Tobacco whitefly-Bemisia tabaci is considered one of the most important pests in tropical and subtropical agriculture, as well as in production systems in glasshouses in temperate zones. Principle research on the identity of B. tabaci began with the recognition of more than one biotype differing in life history parameters, host plant associations, plant-related damage and insecticide resistance. Our laboratory strains of B. tabaci were identified and classified as biotype B and Q, through mtCOI PCR. Also, they were tested for their host plant preference and reaction to different insecticide. Biotype Q prefers to feed on red pepper and tomato, was less susceptible to tested insecticides, for instance acetamipirid, spinosad and thiamethoxam, than the biotype B (feed on tomato alone). There has been a report on the presence of gut bacteria in B. argentifolii (= B. tabaci biotype B) and its influence on the host insect processes. Hence, as a further pursuit, we examined our laboratory B. tabaci biotypes B and Q for their gut bacteria, whether these two biotypes are differed with each other. Gut bacterial strains isolated by standard surface sterilization method was identified through 16S rRNA gene sequence. Gut bacterial strains of B. tabaci biotypes B and Q and their close relatives retrieved from the public database (NCBI) indicated that the biotype B was less diversified only with four genera viz., Bacillus, Micrococcus, Pseudomonas and Staphylococcus, whereas the biotype Q diversified with six such as Bacillus, Janibacter, Micrococcus, Staphylococcus, Stenotrophomonas, and Streptomyces. Results of the present investigation suggesting that there may be a relationship with gut bacterial strains and susceptibility to insecticides and host plant preference of B. tabaci biotype B and Q.

This study was done to evaluate the susceptibility, systemic effect, residual effect and control effect in each developmental stages of biotype Q of sweetpotato whitefly against insecticides, acetamiprid+spinetoram SC and dinotefuran SG. Two insecticides were showed similar activity against the eggs, and showed higher activity in acetamiprid+spinetoram SC against the nymph and adult. In systemic effect, two insecticides have a similar activity. It was showed higher activity in root zone systemic application than leaf zone systemic application. Residual effect was showed higher in acetamiprid+spinetoram SC (92%) than dinotefuran SG (44 %) at seven days after treatment. Control effect was showed all over 90 % activity at tree- and seven days after treatment. Therefore, these insecticides are expected to control the sweetpotato whitefly effectively.