W. P. Stephen

Unscented Color Traps for Non-Apis Bees (Hymenoptera: Apiformes)

Abstract Asian ladybug (semitransparent blue) and Japanese beetle (semitransparent yellow) insect traps (Springstar™) were tested for their utility in studies on bee diversity. The unscented traps were placed at four diverse ecological sites in Oregon in 2004 for approximately 48 hr and catches identified. Trap vanes were highly UV-A and UV-B reflective. The bee catch was diverse with a total of 369 bees, in 17 genera in five families. Bee captures were consistent with bee fauna at each site during the test periods. The semitransparent blue yielded an average of 17.3 bees/trap/day and the yellow 5.75 bees/trap/day. Bombus spp. made up 62.1% of all the bees captured, followed by the halictines (23.8%). It was surprising that Apis was virtually absent from all traps in all zones even though they were abundant in the immediate proximity of each trap. The current study is the first one in which colored traps captured sizeable numbers of bees: 1) in the absence of a pheromone or other attractant; 2) over a short time period of time (48 hr); and, 3) in a selective manner. These studies suggest that a modified SpringStar™ semitransparent blue trap may be a valuable tool in future studies on bee diversity, distribution, seasonal abundance, and bee foraging behavior.

X-Radiography, an Analytical Tool in Population Studies of the Leafcutter Bee Megachile Pacifica

SummaryThe contents and condition of cells of Megachile pacifica could be rapidly and accurately determined by X-radiography. Investigations are described and illustrated on loose cells, in white and Kraft paper straws, and cell series in sections of pre-drilled boards. Live and dead larvae, pupae and adults, pollen masses, parasites (Monodontomerus obscurus, Sapyga pumila, Nemognatha lurida), chalkbrood, and an unidentified disease, were determined from radiographs. The method is rapid and inexpensive, and should have a broad application in bee research and in commerce.

The Effect of Sublethal Doses of Parathion on Honeybee Behaviour. I. Oral Administration and the Communication Dance

SummaryThe oral sublethal dose of parathion in honeybees was determined as less than 0–03 μg per bee. Sublethal doses of parathion prevented bees from communicating the direction of a food source to other bees by dancing. The basic form of the dance of poisoned and nonpoisoned bees was similar, except that the angles at which the poisoned bees danced changed in a disjunct step-wise fashion (instead of linearly) with time. No evidence of changes in other behavioural patterns of foraging bees was observed in these tests, but there are suggestions that parathion at this level caused a temporary interference at an integrating centre outside the brain.

Time related decay in prey antigens ingested by the predator Podisus maculiventris (Hemiptera, Pentatomidae) as detected by ELISA

SummaryIndividual nymphs of the predaceous pentatomid Podisus maculiventris Say were each fed a single first instar Douglas Fir tussock moth larva, Orgyia pseudotsugata McDunnough, and held without further feeding at constant temperature for a known number of days before being frozen. Enzyme-linked immunosorbent assay, ELISA, was used to examine these predators for the presence of prey antigens. The concentration of prey antigens in these predators declined at a linear rate over the 7 days they were held post-feeding. Detectable antigens remained in 50% of the predators after three days at 24°C. On the day in which the prey was consumed (day 0) only 80% of the unstarved predators had detectable prey antigens which suggests the possibility of instinctive killing of prey with little or no subsequent ingestion. The amount of prey antigen in molted and unmolted predators was not statistically distinguishable; although molting interrupts feeding, digestion of the antigen(s) employed in this study seems to be continuous.

Sampling Native Bees in Proximity to a Highly Competitive Food Resource (Hymenoptera: Apiformes)

Abstract The efficacy of sweeping and vacuuming as methods of sampling native bees were compared to those of passive blue and yellow translucent-vane traps located adjacent to a highly attractive forage source, Helianthus spp. (Asteraceae). A total of 35 species of native bees belonging to 12 genera were caught during September, 94% in the passive blue-vane traps, 63% by sweeping, and 54% by vacuuming and yellow-vane traps. Overall, 55.7 % of all the native bees trapped in the study across the four treatments were collected in the blue vane traps. There were almost double the number of species, and over five times more individuals in blue vane traps than in the yellow. Agapostemon virescens (Fabr.) was the predominant species collected across all methods (400 of 1208). The majority of females (> 99%) captured in the blue vane traps lacked pollen suggesting that the bees may have been diverted by the reflected light from the trap during their flight to the floral sources rather than on their return flight to the nest. Very few Apis mellifera (L.) were taken in the traps, whereas they dominated in sweeping and vacuuming samples. These studies suggest that the blue vane traps can serve as an effective sampling tool for bee diversity studies in proximity to stands of intense floral competition.

