Showing papers in "Journal of the Kansas Entomological Society in 1987"

Estimation of bee size using intertegular span (Apoidea)

Abstract: The dry weights of solitary female bees are accurately and readily estimated by a nonlinear, exponential regression equation using the shortest linear distance measured between a female bee's wing tegulae across her thoracic dorsum. The regression equation is y = 0.77(x)0405, where y is intertegular span and x is dry weight. Melittologists often have need of a reliable and direct means to estimate the "size" of a pinned museum specimen without reverting to the cumbersome task of taking dry weights. A size measure is necessary for standardizing comparisons made in studies of bee energetics, foraging ecology, allom etry, anatomy, chemical ecology, reproductive and sexual selection, and nesting biology. Weight, whether wet or dry, is complicated by variations in crop or scopal contents. For example, workers of Apis mellifera foraging at saguaro cacti carry, on average, nearly a fifth of their wet weight in corbicular nectar and pollen (Cooper et al., 1985; Schmidt and Buchmann, 1986). Glandular reservoir contents further complicate weight estimates. Females of the large bee Habropoda (=Emphoropsis) laboriosa will contain from nearly 0 to 6 mg of Dufour's gland lipid secretion (Cane and Carlson, 1984), dependent upon age, time of capture and recency of secretion. Head width has been successfully employed for body size estimation of live male Philanthus wasps (O'Neill, 1983). It is less suitable for comparing the genera of bees, owing to head allometry that may reflect mandibular/labial gland development or nesting biology (e.g., leaf-cutting megachilids have robust mandibular musculature). Body length too has allometric drawbacks, particularly for the more elongate and cylindrical bodies of stem-nesting taxa. An intuitively appealing estimate of bee size would be a measure of thoracic volume. The content of thoracic flight musculature should directly translate into the lift required for flight by a bee of a particular size. The tegulae covering a bee's wing bases provide suitable landmarks between which can be measured a chord distance, the intertegular span, which might satisfactorily estimate bee dry weight. A female of each of 20 species of bees was selected for measures for the regression analysis. None of these species are eusocial, but among them are parasitic taxa, groundand stem-nesting species, which range in size from nearly Drosophila-sized Dialictus to bumblebee-sized carpenter bees. The species measured are: Collet?s inaequalis, Hylaeus rugulosus (Colletidae); Andrena accepta, Calliopsis andreniformis, Per dita coreopsidis (Andrenidae); Protoxaea gloriosa (Oxaeidae); Augochlora pura, Dialictus versatus, Dufourea marginata, Nomia melanderi (Halictidae); Hesperapis carinata (Melitti dae); Anthidiellum notatum, Megachile texana (Megachilidae); Anthophora urbana, Centris atripes, Diadasia olivaceae, Exomalopsis solani, Melissodes agilis, Triepeolus verbesinae, and Xylocopa micans (Anthophoridae). These species together represent the six major (and one minor) non-eusocial bee families and 18 of the tribes. One intact and pinned female (with empty scopae) of each species was first measured using a Wild? dissecting stereomicroscope fitted with an ocular micrometer. The shortest distance between the bases of her tegulae was recorded to the nearest 105 m (Fig. 1, inset). Both tegulae were kept within the shallow focal plane to ensure their alignment. For preliminary comparisons, head widths were also taken, using the greatest perceived width of the head when viewed from the vertex. Bees were then slipped off of their pins (or in the case of smaller species, dry, unpinned specimens were used) and dried for 5 days at 45?C, until they ceased losing weight. They were weighed using a Sartorius model 1712MP8 balance to the nearest 10~5g. Additionally, the weights and intertegular spans of 12 females each of Xylocopa virginica and of Diadasia rinconis were measured as above to assess degrees of intraspecific variability in these measures for a relatively large and a medium-sized bee. They were not included in the regression calculations. The sample of female weights, head widths and intertegular spans of the 20 species were preliminarily submitted to a simple linear regression. Intertegular span linearly increased with bee dry weight (P < 0.01, R2 = 0.945), as did head width (P <0.0l,R2 = 0.904). While significant, these linear regressions yielded unsatisfactory fits for many of the data points when plotted for the smaller bees. This content downloaded from 207.46.13.158 on Wed, 16 Nov 2016 04:30:06 UTC All use subject to http://about.jstor.org/terms 146 JOURNAL OF THE KANSAS ENTOMOLOGICAL SOCIETY

