Edward M. Barrows

Individual odor differences and their social functions in insects.

The evolution of individual or subgroup differences in odors of halictine bees is suggested from possible widespread intraspecific variation in pheromones. An important result of such variation may be maintenance of genetic polymorphisms; in nesting Hymenoptera odor differences may also facilitate individual nest recognition. In Lasioglosum zephyrum males habituate to odors of different females and perhaps thus save time by not trying to copulate with nonreceptive individuals. Guards (females) at nest entrances distinguish their few nestmates (other females) from other conspecific individuals by odors, seemingly pheromones. Duration of the habituation in L. zephyrum is at least an hour (perhaps much more) for males in relation to females and 6 or 7 days for guards in relation to nestmates. Studies of pheromones should take into consideration the possibility of pheromonal polymorphism in any species and the likelihood that it may be significant from biological and practical viewpoints.

Nectar Robbing and Pollination of Lantana camara (Verbenaceae)

Floral robbers are categorized as nectar-foraging, nectar-foraging-perforating, and pollen-foraging. Trigona fulviventris is a nectar-foraging-perforating robber of yellow flowers of Lantana camara. Flower head maturation of L. camara is centripetal and flowers turn from yellow to reddish-orange, resulting in inflorescences of central yellow flowers with peripheral orange and reddish-orange ones. In the laboratory, seed set occurs only after cross-pollination; in the field, the presence of orange and reddish-orange flowers is related to decreased nectar robbery of yellow flowers. Co-evolution of L. camara, its butterfly pollinators, and T. falviventris has presumably involved increased nectar production of this plant to feed both its pollinators and robber. THIS STUDY WAS MADE because of our limited knowledge of the pollination ecology of Latana camara; furthermore, it is the first record of nectar robbery by the stingless bee, Trigona (Trigona) fulviventris, or any other meliponine apid. T. fulviventris is a nectar-foraging-perforating robber of L. csmara which bites holes below the bases of the stamens (fig. 1) and probably effects little if any cross-pollination. Possible effects of its robbing behavior on butterfly pollinators and the general pollination ecology of this plant in Costa Rica were investigated. L. camara is a woody shrub distributed throughout tropical Central America; it has also become naturalized in other tropical and subtropical areas. Flowers gradually turn from yellow to reddish-orange in three days in the plants studied. Dronamraju (1958, 1960) reported that butterflies preferentially visit yellow flowers of Lantana and Muller (1877) hypothesized that having varicolored flowers makes inflorescences more visually attractive in potential pollinators. In Costa Rica, in addition to Lawtana, Trigona spp. rob nectar by perforation from Hamelia patens, Clerodendrum paniculatum, Rondeletia, and Malvaviscus. In other parts of the world, other genera of bees (e.g. Bombus, Apis, Xyloco pa, and Megachile) are or are likely to be nectar-foraging-perforating robbers of various genera of plants having flowers with tubular corollas (see for examples, Sprengel 1793, Darwin 1876, Kerner 1895, Porch 1924, Meidell 1944, Schremmer 1955, Meeuse 1961, Hurd and Linsley 1963, Macior 1966, 1970, 1971, Faegri and van der Pijl 1971).

Individually distinctive odors in an invertebrate

Males of Lasioglossum zephyrum demonstrated that females have odors which are characteristic of individuals. In a sequence of presentations of odors of individual females, male response toward odor of a given female decreased with time. However, renewed response resulted from the presentation of odor of another female. Furthermore males of this species are capable of “remembering” individual odors of females in nature, since in the laboratory they remained habituated to odors of individual females for at least 60–135 min.

Mating behavior in halictine bees (Hymenoptera: Halictidae): III. Copulatory behavior and olfactory communication

