Transmission of plant pathogenic viruses mostly relies on insect vectors. Plant virus could enhance its transmission by modulating the vector. Previously, we showed that feeding on virus infected plants can promote the reproduction of the sweet potato whitefly, Bemisia tabaci MED (Q biotype). In this study, using a whitefly-Tomato chlorosis virus (ToCV)-tomato system, we investigated how ToCV modulates B. tabaci MED reproduction to facilitate its spread. Here, we hypothesized that ToCV-infected tomato plants would increase B. tabaci MED fecundity via elevated vitellogenin (Vg) gene expression. As a result, fecundity and the relative expression of B. tabaci MED Vg was measured on ToCV-infected and uninfected tomato plants on days 4, 8, 12, 16, 20 and 24. The role of Vg on B. tabaci MED reproduction was examined in the presence and absence of ToCV using dietary RNAi. ToCV infection significantly increased B. tabaci MED fecundity on days 12, 16 and 20, and elevated Vg expression on days 8, 12 and 16. Both ovarian development and fecundity of B. tabaci MED were suppressed when Vg was silenced with or without ToCV infection. These combined results suggest that ToCV infection increases B. tabaci MED fecundity via elevated Vg expression.

Tomato yellow leaf curl virus (TYLCV) poses a significant threat to tomato production, leading to severe yield losses. The current control strategies primarily rely on the use of pesticides, which are often nonselective and costly. Therefore, there is an urgent need to identify more environmentally friendly alternatives. Dufulin, a novel compound that has been effective in controlling viral diseases in tobacco and rice, has not yet been tested against TYLCV. This study assessed the efficacy of dufulin in controlling TYLCV over a three-year span from 2021 to 2023 through field trials, by monitoring disease symptoms and viral titers. Additionally, this study assessed the expression levels of genes associated with systemic acquired resistance (SAR), specifically proteinase inhibitor II (PI II) and non-expressor of pathogenesis-related genes 1 (NPR1), using real-time qRT-PCR. The chlorophyll and nitrogen content in the leaves were also measured. Plants treated with dufulin showed reduced symptomatology and lower viral titers compared to the controls. Analysis of gene expression revealed that NPR1 was upregulated in the dufulin-treated plants, whereas PI II expression was consistently downregulated in the TYLCV-infected plants. Interestingly, PI II expression increased in the healthy plants following a seven-day post-treatment with dufulin. Moreover, the treated plants exhibited a higher chlorophyll content than the controls, though no significant differences in the nitrogen levels were observed between the dufulin-treated and water-treated plants. Overall, the application of dufulin significantly bolstered the plant’s defense response, effectively reducing TYLCV symptoms and enhancing resistance.

Insect vectors and insect-borne plant viruses seriously endanger the safety of agricultural production. An insecticide is one of the main methods to prevent insect-borne virus transmission. However, the curious relationship between the resistance of insect vectors and arboviruses has been less studied. In this study, the effect of Tomato chlorosis virus (ToCV) on the insecticide resistance of Bemisia tabaci MED was studied. It was found that the detoxification cytochrome P450, glutathione S-transferase, and carboxylesterase-related genes in ToCV-infected B. tabaci were upregulated. The activity of the three detoxification enzymes all increased at the same time, after 48 h of virus acquisition, with the activity of carboxylesterase being the most pronounced. It was found that cytochrome P450 and glutathione S-transferase activity was the least. ToCV led to the reduced sensitivity of B. tabaci MED to pyrethroids and flupyradifurone. Therefore, it was proven that the insect-borne plant virus ToCV shows the possibility of enhancing insect-borne insecticide resistance.

Bemisia tabaci is a globally important crop pest and virus vector with widespread resistance to conventional insecticides. We evaluated the insecticidal activity of a soybean-derived lecithin preparation and associated physiological responses. Leaf-surface, dried-residue contact, artificial-diet, and egg bioassays were combined with RNA sequencing, untargeted metabolomics, RT-qPCR, histology, and transmission electron microscopy. Dried-residue exposure yielded a 4 h LC₅₀ of 1.16 mg mL⁻¹ (95% confidence interval, 0.948–1.403 mg mL⁻¹), whereas 10 mg mL⁻¹ lecithin caused 100% adult mortality within 4 h and reduced egg hatchability from 99.44% to 37.78%. No mortality was detected after adults were provided with a sucrose diet containing 10 mg mL⁻¹ lecithin for 24 h. Exposure at the 4 h LC₅₀ was associated with differential expression of 135 genes and changes in 599 metabolic features, including responses related to cuticle organization, lysosomal and autophagy pathways, and amino acid metabolism. Histology and transmission electron microscopy revealed altered abdominal tissue organization and cellular ultrastructure. These findings establish contact-associated and egg-stage activity of lecithin against B. tabaci under laboratory conditions and identify accompanying structural, transcriptional, and metabolic responses. The molecular events responsible for mortality and the contribution of ingestion-mediated exposure remain unresolved.