Estimation of bee size using intertegular span (Apoidea)

Abstract: The dry weights of solitary female bees are accurately and readily estimated by a nonlinear, exponential regression equation using the shortest linear distance measured between a female bee's wing tegulae across her thoracic dorsum. The regression equation is y = 0.77(x)0405, where y is intertegular span and x is dry weight. Melittologists often have need of a reliable and direct means to estimate the "size" of a pinned museum specimen without reverting to the cumbersome task of taking dry weights. A size measure is necessary for standardizing comparisons made in studies of bee energetics, foraging ecology, allom etry, anatomy, chemical ecology, reproductive and sexual selection, and nesting biology. Weight, whether wet or dry, is complicated by variations in crop or scopal contents. For example, workers of Apis mellifera foraging at saguaro cacti carry, on average, nearly a fifth of their wet weight in corbicular nectar and pollen (Cooper et al., 1985; Schmidt and Buchmann, 1986). Glandular reservoir contents further complicate weight estimates. Females of the large bee Habropoda (=Emphoropsis) laboriosa will contain from nearly 0 to 6 mg of Dufour's gland lipid secretion (Cane and Carlson, 1984), dependent upon age, time of capture and recency of secretion. Head width has been successfully employed for body size estimation of live male Philanthus wasps (O'Neill, 1983). It is less suitable for comparing the genera of bees, owing to head allometry that may reflect mandibular/labial gland development or nesting biology (e.g., leaf-cutting megachilids have robust mandibular musculature). Body length too has allometric drawbacks, particularly for the more elongate and cylindrical bodies of stem-nesting taxa. An intuitively appealing estimate of bee size would be a measure of thoracic volume. The content of thoracic flight musculature should directly translate into the lift required for flight by a bee of a particular size. The tegulae covering a bee's wing bases provide suitable landmarks between which can be measured a chord distance, the intertegular span, which might satisfactorily estimate bee dry weight. A female of each of 20 species of bees was selected for measures for the regression analysis. None of these species are eusocial, but among them are parasitic taxa, groundand stem-nesting species, which range in size from nearly Drosophila-sized Dialictus to bumblebee-sized carpenter bees. The species measured are: Collet?s inaequalis, Hylaeus rugulosus (Colletidae); Andrena accepta, Calliopsis andreniformis, Per dita coreopsidis (Andrenidae); Protoxaea gloriosa (Oxaeidae); Augochlora pura, Dialictus versatus, Dufourea marginata, Nomia melanderi (Halictidae); Hesperapis carinata (Melitti dae); Anthidiellum notatum, Megachile texana (Megachilidae); Anthophora urbana, Centris atripes, Diadasia olivaceae, Exomalopsis solani, Melissodes agilis, Triepeolus verbesinae, and Xylocopa micans (Anthophoridae). These species together represent the six major (and one minor) non-eusocial bee families and 18 of the tribes. One intact and pinned female (with empty scopae) of each species was first measured using a Wild? dissecting stereomicroscope fitted with an ocular micrometer. The shortest distance between the bases of her tegulae was recorded to the nearest 105 m (Fig. 1, inset). Both tegulae were kept within the shallow focal plane to ensure their alignment. For preliminary comparisons, head widths were also taken, using the greatest perceived width of the head when viewed from the vertex. Bees were then slipped off of their pins (or in the case of smaller species, dry, unpinned specimens were used) and dried for 5 days at 45?C, until they ceased losing weight. They were weighed using a Sartorius model 1712MP8 balance to the nearest 10~5g. Additionally, the weights and intertegular spans of 12 females each of Xylocopa virginica and of Diadasia rinconis were measured as above to assess degrees of intraspecific variability in these measures for a relatively large and a medium-sized bee. They were not included in the regression calculations. The sample of female weights, head widths and intertegular spans of the 20 species were preliminarily submitted to a simple linear regression. Intertegular span linearly increased with bee dry weight (P < 0.01, R2 = 0.945), as did head width (P <0.0l,R2 = 0.904). While significant, these linear regressions yielded unsatisfactory fits for many of the data points when plotted for the smaller bees. This content downloaded from 207.46.13.158 on Wed, 16 Nov 2016 04:30:06 UTC All use subject to http://about.jstor.org/terms 146 JOURNAL OF THE KANSAS ENTOMOLOGICAL SOCIETY

Preliminary observations on thermoregulation, clustering, and energy utilization in African and European honey bees.

