Plant Sciences & Plant Pathology
Permanent URI for this communityhttps://scholarworks.montana.edu/handle/1/12
The Department of Plant Sciences and Plant Pathology is part of the College of Agriculture at Montana State University in Bozeman. An exciting feature of this department is the diversity of programs in Plant Biology, Crop Science, Plant Pathology, Horticulture, Mycology, Plant Genetics and Entomology. The department offers BS, MS, and Ph.D. degree program
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Item Seasonality and alternative floral resources affect reproductive success of the alfalfa leafcutting bee, Megachile rotundata(Taylor & Francis, 2024-08) Delphia, Casey M.; Burkle, Laura A.; Botti-Anderson, Joshua M.; O'Neill, Kevin M.Background: Managed populations of the alfalfa leafcutting bee (ALCB), Megachile rotundata (F.), are often not sustainable. In addition to numerous mortality factors that contribute to this, the dense bee populations used to maximize alfalfa pollination quickly deplete floral resources available to bees later in the summer. Providing alternative floral resources as alfalfa declines may help to improve ALCB reproduction. Methods: We examined the relationship between floral resource availability and ALCB reproduction and offspring condition via (1) a field study using alfalfa plots with and without late-blooming wildflower strips to supply food beyond alfalfa bloom, and (2) a field-cage study in which we provided bees with alfalfa, wildflowers, or both as food resources. Results: In the field study, bee cell production closely followed alfalfa floral density with an initial peak followed by large declines prior to wildflower bloom. Few bees visited wildflower strips, whose presence or absence was not associated with any measure of bee reproduction. However, we found that female offspring from cells provisioned earlier in the season, when alfalfa predominated as a source of provisions, eclosed with greater body sizes and proportion body lipids relative to total body mass. For bees restricted to cages, the proportion of offspring that survived to adults was highest on pure alfalfa diets. Adding wildflowers to cages with alfalfa did not affect adult offspring production or female offspring body size and lipid content. Furthermore, although similar numbers of adults were produced on wildflowers alone as with alfalfa alone, females eclosed with smaller body sizes and lower proportion body lipids on wildflowers despite the higher protein content we estimated for wildflower pollen. We found no evidence that adding the late-season wildflower species that we chose to plant enhanced ALCB offspring numbers. Our results highlight the importance of considering multiple measures of reproductive success, including offspring body size and lipid stores, when designing and evaluating floral resource management strategies for agroecosystems.Item Wildflower Seed Sales as Incentive for Adopting Flower Strips for Native Bee Conservation: A Cost-Benefit Analysis(2019-07) Delphia, Casey M.; O'Neill, Kevin M.; Burkle, Laura A.Improving pollinator habitat on farmlands is needed to further wild bee conservation and to sustain crop pollination in light of relationships between global declines in pollinators and reductions in floral resources. One management strategy gaining much attention is the use of wildflower strips planted alongside crops to provide supplemental floral resources for pollinators. However, farmer adoption of pollinator-friendly strategies has been minimal, likely due to uncertainty about costs and benefits of providing non-crop flowering plants for bees. Over 3 yr, on four diversified farms in Montana, United States, we estimated the potential economic profit of harvesting and selling wildflower seeds collected from flower strips implemented for wild bee conservation, as an incentive for farmers to adopt this management practice. We compared the potential profitability of selling small retail seed packets versus bulk wholesale seed. Our economic analyses indicated that potential revenue from retail seed sales exceeded the costs associated with establishing and maintaining wildflower strips after the second growing season. A wholesale approach, in contrast, resulted in considerable net economic losses. We provide proof-of-concept that, under retail scenarios, the sale of native wildflower seeds may provide an alternative economic benefit that, to our knowledge, remains unexplored. The retail seed-sales approach could encourage greater farmer adoption of wildflower strips as a pollinator-conservation strategy in agroecosystems. The approach could also fill a need for regionally produced, native wildflower seed for habitat restoration and landscaping aimed at conserving native plants and pollinators.Item Acute Toxicity of Permethrin, Deltamethrin, and Etofenprox to the Alfalfa Leafcutting Bee(2018-05) Piccolomini, Alyssa M.; Whiten, Shavonn R.; Flenniken, Michelle L.; O'Neill, Kevin M.; Peterson, Robert K. D.Current regulatory requirements for insecticide toxicity to nontarget insects focus on the honey