SummaryOf the eight species of halictine bees whose mating behavior was studied,Augochlora pura (Augochlorini) andLasioglossum zephyrum (Halictini) were investigated in the greatest detail. Halictine bees have a short, simple courtship. Copulation occurs in the male-above position and its duration, 4 to about 340 seconds, varies significantly among species. Females resisted most mating attempts of males and usually mated only once. Males inseminated more than one female.Males discriminated between conspecific females and those of other species; they did not make significantly more contacts with living, mobile females than with immobile ones killed by freezing. Female odors ofL. zephyrum andA. pura include aphrodisiacs; at least the former has a sex attractant which may be the same compound as the aphrodisiac. Virgin females ofL. zephyrum 2 to 8 days old produce aphrodisiac; it may be present throughout life. Some halictine females were highly attractive to males for up to 15 days, even after the females had mated. Aphrodisiac caused males ofL. zephyrum andA. pura to pounce upon 3 mm black India ink dots, which they probably mistook for females. Heads, mesosomas, and metasomas of females ofL. zephyrum all bore aphrodisiac.ZusammenfassungVon den acht Halictusarten, deren Paarungsverhalten studiert wurde, sindAugochlora pura (Auglochlorini) undLasioglossum zephyrum (Halictini) am genauesten untersucht worden. Halictusbienen haben eine einfache, kurze Balz. Bei der Kopulation reiten die Männchen auf, und die Kopulationsdauer (4 bis ungefähr 340 sec) ist signifikant unterschiedlich bei den einzelnen Arten. Die Weibchen widersetzen sich den meisten Paarungsversuchen der Männchen und kopulieren gewöhnlich nur einmal. Die Männchen begatten mehr als ein Weibchen.Die Männchen unterschieden arteigene Weibchen von solchen anderer Arten. Sie nahmen nicht signifikant mehr Kontakt auf mit lebenden Weibchen als mit unbeweglichen, die durch Einfrieren getötet waren. Duftstoff der Weibchen vonL. zephyrum undA. pura enthält Aphrodisiakum; zumindestL. zephyrum hat einen Sexuallockstoff, der wahrscheinlich mit dem Aphrodisiakum identisch ist. Zwei bis drei Tage alte, unbegattete Weibchen dieser Art produzieren ein Aphrodisiakum, welches vermutlich während der gesamten Lebensspanne vorhanden ist. Einige weibliche Halictinae waren bis zu 15 Tagen hoch attraktiv für die Männchen, sogar nachdem die Weibchen schon kopuliert hatten. Das Aphrodisiakum veranlasste Männchen vonL. zephyrum undA. pura auf 3 mm grosse, schwarze Tuschepunkte zu springen, die sie wohl für Weibchen hielten. Die Duftstoffe aus den Köpfen, Meso- und Metasomas von weiblichenL. zephyrum enthielten alle das Aphrodisiakum.

Sexual behavior in the Japanese beetle, Popillia japonica, and comparative notes on sexual behavior of other scarabs (Coleoptera: Scarabaeidae)

The majority of pairs of Popillia japonica follow the same sequence of sexual behaviors: The male approaches the female, mounts her, intromits, withdraws his genitalia, and remains mounted on her. “Mounted courtship,” that is, courtship exhibited while a male is mounted on the female, also occurs in this beetle. The mean duration of copulation was 132.5 sec for 33 pairs. The leg positions of P. japonica males mounted on females were generally consistent among individuals but varied considerably from those of other scarabs. Males remained mounted on females for up to 2 hr after copulation. Popillia japonica is polygamous in the laboratory and exhibits homosexual behavior. Males comprised 60% of field-collected adults. Sexual and related behaviors, sex ratios, and mating systems are variable in the Scarabaeidae.

male territoriality in the carpenter bee Xylocopa virginica virginica

Abstract Males of the carpenter bee Xylocopa v. virginica are territorial at nest sites, food plants, and landmarks such as boulders and houses. Their territories are defined as hover spaces of about 0.03 m 3 inside hemispherical 20-m-radius attack spaces. They copulated in or near nest-site and food-plant territories. Territorial males frequently fought with other males and chased or flew toward females and other airborne objects, such as heterospecific insects, birds, and aeroplanes. They held territories at nesting sites in April and May, but were seen to mate only in fall and on the first vernal flight days of females in April. Patrolling and interloping males without territories frequently attempted mating in the territories of others.

Mecopteran (Mecoptera: Bittacidae, Meropeidae, Panorpidae) Flight Periods, Sex Ratios, and Habitat Frequencies in a United States Mid-Atlantic Freshwater Tidal Marsh, Low Forest, and Their Ecotone

Abstract As part of a long-term arthropod biodiversity study, we operated six Malaise traps in Dyke Marsh Wildlife Preserve (DMWP), Virginia from April 1998 through December 1999 and obtained 104 adult mecopterans in five species. They were present in samples from late May through early November. Samples indicate that as a group, the mecopterans were more abundant in the forest than in the marsh and the forest-marsh ecotone, and the mecopterans had a female-biased sex ratio. Two of the trapped species are uncommon or of limited distribution in North America. Malaise traps can be used efficiently to survey and monitor certain mecopteran species in DMWP and similar places. To understand the mecopteran biodiversity and phenology in the Preserve more completely, it would be worthwhile to survey the entire Preserve for at least 10 yr with all appropriate sampling methods.

