Fumigant Toxicity of Crushed Bulbs of Two Allium Species to Callosobruchus maculatus (Fabricius) (Coleoptera: Bruchidae)
Fumigant toxicity of crushed fresh bulbs of Allium sativum L. and A. cepa L. to the Callosobruchus maculatus (Fabricius), a major pest of stored cowpea (Vigna unguiculata (L.) Walp.) seeds was assessed under laboratory conditions in Akure, Nigeria. In the tests, 20 g of infested cowpea seeds were suspended in a piece of muslin cloth, over an amount of crushed bulb in a container with a tightly fitted lid. Adult emergence was completely prevented from freshly laid eggs of C. maculatus on cowpea seeds that was fumigated with 6.0 g or more of crushed bulbs of A. sativum. Such fumigated seeds were not holed at all. Other amounts of A. sativum tested (1.0, 2.0, 3.0, 4.0 and 5.0 g) significantly reduced C. maculatus adult emergence from fumigated eggs and seed holing in comparison with the control. Crushed A. sativum was ineffective in preventing adult emergence from fumigated C. maculatus larvae in seeds. The fumigant effect of crushed A. cepa did not kill all C. maculatus eggs. An amount of 7.0 g significantly reduced C. maculatus adult emergence from fumigated eggs and seed holing in comparison with the control. There is good prospect in using crushed bulbs of A. sativum> as fumigant in C. maculatus control in stored cowpea seeds.