Egg-Dumping: A Strategy for Host Range Expansion in Callosobruchus maculatus (Coleoptera: Bruchidae)

Herbivorous and parasitic females often show adaptive behavioral plasticity in response to their resources for oviposition. However, the phenomenon of individuals continuing oviposition on unsuitable places if hosts are unavailable also occurs, which is referred to as egg-dumping behavior. In previous studies, this egg-dumping behavior was considered to be a maladaptive behavior because some physiological constraints. In the current study, by clearly designating individuals as a dumper or nondumper in a population within 24 h, the life-history traits of female weevils, Callosobruchus maculatus (F.), with different oviposition characters were compared, and no significant differences were observed. In addition, this study provides two lines of evidence: 1) the egg-dumping rate was influenced by host experience; and 2) different host acceptance to novel beans between dumper and nondumper females. The inferences are that egg-dumping behavior may be a strategy for host range expansion by cowpea weevils if preferred hosts are not available.