Susan Halbert, Susan.Halbert@FreshFromFlorida.com, Florida Department of Agriculture and Consumer Services, Division of Plant Industry
Joseph E. Eger, email@example.com, Dow Agrosciences
INTRODUCTION: Specimens of the bean plataspid, Megacopta cribraria (Fabricius) (Fig. 1), were found in several counties in northern Georgia in October 2009. Commercial pest control companies received calls about large numbers of insects on houses (Fig. 2). Specimens were forwarded to University of Georgia Homeowner Insect & Weed Diagnostics Laboratory (Lisa Ames) and University of Georgia Extension Specialist Dr. Dan Suiter. Dr. Joseph Eger, Dow AgroSciences, identified the insects (Suiter and Ames 2009).
Bean plataspids, also known as lablab bugs and globular stink bugs, are known pests of legumes in Asia. The insects are voracious feeders on kudzu (Pueraria spp.) (Zhang 1985), but they also feed on numerous agricultural crops, particularly soybean (Zhang 1985) and lablab bean (Schaeffer et al. 2000). Pigeon pea (Cajanus indicus Spreng) (Hoffmann 1932), Phaseolus spp. (mung beans, kidney beans, lima beans, green beans, etc.) (Easton & Pun 1997, Hoffmann 1931), and broad beans (Vicia faba (L.) (Ishihara 1950)) are additional hosts.
DESCRIPTION: Bean plataspids are nearly hemispherical (posterior end flattened) brown bugs with numerous darker punctures (Fig. 1). Size is variable (3-5 mm long). Bean plataspids are the only plataspid bugs known to occur in North America. Plataspid bugs are similar to scutellerids and thyreocorids in that the scutellum covers the abdomen. Plataspids can be distinguished from these families and a few other North American pentatomoid species that have an extended scutellum by their flattened posterior ends. The scutellum is rounded posteriorly in all related North American bugs.
BIOLOGY: In China, there are one to three generations per year. Adults overwinter and become active again in April. Bugs can be found in the fields until October (Zhang 1985). In Karnataka State, India, they are active all year (Thippeswamy and Rajagopal 2005).
HOSTS: Numerous legumes, especially kudzu and soybean (please see above).
ECONOMIC IMPORTANCE: Although their appetite for kudzu may be a good thing, bean plataspids are known pests of legume crops in Asia. The bugs show a preference for petioles and pods, causing wilting and poor seed set (Zhang 1985). In Georgia, large numbers congregate on houses in the fall. The insects exude an acrid odor when disturbed. These bugs have been observed on vehicles and clothing, suggesting that they may hitchhike easily to other locations.
NATURAL ENEMIES: Several egg parasitoids have been reported (Polaszek and Hayat 1990; Takasu and Hirose 1991a, 1991b; Hirose et al. 1996; Takagi and Murakami 1997; Mani and Sharma 1982).
DISTRIBUTION: Asia and Indian Subcontinent, Australia, Georgia, USA.
FLORIDA DISTRIBUTION: Not yet known to occur.
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Figure 1. Adult bean plataspid.
Photograph courtesy of Joseph Eger, Dow AgroSciences
Figure 2. Aggregations of bean plataspids on homes.
Photograph courtesy of Daniel R. Suiter, University of Georgia, College of Agriculture & Environmental Sciences