Etiology and symptomatology of chalkbrood in the alfalfa leafcutting bee, Megachile rotundata

Abstract Aseptically reared larvae of the alfalfa leafcutting bee, Megachile rotundata , are susceptible to infection by spores but not mycelial cultures of Ascosphaera aggregata when introduced per os. The symptoms and signs of chalkbrood vary, depending upon host age at inoculation. Larvae inoculated early in life did not undergo the internal color changes after death that characterized larvae inoculated later. A longer time to death was also evident among larvae inoculated at an early age. Changes in the aerobic state of the host gut at the molt to the fourth instar may account for the difference in average time to death.

Investigating temporal patterns of a native bee community in a remnant North American bunchgrass prairie using blue vane traps.

Abstract Native bees are important ecologically and economically because their role as pollinators fulfills a vital ecosystem service. Pollinators are declining due to various factors, including habitat degradation and destruction. Grasslands, an important habitat for native bees, are particularly vulnerable. One highly imperiled and understudied grassland type in the United States is the Pacific Northwest Bunchgrass Prairie. No studies have examined native bee communities in this prairie type. To fill this gap, the bee fauna of the Zumwalt Prairie, a large, relatively intact remnant of the Pacific Northwest Bunchgrass Prairie, was examined. Native bees were sampled during the summers of 2007 and 2008 in sixteen 40-ha study pastures on a plateau in northeastern Oregon, using a sampling method not previously used in grassland studies—blue vane traps. This grassland habitat contained an abundant and diverse community of native bees that experienced marked seasonal and inter-annual variation, which appears to be related to weather and plant phenology. Temporal variability evident over the entire study area was also reflected at the individual trap level, indicating a consistent response across the spatial scale of the study. These results demonstrate that temporal variability in bee communities can have important implications for long-term monitoring protocols. In addition, the blue vane trap method appears to be well-suited for studies of native bees in large expanses of grasslands or other open habitats, and may be a useful tool for monitoring native bee communities in these systems.

The effect of sublethal doses of parathion. II. Site of parathion activity, and signal integration.

SummaryComparison of dance angles of parathion-treated bees on vertical and on horizontal comb revealed that poison-induced deviations were minimal or absent on the horizontal plane. Marked deviations reappeared upon returning the comb to its vertical position. This suggests that parathion affects the peripheral receptors or the integrating centre involved in geomenotaxis. The behavioural effect of topical application of parathion to part or all of the gravity receptors was comparable to that of oral administration.In a “fan” experiment, recruits interpreted the misinformation supplied by the dances of poisoned bees in a “correct” manner and were so misled. The stimulus strength of the wagtail dance appeared to be greater than that of the odour at the feeding sites in determining the flight direction of new recruits.It is postulated that the thoracic ganglia of honeybees have evolved as secondary centres of integration, and assume control of the fine-structural patterns of the communication dance angle (i...

Phenetic groupings in bees of the tribe bombini based on the enzyme α-glycerophosphate dehydrogenase

Abstract GDH isozyme patterns from thoracic muscle of 21 species of Bombus and 4 species of Psithyrus are each characterized by at least 8 bands arranged in 3 isozyme groups. Four distinctive pattern types were found, one for the species of Psithyrus and three among the Bombus species analyzed. Phenetic groupings of the 25 species are presented. Tissue specific GDH patterns are reported. No quantitative or qualitative differences in GDH patterns from thoracic extracts were associated with caste or age. The enzymes appear to be controlled by four non-allelic genes.

Bombus (Bombus) occidentalis (Hymenoptera: Apiformes): In decline or recovery

Bombus (Bombus) occidentalis Greene, 1858 is readily distinguished from other North American (excluding Alaskan) forms of the subgenus Bombus by its distinctive white pile on the apex of metasomal tergum 4 and on terga 5 and 6 (Stephen 1957, Thorp et al. 1983). It has been treated as a polymorphic species (Franklin 1913, Stephen 1957, Thorp et al. 1983, Scholl et al. 1990) and as a synonym of B. terricola Kirby (Milliron 1971, Poole 1996). As its status has yet to be resolved, we are treating forms with black pile on the metasoma terga 1–3 as B. o. occidentalis (5 typical form) and those with yellow pile on tergum 3 as B. o. nigroscutatus Franklin, 1913. Bombus o. occidentalis was one of the most common Bombus species on the west coast and in the coastal Valleys from the Bay Area of CA to the Alaska Panhandle until the mid 1990’s. It is now thought to be near extinction (Thorp 2003, Thorp & Sheppard 2005, NAS 2006). We have not seen it in the Willamette Valley since the spring of 1997, although a queen was sighted on a blueberry plant at Umpqua, Oregon in 2002 (R. Thorp, personal communication). Another queen, collected on 9 July 2005 in Victoria, British Columbia, Canada, was posted at http:// bugguide.net/node/view/23813. In the summer of 2006, during a study on native bee diversity and abundance in the Willamette Valley of western Oregon, we collected three workers of B. o. occidentalis. The specimens were collected in unscented translucent blue vane traps described in Stephen & Rao (2005), that were set up in clover seed production fields. The specimens will be deposited in the Oregon State University Arthropod Collection. Collection data are: