The toxicity of neem extracts that induce abnormality and lethality is strongly enhanced by the ingestion rather than surface contact. Oral toxicity of neem extracts was analyzed using a plant sapping pest Bemisia tabaci. When adults were allowed to ingest various doses (0, 5, 10, and 50 ppm) of azadirachtin diluted in 20% sugar solution in a double-layered parafilm chamber for 72 h, mortality was 12.5, 77.5, 97.5, 100%, respectively. When a cucumber leaf which has many nymphs were submerged into the solution of neem extract, adult eclosion was decreased to 87.0, 16.6, 16.1, and 6.6%, respectively. Further, when neem extracts were irrigated into the tomato cultivar the average number of nymphs per leaf was decreased to 60.3% in comparison with the untreated control. These result suggest that systemic treatment of neem extracts was effective for the control of whiteflies as well as other sucking insect pests.

Tomato yellow leaf curl virus (TYLCV) causes a highly serious disease in tomatoes in many countries. The most important thing in management is the prevention of virus transmission. TYLCV had been known to be only transmitted by a vector, the sweetpotato whitelfy, Bemisia tabaci. However, we identified two other important routes of TYLCV transmission into tomatoes. It is seed-transmissible. Many seeds available in domestic and global markets were infected by TYLCV. It is also infective into various weeds and other horticultural crops and transmit virus through vector insects. Therefore, we need a new strategy for the virus and vector management.