The effects of different plant foods on the fecundity, fertility and development of a cotton stainer,Dysdercus superstitiosus(F.)

Abstract

Dysdercus superstitiosus(F.) is capable of utilising a much wider range of food-plants than was previously supposed, and is able to complete a full breeding cycle on the several diets other than cotton. This has been demonstrated by rearing and breeding adults and nymphs in the laboratory, in Uganda, on selected food material,e.g., Sorghum vulgare, Pennisetum typhoides, Zea maysandVigna unguiculata, immature seeds of each being used. Diets other than mature cotton seeds are less suitable for breeding, as judged by fecundity of females and development of nymphs, but the influence of nymphal diet on adult fecundity is not consistent. Females reared on sorghum are smaller than those reared on cotton seed and they may lay fewer eggs.There is an indication that varieties of sorghum may differ in their suitability for producing maximum fecundity and fertility. Those varieties to which the stainer exhibits a predisposition in the field may not be the most suitable.When adults are fed on cotton bolls of ages 1–10 weeks, the fecundity of females, and the rate of egg-production increase with increasing age of boll, and the preoviposition period decreases.Stored cotton seed may be less suitable for egg-production than freshly harvested seed cotton.Extraction of oil from cotton seed with petroleum ether does not wholly impair the fecundity rate of females fed on the seed, but may reduce the fertility and nymphal survival in the first instar.A diet of cotton seed, heat treated at 150–190°C. for one hour, reduces the fecundity in the females, possibly by destroying the accessary food factors. Nymphal survival is possible on such treated seed, but not when thus heated for two hours at or above 150°C.