugiperda is currently under investigation. This study is the first to target the V-ATPaseD gene of S. frugiperda using RNAi. Injection of dsRNA-V-ATPaseD into the hemolymph of 4th-instar larvae significantly suppressed gene expression at 24 and 48 h post-injection. Treated larvae showed delayed development and reduced pupation after 7 days. Subsequently, V-ATPaseD silencing was achieved through topical or oral administration of chitosan/dsRNA-V-ATPaseD nanoparticles. Larvae fed these nanoparticles exhibited significant reductions in V-ATPaseD mRNA at 72 h, persisting until 96 h before normalizing. Additionally, the treated larvae displayed disrupted molting and impaired pupation. Furthermore, larvae fed chitosan/dsRNA-V-ATPaseD were more susceptible to emamectin benzoate–lufenuron at LC30 concentrations, resulting in 68% mortality—27% higher than the pesticide alone—72 h post-exposure. Combining chitosan/dsRNA-V-ATPaseD nanoparticles with emamectin benzoate–lufenuron significantly enhanced pest control efficacy, providing new insights into pesticide reduction and sustainable pest control methods for this invasive species. Full article

Pesticides, as an indispensable component in agricultural production, play a crucial role in ensuring global food security. However, the low efficiency of pesticide utilization remains a significant challenge. The key method of improving the effective utilization rate of pesticides is mainly to enhance the affinity between pesticides and leaf surfaces while improving their deposition and adhesion properties. In this study, we utilized PEG 4000 as a carrier and emulsifier 600 and emulsifiers 700 as surfactants to prepare solid nano-dispersion of emamectin benzoate (SND-EB) by the melting method. SND-EB particles were spherical with an average diameter of 17 nm, a loading capacity of up to 50%, and excellent dispersibility. Contact angle and bouncing behavior tests on cabbage and pepper leaves demonstrated that SND-EB had superior wetting properties and spreading capabilities. Surface tension and leaf retention measurements further confirmed that SND-EB possessed excellent adhesion and leaf affinity. The SND-EB showed a 1.8-fold increase in biological activity against Spodoptera exigua compared to commercial emamectin benzoate water-dispersible granule (WDG-EB). In addition, the fabricated nanoparticles exerted no toxic effect on HepG2 cells. These results demonstrated that a 50% content of SND-EB exhibited excellent water dispersity, wettability, and insecticidal activity, providing a novel and efficient strategy for pest control. Full article

Fluxametamide, an innovative isoxazoline insecticide, acts as an antagonist of γ-aminobutyric acid-gated chloride channels. Its distinct mode of action sets it apart, lacking known cross-resistance with current insecticides. This positions fluxametamide as a promising tool for addressing insecticide resistance in Lepidoptera, thysanoptera, coleoptera, and diptera pest insects. To develop and implement successful resistance management strategies, it is crucial to establish the baseline susceptibility to this insecticide before it is registered and widely used in China. In this study, we assessed the baseline susceptibility of two widespread lepidopteran pest species, Plutella xylostella and Spodoptera exigua, to fluxametamide. The insecticide exhibited remarkably high efficacy against populations of the two lepidopteran species sampled in their primary distribution areas in China. For P. xylostella and S. exigua, the median lethal concentrations (LC₅₀) ranged between 0.040 and 0.247 mg/L, and 0.211 and 0.761 mg/L, respectively. Among populations, there was a relative low variability in susceptibility to fluxametamide, showing a 6.18-fold difference for P. xylostella and 3.61-fold for S. exigua. The suggested diagnostic concentrations for P. xylostella and S. exigua were 10 and 15 mg/L, respectively. Fluxametamide exhibited high toxicity to the selected resistant strains, which displayed strong resistance to abamectin, emamectin benzoate, and deltamethrin. No cross-resistance to fluxametamide was detected in the laboratory diamide-resistant strain. Our findings offer essential insights for crafting successful resistance management initiatives to maintain the effectiveness of fluxametamide against these significant pests. Full article

