The host range and oviposition behavior of Ochrimnus mimulus (Hemiptera: Lygaeidae) in central Texas

Ochrimnus mimulus is a univoltine seed predator occurring on Baccharis sp. and other Asteraceae in the southern United States and northern Mexico. The insect displayed a preference for Baccharis in the field, with 76% of adults and nymphs found on Baccharis, 15% on asteraceous plants, and 9% on plants outside the tribe in 1993; similar patterns were observed in 1997. When ovipositing in dichotomous choice experiments, O. mimulus females laid 81% of their eggs in Baccharis inflorescences and 19% in non-Baccharis inflorescences. Adult O. mimulus populations on 2 to 6 year-old Baccharis were estimated to range from 64 to 165 individuals during the mating season. A significant interaction (P = 0.017) occurs between the effects of photoperiod and food availability on O. mimulus oviposition, with the most eggs being laid under short photoperiod and in the presence of seeds. We believe that Baccharis is the principal host of O. mimulus, and that the insect's phenology is closely tied to that of the plant such that it maximizes its access to good quality Baccharis seeds and ovules.