Pest Management Science最新文献

Background: The emerald ash borer (EAB) is an invasive pest of global concern. Accurate detection of EAB is crucial for effective management. Traditional field surveys fail to meet large-scale monitoring requirements. Remote sensing methods offer a potential solution, but the phenological decline of ash trees may obscure the remote sensing features for detecting EAB. Therefore, determining the timing of leaf abscission caused by EAB before phenology is crucial for effective detection. We collected time-series data of Leaf Area Index (LAI), leaf sizes, and hyperspectral images of damaged ash trees throughout the growing season to determine the optimal detecting time window for EAB detection using field surveys or remote sensing techniques.

Results: Significant differences in LAI and leaf size were observed throughout the growing season among ash trees with different EAB infestation degrees, providing a basis for small-scale field surveys. However, in May and June, the hyperspectral reflectance showed no variation. The difference began to appear in July and became apparent from August to October. By October, severely EAB-infested ash trees had almost completely defoliated. Machine learning classification results showed that accuracies after July were higher than before July. After July, the highest classification accuracy reached 100%, while the highest accuracy before July was only 88.57%.

Conclusions: Selecting the optimal monitoring time significantly enhanced detection accuracy. The optimal period for field surveys is from May to November, whereas for remote sensing it is from August to October. Identifying the optimal months enables us to achieve more efficient decision-making and management. © 2024 Society of Chemical Industry.

Background: In a global context of pesticide reduction, the sustainable management of aphids is a major challenge in maintaining economically viable fruit production. Intercropping with companion plants (CPs) that emit volatile organic compounds (VOCs) with repellent or attractive properties could be successful in the laboratory. Still, their effects on the orchard have been little documented. We tested in 2018 and 2019 the hypotheses that the introduction of basil or French marigold, decreases the populations of Dysaphis plantaginea Passerini, the rosy apple aphid (RAA) and increases the abundance of its natural enemies (NEs) in an apple orchard in the south of France.

Results: Laboratory tests confirmed that both CPs altered RAA reproduction performance. In orchards, they attracted more NEs around the pots and at some dates in the aphid colonies near the pots in both years (apart from basil in 2019), without a significant reduction in aphid populations in 2018. In contrast, in 2019, the number and spatial expansion of aphid colonies were significantly lower, close to basil.

Conclusion: Further investigation is needed to disentangle the mechanisms explaining the observed effects (e.g., repellent action in autumn, etc.) but the results highlight the potential of CPs to control aphids in orchards and contribute to agroecological production of apple. Thus, this study shows the potential of CPs in a strategy combining aphid repellency and NEs attraction to control aphids in orchards, provided that CP installation lasts over several consecutive years. © 2024 Society of Chemical Industry.

Background: Helicoverpa armigera is a highly polyphagous species that causes huge losses to agricultural and horticultural crops worldwide. In the cotton industry, H. armigera, including the Australian subspecies Helicoverpa armigera conferta, is largely managed using genetically modified crops that express insecticidal toxins, such as Cry1Ac. Resistance to Cry1 proteins occurs and, in some cases, is mediated by changes to HaCad1, a gene that encodes the midgut protein cadherin. Around the world, numerous resistance-associated polymorphisms have been identified in the HaCad1 gene of H. armigera, but Cry1Ac resistance is rare in the Australian subspecies. We used CRISPR/Cas9 to disrupt the cadherin gene in H. armigera conferta and characterised the resulting phenotype with bioassays and transcriptomics.

Results: Compared to the parental strain, the newly generated HaCad1 knockout strain is 44-fold and 16-fold more resistant to Cry1Ac and Cry1A.105, respectively, while wild-type and knockout insects were equally insensitive to Cry1F.

Conclusion: The disruption of the HaCad1 gene causes Cry1Ac resistance in Australian H. armigera conferta. However, Cry1Ac resistance remains rare in Australian field populations suggesting that Australia's approach to pest management in cotton has prevented widespread Cry1Ac resistance. © 2024 CSIRO. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Background: Bacillus thuringiensis (Bt) can produce insecticidal crystal proteins during sporulation, and these are the basis of the most successful microbial insecticides in use today. However, the susceptibility of insecticidal crystal proteins to inactivation by ultraviolet (UV) radiation from sunlight causes damage to the insecticidal crystals and subsequent loss of toxicity. The deletion of the mclX gene, an unknown functional gene, can make the insecticidal crystal proteins become encapsulated by the cell wall which provides some protection against UV radiation. This study evaluates the potential of this innovative strategy during the industrial process of commercial strain KN11.

