Evaluation of mature soybean pod as a food source of Riptortus pedestris (Hemiptera: Alydidae) and Halyomorpha halys (Hemiptera: Pentatomidae)

Riptortus pedestris (Fabricius) and Halyomorpha halys (Stål) cause damage on soybean by piercing and sucking pods and seeds during cultivation period. Growers believe that there is less damage during near-harvest period despite the occurrence of the bugs. However, damage on soybean pod during the late cultivation period has never been assessed. We evaluated mature soybean pod containing seeds and dried soybean seeds as food sources of the two bugs by assessing their biological, behavioral, and morphological attributes in laboratory. Both species can develop and reproduce on those tested food sources. Bugs fed on pods had longer development time and 2.2 to 5 times higher mortality than those fed on seeds. Furthermore, adult longevity of R. pedestris and H. halys fed on pods became 8.4 and 7.5 days shorter, respectively. However, pod feeding didn’t affect fecundity and hatchability. In behavioral choice test, R. pedestris preferred seed and had longer probing duration. Halyomorpha halys showed similar trend except giving up their first choice of pod (15.6%) more than R. pedestris (0%). As proboscis length of either nymph or adult of both species was much longer than thickness of pod shell, morphology of mouthpart might not be a limiting factor in their feeding on pod. In conclusion, as mature soybean pod can be an appropriate food source for these bug species despite some negative effects, attention should be paid to near-harvest bug management in soybean.

Key Words: bean bug, brown marmorated stink bug, pod feeding, development, mortality, stink bug, proboscis