Intercropping of aromatic plants provides an environmentally benign route to reducing pest damage in agroecosystems. However, the effect of intercropping on natural enemies, another element which may be vital to the success of an integrated pest management approach, varies in different intercropping systems. Rosemary, Rosmarinus officinalis L. (Lamiaceae), has been reported to be repellent to many insect species. In this study, the impact of sweet pepper/rosemary intercropping on pest population suppression was evaluated under greenhouse conditions and the effect of rosemary intercropping on natural enemy population dynamics was investigated. The results showed that intercropping rosemary with sweet pepper significantly reduced the population densities of three major pest species on sweet pepper, Frankliniella intonsa, Myzus persicae, and Bemisia tabaci, but did not affect the population densities of their natural enemies, the predatory bug, Orius sauteri, or parasitoid, Encarsia formosa. Significant pest population suppression with no adverse effect on released natural enemy populations in the sweet pepper/rosemary intercropping system suggests this could be an approach for integrated pest management of greenhouse-cultivated sweet pepper. Our results highlight the potential of the integration of alternative pest control strategies to optimize sustainable pest control.

The fall armyworm, Spodoptera frugiperda (J.E. Smith), is a voracious insect pest that is difficult to control due to resistance to insecticides and Bt proteins. We assessed cross-resistance, resistance mechanism, and fitness costs based on the life history traits of S. frugiperda. We established an S. frugiperda strain selected for resistance to indoxacarb (Ind-SEL) from a field-collected population and an unselected strain, Ind-UNSEL. Results indicated that after 24 generations of selection, the resistance to indoxacarb was increased by 472.67-fold as compared to the Ind-UNSEL. There was high cross-resistance to deltamethrin (31.23-fold) with very low or negligible cross-resistance to chlorantraniliprole, emamectin benzoate, and/or methoxyfenozide in the Ind-SEL population. Butoxide synergist increased susceptibility to indoxacarb, indicating that P450 enzymes may be involved in indoxacarb resistance. Significantly longer developmental time of larvae extended pupal duration, shorter adult longevity, and lower fecundity were observed in Ind-SEL as compared with the Ind-UNSEL population. The Net reproductive rate (R₀) was the only growth parameter that differs between crosses of Ind-SEL♂ × Ind-UNSEL♀ (176 ± 46) and Ind-SEL♀ × Ind-UNSEL♂ (328 ± 57). On the other hand, all population growth parameters differ between Ind-SEL and Ind-UNSEL strains. Our work contributes to the growing body of research that demonstrates the importance of strain genetics in fitness cost experiments and helps resistance management programs make decisions.

How herbivorous insects adapt to host plants is a key question in ecological and evolutionary biology. The fall armyworm, (FAW) Spodoptera frugiperda (J.E. Smith), although polyphagous and a major pest on various crops, has been reported to have a rice and corn (maize) feeding strain in its native range in the Americas. The species is highly invasive and has recently established in China. We compared behavioral changes in larvae and adults of a corn population (Corn) when selected on rice (Rice) and the molecular basis of these adaptational changes in midgut and antennae based on a comparative transcriptome analysis. Larvae of S. frugiperda reared on rice plants continuously for 20 generations exhibited strong feeding preference for with higher larval performance and pupal weight on rice than on maize plants. Similarly, females from the rice selected population laid significantly more eggs on rice as compared to females from maize population. The most highly expressed DEGs were shown in the midgut of Rice vs. Corn. A total of 6430 DEGs were identified between the populations mostly in genes related to digestion and detoxification. These results suggest that potential adaptations for feeding on rice crops, may contribute to the current rapid spread of fall armyworm on rice crops in China and potentially elsewhere. Consistently, highly expressed DEGs were also shown in antennae; a total of 5125 differentially expressed genes (DEGs) s were identified related to the expansions of major chemosensory genes family in Rice compared to the Corn feeding population. These results not only provide valuable insight into the molecular mechanisms in host plants adaptation of S. frugiperda but may provide new gene targets for the management of this pest.

The fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is a polyphagous, invasive insect pest which causes significant losses in important crops wherever it has spread. The use of pesticides in agriculture is a key tool in the management of many important crop pests, including S. frugiperda, but continued use of insecticides has selected for various types of resistance, including enzyme systems that provide enhanced mechanisms of detoxification. In the present study, we analyzed the de novo transcriptome of S. frugiperda larvae exposed to Noposion Yihaogong^® 5% emulsifiable concentrate (EC) insecticide focusing on detoxification genes and related pathways. Results showed that a total of 1819 differentially expressed genes (DEGs) were identified in larvae after being treated with Noposion Yihaogong^® 5% EC insecticide, of which 863 were up- and 956 down-regulated. Majority of these differentially expressed genes were identified in numerous Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, including metabolism of xenobiotics and drug metabolism. Furthermore, many of S. frugiperda genes involved in detoxification pathways influenced by lambda-cyhalothrin stress support their predicted role by further co-expression network analysis. Our RT-qPCR results were consistent with the DEG’s data of transcriptome analysis. The comprehensive transcriptome sequence resource attained through this study enriches the genomic platform of S. frugiperda, and the identified DEGs may enable greater molecular underpinnings behind the insecticide-resistance mechanism caused by lambda-cyhalothrin.

Temperature and host stage are important factors that determine the successful development of parasitoids.Aenasius bambawaleiHayat (Hymenoptera: Encyrtidae) is a primary parasitoid of the newly invasive mealybug,Phenacoccus solenopsisTinsley (Hemiptera: Pseudococcidae). The effects of temperature on the parasitic characteristics ofA. bambawaleihave seldom been investigated. In the study, we explored the effects of temperature, exposure time, and host stage on the parasitization rate and offspring sex ratio (female to male) ofA. bambawaleiunder laboratory conditions. The laboratory results showed that the successful parasitization rate ofA. bambawaleiincreased with higher temperatures and older host stages. When the parasitoids were exposed to 36 °C for 24 h, the parasitization rate of female adults (52%) was nearly two times that of 3rd instar nymphs. Additionally, heat stress duration and host stage resulted in an increase in the offspring sex ratio ofA. bambawalei. WhenA. bambawaleiwas exposed to 36 °C for 24 h, the offspring sex ratio increased dramatically to 81.78% compared with those exposed for 12 h, and it increased to 45.34% compared with those exposed for 16 h. The offspring sex ratio was clearly higher when the host stage was an adult female mealybug Our findings provide important guidance for the mass rearing and field releases ofA. bambawaleifor the management ofP. solenopsisin the future.

The diamide insecticide tetraniliprole is a valuable tool for managing major insect pests like the invasive tomato pinworm, Tuta absoluta (Meyrick). However, the mechanisms underlying tetraniliprole resistance, as well as its associated fitness costs, remain unclear. In this study, we assessed the fitness of tetraniliprole-resistant (TetraRS) and susceptible (SS) strains of T. absoluta and conducted Illumina RNA-seq to compare their transcriptomes. We also used nanocarrier-mediated RNA interference (RNAi) to knockdown P450 genes and evaluate their role in tetraniliprole resistance. After eight generations of selection, T. absoluta developed a 20.80-fold resistance to tetraniliprole, accompanied by fitness costs. RNA-seq analysis revealed 3332 differentially expressed genes (DEGs), with 1707 upregulated and 1625 downregulated in the TetraRS compared to the SS strain. Gene Ontology (GO) annotations showed significant enrichment in categories related to metabolic processes, cellular processes, catalytic activity, cellular anatomical entity, and binding. These genes were also identified in key KEGG pathways such as cytochrome P450, drug metabolism, carbon metabolism, oxidative phosphorylation, fatty acid metabolism, and protein processing. RT-qPCR analysis confirmed that P450 genes (CYP405D1, CYP6AB269, and CYP4AU1) were upregulated in TetraRS insects, in line with the RNA-seq results. Cytochrome P450 activity was significantly higher in the TetraRS strain than in the SS strain. Notably, nano-encapsulated dsRNA targeting these overexpressed P450 genes increased the susceptibility of T. absoluta to tetraniliprole. Further, cytochrome P450 activity was significantly reduced following silencing of P450 genes. These findings suggest that multiple genes and pathways, particularly P450 genes, contribute to tetraniliprole resistance in T. absoluta. This study provides valuable insights into the molecular mechanisms underlying insecticide resistance in this key pest species.