Biology and Management of Megacopta cribraria (Fabricius) (Heteroptera: Plataspidae): A Recent Invader to The United States
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Entomology and Plant Pathology
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Identified as both an agricultural pest of soybean and a residential nuisance pest, Megacopta cribraria (F.) (Heteroptera: Plataspidae), is a recently invasive pest species to the southeastern United States. Isolated to a few northeastern Georgia counties upon initial detection in the fall of 2009, it has subsequently spread to 13 states where it can now be found as far north as Washington D.C. and as far west as Arkansas. Most of the research regarding this pest insect is focused on its impacts on agriculture and urban environments, however its biology and physiology seem currently overlooked. Information on these aspects could provide an important understanding of this insect in its new habitat. Therefore investigations were completed on some biological and physiological traits of M. cribraria that may provide an understanding of the rapid spread and success of this insect in its newly exploited geographical range. Through laboratory and field experiments, it was demonstrated that approximately 15% of females in three overwintering populations in Lee Co. (Auburn, AL) had mated before entering winter dormancy and sperm was stored in their spermatheca for up to seven months, oocytes in mated overwintering females proceeded to post-blastoderm stage before the onset of spring feeding/mating, all of the overwintering males had sperm in their testes, and the ratio of females gradually increased in populations during overwintering. This study indicates that both males and females are capable of reproductive quiescence. It also suggests that pre-overwinter mate females, containing both eggs and sperm, may be able to invade new territories and produce a subsequent generation in the absence of males; and the spread of this insect may be attributed to founders effect. The ability of M. cribraria to bypassing feeding on the presumed obligatory host, kudzu (Pueraria montana (Lour.) Merr. variety lobata (Willd.) Maesen and S. Almeida), was also addressed. Through no-choice greenhouse assays, overwintered generation M. cribraria could bypass feeding on kudzu to oviposition on mung bean (Vigna radiata (L.) R. Wilczek), soybean (Glycine max (L.) Merrill), butter bean (Phaseolus lunatus L.), and black-eyed pea (Vigna unguiculata (L.) Walp). No significant differences were observed in the number of egg masses, individual eggs, or in hatch rate among the five legume species. First-generation M. cribraria developed on all legume species except black-eyed pea, in approximately 55.6 d. Mortality from egg to adult was highest on black-eyed pea and butter bean followed by kudzu, mung bean and soybean. Results of this study suggest that kudzu is not an obligatory host for M. cribraria. Lastly, preliminary field surveys in the summer 2013 and 2014 discovered a native Dipteran (Tachinidae) species Strongygaster triangulifera utilizing adult M. cribraria for the development of its offspring, while the non-native, but natural occurring, Paratelenomus saccharalis (Hymenoptera: Platygastridae), was found in AL, GA, and MS.