The parasitic mite Varroa destructor (Acari: Varroidae) is a major cause of overwintering honey bee (Apis mellifera) colony losses in the United States, suggesting that beekeepers must control Varroa populations to maintain viable colonies. Beekeepers have access to several chemical varroacides and nonchemical practices to control Varroa populations. However, no studies have examined large-scale patterns in Varroa control methods in the United States. Here we used responses from 4 yr of annual surveys of beekeepers representing all regions and operation sizes across the United States to investigate use of Varroa control methods and winter colony losses associated with use of different methods. We focused on seven varroacide products (amitraz, coumaphos, fluvalinate, hop oil, oxalic acid, formic acid, and thymol) and six nonchemical practices (drone brood removal, small-cell comb, screened bottom boards, powdered sugar, mite-resistant bees, and splitting colonies) suggested to aid in Varroa control. We found that nearly all large-scale beekeepers used at least one varroacide, whereas small-scale beekeepers were more likely to use only nonchemical practices or not use any Varroa control. Use of varroacides was consistently associated with the lowest winter losses, with amitraz being associated with lower losses than any other varroacide product. Among nonchemical practices, splitting colonies was associated with the lowest winter losses, although losses associated with sole use of nonchemical practices were high overall. Our results suggest potential control methods that are effective or preferred by beekeepers and should therefore inform experiments that directly test the efficacy of different control methods. This will allow beekeepers to incorporate Varroa control methods into management plans that improve the overwintering success of their colonies.

Bees depend on pollen as the primary protein source for their larvae and should be strongly selected to identify cues associated with the most rewarding flowers. We examined the ability of bumble bees (Bombus impatiens) to identify the most rewarding foraging opportunities using arrays of live monkeyflowers (Mimulus guttatus), artificial plants, and pairwise olfactory tests. Bees could identify pollen rewards by scent and tended to visit the most rewarding artificial flowers. They seemed less able to identify the best pollen sources when foraging on live plants. We suggest that live plants may provide conflicting or deceptive signals to pollinators.

Floral odours play an important role in attracting insect pollinators. Because pollinators visit flowers to obtain pollen and nectar rewards, they should prefer floral odour profiles associated with the highest‐rewarding flowers (honest signals). In previous work, bumblebees exhibited a preference for flowers from outbred over inbred Mimulus guttatus plants. Pollen is the only floral reward in M. guttatus, and pollen viability (a reliable indicator of protein content) is reduced in inbred plants. Yet, differences in pollen viability did not explain the observed preferences. In this study, we examined the floral volatile profiles of inbred and outbred M. guttatus to identify inbreeding effects and associations between volatile compounds and the number of viable pollen grains per flower, designated “PRQ” (pollen reward quality). We also conducted pairwise choice tests with Bombus impatiens to evaluate the ability of bees to discriminate between odours of rewarding and non‐rewarding flowers and to determine whether bumblebee preferences are explained by differences in the floral odours of inbred and outbred plants. Inbred plants exhibited reduced emission of β‐trans‐bergamotene, the second‐most abundant compound in the volatile blend of outbred plants. Furthermore, pollen and fertile anthers emitted nonadecane. Six other compounds in the floral blend were positively correlated with PRQ. There was no overlap between compounds affected by inbreeding and compounds associated with PRQ. Even when given prior experience foraging on M. guttatus, bumblebees did not distinguish between the floral odours of rewarding and non‐rewarding outbred plants. However, they preferred floral odours from non‐rewarding outbred plants over rewarding inbred plants. Bumblebees without prior experience of flowers preferred volatile blends with higher versus lower amounts of β‐trans‐bergamotene. Taken together, these results suggest that the volatile emissions of M. guttatus provide reliable indicators of pollen rewards (potential honest signals), but that the preference of bumblebees for outbred plants is not driven by these cues but rather by a sensory bias for β‐trans‐bergamotene. This may represent a subtle form of deceit‐pollination that allows plants to attract pollinators while minimizing investment in costly rewards. A http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.13246/suppinfo is available for this article.

Abstract. Inbreeding in plants is well known to affect plant-herbivore interactions, but these effects can depend on herbivore host breadth. If the phenotypic effects of inbreeding are analogous to those of environmental stress, the plant stress hypothesis predicts that generalist herbivores will perform better on inbred relative to outbred plants because inbreeding is expected to lower chemical defenses. The plant vigor hypothesis predicts that specialist herbivores will perform better on outbred relative to inbred plants because specialists are more tolerant of plant defenses and benefit from the higher nutritional quality of outbred plants. However, these plant defense theories do not account for structural defenses. Using a factorial design, we examined effects of inbreeding and trichome density in Mimulus guttatus on performance of the generalist, Helicoverpa zea, and the specialist, Junonia coenia. We also examined preferences of each herbivore for leaf disks and olfactory cues from inbred vs. outbred plants. The generalist H. zea developed most efficiently on inbred plants. The specialist J. coenia exhibited the greatest mass gain and pupal mass and developed fastest on outbred plants. Trichomes negatively affected performance of both species. Helicoverpa zea did not exhibit strong preferences for inbred vs. outbred plants, but J. coenia consistently preferred outbred plants. Our results support predictions on the effects of inbreeding on herbivore performance, but trichomes reduced performance of both herbivores. We conclude that the ability of the plant stress and plant vigor hypotheses to predict inbreeding effects on plant-herbivore interactions may depend on which plant traits are affected by inbreeding.

The striped cucumber beetle [StCB; Acalymma vittatum (F.) (Coleoptera: Chrysomelidae)] and the western striped cucumber beetle [WStCB; Acalymma trivittatum (Mannerheim)] are closely related species of herbivores endemic to North America that specialize on Cucurbitaceae plants. StCB and WStCB are key pests of cucurbit crops that can reduce quantity and quality of yield or even kill plants, especially seedlings, by feeding and by vectoring pathogens. Insecticides can be used to control StCB and WStCB, but a number of more selective nonchemical management methods are also available to help control these pests. Here, we describe the biology, life stages, and damage caused by StCB and WStCB and discuss methods for managing these pests in cucurbit crops.