Honey bee workers will perform vibration signals on adult drones, which respond by increasing the time spent receiving trophallaxis. Because trophallaxis provides the proteins for sexual maturation, workers could direct vibration signals towards drones showing certain physical characteristics, potentially influencing drone development and colony reproductive output. We examined the influence of drone condition on the likelihood of receiving vibration signals by comparing body weight, protein concentrations, and hemolymph juvenile hormone (JH) titers between drones that received the vibration signal and same-age, nonvibrated controls. Vibrated and control drones did not differ in total body weight, abdomen weight, abdomen-to-body weight ratio, total protein concentrations, or hemolymph JH titers. In contrast, vibrated drones had significantly lower thorax weight and smaller thorax-to-body weight ratios compared with controls. Because relative thorax weight may affect flight ability and mating success, workers could use the vibration signal to increase the care received by less developed drones, potentially contributing to the production of greater numbers of competitive males. However, the differences in thorax weights, while significant, were very small, and it is unknown how such slight differences might be assessed by workers or affect drone performance. Nevertheless, vibration signals performed on drones may provide opportunities for exploring the effect of the quality of reproductive individuals on caste interactions in honey bees.

Colony reproduction in honey bees involves complex interactions between sterile workers and reproductive castes. Although worker–queen interactions have been studied in detail, worker–drone interactions are less well understood. We investigated caste interactions in honey bees by determining the age and behavior of workers that perform vibration signals, trophallaxis, and grooming with drones. Workers of all ages could engage in the different interactions monitored, although workers that performed vibration signals on drones were significantly older than those engaging in trophallaxis and grooming. Only 3–8% of workers engaged in the different behaviors were monitored. Compared with workers that performed vibration signals only on workers (‘worker vibrators’), those that performed signals on both workers and drones (‘drone vibrators’) had greater movement rates inside the nest, higher vibration signaling rates, and were more likely to have an immediate association with foraging. Both worker vibrators and drone vibrators contacted drones of all ages as they moved through the nest. However, drone vibrators contacted drones at higher rates, contacted slightly, but significantly younger drones, and were more likely to engage in trophallaxis and grooming with drones, in addition to vibrating them. Taken together, our results suggest that tiny proportions of workers belonging to separate, but overlapping age groups provide most of the care received by adult drones, and that drone vibrators comprise a subset of signalers within a colony that have an increased tendency to contact and interact with drones. Vibratory, tactile signals are involved in colony reproductive and movement decisions in a number of species of bees, wasps and ants, and may provide valuable tools for investigating caste interactions in many insect societies.

Integrated pest management (IPM) recommendations, including scouting and economic thresholds (ETs), are available for North Carolina flue-cured tobacco growers, although ETs for key pests have not been updated in several decades. Moreover, reported IPM adoption rates by flue-cured tobacco growers remain low, at < 40%, according to NC cooperative extension surveys conducted during the last four years. Previous research has suggested that timing insecticide treatments using currently available ETs can reduce the average number of applications to two or fewer per season. We conducted field-scale trials at nine commercial tobacco farms, three in 2104 and six in 2015, to quantify inputs associated with current scouting recommendations, to determine if current ETs were able to reduce insecticide applications as compared to grower standard practices, and to assess the impacts of reduced insecticide applications on end of season yield and pesticide residues. Two fields were identified at each farm and were scouted weekly for insects. One field was only treated with insecticides if pests reached ET (IPM), while the other field was managed per grower discretion (Grower Standard). IPM fields received an average of two fewer insecticide applications without compromising yield. More insecticide applications resulted in higher pesticide residues in cured leaf samples from Grower Standard fields than those from IPM fields. Reductions in insecticides and management intensity also resulted in larger beneficial insect populations in IPM fields.

SLONE, JEREMY DARRYL. Overcoming Barriers to IPM adoption in Flue Cured Tobacco. (Under the direction of Hannah Burrack). Although established integrated pest management (IPM) recommendations for flue cured tobacco are available, many North Carolina (NC) growers do not follow these guidelines at a potential cost to their operation. Surveys suggest that many growers may not utilize scouting recommendations or economic thresholds (ETs) and may be making unnceccesary chemical applications. Small plot experiments at two NC research stations allowed us to determine the average number of insecticidal applications necessary to maintain foliar feeding pests below ET. Several insecticides were evaluated across a range of rates, and an average of two sprays per season was sufficient to reduce pest populations below ET without comprosmising yield. We next conducted field-scale trials on NC farms over the course of two years comparing IPM practices to grower standards. Weekly scouting was conducted at all sites in which a random sample of plants were evaluated for pest presence. The number of stops was determined based on field size, with five consecutive plants inspected at each stop. Each site included a grower standard field, which was managed according to standard practice for each cooperator with insecticide applications at their discretion, and an IPM field, which only received insecticide applications if pest populations surpassed the ET. During 2014, fewer insecticides were applied to IPM fields, but there was no difference in yield between treatments. In 2015, fewer insecticdes were applied to all IPM fields again without an impact on yield, with the exception of one site where the same number of insecticide applications were made to both fields. Although there is a cost associated with the labor of scouting, it was offset by the reduction of insecticide input costs at the majority of our sites. Additionally, fewer chemical applications have the potential to result in lower pesticide residues on cured leaf. When residues were detected, the were generally lower on cured leaf samples collected in IPM fields compared to those from grower standard fields. During 2015 we performed additional scouting in each field to validate recommendations for sampling path through the field and number of stops. Each field was scouted weekly according to current guidelines, with stops randomly distributed through fields and was then scouted a second time along a strip path, where stops were made while passing down entire rows. Pest populations were estimated at different stop frequencies using subsampled observations from all stops to determine if pest populations had reached the ET. Both evaulated paths resulted in similar estimates of infestation levels, but the strip path took longer. Few differences were detected among stop rates, suggesting that scouting labor inputs could be reduced without compromising ET efficacy. Grower surveys reported an average of over four insecticide applications over the season. Treating only when pests ...