Abstract: Honey bees of the African race Apis mellifera scutellata evolved under tropical and subtropical conditions, while the different races of European bees evolved under temperate conditions (Ruttner, 1975, 1976). Although Africanized bees have been thought of as hybrids between these two groups of bees, they are more similar to their African ancestors in morphology (Daly and Balling, 1978) and behavior (Fletcher, 1978; Winston et al., 1979; Otis, 1980; Winston et al., 1983). African (Africanized) and European bees have notable differences in morphology, behavior, and physiology of adaptive value to "tropical" and "temp?rate" en vironments, respectively (Winston et al., 1983). This concept is clearly substan tiated by the failure of European bees over centuries to form noticeable feral populations in the American tropics, contrasting with the dramatic success of African bees in colonizing a vast portion of the continent (Taylor, 1977). On the other hand, European bees form feral populations in temperate regions of America, and African bees have failed to colonize at high densities such areas in Argentina (Taylor, 1977; Kerr et al., 1982). Some of the comparisons that have been made between European and African bees consider the characteristics of each race in habitats similar to the ones in which each race evolved. Although side-by-side comparisons would be most meaningful, several biologically important trends are discernible from studies of each race in different regions. Individual African bees are smaller (Otis, 1982), develop faster (Kerr et al., 1972; Fletcher, 1978), forage at an earlier age (Winston and Katz, 1982), and have shorter lifespans (Winston and Katz, 1981). These African characteristics promote faster colony growth and rapid arrival at a swarm ing-age structure (Winston et al., 1980), leading to frequent reproduction by swarming (Otis, 1980), and on the average smaller sizes of colonies with less stores accumulated (Winston et al., 1983). Absconding is the most viable strategy for African colonies encountering periods of regional lack of resources or other un favorable local conditions, while maximum storage is advantageous for European colonies faced with more predictable and widespread unfavorable winter condi tions (Winston et al., 1983). Another adaptation of African bees toward unpre dictable tropical daily conditions is a tendency towards "individual foraging" which makes them more successful on scattered low-reward food sources (Rin dereretal., 1984). The differences encountered so far between African and European honey bees

Pollen Dispersal in Cuc?rbita foetidissima (Cucurbitaceae) by Bees of the Genera Apis, Peponapis and Xenoglossa (Hymenoptera: Apidae, Anthophoridae)

Abstract: Dispersal of buffalo gourd {Cuc?rbita foetidissima) pollen in Arizona at two sites and by two groups of pollinators is compared. Honey bees (Apis mellifera) were the primary pollen vectors in one cultivated field, and the squash bees Xenoglossa angustior, Peponapis timberlakei and P. pruinosa were floral visitors in another field. The foraging behavior of these bees is compared. Pollen admixed with fluorescent powders was used to indicate the distribution of pollen through each field. Statistical analysis of the distribution of flowers with marked pollen was made by the Kolmogorov-Smirnov two sample test and by logistic regression analysis. Although marked pollen was distributed farther by squash bees than by honey bees, the significantly different distribution of flowers on the vines in the two fields made analysis difficult. Squash bees dispersed marked pollen throughout the field and utilized all available pollen. Honey bees did not utilize all pollen but flowers and pollen dispersal were more uniform. Competition for pollen between honey bees and squash bees was reduced since the latter harvested most of the pollen standing crop before the honey bees became active. Both the native pollinators and honey bees in the absence of the other could effectively distribute pollen in their respective fields but honey bees could probably not compete as efficiently with native bees for pollen where the two groups occurred together. Buffalo gourd, Cuc?rbita foetidissima H.B.K. (Cucurbitaceae), is a native xero phytic gourd of the grasslands and dry desert washes of the southwestern United States and Mexico. The possible development and use of this plant as an arid lands crop depends on exploitation of oil and protein rich seeds and its large, starchy, perennial, storage root (Bemis et al., 1978). Vines emerge from the rootstocks in late spring. The flowers appear in late April or May and last until August or rarely September in the vicinity of Tucson, Arizona. The species has a gynomonoecious breeding system with most plants being hermaphroditic, bearing both male and female flowers. In natural popu lations of southwestern Arizona, however, about 30% of the plants are gynoecious, having only female flowers (J. Kohn, pers. comm.). Both within plant (gneitoga mous) and between plant (xenogamous) pollination occurs. There is no apomyxis or parthenocarpic seed development in this species; therefore all seeds result from ovules that are fertilized by pollen delivered to the stigmas by bees, the only reliable pollen vectors. Previous studies (Buchmann, unpubl.) have demonstrated the need for at least 50 (usually more) pollen grains per stigma to achieve fruit set. There is great variability, however, with about 44 grains to every ovule (with a range of 200-400 ovules per ovary) and with natural open-pollinated stigmatic loads of 10,000 to 30,000 grains not uncommonly found.

