Plant viruses can directly influence their insect vectors, and indirectly through their shared host plant, altering their behavior and performance in a mutualistic or rather antagonistic manner. One of the most studied begomovirus, Tomato yellow leaf curl virus (TYLCV), may also facilitate the expansion of its vector, the whitefly Bemisia tabaci (Gennadius). Considering the likely expansion of the disease and its major vector, we studied the direct and the indirect effects of a Mediterranean isolate of this virus (TYLCV-IL) on the biological performance of the Q biotype of B. tabaci. The following parameters were examined: development time and viability of nymphs, sex ratio, fecundity, and fertility and longevity. The results varied from positive to neutral depending on the parameter and the effect studied. TYLCV accelerated nymphal developmental and increased male longevity of B. tabaci when viruliferous insects developed on TYLCV-immune eggplants (direct effects). An indirect, positive effect of TYLCV-infected plants was observed on fecundity of B. tabaci, which laid more eggs on virus-infected than on noninfected tomato plants. Our results show that TYLCV enhances the population increase of its whitefly vector and that there is a high risk of rapid expansion of both the virus and its vector—the MED species of B. tabaci—into new areas when both agents interact together.

Tomato chlorosis virus (ToCV) is a phloem-limited crinivirus transmitted by whiteflies and seriously affects tomato crops worldwide. As with most vector-borne viral diseases, no cure is available, and the virus is managed primarily by the control of the vector. This study determined the effects of the foliar spraying with the insecticides, acetamiprid, flupyradifurone and cyantraniliprole, on the feeding behavior, mortality, oviposition and transmission efficiency of ToCV by B. tabaci MEAM1 in tomato plants. To evaluate mortality, oviposition and ToCV transmission in greenhouse conditions, viruliferous whiteflies were released on insecticide-treated plants at different time points (3, 24 and 72 h; 7 and 14 days) after spraying. Insect mortality was higher on plants treated with insecticides; however, only cyantraniliprole and flupyradifurone differed from them in all time points. The electrical penetration graph (DC-EPG) technique was used to monitor stylet activities of viruliferous B. tabaci in tomato plants 72 h after insecticide application. Only flupyradifurone affected the stylet activities of B. tabaci, reducing the number and duration of intracellular punctures (pd) and ingestion of phloem sap (E2), a behavior that possibly resulted in the lower percentage of ToCV transmission in this treatment (0–60%) in relation to the control treatment (60–90%) over the periods evaluated. Our results indicate that flupyradifurone may contribute to management of this pest and ToCV in tomato crops.

The corn leafhopper Dalbulus maidis is an important transmitter of viruses and bacteria to maize plants. Data on the stylet probing and ingestion behavior of D. maidis, gathered using the DC-electrical penetration graph (DC-EPG) technique, are limited. The increasing prevalence of this pest and the diseases that it transmits in maize crops heighten the importance of studying how control tools affect the probing behavior of these insects, to reduce or prevent the chances of pathogen transmission and the damage from feeding. Our study recorded stylet activities of D. maidis, using a DC-EPG system and compared the appearances of waveforms with those from published AC and AC-DC EPG studies. All types of systems produced similar waveform appearances; therefore, we used the waveform nomenclature previously published. We also determined the effects of the entomopathogenic fungus Cordyceps javanica on the probing behavior of D. maidis at different time points after the fungus was applied by spraying. Forty-eight hours after the insects were sprayed, the effects were pronounced, with significant disruption of the stylet activities in phloem and non-phloem phases. Our study indicated that this commercial microbiological product, with the active ingredient C. javanica, can alter the probing behavior of D. maidis and may be helpful in management of the vector.