Asian corn borer (ACB), Ostrinia furnacalis, is a predominant pest species that is widely distributed across major corn-growing regions in China. Tetraniliprole, a novel diamid insecticide, exhibited good efficacy on lepidopteran insect pests and was officially sanctioned for controlling ACB in China. In this study, a tetraniliprole-resistant strain called ACB-TLR was obtained from a susceptible strain, ACB-SS, after 10 continuous generation selections with tetraniliprole. Additionally, the fitness cost of the ACB-TLR strain was assessed. The results showed that ACB developed 11.58-fold resistance to tetraniliprole and the realized heritability was estimated as 0.213. The ACB-TLR strain displayed 2.10 times cross-resistance to chlorantraniliprole, but we found no cross-resistance to emamectin benzoate and deltamethrin. The development time of larvae and pupae was significantly prolonged, the adult longevity was significantly shorter, and the pupation and emergence rates were significantly reduced in the ACB-TLR strain than in the ACB-SS strain, with a relative fitness of 0.39. The current study indicated that ACB has the potential to develop resistance to tetraniliprole in the field. However, the decreased fitness may allow insecticide resistance to be managed. Full article

Pine wood nematodes (Bursaphelenchus xylophilus, PWNs) are a major threat to Pinus koraiensis in northeast China, and emamectin benzoate (EB) is commonly used for their control. Although high doses of EB can alleviate symptoms of pine wilt disease (PWD), they do not fully eradicate PWNs due to their detoxification mechanisms. This study investigates the content of EB in P. koraiensis and its efficacy in controlling PWNs after exogenous application of EB. We found that while EB significantly reduced PWN populations, it did not eliminate them. Transcriptomic analysis of PWNs treated with concentration at 20% (LC₂₀) revealed that PWNs exhibit detoxification responses to low EB concentrations (LC₂₀), driven by the Bx-SDR3 gene. RNA interference (RNAi)-mediated silencing of this gene decreased the detoxification ability of PWNs and enhanced the toxic effects of LC₂₀ EB by 20.9%. These results highlight the key role of Bx-SDR3 in PWN detoxification and suggest that targeting this gene could improve the effectiveness of EB, offering a promising strategy for more efficient and eco-friendly pest management. Full article

Pesticide residues still pose a risk to human health. With the rapid development of rapid testing technology, the levels of different types of pesticide residues in agricultural products can be identified in a shorter period; thus, the safety of food can be guaranteed. However, the effectiveness of commercially available testing products has yet to be evaluated. In this study, colloidal gold immunochromatographic qualitative testing products manufactured by 34 companies were tested for their assay performance on Emamectin Benzoate, Isocarbophos, and fipronil with standardized cowpea samples. The results indicated that most of the evaluated products were identified as having ‘passed’. Most pesticide residue rapid test immunoassay products can be considered ideal means for testing certain pesticide residues. However, further evaluation of pesticide residue rapid test immunoassay products is needed, as detection technologies are still developing. Full article

Residues of the pesticides chlorfenapyr (CFP) and emamectin benzoate (EMB) often coexist in the environment and can be accumulated in the body. To understand the impact of these two chemicals on health, we investigated their effect on the kidneys. In this study, rats were treated with CFP and/or EMB at low/medium/high doses of 1/3/9 mg/kg/day and 0.2/0.6/1.8 mg/kg/day, respectively, via oral gavage for 60 days. Kidneys and serum samples were collected and serum biochemistry and kidney histopathological changes were analyzed and examined. Kidney metabolome alterations were analyzed by using gas chromatography–mass spectrometry. The results showed that combined exposure to CFP and EMB elevated BUN levels and induced pathological damage, which presented as thinner renal tubular epithelial cells, an abnormal glomerular morphology, and an increased fibrotic area. CFP and/or EMB disrupted glutathione metabolism and carbohydrate metabolism, resulting in the alteration of kidney metabolomes and inducing oxidative stress in the cells of kidney tissues. In addition, CFP decreased ATP content and inhibited pyruvate PDH activity in the kidneys. These findings suggest that long-term exposure to CFP and EMB at environmentally relevant levels induce alterations in the renal metabolome, oxidative stress, and an insufficient energy supply, which may contribute to renal histopathological damage. Full article

