ABSTRACT
During dispersal into fruit-bearing wild blueberry fields, blueberry maggot flies were highly active during all daylight hours as revealed by trap captures, although in one trial afternoon activity was greater than morning activity. Flies were not captured in traps at night, although observations in growth chambers showed that their activity at night, measured as displacement of position, was equal to daylight conditions. Flies were shown to fly at low altitude, just above the crop canopy, and screen fencing was shown to be effective at reducing colonization of plots, presumably due to their low height during flight. Over a 4-yr mark-capture study, colonization rate was shown to be low at 9.7 m/d, although a separate 2010 study showed higher rates at 14.1 and 28.0 m/d. Movement was shown to be nondirectional or random in the field, but a constrained random walk exhibiting direction into the field. Weed cover and high fruit density were associated with higher fly relative abundance, suggesting these field characteristics served as attractors slowing colonization rate into a field. Transect trap studies showed the temporal and spatial pattern of fly colonization into commercial wild blueberry fields, one of a slow wave that penetrates into the field interior as the season progresses. There is also an increase in fly abundance within-field edges and adjacent forest. The 'stacking' of flies along a field edge and slow movement rate into a field was shown through simulation to be a result of nondirectional short-distance dispersal of flies.
Subject(s)
Blueberry Plants , Diptera , Tephritidae , Animals , Forests , Fruit , Insect ControlABSTRACT
Insect-mediated pollination is critical for lowbush blueberry (Ericaceae: Vaccinium angustifolium Aiton) fruit development. Past research shows a persistent presence of wild bees (Hymenoptera: Apoidea) providing pollination services even when commercial pollinators are present. We undertook the study to 1) provide a description of bee communities found in lowbush blueberry-growing regions, 2) identify field characteristics or farm management practices that influence those communities, 3) identify key wild bee pollinators that provide pollination services for the blueberry crop, and 4) identify non-crop plants found within the cropping system that provide forage for wild bees. During a 4-year period, we collected solitary and eusocial bees in over 40 fields during and after blueberry bloom, determining a management description for each field. We collected 4,474 solitary bees representing 124 species and 1,315 summer bumble bees representing nine species. No bumble bee species were previously unknown in Maine, yet we document seven solitary bee species new for the state. These include species of the genera Nomada, Lasioglossum, Calliopsis, and Augochloropsis. No field characteristic or farm management practice related to bee community structure, except bumble bee species richness was higher in certified organic fields. Pollen analysis determined scopal loads of 67-99% ericaceous pollen carried by five species of Andrena. Our data suggest two native ericaceous plants, Kalmia angustifolia L. and Gaylussacia baccata (Wangenheim), provide important alternative floral resources. We conclude that Maine blueberry croplands are populated with a species-rich bee community that fluctuates in time and space. We suggest growers develop and maintain wild bee forage and nest sites.
