Axenic culture of the foreign grain beetle,Ahasverus advena(Waltl) (Coleoptera, Silvanidae), and the rôle of fungi in its nutrition

Abstract

The extent of the dependence of the foreign grain beetle,Ahasverus advena(Waltl), upon moulds in its diet was investigated.Using a simple technique, the insect was cultured axenically at controlled temperature and relative humidity on an autoclaved mixture of rolled oats, wheatfeed and dried yeast. After the mixture was sterilised by exposure to propylene oxide vapour, virtually no larvae completed development on it in the absence of living micro-organisms, and this effect was unchanged by the addition of a mixture of B-vitamins followed by autoclaving. However, when fungi were grown on the food previously sterilised with propylene oxide, it again permitted the complete development of the insect.Autoelaved wheat germ was not a suitable diet forA. advenaunless a small proportion of dried yeast was added before autoclaving. It is concluded that living fungi are not essential in the diet of the insect, but that they may supplement an otherwise inadequate diet.The minimum development time from egg to adult on a complete food at 80 per cent. E.H. and 30°C. varied from 18 to 25 days.