Seasonal occurrence pattern and within-plant egg distribution of bean bug, Riptortus pedestris (Fabricius) (Hemiptera: Alydidae), and its egg parasitoids in soybean fields

Abstract

A study on the seasonal occurrence and within-plant distribution of Riptortus pedestris (Fabricius) (Hemiptera: Alydidae) and its two egg parasitoids was conducted to evaluate the effectiveness of parasitoids as a biological control agent in soybean fields. We sampled soybean plants during the planting seasons in 2007 and 2008 in Andong, Korea. Adult R. pedestris occurrence and egg deposition began at the R2-R4 stage of soybean. Nymphs started to appear during the R5 stage of soybean. Peak population densities of both eggs and adults were recorded in the R5 stage of soybean, whereas that of nymphs started in the R6 stage. Seasonal total parasitism by Ooencyrtus nezarae Ishii (Hymenoptera: Encyrtidae) was significantly higher than Gryon japonicum (Ashmead) (Hymenoptera: Scelionidae). For the withinplant distribution of R. pedestris eggs, 90% were found on leaves and 70% on the under-leaf surface. Egg parasitism by O. nezarae was higher on the leaf surface than on pods. Results suggest that R. pedestris starts to occur at the R2-R4 stages of field soybeans regardless of seed sowing time, and population density peaks after the R5 stage. Sampling eggs on leaves is an alternative method to measure R. pedestris populations in the field since most eggs are found on leaves. Since O. nezarae was synchronous with the bugs' occurrence, it would be a more efficient biological control agent of R. pedestris than G. japonicum.

Evaluation of mature soybean pods as a food source for two pod-sucking bugs, Riptortus pedestris (Hemiptera: Alydidae) and Halyomorpha halys (Hemiptera: Pentatomidae)

“…Hemipterans preferentially feed on young, tender growth and developing seeds (growth stages R4-R6 in soybean) [ 16 , 17 ], but peak infestation of stink bugs in soybean fields generally occurs at the mid to late pod filling stage (stages R5-R7) [ 16 , 18 , 19 , 20 , 21 ]. However, Kim and Lim [ 22 ] and our preliminary observations found R . pedestris and H .…”

Occurrence and Control Method of Riptortus pedestris (Hemiptera: Alydidae): Korean Perspectives

“…재와는 달리 난괴로 산란하지 않고 대체로 잎당 한 개의 알을 식물체 상부의 잎 뒷면에 낳는다 (Jung et al, 2008, Kim andLim, 2010a). 또한 기주식물뿐만 아니라 비기주식물에도 흩트 려 산란하는 행동 습성을 보이는데, Leal et al (1995) (Suzuki et al, 1991;Lee et al, 2004 (Lee et al, 2004, Jung et al, 2005a.…”

Changes in Nutritional Composition of Soybean Seed Caused by Feeding of Pentatomid (Hemiptera: Pentatomidae) and Alydid Bugs (Hemiptera: Alydidae)

“…All of the tested species were found to occur and damage soybean in the Þeld (Son et al 2000) by attacking pods (Wang 1980). Among them peak nymphal density of R. pedestris were found to occur in soybean Þelds at R6 (top nodes have full size seeds in their pods) stage (Kim and Lim 2010). These aforementioned studies suggest that the hemipteran attack mature soybean seeds and can inßict damage in terms of quality, quantity, and germination potential.…”