Larvicidal and repellent activity of tetradecanoic acid against Aedes aegypti(Linn.) and Culex quinquejasciatus(Say.)(Diptera:Culicidae)

Objective:To investigate the larvicidal and repellent efficacy of tetradecanoic acid against Aedes aegrpti（Ae.aegypti） L,and Culex quinquefasciatus（Cx.quinquefasciatus） Say（Diptera: Culicidae）.Methods:Larvicidal efficacy of tetradecanoic acid was tested at various concentrations against the early third instar larvae of Ae.aegypti and Cx.quinquefasciatus. The repellent activity was determined against two mosquito species at three concentrations viz..1.0.2.5 and 5.0 ppm under the laboratory conditions.Results:The tetradecanoic acid was found to be more effective against Cx.quinquefasciatus than Ae.aegypti larvae.The LC50 values were 14.08 ppm and 25.10 ppm,respectively.Tetradecanoic acid showed lesser repellency against Ae.aegypti and Cx.quinquefasciatus.The highest repellency was observed in higher concentration of 5.0 mg/cm2 provided 100%protection up to 60 and 90 min against Ae.aegypti and Cx.quinquefasciatus respectively.Conclusions:From the results it can be concluded the tetradecanoic acid is a potential for controlling Cx.quinquefasciatus and Ae.aegypti mosquitoes.

Fatty acids derived from oviposition systems guide female black soldier flies(Hermetia illucens)toward egg deposition sites

The black soldier fly,Hermetia illucens,comes with big promises for industrial purposes since its larvae feed polyphagously on a broad spectrum of organic substrates.However,research focusing on adult flies is scarce,which is inconsistent with their reproductive relevance within the rearing cycle.In particular,directed oviposition is a challenge in artificial systems.Currently,decomposing organic matter is commonly used as oviposition substrate,which has extensive potential for improvement in view of the lack of standardization and the risk of microbial contamination.Here,we identified three fatty acids and one fatty acid methyl ester derived from the surface of old oviposition sites and targeted to elucidate their effect on preference behavior and oviposition site selection using Y-olfactometry and prepared oviposition sites,respectively.Exposure to tetradecanoic acid attracted gravid females and stimulated oviposition most strongly,while decanoic acid demonstrated a repulsive effect.Females kept in mixed-sex populations were attracted by tetradecanoic acid,resulting in a higher egg mass found in the compound box(3.0–11.4 fold),a≥2.3 fold reduction of nonspecifically deposited eggs,and the highest total egg mass.Conversely,decanoic and dodecanoic acid caused females to lay a greater proportion of eggs nonspecifically outside both boxes.Our data suggest that fatty acids,especially tetradecanoic acid,are important cues for oviposition site selection in black soldier flies.In order to achieve a directed oviposition behavior,the role of further short-and long-chain fatty acids as attractants should be examined.