Yaofa Li

Cloning, expression and characterisation of a novel gene encoding a chemosensory protein from Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae)

Chemosensory proteins (CSPs) are thought to play an important role in olfactory mediating perception, identification, transportation, and transduction of semio-chemicals. These proteins are also associated with the regulation of circadian rhythms and maturation of certain tissues or appendages. In this study, a cDNA from Bemisia tabaci encoding a CSP (GU250808), denoted BtabCSP was cloned by RT-PCR and rapid amplification of cDNA ends (RACE) technique. The genomic DNA sequence comparisons revealed a 1490 bp intron flanking the full length cDNA. Sequencing and structural analyses of the full length cDNA indicated that BtabCSP is 381 bp in length, encoding 126 amino acid residues of which a 22 amino acid residue coded for a signal peptide. The predicted molecular weight of BtabCSP is 14.17 kDa. The BtabCSP amino acid residues deduced from the respective full-length cDNA shares four conserved cysteine motifs with known CSPs from other insects. Homology modelling indicated a very good fit between the structural conformation of BtabCSP and a moth CSP molecule. The results of phylogenetic analyses indicates that the CSPs gene of Hemipteran insects have two more sub-families. The recombinant BtabCSP was successfully expressed in Escherichia coli cells. This is the first report on the existence of chemosensory protein-coding gene in whiteflies. It will help us to elucidate the molecular basis of whitefly behaviour, and explore new approach for the management of this major pest.

Attraction of Coffee Bean Weevil, Araecerus fasciculatus, to Volatiles from the Industrial Yeast Kluyveromyces lactis

The coffee bean weevil (CBW), Araecerus fasciculatus (De Geer, 1775) (Coleoptera: Anthribidae) is an important pest of stored products such as grains, coffee beans, cassava, and traditional Chinese medicine materials. In China, CBW causes large losses of Daqu, a traditional Chinese liquor fermentation starter, and, unfortunately, the use of conventional insecticides against CBW is not suitable in Daqu storage. We found CBW to be highly attracted to fermenting yeast cultures, such as Kluyveromyces lactis. Eight volatile compounds, produced by fermenting cultures and not by sterile samples, were identified by gas chromatography coupled with mass spectrometry. Five of these substances elicited significant responses in Y-tube behavioral bioassays. Field trapping experiments revealed 2-phenylethanol and 2-phenylethyl acetate to be crucial for attraction of CBW. Results show that yeast volatiles play an important role in host location, and that 2-phenylethanol and 2-phenylethyl acetate could be utilized as potential attractants in monitoring and control systems against this important pest.

Synthesis and biological activity of novel benzimidazole derivatives as potential antifungal agents

In the present study, a series of novel benzimidazole derivatives containing chrysanthemum acid moieties was designed and synthesized. Preliminary investigation of biological activity indicated that all of the compounds exhibited lower activity than that of beta-cypermethrin against Plutella xylostella and Lipaphis erysimi; meanwhile, they showed good inhibitory activity against Botrytis cinerea and Sclerotinia sclerotiorum in vitro. The fungicidal activity of compound 8a against B. cinerea was approximately equal to that of thiabendazole and was twice as active against S. sclerotiorum as was thiabendazole. In addition, compound 9e displayed the most potent inhibitory activity against both fungi and was almost twice as potent as thiabendazole.