Response of Pheidole morrisi to two species of enemy ants, and a general model of defense behavior in Pheidole (Hymenoptera: Formicidae).

Abstract: Pheidole morrisi Forel is an omnivorous ant common throughout the eastern United States. Like all members in the genus Pheidole the worker force is composed of morphologically distinct soldiers and workers. The aggressive ants Lasius alienus (Foerster) and Solenopsis geminata (F.) are frequently abundant in the same habitats occupied by P. morrisi. Experimental introductions of these two enemy species indicate that Florida col onies of P. morrisi alarm-recruit soldiers and workers against L. alienus but not against S. geminata. These enemy-specific defense responses are compared with defense responses in other Pheidole species and a general model of defense behavior is presented. Recent studies on Pheidole dentata Mayr and Pheidole militicida Wheeler in dicate that the soldier castes, which differ markedly in these two species, are specialized to defend nest sites and food sources against a small subset of potential enemy ant species (Feener, 1981, 1986; Wilson, 1975, 1976a, b). In particular, workers of both these species alarm-recruit soldiers against ants in the genus Solenopsis but do not alarm-recruit soldiers against a variety of other ant species. Carlin and Johnson (1984) discovered that the alarm-recruit response of P. dentata soldiers against Solenopsis is innate, however colonies can also learn to alarm recruit soldiers against other ant species, including species with no previous contact with P. dentata. The discovery of such enemy-specific defense behavior is of general interest for two reasons. First, it demonstrates that caste division of labor can be unexpectedly specific. Moreover, these studies indicate that morphology and behavior are not necessarily closely associated (Feener, 1986). Second, enemy-specific defense be havior clearly shows that ant colonies not only distinguish between nestmates and alien workers, but also among different species of ants. Differences among species in the expression of this behavior presumably reflect differences in the evolutionary and ecological history of interspecific interactions. In this paper, I examine the defense behavior of Pheidole morrisi Forel against two species of enemy ants, Lasius alienus (Foerster) and Solenopsis geminata (F.). P. morrisi is broadly distributed throughout the eastern United States. It prefers to nest in sandy soil in blow-outs, pastures and open woodlands. The diet of this species consists mostly of insects and other arthropods, and workers occasionally collect seeds. Most of the prey items returned to nests are retrieved by single workers, but nestmates can also effectively cooperate to retrieve prey items that are too large for individual workers. 1 Present Address: Smithsonian Tropical Research Institute, Apartado 2072, Balboa, Republic of Panama. Accepted for publication 4 February 1987. This content downloaded from 207.46.13.73 on Thu, 11 Aug 2016 06:01:58 UTC All use subject to http://about.jstor.org/terms 570 JOURNAL OF THE KANSAS ENTOMOLOGICAL SOCIETY L. alienus and S. geminata are aggressive species that nest in the same habitat as P. morrisi. L. alienus is geographically widespread, but is most abundant in the north and central eastern United States (Wilson, 1955). S. geminata, in con trast, does not occur in the northeastern United States, but it is abundant in the southeast (Creighton, 1950). The diet of L. alienus consists of arthropod prey and honeydew, whereas the diet of S. geminata consists of arthropod prey and seeds. Both species employ efficient mass recruitment systems to usurp and defend large or persistent food sources. Where they occur, these species are frequently nu merically and aggressively dominant and present a significant competitive threat to other ant species. Materials and Methods Field work was conducted between 29 July and 4 August 1983 in open hard wood-pine woodland in the Apalachicola National Forest, 25 km south of Tal lahassee, Leon Co., Florida. P. morrisi and S. geminata were the most abundant soil-nesting species at this locality. Other species present included Conomyrma sp., Pheidole dent ata Mayr, Pheidole metallescens Emery and Pogonomyrmex badius (Latreille). L. alienus did not occur at this locality and, in fact, is rare in northern Florida, the southern limit of its range. I did not find the imported fire ant, Solenopsis invicta Buren, in this study site, although it was very abundant in surrounding areas. Presumably P. morrisi colonies at this locality had no previous contact with either L. alienus or S. invicta. S. geminata workers used in the experiments described below were collected from colonies in the study area. L. alienus workers were collected from captive queenless colonies collected in Iroquois Co., Illinois and transported to Florida for the present study. P. morrisi was common at this Illinois locality, but S. geminata was absent. Responses of P. morrisi colonies to contact with L. alienus and S. geminata were assessed using the following experimental protocol. Recruitment trails of P. morrisi were established by attracting workers to small pieces of tuna fish placed 1.0 m from nest entrances. The number of workers recruited to these tuna baits usually stabilized within 20-30 min. Once recruitment had stabilized, I counted the maximum number of soldiers and workers located within 5 cm of the baits for five successive 1 min periods. After these censuses, I introduced 20 workers of either L. alienus or S. geminata to the area around the baits and again counted the maximum number of P. morrisi soldiers and workers for each of the succeeding 15 min. I collected enemy ants by aspirating them into vials and then introduced them to the area around the baits by placing the vials on their sides and allowing enemy workers to walk out. The collection and introduction procedures did not apparently affect the behavior of either enemy ant species. Recruitment trails emerging from a total of 12 different colonies were subjected to the experimental procedure described above. In order to minimize learning (Carlin and Johnson, 1984) or other possible carryover effects during the exper iments, I introduced each enemy ant species once to each colony. Order of enemy introduction was determined randomly and at least 18 hr separated introductions to each colony. Results of these experiments were analyzed with a repeated measures analysis of variance (Winer, 1971). The experimental design included enemy and time This content downloaded from 207.46.13.73 on Thu, 11 Aug 2016 06:01:58 UTC All use subject to http://about.jstor.org/terms VOLUME 60, NUMBER 4 571 main effects (1 and 19 d.f., respectively) and an enemy x time interaction (19 d.f.) repeated across colonies (11 d.f.). Because the primary objective of this study was to determine whether the responses of P. morrisi to L. alienus and S. geminata were different through time, only the enemy x time interaction term was of interest. The correct mean square error term for this interaction term is the mean square for the enemy x time x colony interaction. Significant differences among the means for the enemy x time interaction term were determined by Tukey's Test for Honestly Significant Differences. To ensure that the variances of the enemy x time cells were homogeneous, I used a log transform [log(x + 1)] on soldier and worker counts.

