Mitigating trans-boundary movement of Bemisia tabaci (Hemiptera: Aleyrodidae) on Mentha sp. by pre-shipping treatments of biopesticides

Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) cryptic species complex represents a major threat to several important crops including vegetables, cereals, fruits, and ornamentals worldwide. One important mode of its dispersal is through the trans-boundary (domestic, international) movement of infested plant materials. To prevent the spread of this invasive insect pest on inter-state ornamental shipments, the efficacy of biopesticides was tested through dip treatments of plant material pre-shipping. In several experiments, clean Mentha sp. (Lamiaceae), mint plants were exposed to adults of B. tabaci for 1 or 6 days. Adults were removed from plants and eggs, and immature stages were treated with one or a combination of the following: entomopathogenic fungi Beauveria bassiana (BotaniGard®), Isaria fumosorosea (Preferal®), the surfactant Natur'l Oil™, and soap (Publix®). After treatment application, plants were placed in commercial cardboard boxes and shipped from Apopka, Florida (FL) to Fort Pierce, FL. Assessments for the treatment efficacies were conducted at 3, 7, and 14 days post arrival of the shipment. Fungal entomopathogens; B. bassiana, I. fumosorosea, and the surfactant Natur'l Oil™, showed significant reduction in the whitefly population compared to the untreated control (P < 0.05). Significantly higher corrected mortality of the whitefly populations was observed when B. bassiana was applied alone (81%) or in combination with Natur'l Oil™ (86%), as well as I. fumosorosea applied in combination with Natur'l Oil™ (77%). Our results showed that pre-shipping dip treatment applications of either Natur'l Oil™ mixed with B. bassiana or I. fumosorosea or B. bassiana applied alone could help mitigate the inter-state spread of whitefly on ornamental shipments.