Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/27/2006
Publication Date: 3/15/2006
Citation: Lord, J.C. 2006. Interaction of Mattesia oryzaephili with Cephalonomia spp. (Hymenoptera: Bethylidae) and their hosts Cryptolestes ferrugineus (Coleoptera: Laemophloeidae) and Oryzaephilus surinamensis (Coleoptera: Silvanidae). Biological Control 37: 167-172. Interpretive Summary: A protozoan disease that was recently discovered in North America is highly pathogenic for grain beetles and has unknown potential as a biological control agent. An important consideration is its effect on beneficial wasps that attack the pest beetles. In this work, it was discovered that female wasps of two species are susceptible to the pathogen but disease progression is gradual with survival time of several weeks. The long survival time of infected wasps fosters egg deposition and minimizes the pathogens effect on wasp pest control performance. After attacking infected beetles, the wasps deposit the pathogen in the hosts’ habitat in feces and ultimately in their cadavers. Male wasps do not attack the beetle larvae and do not become infected. This study provides the basis for a potentially synergistic use of two natural agents for suppression of beetle pests of grain without the use of chemicals.
Technical Abstract: The neogregarine, Mattesia oryzaephili, is pathogenic for several stored-grain pest insects, including the sawtoothed grain beetle, Oryzaephilus surinamensis, and the rusty grain beetle, Cryptolestes ferrugineus. It also infects their respective bethylid parasitoids, Cephalonomia tarsalis and Cephalonomia waterstoni. Male wasps do not attack the beetle larvae and do not become infected, but the disease is transmitted per os to nearly all female wasps when they paralyze or feed on infected hosts. The mean survival time of infected female C. tarsalis after exposure to heavily infected O. surinamensis was 20.0 d, while that of healthy C. tarsalis was 38.0 d. For C. waterstoni females, the mean survival times were 36.1 d when infected and 45.9 d when uninfected. The long survival time of infected wasps fosters oviposition and inoculum deposition in the hosts’ habitat. The wasps sting and bite infected host larvae and sometimes oviposit. Wasp progeny that deposited on infected host larvae rapidly succumb to M. oryzaephili. Two hour wasp confinement with patently infected larvae resulted in no transmission from C. waterstoni to C. ferrugineus and 4% transmission from C. tarsalis to O. surinamensis. Contamination of wheat by wasps after they had attacked infected beetles resulted in 8.9% infection of O. surinamensis that developed from eggs that were placed on the contaminated wheat. It is proposed that Cephalonomia spp. can be used as a means to inoculate M. oryzaephili into pest grain beetle populations and aid in its dispersal to help suppress pest populations.