Evaluation of three plant seeds as potential pre-season diets for Riptortus pedestris

Abstract

Riptortus pedestris (Fabricius) (Hemiptera: Alydidae) is a polyphagous pest causing serious economic damage especially in soybean (Glycine max L.). R. pedestris start to emerge earlier in spring when reproduction is not possible due to scarcity of nutritious food sources, thus host exploitation pattern is not well known. In order to understand the patterns of seasonal occurrence and how it relates to suitability of host plants in the spring, we evaluated the seeds of barley (Hordeum vulgare L.), sesame (Sesamum indicum L.), and black locust (Robinia pseudoacacia L.) as pre-season food sources for R. pedestris. A diet of soybean seed was also compared as a control. When nymphs fed sesame seeds only, R. pedestris never became third instars. Only 2.5 and 5% of R. pedestris fed on barley and barley+sesame, respectively, successfully became adults. Only when supplemented with soybean seeds could barley and sesame seeds support nymphal development and reproduction of R. pedestris. This indicates that neither barley nor sesame is adequate food sources for the development and the reproduction of R. pedestris even though they occur in those crop fields in spring and summer. However, seeds of black locust supported the complete development and reproduction of R. pedestris. Thus, black locust can be an additional leguminous host plant for R. pedestris during the period when suitable food sources are limited.