Development and Behavior of Immature Stages of the Maize Weevil (Coleoptera: Curculionidae) within Kernels of Resistant and Susceptible Maize

Abstract

Development and behavior of the maize weevil, Sitophilus zeamais Motschulsky, were studied in artificially infested kernels of resistant and susceptible maize. Four instars and the prepupal and pupal stages were determined by observing daily radiographs of 76 larvae. Larval molt was determined by a sudden increase in tunnel diameter. The lengths of the first, second, and third stadia were similar in both resistant and susceptible maize. The fourth stadium was significantly shorter in the resistant types. In general, the first and second stadia were significantly longer than the others, probably because of handling stress. Longer first stadia also occurred when larvae were placed in the endosperm. Feeding at the interface between endosperm and germ promoted significantly faster development of the second, third, and fourth instars. The larvae made short, wide tunnels in resistant maize and long, narrow tunnels in susceptible maize. The prepupal stage lasted 1 d and the pupal stage 5.5 d. The duration of the preemerged adult stage was longer in resistant than in susceptible varieties.