Studies on the humidity and temperature reactions of Dermestes maculatus Deg. (Col., Dermestidae), with reference to infestation in dried fish in Nigeria

Abstract

Infestations of Dermestes maculatus Deg. in dried fish at Dugbe market, Ibadan, are favoured by traditional packaging and display methods. In laboratory experiments last-instar larvae and adults showed low thigmokinesis and a bias towards the dry end of a 50–100% r.h. gradient; in alternative humidities between 40% and 100% last-instar larvae and adults selected 60–80% r.h., adults having a stronger preference than the larvae for the higher humidity; in a temperature gradient last-instar larvae and adults avoided the 30–45° C zone and showed low thigmokinesis and immobilisation at 19° C. These findings were generally consistent with observations in the market. Heating dried fish in an oven at 60° C for 30 min killed all larvae and adults of D. maculatus present. Two 30-min heat treatments at four-day intervals in a simple charcoal-fired oven and storage in metal containers would control the pest.