Frank Drummond

Commercial Bumble Bee Pollination of Lowbush Blueberry

The commercial bumble bee, Bombus impatiens, has been used in Maine lowbush blueberry since the late 1990s. Studies conducted in 1995–1998 and published in 2001 showed that B. impatiens was a good pollinator of lowbush blueberry. Stocking density was estimated at ¾–1 quad (set of four, 250-bee colonies) per acre. Subsequent research reported here has shown that on an individual bee basis, B. impatiens is 2.5 times more efficient per floral visit in placing pollen on the stigma. Foraging behavior suggests that bumble bees may be more consistent at producing outcrossing among clones than honey bees, although individual honey bees are more likely to be floral constant than bumble bees. By 2004, some blueberry growers questioned the efficacy of commercial bumble bees. To address these concerns, a three-year validation experiment was conducted from 2005–2007. Seven to nine isolated individual small blueberry fields (2–25 acres) were selected each year to compare bumble bees with honey bees or no commercial pollinators (n = 3 to 5 fields per treatment) It was verified that 2.5 quads/ha was a suitable stocking density and did not differ in pollination level from 7.5–10 honey bee hives per ha. A central place foraging behavior could not be demonstrated with bumble bees in these smaller fields. It was established that as the foraging force of bumble bees increased, which varied between hives and fields, better fruit set resulted.

Ants as biological control agents in agricultural cropping systems

Ants positively impact agricultural systems by rapidly consuming large numbers of pest insects, disturbing pests during feeding and oviposition, and increasing soil quality and nutrients. The ability of ants to control pest species has been recognized since the year 300 A.D. and farmers continue to conserve and promote ant populations in agricultural systems worldwide. Naturally occurring ant species in milpas, mango, citrus, coconut, cashews, and cotton control many pest insects. Through judicious insecticide application and changes in management practices such as tillage, and other manipulations of vegetation and crop structure, beneficial ant populations are conserved in a variety of agroecosystems. The first recorded example of biological control was the manipulation of ants throughout citrus orchards in Asia. Augmentation continues in citrus, and methods of ant introduction have been developed in Malaysian and Indonesian cocoa plantations, as well as to control sweet potato and banana weevils in Cuba. Ant species have been formally incorporated into other integrated pest management programs for cashew in Australia, cocoa in Papua New Guinea, and mango in Australia and Vietnam. With efforts to reduce chemical pesticide input in agricultural systems, research evaluating the ability of generalist ant species to control pest insects must continue.

A global review of arthropod-mediated ecosystem-services in Vaccinium berry agroecosystems

Native beneficial arthropods, including bees, predators, and parasitoids, provide valuable ecosystem services, which help to maintain agricultural productivity and reduce the need for pesticide inputs. Vaccinium berry species are somewhat unique compared to many of the world’s fruit crops in that, up until recently, most of the harvesting and culture of species for food occurred in the geographic regions of their origin. This suggests that insects involved in many of the ecosystem services for these berries are native species that have a shared co-evolutionary history. Due to the shared phylogenetic origins of the Vaccinium spp. agroecosystems, the shared need for efficient pollination, and a number of shared agricultural pests, the potential exists for research from these related systems to closely apply to agroecosystems within the same genus. This review brings together research regarding arthropod-mediated ecosystem services from a number of prominent Vaccinium agroecosystems worldwide. In total, thirty-nine ecosystem service studies are discussed. These studies quantified arthropod-mediated ecosystem services being provisioned to Vaccinium agroecosystems. Additionally, thirty-nine surveys of arthropods closely associated and/or providing ecosystem services to Vaccinium systems are also reviewed. Studies took place almost exclusively in temperate regions with a heavy emphasis on insect pest biological control and pollination services. It is our hope that by synthesizing this body of literature, researchers and growers might be able to utilize research methods, results, and conservation recommendations despite differences in production practices and local arthropod fauna.

