Bemisia tabaci (Gennadius) Middle East-Asia Minor 1 (MEAM1) is a well known invasive insect species. Little information is available on immune system of B. tabaci to date. In this study, one of the Toll-like receptors (TLR; namely BtToll) was cloned in MEAM1 B. tabaci which contains an open reading frame of 3153bp, encoding putative 1050 amino acids. Phylogenetic analysis indicated that BtToll is highly identitical with other members of the TLR family. Transcripts of BtToll detected through qRT-PCR were expressed in all developmental stages of B. tabaci and the highest expression level was observed in the 3rd nymphal instar. BtToll was highly expressed in response to immune challenge. RNA interference was used to knockdown the BtToll expression in adults through the oral route which resulted in significant reduction of BtToll transcript. When the adults were challenged with a mycotoxin from entomogenous fungi - destruxin A (DA) and RNAi, the median lethal concentration (LC50) decreased by 70.67% compared to DA treatment only. Our results suggest that BtToll is an important component of the B. tabaci immune system. RNAi technology using dsToll combined with general control methods (using toxin only) can be used as a potential strategy in integrated B. tabaci management programs.

The Mediterranean fruit fly, Ceratitis capitata (Wiedemann), is considered one of the most invasive tephritid species. It has spread and established populations successfully throughout many of the tropical temperate regions, partially owing to the increase in global trading activity that facilitates diffusion of species. However, C. capitata has never been detected in China, even though some areas of the country have favorable climate and ample food resources. Historically, some researchers have hypothesized that the principal reasons for its absence are the defenses mounted by native Bactrocera species against C. capitata. We evaluated the modes and strengths of interspecific competition between C. capitata and two Bactrocera species (Bactrocera dorsalis Hendel and Bactrocera correcta Bezzi) by conducting experiments on behavioral interference between the adults of these fruit fly species. Under appropriate conditions, the two Bactrocera species showed a distinct advantage in competition for oviposition, noticeably suppressing C. capitata. Although no mating interference between C. capitata and the two Bactrocera species was observed, the role of interference competition in the prevention of C. capitata invasion is still worthy of being discussed.

Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is a serious pest of agricultural crops in different regions of the world. Destruxin A (DA) is one of 39 derivatives of destruxins, which are secondary metabolites produced by entomopathogenic fungi. Due to the high insecticidal activity, DA have great application potential in biological control of B. tabaci . In order to understand the impact of destruxin A on the energy substances of the global pest B. tabaci , we measured the changes in energy substance content of the B. tabaci adults treated with DA at LC ₁₀ and LC ₅₀ concentrations after 4, 8, and 12 hours. The results revealed that DA caused varying degrees of decline in trehalose, soluble sugars, and glycogen content, indicating its ability to influence the energy substance content of whiteflies. After DA treatment, the content of trehalose in B. tabaci decreased significantly, while the activity of trehalase, a specific hydrolase for trehalose, increased significantly. Further study of the expression levels of two genes ( BtTre-1 and BtTre-2 ) encoding trehalases in B. tabaci after DA treatment showed that the soluble trehalase gene, BtTre-1 , was induced in both low and high concentrations of DA, while the membrane-bound trehalase gene, BtTre-2 , did not show significant changes in expression level.