Insecticidal activity of some vegetable oils against Dermestes maculatus Degeer (Coleoptera: Dermestidae) on dried fish

Abstract

The insecticidal activity of some vegetable oils against Dermestes maculatus Degeer on dried trout ( Salmo gairdnerii) was investigated. In experiments under simulated storage conditions, the application of oils (groundnut, traditional coconut, industrial coconut, palm, shark liver oil) to exposed surface of dried trout significantly reduced the development of progeny of D. maculatus only at dosages in excess of 56 ml/kg. However, when D. maculatus eggs were assayed against groundnut oil, freshly applied on dried trout surfaces, the LC 50 value was found to be as low as 18.29 ml/kg. It was observed that absorption of surface oil by fish muscle over time reduced activity against eggs. Generally, the oils were shown to act mainly against eggs and to have no direct toxicity against active stages of the insect. Topical and glass film application of vegetable oils against adults and larvae confirmed these observations. On the basis of available data, the possibility of using successive applications of fixed vegetable oils in controlling D. maculatus on dried fish is discussed.