Male competition and mating behavior within mating aggregations of Glenostictia satan Gillaspy (Hymenoptera: Sphecidae)

Abstract: Individuals of Glenostictia satan Gillaspy emerged from a small, sparsely vegetated area in Upper Sonoran desert. Males were considerably more numerous at the site than females and as many as 3000 males patrolled within this area at peak emergence. Males were site-constant, returning daily to restricted ranges within the total emergence area. These ranges were not defended against other males, and no male/male aggression was observed during periods of flying or walking. Numerous males clustered at digging sites, and upon discovering a female, attempted to mount her as she emerged from the ground. Males apparently were damaged in such clusters. One male would invariably succeed in mounting the female. The mounted pair walked away from the cluster, and other males in the cluster eventually dispersed. Dense concentrations of patrolling males are known to occur in some species of aculeate Hymenoptera. Among closely related species of Bembicini (Steniolia, Stictiella, and Gle nostictia), G. scitula forms dense nesting aggregations, and while the mating system is not fully known, it may resemble that of G. satan. In some less closely related aculeates (e.g., bees and other Sphecidae) where large nesting aggregations occur, similar mating systems have convergently evolved. G. satan is unusual in that pairs walk in copula, rather than fly, away from mating "balls". The site-constancy of males within the aggregation is known from some other species and may be more widespread than previously thought. The degree of aggregation of nests is a prominent factor which influences male mating strategies in aculeate Hymenoptera, in that it affects distribution of re ceptive females. If females emerge over an extended period of time within a restricted area, males can potentially mate with numerous females. Males may enhance their reproductive success by defending portions of the emergence area, or where higher nest densities are present, by patrolling emergence areas (Alcock