Rearing cactoblastis cactorum (Lepidoptera: Pyralidae) on a Factitious Meridic Diet at Different Temperatures and Larval Densities

Abstract

Cactoblastis cactorum (Berg) is an invasive pest that represents an economic and ecological threat to native cacti in the U. S. and Mexico and that is currently the object of an eradication/control program in both countries. One tactic used to mitigate the threat of this species involves the SIT (Sterile Insect Technique), in which large numbers of larvae are reared on artificial diet or cactus cladodes, preferably the former, and released as sterile adults to mate with wild individuals at or near the leading edge of invasion. We studied combinations of 3 different rearing temperatures (22, 26, and 29°C) and 3 different crowding levels (50, 215, and 500 eggs) to determine percent survival to the adult stage, pupal size of each gender, and fecundity of C. cactorum reared on a factitious meridic diet. Temperature and crowding levels affected survival. The lowest rearing temperature and the low and high crowding levels adversely affect survival. Female pupae were larger than male pupae, and pupal size of males, but not females, was affected by rearing temperature, with smaller male pupae produced at the lowest temperature. Length and width, but not weight, of female pupae were affected by crowding levels, with slightly larger pupae produced at the intermediate level. For both genders, there was significant regression of pupal weight on percent survival, with larger pupae produced from treatment combinations that produced higher percent survival to the adult stage. Number of eggs laid per female was positively correlated with weight of the female as a pupa.