Trap and Synthetic Lure for the Checkered Flower Beetle, 1 a Serious Predator of Alfalfa Leafcutting Bees 2

Nelson

et al. 2022

Preprint

The alfalfa leafcutting bee Megachile rotundata Fabricius (HYMENOPTERA: Megachilidae) is an important pollinator for multiple agricultural seed commodities in the United States. Megachile rotundata is a solitary bee that forms brood cocoons where its larvae can develop. During the developmental stages of growth, broods can be preyed upon by multiple different fungal and bacterial pathogens and insect predators and parasitoids, resulting in the loss of the developing larvae. Larval loss is a major concern for alfalfa (Medicago sativa L.) seed producers because they rely on pollinator services provided by Megachile rotundata and reduced pollination rates result in lower yields and increased production costs. In the present study, we examined the taxonomic composition of organisms found within M. rotundata brood cells using a multiplex PCR assay which was developed for the detection of the most common bacterial, fungal, and invertebrate pests and pathogens of M. rotundata larvae. Known pests of M. rotundata were detected, including members of the fungal genus Ascosphaera, the causative agent of chalkbrood. Co-infection of single brood cells by multiple Ascosphaera species was confirmed, with potential implications for chalkbrood disease management. The multiplex assay also identified DNA from more than 2,400 total species including multiple new predators and pathogenetic species not previously documented in associated with M. rotundata brood cells.

Section: Introductionmentioning

confidence: 99%

Multiplex PCR reveals unique trends in pathogen and parasitoid infestations of alfalfa leafcutting brood cells

Nelson

et al. 2022

Preprint

“…In order to reduce cell loss, growers can use a combination of disinfectants and lures to protect bee cells from different pathogens and parasitoids. However, if stocks contain a high percent of any of these pathogens and parasitoids, growers are forced to burn/bury their current bee cell stocks, sterilize bee boards and housing, and purchase new bee cell stocks from commercial vendors [18–20]. Currently, the acceptable cutoffs for any of these pathogens are not well defined.…”

Section: Introductionmentioning

confidence: 99%

Examining historical rates of leafcutting bee cell pathogens to establish baseline infectivity rates for alfalfa seed growers

Nelson

et al. 2022

Preprint

The alfalfa leafcutting bee (Megachile rotundata) is one of the primary pollinators for the alfalfa seed industry. The alfalfa leafcutting bee is a solitary cavity nesting bee. Female Megachile rotundata bees will construct and provision individual brood cells lined with cut leaves (cocoon) and will gather nectar and pollen to place within the constructed cocoon. The female bee will lay a single egg within the constructed cocoon and leave the egg to undergo larval stage development and pupation into the adult stage. During this time multiple pathogens and parasitoids can prey on the developing larvae, resulting in the loss of the future adult bee. A major concern for commercial alfalfa seed growers is the presence of invertebrate pests and fugal pathogens. In the present study, we used historical data from the Parma Cocoon Diagnostic Laboratory to determine baseline rates of pathogen and parasite infection of Megachile rotundata cells and used this analysis to determine historical infection rates and cutoffs for management practices. Additionally, using a Faxitron (X-ray) analysis for Megachile rotundata cell obtained in 2020, we compared the presence of chalkbrood, pathogens, and parasitoids in samples collected from both growers stocks and newly purchased Canada bees. The results of the investigation demonstrate historical averages of the presence of chalkbrood, pathogens, and parasitoids. We also show a significant increase in chalkbrood and predators in 2007-2011 and a significant difference in chalkbrood and predators between bee samples obtained from Canada and grower stocks.

“…In order to reduce cell loss, growers can use a combination of disinfectants and lures to protect bee cells from different pathogens and parasitoids. However, if stocks contain a high percent of any of these pests, growers are forced to burn/bury their current bee cell stocks, sterilize bee boards and housing, and purchase new bee cell stocks from commercial vendors ( Davis et al 1979 , Hill et al 1984 , James 2011 ). Currently, the acceptable cutoffs for any of these predators, pathogens, and parasitoids are not well defined.…”

mentioning

confidence: 99%

Examining Historical Rates of Leafcutting Bee Brood Cell Pathogens, Parasitoids, and Predators to Establish Baseline Infectivity Rates for Alfalfa Seed Growers

Barbour

Journal of Economic Entomology

et al. 2022

The alfalfa leafcutting bee Megachile rotundata (Fabricius) (Hymenoptera: Megachilidae) is the primary pollinator for the alfalfa seed industry. It is a solitary cavity nesting bee that utilizes leaf lined brood cells provisioned with pollen for larval development and pupation into the adult stage. During development, multiple pathogens, parasitoids, and predators can prey upon or use the larvae as a host, resulting in the loss of the future adult bee. As such, the presence of invertebrate pests and fungal pathogens presents a major concern for commercial alfalfa seed growers. In the present study, we used historic data from the Parma Cocoon Diagnostic Laboratory to determine baseline rates of pathogens, parasitoids, and predators of Megachile rotundata brood cells and used this analysis to determine cutoffs for management practices to inform growers when the purchase of new bee stocks should be considered. Additionally, we compared the presence of chalkbrood, predators, and parasitoids in samples collected from both grower-produced stocks and newly purchased Canadian bees. The results of the investigation provide historic averages of the presence of chalkbrood, predators, and parasitoids, show a significant increase in chalkbrood and predators in 2007–2011, and find a significant difference in rates of chalkbrood and predators between samples from Canadian suppliers and grower stocks. We speculate that these differences may have resulted from economic conditions that increased the cost of Canadian Megachile rotundata cells and likely resulted in increased reliance on 2nd-year U.S. grower stocks and subsequently increased infection rates during this time period.