Crop plants suffer severe yield losses due to the significant damages caused by aphids. RNA interference (RNAi) technology is a versatile and environmentally friendly method for pest management in crop protection. Transgenic plants expressing siRNA/dsRNA and non-transformative methods such as spraying, microinjection, feeding, and a nanocarrier-delivery-mediated RNAi approach have been successfully applied for agricultural insect pest management. In this review, we summarize the application of host-induced gene silencing (HIGS)-mediated RNAi, spray-induced gene silencing (SIGS)-mediated RNAi, and other delivery-method-mediated RNAi methods for aphid control. We further discuss the challenges in RNAi application and propose potential solutions to enhance RNAi efficiency.

Entomopathogenic fungi (EPF)-based biopesticides have attracted growing interest in pest management as alternatives to neurotoxic insecticides. Their potential was evaluated against various pests, including the broad bean weevil (Bruchus rufimanus Boheman 1833), a significant threat to faba bean (Vicia faba L.) crops. This study examined the entomotoxic effects and sublethal impacts (on oviposition) of three fungal strains under laboratory conditions: Beauveria bassiana (GHA), Metarhizium brunneum (USDA 4556), and M. brunneum (V275) on B. rufimanus adults. Subsequently, a large-scale field trial assessed the efficacy of B. bassiana (GHA) against B. rufimanus infestations using conventional anti-drift and dropleg spraying methods. The laboratory LT₅₀ values ranged from four days for B. bassiana to eight days for M. brunneum (V275). The mortality rates recorded after ten days ranged from 86.6% for M. brunneum (V275) to 96.6% for B. bassiana (GHA). The inhibition of oviposition rates ranged from 12% for M. brunneum (USDA 4556) to 36% for B. bassiana (GHA). Field trials showed that the dropleg nozzles targeted faba bean pods, the oviposition sites of B. rufimanus, more effectively than the anti-drift nozzles. However, both fungal and chemical treatments applied via dropleg nozzles offered limited protection, reducing the infestation rates by 7% and 14%, respectively, with only a 3% improvement over anti-drift nozzles. This suggests that the large-scale spraying of chemical or fungal agents, including B. bassiana GHA, is not an optimal IPM strategy for managing B. rufimanus in faba beans. These laboratory and field results highlight the potential of EPF for managing B. rufimanus. However, the limitations of spray-applied plant protection methods underscore the need to redirect research toward more targeted strategies, such as attract-and-infect or endophytic EPF approaches.

Broad bean weevils (BBWs–Coleoptera: Chrysomelidae) are serious pests of field bean seeds that hamper the promotion of this crop in the diversification of European cropping systems. Recent research has identified different semiochemical lures and trap devices for the development of semiochemical-based control strategies of BBWs. In this study, two field trials were carried out in order to provide necessary information supporting the implementation of sustainable field use of semiochemical traps against BBWs. More particularly, three principal objectives were followed including (i) the identification of the most efficient traps for BBWs capture and the influence of trapping modality on BBWs sex-ratio, (ii) the assessment of eventual collateral effects on crop benefits including aphidophagous and pollinator insects such as Apidae, Syrphidae and Coccinellidae, (iii) the assessment of the crop developmental stage influence on the capture by semiochemical traps. Three different semiochemical lures were tested in combination with two trapping devices across two field trials in early and late flowering field bean crops. The crop phenology and climate parameters were integrated into the analyses to interpret the spatiotemporal evolution of the captured insect populations. A total of 1380 BBWs and 1424 beneficials were captured. White pan traps combined with floral kairomones were the most efficient traps for the capture of BBWs. We demonstrated that the crop phenology (c.f., the flowering stage) exerted strong competition on the attractiveness of semiochemical traps. Community analysis revealed that only one species of BBWs was captured in field bean crops (i.e., Bruchus rufimanus), and no trend was highlighted concerning the sex ratios according to the trapping devices. The beneficial insect community included 67 different species belonging to bees, hoverflies and ladybeetles. Semiochemical traps manifested a strong impact on beneficial insect communities that included some species under extinction threats and need to be further adapted to minimize such collateral effects. Based on these results, recommendations are provided for the implementation of the most sustainable BBWs control method that minimizes the impact on the recruitment of beneficial insects, which is an important ecosystem service for faba bean crops.

Bruchids are the most important pests of leguminous seeds in the world. In this study, the focus was done on Callosobruchus maculatus, a serious pest of Vigna unguiculata seeds. As no efficient control methods preventing collateral effects on beneficials currently exist, this study investigated whether RNA interference (RNAi) could provide a new biotechnological and selective tool for bruchids control. Three principal objectives were followed including (i) the identification of all RNAi machinery core components and a key protein to silence in C. maculatus genome (c.f., dicer-2, argonaute-2, R2D2, and laccase 1), (ii) the identification of suitable reference gene for RT-qPCR analyses, and (iii) the micro-injection of dsRNA coding for laccase 1 to adults of C. maculatus to assess gene expression levels by RT-qPCR and potentially related mortalities. Phylogenetical analyses performed from transcriptomic information successfully identified all necessary proteins in the RNAi mechanism and also the open reading frame of laccase 1 in C. maculatus. A new reference gene was identified (i.e., alpha-tubuline 1) and coupled with glutiathone S transferase for RT-qPCR analyses. Double-stranded RNAs coding for laccase 1 and green fluorescent protein (control) were produced and 400 ng of each dsRNA were micro-injected into C. maculatus adults. RT-qPCR analyses revealed a stable significant decrease in laccase 1 expression in about 80% of adults treated with laccase 1 dsRNA after three days post-injection. No significant mortalities were observed which is probably related to the non-exposure of adults to anti-nutritional factors that are usually regulated by laccase. Further research should focus either on the feeding larval stage which is directly exposed to anti-nutritional factors, or on other target genes to induce dead phenotypes. This study is the first gene silencing report on a bruchid species and supports RNAi as a potential future method of control.

Madagascar, renowned for its unique biodiversity, faces significant environmental threats. Despite their vital ecosystem services, invertebrates, such as Lepidoptera, remain understudied, especially within the Malagasy Island. Indeed, butterflies and moths often serve as biodiversity indicators. This study investigates lepidopteran community structure across different habitat types: protected areas and anthropized areas, represented by forest edges and agroforestry through four expeditions to Madagascar’s moist eastern forests. Both sampling methods were employed including butterfly nets and fermented fruit-baited traps. While nets accounted for 90% of captures, highlighting operator bias, bait traps captured unique species, emphasizing the complementarity of these methods. With over 891 captured specimens, 418 macrolepidopterans were identified at the species level for a total of 50 species. Protected forests hosted 80% of endemic Lepidoptera reliant on specialized ecological niches, while anthropized zones were dominated by common generalist species which are resilient to habitat changes. While the species richness and composition of sampled microlepidoptera are similar, habitat fragmentation created diverse environmental conditions, hosting specific populations. Conservation challenges persist, particularly for endemic species vulnerable to poaching. It is crucial to continue sampling Madagascar’s lepidofauna, as this offers considerable potential for the sustainable maintenance of ecosystems and the long-term preservation of biodiversity of the Malagasy Island.