Theses and Dissertations from UMD
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Item UNDERSTANDING THE RELATIONSHIP BETWEEN THE BROWN MARMORATED STINK BUG, HALYOMORPHA HALYS (STÅL), AND ITS SYMBIONT, PANTOEA CARBEKII, WITH IMPLICATIONS FOR STINK BUG MANAGEMENT(2016) Taylor, Christopher Michael; Mitter, Charles; Entomology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Symbiotic relationships between insects and beneficial microbes are very common in nature, especially within the Hemiptera. The brown marmorated stink bug, Halyomorpha halys Stål, harbors a symbiont, Pantoea carbekii, within the fourth region of the midgut in specialized crypts. In this dissertation, I explored this insect- microbe relationship. I determined that the brown marmorated stink bug is heavily reliant on its symbiont, and that experimental removal of the symbiont from the egg mass surface prior to nymphal acquisition led to lower survival, longer development, lower fecundity, and aberrant nymphal behavior. Additionally, I determined that even when the symbiont is acquired and housed in the midgut crypts, it is susceptible to stressors. Stink bugs reared at a higher temperature showed lower survival, longer development, and a cease in egg mass production, and when bugs were screened for their symbiont, fewer had successfully retained it while under heat stress. Finally, with the knowledge that the stink bug suffers decreases in fitness when its symbiont is missing or stressed, I wanted to determine if targeting the symbiont was a possible management technique for the stink bug. I tested the efficacy of a number of different insecticidal and antimicrobial products to determine whether prevention of symbiont acquisition from the egg mass was possible, and results indicated that transmission of the symbiont from the egg mass to the newly hatched nymph was negatively impacted when certain products were applied (namely surfactants or products containing surfactants). Additionally, direct effects on hatch rate and survival were reported for certain products, namely the insect growth regulator azadirachtin, which suggests that nymphs can pick up residues from the egg mass surface while probing for the symbiont. I conclude that P. carbekii plays a critically important role in the survival of its host, the brown marmorated stink bug, and its presence on the egg mass surface before nymphal hatch makes it targetable as a potential management technique.Item An assessment of host preference, reproductive suitability and feeding injury of the brown marmorated stink bug, Halyomorpha halys, on selected vegetables(2014) Zobel, Emily S.; Hooks, Cerruti R.R.; Entomology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The brown marmorated stink bug, Halyomorpha halys (Heteroptera), is an invasive insect from Asia that has become a major agricultural pest of field and vegetable crops in the Mid-Atlantic States. A field study was conducted to asses the seasonal abundance, host plant preference, reproductive suitability, and injury potential of H. haly on green bean, sweet corn, eggplant, okra and bell pepper. H. halys abundance, life stage phenology, and resulting feeding injury were monitored biweekly throughout the growing season. Overall seasonal abundance consisted of both overwintered adults and their F1 progeny. Sweet corn, okra and bell pepper had significantly higher abundances of H. halys compared to green bean, eggplant, and tomato. Eggplant, okra and bell pepper were the most suitable host plants for H. halys reproduction and development. Sweet corn, okra, bell pepper and tomato were very susceptible to feeding injury and experienced the highest injury rate per stink bug day. The implications of these findings with respect to sampling and management of H. halys in vegetable production are discussed.Item INDIGENOUS NATURAL ENEMIES OF THE INVASIVE BROWN MARMORATED STINK BUG, HALYOMORPHA HALYS (HEMIPTERA: PENTATOMIDAE)(2013) Jones, Ashley Lynn; Shrewsbury, Paula M; Hooks, Cerruti RR; Entomology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Brown marmorated stink bug (BMSB), Halyomorpha halys (Stål), is an invasive species native to Southeastern Asia. Since its arrival into the U.S., BMSB has become an economically important pest in many cropping systems, including woody ornamental plants. Here I have explored the potential impact of indigenous natural enemies on BMSB in woody ornamental nursery systems in Maryland. When sampling for indigenous natural enemies in 2012 and 2013, I found seven species of egg parasitoids attacking BMSB with especially high parasitism rates from Anastatus reduvii. Overall egg mortality averaged 58% and parasitism rates increased from32% in 2012 to 44% in 2013. When sampling for predators as biological control agents, predation was low overall. I found that Arilus cristatus consumed more BMSB than any other predator species tested though low abundances were observed in the field. I also found that the use of sentinel egg masses may underestimate rates of parasitism.