Monday, December 10, 2007 - 8:53 AM

Effect of temperature on the maintenance of pentatomid gut-associated symbionts

Simone Prado,, University of Hawaii - Manoa, Plant and Environmental Protection Sciences, 3050 Maile Way, Room 310, Honolulu, HI, Kim Hung,, University of California at Berkeley, ESPM, 137 Mulford Hall, Berkeley, CA, and Rodrigo Almeida,, University of California - Berkeley, Environmental Science, Policy and Management, 137 Mulford Hall, Berkeley, CA.

Acrosternum hilare (Say) and Murgantia histrionica (Hahn) (Hemiptera, Pentatomidae) have vertically transmitted Erwinia-like bacterial symbionts in the posterior region of their midgut. We determined the impact of temperature (25C and 30C) on the biology of both insects and their symbionts. A. hilare showed higher mortality in the 1st and 5th instars at 30C (26% and 6%, respectively) when compared with 1st and 5th at 25C (12% and 2%, respectively); its developmental time was not affected by the temperature. Egg masses, 5th instars and adults of A. hilare were symbiont-positive at 25C, but those at 30C were symbiont-negative from the 2nd instar on. M. histrionica had similar developmental time at both temperatures, but 2nd instar's mortality at 25C (14%) was higher than at 30C (8.7%). M. histrionica had 73.3% of 5th instars positive for their gut symbiont at 25C, but all were negative at 30C. Our results show that 30C affected the maintenance of this symbiosis in both insects. M. histrionica increased mortality at 25C suggests that this association may be pathogenic and have a fitness cost. In summary, our data show that increased temperature cleared two pentatomid species of gut-associated symbionts and differentially affected their fitness.

Species 1: Hemiptera Pentatomidae Acrosternum hilare (green stink bug)
Species 2: Hemiptera Pentatomidae Murgantia histrionica (harlequin bug)