Articles

Efficacy of Botanical Oils on Adult Mortality, Egg Laying, Hatchability and Adult Emergence of Callosobruchus. Maculatus (F.) (Coleoptera: Chrysomelidae: Bruchidae)

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The cowpea weevil Callosobruchus maculatus Fabricius, is the major insect pest that threatens effective legume storage. The laboratory experiment was conducted to assess the efficacy of four different botanical oils (Clove, Eucalyptus, Jojoba and Lemon) against the cowpea weevil, C. maculatus by using residual film technique. All the botanical oils were applied at two different concentration levels (0/50 and 0.75%). The results showed that all used oils significantly increased the mortality and reduced the mean number of eggs laying, hatchability and emergence percentages compared to the untreated control. The treatment of cowpea seeds with oils reduced slightly the germination but swelling percentage was higher in treated seeds than control. The results also indicated variation in the activity of botanical oils regarding the stage of the insect, the plant origin of the oils and concentration level. The present study suggested that botanical oils (Clove, Eucalyptus, Jojoba and Lemon) may be preferred option than conventional pesticides far the protecting stored pulse grains against stored products insect pests’ infestation, especially C. maculatus.

The Differences in Toxicity of Pletekan Leaf Extracts (Ruellia tuberosa L.) and Lime (Citrus auraiflia) on Mortality of Culex sp. Mosquito Larvae

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Mosquitoes Culex sp. is the main vector of filariasis. Population control using chemical larvicides continuously can cause resistance. The leaves of the pletekan plant (Ruellia tuberosa L.) and lime fruit (Citrus aurantifolia) have the potential as natural larvicides. This study aims to determine the differences in high toxicity (LC50) of pletekan leaf extract and lime fruit on the mortality of Culex sp. mosquito larvae with an exposure time of 24 hours. Pletekan leaf extract and lime fruit were extracted by maceration using 97% ethanol. The LC50 can use probit analysis with SPSS applications. The results showed that pletekan leaves were toxic to Culex sp. mosquito larvae with an LC50 value of 710.169 ppm with the lowest concentration of 615.231 ppm and the highest concentration of 796.157 ppm. The LC50 value of lime fruit extract was 1026.749 ppm, with a lower limit of 846.406 ppm and an upper limit of 1294.531 ppm.