Isolation and Characterization of Insecticidal Toxins from the Venom of the North African Scorpion, Buthacus leptochelys

Various bioactive peptides have been identified in scorpion venom, but there are many scorpion species whose venom has not been investigated. In this study, we characterized venom components of the North African scorpion, Buthacus leptochelys, by mass spectrometric analysis and evaluated their insect toxicity. This is the first report of chemical and biological characterization of the B. leptochelys venom. LC/MS analysis detected at least 148 components in the venom. We isolated four peptides that show insect toxicity (Bl-1, Bl-2, Bl-3, and Bl-4) through bioassay-guided HPLC fractionation. These toxins were found to be similar to scorpion α- and β-toxins based on their N-terminal sequences. Among them, the complete primary structure of Bl-1 was determined by combination of Edman degradation and MS/MS analysis. Bl-1 is composed of 67 amino acid residues and crosslinked with four disulfide bonds. Since Bl-1 shares high sequence similarity with α-like toxins, it is likely that it acts on Na+ channels of both insects and mammals.

Monitoring the concentration of methyl bromide in the treated space during commercial fumigation of logs

Development of sciencebased fumigation schedules for phytosanitary treatments relies on an understanding of the factors which influence the effectiveness of a fumigant under different conditions Understanding the sorption characteristics of a fumigant is a critical step in establishing commercial treatment schedules as this process which involves adsorption and absorption of fumigant molecules influences the concentration of the fumigant remaining in the treated space after fumigation and hence the amount of fumigant available to kill insects We monitored the concentration of methyl bromide during commercial fumigation of three log stacks (average volume 4078 m3) with 120 g/m3 methyl bromide for 13 h under a tarpaulin Pine (Pinus radiata D Don) logs were fumigated at South Port Bluff (New Zealand) during April 2015 Gas samples from the treated space were taken at 05 1 2 3 the treated space indicating that the rest of the fumigant was sorbed These data can now be combined with insect toxicity studies to guide the development of improved commercial treatment schedules to treat log exports from New Zealand

Toxicity of selected agrichemicals to clover root weevil and its parasitoid Microctonus aethiopoides

White clover (Trifolium repens) crops are attacked by various insect pests including Sitona obsoletus (S lepidus) (CRW) Laboratory experiments were conducted to measure the toxicity of eight agrichemicals used against white clover insect pests or for weed control on CRW (parasitised and nonparasitised) and adults of its parasitoid Microctonus aethiopoides Laboratory experiments evaluated insect toxicity through direct contact with the agrichemical spray or via exposure to residues on clover foliage At field rates pymetrozine had the lowest impact on CRW biocontrol but had poor activity against nonparasitised CRW Taufluvalinate provided 60 control of CRW while having reduced impact on M aethiopoides adults (060 mortality) and was considered the best option in the field over the summer period Lambdacyhalothrin and diazinon were the most detrimental to CRW and its biocontrol agent when applied directly and through exposure to residues Diquat and an adjuvant caused some mortality to CRW and parasitoid Field studies are needed to corroborate these results