Homopterans and an Invasive Red Ant, Myrmica rubra (L.), in Maine

ABSTRACT Myrmica rubra (L.), is an invasive ant that is spreading across eastern North America. It is presently found in over 40 communities in Maine and areas in Vermont, New Hampshire, Massachusetts, New York, and several provinces in the Canadian Maritimes and Ontario. In addition to disrupting native ant faunas, invasive ants also have been shown to influence homopteran abundance and species composition. We conducted surveys of Homoptera in infested and noninfested sites and conducted manipulative experiments to quantify the effects of M. rubra on homopteran abundance and composition in the summers of 2003, 2006, and 2007 on Mount Desert Island, ME. In 2003, Homoptera family-level richness was higher in infested sites compared with noninfested sites with two out of three sampling methods. Homopteran abundance in infested compared with noninfested sites depended upon the site. The sites with the highest population of M. rubra were associated with significant differences in Homoptera population abundance. In 2006 and 2007, two out of three host plants sampled had significantly higher abundances of the aphids, Aphis spiraephila Patch and Prociphilus tessellatus Fitch. An ant exclusion field experiment on the native plant, meadowsweet (Spiraea alba Du Roi), resulted in higher abundances of A. spiraephila with M. rubra tending compared with native ant tending. A predator exclusion field experiment was conducted on meadowsweet using adult ladybeetles, Hippodamia convergens Guérin-Méneville, larval green lacewings, Chyrsoperla cornea Stephens, and no predators. Predator impacts on aphid populations were reduced in the presence of M. rubra with C. cornea and moderately reduced with H. convergens.

Assessing Honey Bee (Hymenoptera: Apidae) Foraging Populations and the Potential Impact of Pesticides on Eight U.S. Crops

ABSTRACT Beekeepers who use honey bees (Apis mellifera L.) for crop pollination services, or have colonies making honey on or in close proximity to agricultural crops, are concerned about the reductions of colony foragers and ultimate weakening of their colonies. Pesticide exposure is a potential factor in the loss of foragers. During 2009–2010, we assessed changes in the field force populations of 9–10 colonies at one location per crop on each of the eight crops by counting departing foragers leaving colonies at regular intervals during the respective crop blooming periods. The number of frames of adult bees was counted before and after bloom period. For pesticide analysis, we collected dead and dying bees near the hives, returning foragers, crop flowers, trapped pollen, and corn-flowers associated with the cotton crop. The number of departing foragers changed over time in all crops except almonds; general patterns in foraging activity included declines (cotton), noticeable peaks and declines (alfalfa, blueberries, cotton, corn, and pumpkins), and increases (apples and cantaloupes). The number of adult bee frames increased or remained stable in all crops except alfalfa and cotton. A total of 53 different pesticide residues were identified in samples collected across eight crops. Hazard quotients (HQ) were calculated for the combined residues for all crop-associated samples and separately for samples of dead and dying bees. A decrease in the number of departing foragers in cotton was one of the most substantial crop-associated impacts and presented the highest pesticide risk estimated by a summed pesticide residue HQ.

Using Peer Discussion Facilitated by Clicker Questions in an Informal Education Setting: Enhancing Farmer Learning of Science

Blueberry growers in Maine attend annual Cooperative Extension presentations given by university faculty members. These presentations cover topics, such as, how to prevent plant disease and monitor for insect pests. In 2012, in order to make the sessions more interactive and promote learning, clicker questions and peer discussion were incorporated into the presentations. Similar to what has been shown at the undergraduate level, after peer discussion, more blueberry growers gave correct answers to multiple-choice questions than when answering independently. Furthermore, because blueberry growers are characterized by diverse levels of education, experience in the field etc., we were able to determine whether demographic factors were associated with changes in performance after peer discussion. Taken together, our results suggest that clicker questions and peer discussion work equally well with adults from a variety of demographic backgrounds without disadvantaging a subset of the population and provide an important learning opportunity to the least formally educated members. Our results also indicate that clicker questions with peer discussion were viewed as a positive addition to university-related informal science education sessions.

Harvestman (Opiliones) fauna associated with Maine lowbush blueberry fields in the major production areas of Washington and Hancock counties.

ABSTRACT Over a period of 19 yr, the harvestman (Opiliones) community associated with the lowbush blueberry agro-ecosystem in Maine was studied. Eight species representing five genera, four subfamilies, and two families of harvestmen belonging to the suborder Eupnoi were collected. The harvestman community was dominated by two introduced, synanthropic species: Phalangium opilio in all but 1 yr (that year dominated by Rilaena triangularis). Rilaena was recorded for the first time from eastern North America. Relative abundance of harvestman adults increases throughout the season and the temporal pattern of trap capture does not refute speculated life cycles of the harvestmen being univoltine with overwintering eggs. Some blueberry management practices were found to affect trap capture. We did find that on average (with opposite results 1 yr) trap captures are greater in pruned fields than in fruit-bearing fields. Organic fields were found to have higher relative abundance of harvestmen than conventionally managed fields. Conventionally managed fields with reduced-risk insecticides showed no difference in harvestmen relative abundance compared with those conventionally managed fields using the older more persistent organophosphate insecticides. Insecticide trials with common insecticides used in blueberry insect pest management showed that the organophosphate insecticide, phosmet, and the pyrethroid insecticide, esfenvalerate, were detrimental to P. opilio adults when exposed to leaf residues, whereas the reduced-risk insecticide, spinosad, showed no negative effects compared with nonsprayed foliage.

