Role of symbiotic gut bacteria in the development of Acrosternum hilare and Murgantia histrionica

The green stink bug, Acrosternum hilare (Say), and the harlequin bug, Murgantia histrionica (Hahn) (both Heteroptera: Pentatomidae), are pests of many economically important crops. Although both species have been studied extensively, until recently their relationships with symbiotic gut bacteria have remained unknown. The endosymbionts may be important, as other pentatomomorphan species harbor vertically transmitted gut bacteria that play an important role in the biology of their host insects. We report the role of gut symbiotic bacteria on the development and fitness of A. hilare and M. histrionica by comparing control insects with individuals that hatched from surface sterilized egg masses. We studied the life history of A. hilare and M. histrionica under laboratory conditions at 23 +/- 2 degrees C and L16:D8, measuring nymphal mortality and development time, and estimating other demographic parameters. We also evaluated egg masses, nymphs, and adults of both species with diagnostic PCR primers for the presence of specific gut symbiotic bacteria for both treatments. Our results show that egg mass surface sterilization eliminates or reduces the prevalence of this bacterium-insect symbiosis in both species. Acrosternum hilare's development time, survivorship, and other demographic parameters were negatively affected by surface sterilization of egg masses. Conversely, M. histrionica's survivorship was marginally increased by clearing its symbiont infection during the first generation; however, mean generation time was significantly longer. Our data indicate that the degree of mutualism in this association for pentatomid species is variable, given that A. hilare requires its symbiont for adequate development and survival, whereas M. histrionica's symbiont may not be required for development and survival under the experimental conditions used.