Emamectin benzoate (EB) is a highly effective broad-spectrum insecticide and acaricide. However, because EB is easily degraded, the conventional formulations of EB are often overapplied. In this study, polylactic acid (PLA)-based microspheres were prepared using the modified solvent evaporation method for the controlled release of EB. The microspheres were optimized to achieve higher EB loading. The effects of process parameters on the properties of microspheres, including encapsulation efficiency (EE), particle size, and pesticide loading, were investigated. Additionally, the controlled release behavior of EB microspheres was compared with that of conventional EB emulsifiable concentrate (EC). Spherical-shaped microspheres were obtained with an EE reaching 90.63 ± 1.90%, and introducing an external aqueous phase into the system can significantly enhance the EE of microspheres by over 30%. FTIR, DSC, and XRD analyses indicate that the preparation process of PLA microspheres was mainly physical encapsulation and had no chemical effect on EB. Notably, the EB microspheres displayed more potent control efficacy compared to commercial formulation EB EC against Plutella xylostella. The corrected mortality for the EB microspheres reached 90.00 ± 5.77% after 21 days of application, whereas the corrected mortality for the EB EC was only 19.23 ± 6.66% after 14 days of application. Our study demonstrates that EB-encapsulated PLA microspheres have strong potential as environmentally friendly control release EB formulations. Full article

The pupal parasitoid Trichopria drosophilae (Hymenoptera: Diapriidae) has been evaluated as a biological agent of Drosophila suzukii. Integrated pest management strategies mostly rely on combined application of multiple insecticides and natural enemies. This study assessed the toxicity of eight common insecticides against D. suzukii in fruit orchards and the effects of semilethal and sublethal doses on T. drosophilae. The eight insecticides had higher toxicities to D. suzukii larvae with lower LC₅₀ values than those for adults. Adults and larvae showed high susceptibility to emamectin benzoate, spinetoram, lambda-cyhalothrin, abamectin, and sophocarpidine. The median lethal doses (LC₅₀) of lambda-cyhalothrin and imidacloprid to T. drosophilae adults were 60.41 mg/L and 100.58 mg/L, higher than the toxicities of the other six insecticides. Applying chlorantraniliprole, emamectin benzoate, sophocarpidine, abamectin, azadirachtin, and spinetoram resulted in low toxicity to D. suzukii pupae. However, the exposure of D. suzukii pupae or larvae to these insecticides at semilethal and sublethal doses decreased the parasitism or eclosion rate of T. drosophilae. These results improve our understanding of the effects of insecticide residues on T. drosophilae development and provide a basis for the combined use of chemical and biological options for managing D. suzukii. Full article

This study focused on the persistence, distribution, and efficacy of trunk-injected pesticides in Pinus koraiensis (Korean pine) with regard to controlling pinewood nematodes (PWNs, Bursaphelenchus xylophilus), the causative agent of pine wilt disease (PWD). In this study, we compared pesticide residues in the needles and branches of Korean pine, revealing significant declines in pesticide residues over time after treatments were applied. Notably, abamectin residues decreased from 0.2325 mg/kg to 0.0901 mg/kg in branches over a period of 18 months. In contrast, emamectin benzoate showed a variation in residue decline depending on the formulation, with the residue level in branches decreasing from 0.1220 mg/kg to 0.0328 mg/kg over the same period. From a spatial perspective, the results revealed minimal differences in pesticide residue at varying tree heights, although a decrease in upper canopy residue was observed in some cases. The nematicidal efficacy test demonstrated that none of the treated trees developed PWN symptoms. Overall, the findings suggest that the trunk-injected pesticides abamectin and emamectin benzoate can persist for two years, with the residue levels being sufficient to prevent PWN propagation, even when the levels are below critical inhibition concentrations. Full article