Role of Climatic Factors on Damage Incidence by Dermolepida albohirtum (Coleoptera: Scarabaeidae), in Burdekin Sugarcane Fields, Australia

Abstract Inconsistent control of Dermolepida albohirtum (Waterhouse) (Coleoptera: Scarabaeidae) in the period after the removal of organochlorines allowed us to study the impact of climatic variables and insecticide application on subsequent damage in sugarcane (Saccharum spp.). D. albohirtum damage records from the Invicta and Inkerman mill areas of the Burdekin district of North Queensland were compared with climatic averages during spring from 1989 to 2003. D. albohirtum damage demonstrated autocorrelation, indicating that the area of damage will increase from one year to the next if the grub is not effectively controlled. Insecticide use did not significantly impact on the area of damage between 1989 and 2003. Of the climatic variables evaluated, only pan evaporation was significant, and it was inversely related to the subsequent area of grub damage. Therefore, we suggest that weather conditions in spring impact on beetle emergence, feeding, and oviposition. Hot and dry spring weather may reduce beetle activity and ultimately the severity of crop damage, whereas wet and mild spring weather may favor beetle activity and an increase in the area of potential crop damage.

Suppression of Escherichia coli O157:H7 by Dung Beetles (Coleoptera: Scarabaeidae) using the lowbush blueberry agroecosystem as a model system.

Wildlife as a source of microbial contamination is a food safety concern. Deer feces (scat) have been determined as a point source for Escherichia coli O157:H7 contamination of fresh produce. The ecological role of the scooped scarab (Onthophagus hecate (Panzer)), a generalist dung beetle species common in Maine blueberry fields, was explored as a biological control agent and alternatively as a pathogen vector between deer scat and food. A large-scale field survey of wildlife scat indicated that pathogenic E. coli O157:H7 was present, albeit at a low prevalence (1.9% of samples, n = 318), in the Maine lowbush blueberry agroecosystem. A manipulative field experiment verified that, should contact occur between deer scat and blueberry plants and fruit during the summer, contamination with E. coli O157:H7 can occur and persist for more than 72 h. For both the positive control and an experimental scat inoculation treatment, the levels of the bacterial population decreased over time, but at different rates (treatment x time interaction: F (1.9,18.8) = 358.486, P < 0.0001). The positive control inoculation, which resulted in a higher initial E. coli level on fruit, decayed at a faster rate than inoculation of fruit via scat in the experimental treatment. We conducted 2 laboratory studies to elucidate aspects of dung beetle feeding ecology as it relates to suppression of E. coli O157:H7 from deer scat to lowbush blueberry fruit. In both experiments, dung beetles buried the same amount of scat whether or not the scat was inoculated with the pathogen (F (1,6) = 0.001; P = 0.999 and (F (2,17) = 4.10, P = 0.147). Beetles feeding on E. coli inoculated deer scat were not found to vector the pathogen to fruit. In two studies, beetles lowered the amount of pathogenic E. coli persisting in soils compared to soils without beetles (F (2,9) = 7.757; P = 0.05 and F (2,17) = 8.0621, P = 0.004). Our study suggests that the dung beetle species, Onthophagus hecate, has the potential to contribute to the suppression of E. coli O157:H7 in agricultural landscapes.

Organic Lowbush Blueberry Research and Extension in Maine

A six-year organic systems research project was conducted in Maine from 2004 to 2009. The project had several components: (1) a large replicated interdisciplinary multifactor (fertility, weed, insect, and pathogen) experiment over three cropping cycles (6 years), (2) single disciplinary experiments designed to develop organic management tools for pest management, (3) an economic analysis of current organic production, (4) a survey of organic growers for the purpose of deriving a descriptive profile and the development of grower case studies, and (5) organic Extension workshops and field meetings and production of an organic wild blueberry growers guide. This article highlights some of the outcomes of this project including: ecological interactions among pests and fertility, novel management tactics, niche-market diversity, and economic viability.