The bruchid Callosobruchus maculatus (F.) causes major losses during the storage of seeds of Vigna unguiculata (Walp.) in West Africa. An endemic parasitoid, the pteromalid Dinarmus basalis (Rond.) reduces the increase in bruchid populations in stores and could be used for biological control. African farmers often introduce essential oils into granaries at harvest time. In Togo, essential oils were extracted from two Gramineae, Cymbopogon nardus (L.) and Cymbopogon schoenanthus (L.) and from a Lamiaceae, Ocimum basilicum (L.). The major components of these essential oils were citronellal in C. nardus, carene-2 and piperitone in C. schoenanthus and estragol in O. basilicum. Cymbopogon schoenanthus was the most toxic oil for C. maculatus adults. D. basalis adults were more susceptible to the three essential oils than the adults of their hosts C. maculatus. In the presence of cowpea seeds, the LC50s of the three essential oils were lower than in their absence, suggesting that the seeds may absorb a part of the volatiles. High doses of three essential oils slightly affected the survival of the fourth instar or the pupae of C. maculatus. This high survival was due to protection of larvae from volatiles by the surrounding seeds. The D. basalis were more affected by the oil volatiles than their hosts. Sub-lethal doses of essential oils reduced the duration of the adult life of both insect species and fecundity of the females. The differences in sensitivity of the host and its parasitoid could influence their population dynamics. The introduction of the essential oils into storage systems potentially could reduce density of parasitoid populations and increase seed losses.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.
Vol. 95 • No. 1