Results: Gene mclX was deleted from a commercial Bt strain KN11 successfully, and the mutant strain was cultured under different conditions, including laboratory and industrial fermentation conditions. The mother cells of the mclX mutant strain remained nonlysed after industrial processes. The deletion of mclX had no adverse effects on the production of Cry1Ac protein and no impact on the insecticidal activity. Most noteworthy, the ΔmclX mutant had improved UV resistance and insecticidal activity compared to the wild-type KN11 strain.

Conclusion: This finding suggests that commercial strains can be genetically modified to encapsulate insecticidal crystal in Bt products using the mclX mutation strategy. This study evaluated the ability of commercial strains lacking the mclX gene to encapsulate crystals giving resistance to UV radiation. © 2024 Society of Chemical Industry.

Background: Resistance of Busseola fusca (Lepidoptera: Noctuidae) to Cry1Ab was documented in 2006, 7 years after the first cultivation of MON 810 in South Africa. This was mitigated by introducing a second-generation Bacillus thuringiensis (Bt) maize (MON 89034), which contains the Cry1A.105 and Cry2Ab2 proteins. The first reports of B. fusca infestations of MON 89034 maize came in the KwaZulu-Natal province (2017-2018 cropping season), followed by reports in the Mpumalanga province (2022-2023 season). Here we report results of artificial diet- and plant-based laboratory assays to assess the susceptibility of B. fusca populations to the Bt proteins in MON 89034.

Results: Larvae were sampled from nine locations which included three where greater than expected injury due to B. fusca had been reported to MON 89034. Larval mortality in assays with diet-incorporated Cry2Ab2 protein was 100% for all except the three problem populations, showing that the Cry2Ab2 protein in MON 89034 is highly efficacious against B. fusca. In contrast, assays with Cry1A.105 did not cause significant mortality in any of the B. fusca populations including larvae from a susceptible reference. Larval survival on leaf tissue of MON 89034 maize after 7 days ranged between 75% and 91% for the three problematic B. fusca populations, compared to 0.4% to 9.6% for the five other populations.

Conclusion: Therefore, MON 89034 is effectively a single-mode-of-action technology against B. fusca and carries an inherent high risk for the evolution of resistance. This study shows that the three B. fusca populations collected from locations with greater than expected damage to MON 89034 have resistance to the Cry2Ab2 protein and therefore to MON 89034 maize. This research emphasizes the importance of resistance monitoring and implementation of effective insect resistance management tactics. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Background: Piercing-sucking insects secrete diverse repertoires of effectors into their hosts to weaken host defenses and promote infestation. The Asian citrus psyllid, Diaphorina citri Kuwayama, is the most destructive insect pest in citrus orchards because of its role as a vector for the huanglongbing pathogen, Candidatus Liberibacter asiaticus (CLas). However, specific effector proteins and their functions in D. citri remain unclear.

Results: We demonstrate that DcE1, a salivary protein gene from D. citri, is predominantly expressed in the salivary gland tissues and is delivered into host plants during feeding. Transient expression in tobacco leaves revealed that DcE1 was subcellularly localized in the cytoplasm and plasma membrane, where it inhibited BAX- and INF1-induced cell death, suppressed callose deposition, and activated the salicylic acid pathway by upregulating the expression of endo-β-1,3-glucanase NtBGL2 and regulatory protein NtNPR1. Further, DcE1 knockdown by double-stranded RNA (dsRNA) injection decreased the survival rates of D. citri and interrupted D. citri phloem-feeding on host plants.

Conclusion: These results indicate that DcE1 is a novel effector that promotes plant susceptibility and enables D. citri feeding. These findings enhance our understanding of D. citri-plant interactions and offer a potential new target gene for the development of citrus protection strategies. © 2024 Society of Chemical Industry.