Bemisia tabaci is a species complex consist of about 40 cryptic species. This species is also a vector of at least 100 begomovirus including Tomato yellow leaf curl virus (TYLCV). TYLCV transmitted by B. tabaci in a circulative propagative manner but its molecular mechanism is remain unclear. We investigate the transcriptional response of B. tabaci MED to TYLCV infection using next generation sequencing (NGS) analysis. In total 16757 differentially expressed genes between viruliferous and non-viruliferous whiteflies were analyzed. Among them 289 transcripts found significant, where 116 up-regulated and 173 down-regulated. Our results reveal the whitefly-TYLCV relationship and provide important molecular information about virus transmission of vector insects.

Spodoptera litura Fabricius is the serious, polyphagous pest of various crops. Due to the high resistant to most of chemical pesticides, it is hard to control S. litura in the fields. We investigated the virulence of four entomopathogenic nematodes (EPNs) in each larval stage. All EPNs were more effective to younger larvae than older larvae. Mortality, larval penetration rate and reproduction rate were significantly higher in H. indica, S. carpocapsae and S. longicaudum than the H. bacteriophora. Three high effective EPNs induced complete mortality of first instar larvae within 48 h, but of fifth instar larvae within 72 h. These EPNs also highly effective to control S. litura in pot assay. Thus, H. indica, S. carpocapsae and S. longicaudum, can be used as efficient biological control agents of S. litura.

Tomato yellow leaf curl virus (TYLCV) and its vector insect, the sweet potato whitefly Bemisia tabaci, are major threats to tomato and pepper production in all around world. Since the last three decades, both B. tabaci and TYLCV have been invaded into many countries via different routes. Our studies showed that various geminiviruses including TYLCV can be transmissible by seeds as well as whiteflies. Furthermore, commercially developed resistant tomato strains against TYLCV infection can serve as TYLCV reservoirs and potentially influence on TYLCV epidemics. Therefore, transmission pathways through both insect vectors and seeds should be concerned for suitable management of geminiviruses and whiteflies.

Methyl benzoate (MB) is a natural compound in many plants and shows insecticidal toxicity against various insect pests. We determined contact, fumigant, and repellent activities of MB against the sweetpotato whitefly Bemisia tabaci and the greenhouse whitefly Trialeurodes vaporariorum (Hemiptera: Aleyrodidae). Complete contact mortality was obtained by 4% MB. Contact mortality at 2% MB into eggs, 4th instar nymphs and adults were 69.4%, 91.6% and 80%, respectively. Fumigation of 2% MB killed 95% of adults. In addition, treatment of 4% MB repelled 60% adults. There was no significant different between two species. Our results suggest that MB has high potential as an natural pesticide for sustainable pest management in crop production.

Fungus gnat, Bradysia impatiens is the most serious pest of different vegetable crops, mushroom and ornamental crops. In this study, we compared the control efficacy of two entomopathogenic nematode; Steinernema carpocapsae and Heterorhabdistis indica in Bradysia impatiens last instar maggots at 25℃ in laboratory. Our present study shows that, nematode infection and reproduction both were higher in the warm adapted nematode H. indica than the cold adapted S. carpocapsae. Therefore, entomopathogenic nematode H. indica can be use for control the Badysia impatiens as the efficient biological control agent.

Bemisia tabaci is a vector of Tomato yellow leaf curl virus (TYLCV) but Trialeurodes vaporariorum is not. To determine the effect of TYLCV acquisition on vector and non-vector, we compared various physiological characteristics between two species. Our results showed that TYLCV acquisition significantly affected B. tabaci but not T. vaporariorum. The B. tabaci increased susceptibility against thermal stress but weakened chill coma recovery, shortening of longevity, low fecundity and abbreviated developmental time by virus acquisition. At the molecular level, B. tabaci increased hsp70 and hsp90 levels by TYLCV ingestion. However, T. vaporariorum did not shown any changes of those characteristics. Therefore, the physiological manipulation of TYLCV was specific to vector species but not non-vector species.

The sweetpotato whitefly Bemisia tabaci is one of the most serious pests in the greenhouse. They can infest variouscrop plants even in high warm greenhouse condition in summer. To understand the effect of heat acclimation ability ofB. tabaci, mortality was determined at various temperature conditions of the greenhouse. Adult whiteflies survived evenin 63°C in tomato greenhouse. The median lethal temperature (LT50) of the greenhouse colony was 59.9°C however LT50of the lab colony was 47.6°C. The relative expression level of heat shock proteins (hsp23, hsp70 and hsp90) were significantlylower in the greenhouse colony compare to the lab colony. This result suggests B. tabaci has very high thermal adaptability(acclimation) and its mechanism is associated with heat shock protein system.

The sweetpotato whitefly Bemisia tabaci is a serious pest and virus vector of many crops. To understand thermal tolerance of B. tabaci at molecular level, effects of rapid and acclimated thermal stress were analyzed by measuring mRNA levels of two heat shock proteins (hsp), hsp23 and hsp90, of B. tabaci using quantitative real-time RT-PCR. Mortality of adult whiteflies were 65.5% by 45°C for 1 h but 100% by 50°C for 1 h. However, mortality by subsequent exposures to 35°C for 1 h then 45°C for 1 h was 43.3%. Comparison between rapid and acclimated heat shock treatments showed that different patterns between hsp23 and hsp90 levels. At acclimated condition, hsp90 was higher but hsp23 was lower than rapid heat shock. The results suggest that the heat acclimation response is possibly advantageous to whiteflies that are often exposed to drastic temperature fluctuations.

The sweetpotato whitefly Bemisia tabaci (Gennadius) is one of the most important sap sucking pests causing economic losses in a variety of vegetables in Bangladesh and as well as around the world. In the present study, the mtCOI sequence of B. tabaci was analysed using samples collected from different host plants (Potato, Brinjal, Tomato, Sweet potato, Bean) from district Gazipur, Patuakhali, Rajshahi and Nilphamari of Bangladesh. Phylogenetic analysis of our samples and relative sequences of B. tabaci in NCBI database was shown three independent clusters. Samples in Bangladesh were most similar with those of Thailand, Vietnam, Pakistan, China and India but did not show any B and Q aggressive biotypes.