bee, Apis mellifera (L.; Hymenoptera: Apidae), but this species cannot represent all insect pollinator species in terms of response to insecticides. Therefore, we characterized the toxicity of pyrethroid insecticides used for adult mosquito management (permethrin, deltamethrin, and etofenprox) on a nontarget insect, the adult alfalfa leafcutting bee, Megachile rotundata (F.; Hymenoptera: Megachilidae) in two separate studies. In the first study, the doses causing 50 and 90% mortality (LD50 and LD90, respectively) were used as endpoints and 2-d-old adult females were exposed to eight concentrations ranging from 0.0075 to 0.076 μg/bee for permethrin and etofenprox, and 0.0013–0.0075 μg/bee for deltamethrin. For the second study, respiration rates of female M. rotundata were also recorded for 2 h after bees were dosed at the LD50 values to give an indication of stress response. Results indicated a relatively similar LD50 for permethrin and etofenprox, 0.057 and 0.051 μg/bee, respectively, and a more toxic response, 0.0016 μg/bee for deltamethrin. Comparatively, female A. mellifera workers have a LD50 value of 0.024 μg/bee for permethrin and 0.015 μg/bee for etofenprox indicating that female M. rotundata are less susceptible to topical doses of these insecticides, except for deltamethrin, where both A. mellifera and M. rotundata have an identical LD50 of 0.0016 μg/bee. Respiration rates comparing each active ingredient to control groups, as well as rates between each active ingredient, were statistically different (P < 0.0001). The addition of these results to existing information on A. mellifera may provide more insights on how other economically beneficial and nontarget bees respond to pyrethroids.Item Effects of an Ultra-low-Volume Application of Etofenprox for Mosquito Management on Megachile rotundata (Hymenoptera: Megachilidae) Larvae and Adults in an Agricultural Setting(2018-02) Piccolomini, Alyssa M.; Flenniken, Michelle L.; O'Neill, Kevin M.; Peterson, Robert K. D.The alfalfa leafcutting bee, Megachile rotundata F. (Hymenoptera: Megachilidae), is one of the most intensively managed solitary bees and greatly contributes to alfalfa production in both the United States and Canada. Although production of certain commodities, especially alfalfa seed, has become increasingly dependent on this species\' pollination proficiency, little information is known about how M. rotundata is affected by insecticide exposure. To better understand the risk posed to M. rotundata by the increasing use of insecticides to manage mosquitoes, we conducted field experiments that directly exposed M. rotundata nests, adults, and larvae to a pyrethroid insecticide via a ground-based ultra-low-volume (ULV) aerosol generator. We directly targeted nest shelters with Zenivex E20 (etofenprox) at a half-maximum rate of 0.0032 kg/ha at dusk and then observed larval mortality, adult mortality, and the total number of completed nests for both the treated and control groups. There was no significant difference in the proportion of dead (P = 0.99) and alive (P = 0.23) larvae when the control group was compared with the treated group. We also did not observe a significant difference in the number of emerged adults reared from the treated shelters (P = 0.22 and 0.50 for females and males, respectively), and the number of completed cells after exposure to the insecticides continued to increase throughout the summer, indicating that provisioning adults were not affected by the insecticide treatment. The results from this study suggest that the amount of insecticide reaching nest shelters may not be sufficient to cause significant mortality.Item Bumble Bees (Hymenoptera: Apidae) of Montana(2017-09) Dolan, Amelia C.; Delphia, Casey M.; O'Neill, Kevin M.; Ivie, Michael A.Montana supports a diverse assemblage of bumble bees (Bombus Latreille) due to its size, landscape diversity, and location at the junction of known geographic ranges of North American species. We compiled the first inventory of Bombus species in Montana, using records from 25 natural history collections and labs engaged in bee research, collected over the past 125 years, as well as specimens collected specifically for this project during the summer of 2015. Over 12,000 records are included, with 28 species of Bombus now confirmed in the state. Based on information from nearby regions, four additional species are predicted to occur in Montana. Of the 28 species, Bombus bimaculatus Cresson and Bombus borealis Kirby are new state records. The presence of B. borealis was previously predicted, but the presence of B. bimaculatus in Montana represents a substantial extension of its previously reported range. Four additional \ eastern\" bumble bee species are recorded from the state, and three species pairs thought to replace one another from the eastern to western United States are now known to be sympatric in Montana. Additionally, our data are consistent with reported declines in populations of Bombus occidentalis Greene and Bombus suckleyi Greene, highlighting a need for targeted surveys of these two species in Montana."