Insecticidal activity of crude essential oils of four aromatic plants against Callosobruchus maculatus (Coleoptera: Bruchidae) [electronic resource].

Includes references.

The contact toxicity, fumigant and oviposition deterrent activities of the essential oils from four plant species, geranium (Pelargonium graveolens), aniseed (Pimpinella anisum), German chamomile (Matricaria chamomilla) and Bitter orange bigarade (Citrus aurantium) were evaluated against Callosobruchus maculatus adults. Residue contact toxicity assayed by exposure of insect adults to thin film of oil in Petri dish showed that, at 24 h of treatment, P. graveolens oil was the most effective (LC50 = 3.5 mg/L) followed by P. anisum oil (LC50 = 4.9 mg/L). However, in the fumigation assay, after 24 h exposure, the LC50 values demonstrated that the most effective essential oils were P. graveolens (29.4 mg/L air) followed by P. anisum (50.0 mg/L air), and C. aurantium 79.38 mg/L air. The fumigant toxicity increased with increasing in exposure periods. The time needed for the essential oil to cause LT50 (median lethal time) was also estimated at the highest concentration used (2000 mg oil per kg cowpea seeds). Based on LT5O values, it was shown that C. aurantium oil was the most toxic material against insect LT50 = 10.24 hrs) followed by oils of P. anisum and M. chamomilla (LT50s were 19.5 h and 16.2 h, respectively). Key words: Essential oils, contact toxicity, fumigant, oviposition deterrent, GC/MS analysis, cowpea seed beetle .

Summary in Arabic.

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