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Background Plutella xylostella is one of the most serious insect pests of cruciferous crops. This study was conducted to determine the toxicity of 21 constituents from Lavandula angustifolia essential oil (LA-EO) and another 16 previously known LA-EO constituents and the toxicity of six experimental spray formulations containing the oil (1-6 g L(-1) sprays) to susceptible KS-PX and pyrethroid-resistant JJ-PX P. xylostella larvae, as well as to its endoparasitoid Cotesia glomerata adults. Results Linalool and linalool oxide (LC50 = 0.016 mg cm(-3) ) were the most toxic fumigant compounds and were 10.7-fold less toxic than dichlorvos to KS-PX larvae. Either residual or fumigant toxicity of these compounds was almost identical against larvae from either of the two strains. Against C. glomerata, dichlorvos (LC50 = 7 × 10(-6) mg cm(-3) ) was the most toxic insecticide. LA-EO was ∼1430 times less toxic than dichlorvos. The oil applied as 6 g L(-1) spray and emamectin benzoate 21.5 g L(-1) emulsifiable concentrate provided 100% mortality against larvae from either of the two strains. Conclusion Reasonable P. xylostella control in greenhouses can be achieved by a spray formulation containing the 6 g L(-1) oil as potential contact-action fumigant. © 2015 Society of Chemical Industry.

BACKGROUND An assessment was made of the repellency to female stable flies of tamanu nut oil fatty acids or their esters alone (each 0.5 mg cm−2) or in combination with cuminyl alcohol, cuminaldehyde and α-phellandrene (each 0.25 mg cm−2), using an exposed human hand bioassay. Results were compared with those of synthetic repellent DEET (0.25 mg cm−2). RESULTS Based upon protection time (PT) (time to first bite of stable fly), oleic acid, linoleic acid, methyl oleate or methyl linoleate synergised the repellency of each monoterpenoid and DEET. For example, the binary mixture of oleic acid and cuminyl alcohol (PT 2.05 h) resulted in significantly greater repellency than either oleic acid (0.55 h), cuminyl alcohol (0.70 h) or DEET alone (1.50 h). The binary mixtures of oleic acid and cuminyl alcohol or DEET (PT 2.10 h) did not differ significantly in repellency. The structure–activity relationship indicates that the degree of saturation, the side chain length and the functional group of fatty acids appear to play a role in determining the fatty acid repellency to stable flies. CONCLUSION Mixtures formulated from fatty acid and monoterpenoid could be useful as potential repellents for protecting humans and possibly domestic animals from bites caused by stable fly. © 2014 Society of Chemical Industry

Plutella xylostella is one of the most serious insect pests of cruciferous crops. This study was conducted to determine the toxicity of 21 constituents from Lavandula angustifolia essential oil (LA-EO) and another 16 previously known LA-EO constituents and the toxicity of six experimental spray formulations containing the oil (1-6 g L(-1) sprays) to susceptible KS-PX and pyrethroid-resistant JJ-PX P. xylostella larvae, as well as to its endoparasitoid Cotesia glomerata adults.Linalool and linalool oxide (LC50 = 0.016 mg cm(-3) ) were the most toxic fumigant compounds and were 10.7-fold less toxic than dichlorvos to KS-PX larvae. Either residual or fumigant toxicity of these compounds was almost identical against larvae from either of the two strains. Against C. glomerata, dichlorvos (LC50 = 7 × 10(-6) mg cm(-3) ) was the most toxic insecticide. LA-EO was ∼1430 times less toxic than dichlorvos. The oil applied as 6 g L(-1) spray and emamectin benzoate 21.5 g L(-1) emulsifiable concentrate provided 100% mortality against larvae from either of the two strains.Reasonable P. xylostella control in greenhouses can be achieved by a spray formulation containing the 6 g L(-1) oil as potential contact-action fumigant. © 2015 Society of Chemical Industry.

An assessment was made of the repellency to female stable flies of tamanu nut oil fatty acids or their esters alone (each 0.5 mg cm(-2) ) or in combination with cuminyl alcohol, cuminaldehyde and α-phellandrene (each 0.25 mg cm(-2) ), using an exposed human hand bioassay. Results were compared with those of synthetic repellent DEET (0.25 mg cm(-2) ).Based upon protection time (PT) (time to first bite of stable fly), oleic acid, linoleic acid, methyl oleate or methyl linoleate synergised the repellency of each monoterpenoid and DEET. For example, the binary mixture of oleic acid and cuminyl alcohol (PT 2.05 h) resulted in significantly greater repellency than either oleic acid (0.55 h), cuminyl alcohol (0.70 h) or DEET alone (1.50 h). The binary mixtures of oleic acid and cuminyl alcohol or DEET (PT 2.10 h) did not differ significantly in repellency. The structure-activity relationship indicates that the degree of saturation, the side chain length and the functional group of fatty acids appear to play a role in determining the fatty acid repellency to stable flies.Mixtures formulated from fatty acid and monoterpenoid could be useful as potential repellents for protecting humans and possibly domestic animals from bites caused by stable fly.

BACKGROUND: The repellency to stable fly, Stomoxys calcitrans (L.), of Zanthoxylum piperitum (L.) DC pericarp steam distillate (ZP-SD), Zanthoxylum armatum DC seed oil (ZA-SO) and their constituents alone or in combination with Calophyllum inophyllum L. nut oil (CI-NO), as well as six aerosol formulations containing ZP-SD or ZP-SO and CI-NO, was compared with that of a synthetic repellent, DEET, using an exposed human hand bioassay. RESULTS: At 0.20 mg cm−2, ZP-SD treatments resulted in 91 and 68% repellency following 30 and 60 min exposure respectively, while DEET gave 100 and 84% repellency. ZA-SO was less effective than ZP-SD. At 0.2 mg cm−2, the most active constituents, cuminaldehyde, cuminyl alcohol, limonene and methyl cinnamate, gave 82, 74, 74 and 64% repellency at 30 min respectively, but DEET gave 100 and 87% repellency at 30 and 60 min. An increase in effectiveness and duration of repellency was produced by binary mixtures of ZP-SD, ZA-SO or bioactive constituents (each 0.01 mg cm−2) and CI-NO (0.99 mg cm−2). The repellency of aerosols containing 2.5% ZP-SD or 2.5% ZA-SO and 2.5% CI-NO was comparable with that of 5% DEET aerosol. CONCLUSION: Mixtures formulated from ZP-SD, ZA-SO or bioactive constituents and CI-NO could be useful as potential repellents for the control of stable fly populations in light of global efforts to reduce the level of highly toxic synthetic repellents. Copyright © 2010 Society of Chemical Industry