Biogeochemical prospecting for gold-bearing quartz veins of the Piedmont, Great Falls, Maryland

Abstract A plant-soil chemistry exploration survey of gold-quartz mineralization in the Wissahickon Formation of the Appalachian Piedmont was done in the vicinity of the Ford Mine, near Great Falls, Maryland, USA. Leaf samples were collected from nine plant species available at 73 sites: Acer rubrum (red maple), Asimina triloba (pawpaw), Carpinus caroliniana (ironwood), Cornus florida (flowering dogwood), Fagus grandifolia (American beech), Kalmia latifolia (mountain laurel), Nyssa sylvatica (black gum), Polystichum acrostichoides (Christmas fern), and Viburnum acerifolium (maple-leaf viburnum). Soil samples from the B horizon ( In soils, high concentrations of Au (33 ppb), Sb (1.8 ppm), Zn (646 ppm), and a high K2O/Na2O value (9.6) were directly related spatially to a gold-quartz vein along one traverse. F. grandifolia had strong concentrations of Au (to 17 ppb) and Zn (to 104 ppm) and a high K2O/Na2O (to 136) value displaced downslope up to 140 m from the vein along this same traverse. Soil would be the best prospecting sample in these situations. Of the nine plants species analysed (n = 25), one specimen of N. sylvatica of three analysed had the highest Au content (66 ppb vs.

Self-pollination rate and floral-display size in Asclepias syriaca (Common Milkweed) with regard to floral-visitor taxa

BackgroundAnimals fertilize thousands of angiosperm species whose floral-display sizes can significantly influence pollinator behavior and plant reproductive success. Many studies have measured the interactions among pollinator behavior, floral-display size, and plant reproductive success, but few studies have been able to separate the effects of pollinator behavior and post-pollination processes on angiosperm sexual reproduction. In this study, we utilized the highly self-incompatible pollinium-pollination system of Asclepias syriaca (Common Milkweed) to quantify how insect visitors influenced male reproductive success measured as pollen removal, female reproductive success measured as pollen deposition, and self-pollination rate. We also determined how floral-display size impacts both visitor behavior and self-pollination rate.ResultsFour insect taxonomic orders visited A. syriaca: Coleoptera, Diptera, Hymenoptera, and Lepidoptera. We focused on three groups of visitor taxa within two orders (Hymenoptera and Lepidoptera) with sample sizes large enough for quantitative analysis: Apis mellifera (Western Honey Bee), Bombus spp. (bumble bees) and lepidopterans (butterflies and moths). Qualitatively, lepidopterans had the highest pollinator importance values, but the large variability in the lepidopteran data precluded meaningful interpretation of much of their behavior. The introduced A. mellifera was the most effective and most important diurnal pollinator with regard to both pollen removal and pollen deposition. However, when considering the self-incompatibility of A. syriaca, A. mellifera was not the most important pollinator because of its high self-pollination rate as compared to Bombus spp. Additionally, the rate of self-pollination increased more rapidly with the number of flowers per inflorescence in A. mellifera than in the native Bombus spp.ConclusionsApis mellifera’s high rate of self-pollination may have significant negative effects on both male and female reproductive successes in A. syriaca, causing different selection on floral-display size than native pollinators.

Effect of diflubenzuron on flight of adult aquatic insects (Plecoptera, Trichoptera) following emergence during the second year after aerial application.

Abstract With Malaise traps, we monitored the flight of adult Plecoptera andTrichoptera following emergence from headwater streams in the FernowExperimental Forest, WV, during the second year after application ofdiflubenzuron. We placed five traps at various distances from eachstream during May through September of 1991, 1992, and 1993. Wecollected pretreatment samples during the first year. In May 1992,diflubenzuron was applied to two watersheds, and the other twowatersheds were used as untreated references. The 1992 study tested theeffects of diflubenzuron that fell directly into the streams or werewashed into the stream during the first year. For 1993, we tested thehypothesis that diflubenzuron affected adult flight following emergenceduring the year following abscission and possible ingestion of thetreated leaves. The analysis compared the regressions of the number ofadults caught in each trap versus distance of the trap from the streamamong years and between treatments for each species. The flight of thestonefly Leuctra ferruginea (Walker) was reduced in thetreatment watersheds compared with the reference watersheds during theyear following abscission of the treated leaves. Adult flight of otherspecies did not decrease in the treatment watersheds during 1993. Theseresults show a relatively small effect of diflubenzuron on theseaquatic insects; however, our study involved only a single applicationof diflubenzuron. Additional research may be needed to predict thepossible effects of multiple applications of diflubenzuron over severalyears as often occurs during actual efforts to suppress gypsy moth,Lymantria dispar (L.).