Effect of food deprivation period on the development and reproduction of R. pedestris (Hemiptera: Alydidae), and its egg parasitism

The bean bug, Riptortus pedestris (Fabricius) (Hemiptera: Alydidae), is one of the most important polyphagous pest of many crops including soybean in Korea and Japan. Because soybean has been reported to be the most important host plant for R. pedestris, we assessed the effect of soybean deprivation period during nymphal stage on the development and reproduction of R. pedestris and on its egg parasitism by Gryon japonicum (Ashmead) and Ooencytrus nezarae Ishii. We found the highest mortality in R. pedestris group provided with soybean from 5th instar. R. pedestris provided with soybean from 4 or 5th instar nymph developed slowly compared to those provided with soybean from 1 to 3rd instar. We found the shortest pre-ovipositional period and the highest 6 days fecundity in R. pedestris group provided with soybean from 3th instar. However, hatchability and egg parasitism rate by both G. japonicum and O. nezarae were not affected by the different soybean deprivation period during nymphal stage. Study showed that longer soybean deprivation period affects development time and mortality negatively, but has no effect on reproduction of R. pedestris and its parasitism.

Key words: Riptortus pedestris, Gryon japonicum, Ooencytrus nezarae, development, survivorship, nutritional condition, parasitism rate