Richard S. Vetter

House-hunting by honey bee swarms: collective decisions and individual behaviors

Summary: Thousands of individuals in a house-hunting honey bee swarm make a collective decision for one among many nest sites discovered. We recorded the dances on swarms in a forested area, where one swarms search encompassed about 150 km2 and many different sites. We then analyzed swarms in a desert area with only nest sites that we provided and monitored, to study how the swarm winnows multiple finds to a single site over the course of a few days. Most bees did not visit any site, very few visited more than one. Apparently choices were made with little or no direct comparison, through the interaction of two mechanisms: positive feedback through recruitment leading to growth in the number of scouts visiting good nest sites, and attrition reducing activity and recruitment for non-chosen sites. Individual differences between bees substantially affected these dynamics. Scouts varied considerably in amount of dancing and persistence, but most that danced did so vigorously after their first few visits, and then dropped out, ceasing their dancing though continuing to visit the nest site. Dances were nearly twice as long as reported for nectar and pollen. Scouts followed dances of others, and occasionally visited alternative sites, but rarely switched their dancing. When unanimity is reached, the bees must recognize that a decision has been made, break up the swarm cluster, and fly to the nest site. Buzz-running (Schwirrlaufen) probably plays a role here, but we observed less buzz-running than previously reported, and this occurred even early in the process; it might function as a chain-reaction effect triggering the end of the house-hunting process. Our results suggest that the choice among nest sites relies less on direct comparison of nest sites, and more on inherent processes of positive feedback and attrition by dancers dropping out.

Behavioral responses of maleHeliothis virescens in a sustained-flight tunnel to combinations of seven compounds identified from female sex pheromone glands

Each of the seven compounds that have been identified from femaleHeliothis virescens sex pheromone glands was examined for its ability to elicit sexual responses from male moths in a flight tunnel. The two compounds initially described as pheromone components, (itZ)-11-hexadecenal and (itZ)-9-tetradecenal, were necessary for behavioral activity to occur. Of the remaining five compounds, hexadecanal was most consistent in elevating behavioral activity of males when it was added to treatments. Live, calling females elicited greater sexual activity from males than did the 7-compound mixture on rubber septa.

Removing bee stings

BACKGROUND Conventional advice on immediate treatment of honey-bee stings has emphasised that the sting should be scraped off, never pinched. The morphology of the sting suggested little basis for this advice, which is likely to slow down removal of the sting. METHODS The response to honey-bee stings was assayed with a measurement of the size of the resulting weal. Injection of known quantities of venom showed that this measurement is a good indicator of envenomisation. FINDINGS Weal size, and thus envenomisation, increased as the time from stinging to removal of the sting increased, even within a few seconds. There was no difference in response between stings scraped or pinched off after 2 s. INTERPRETATION These data suggest that advice to patients on the immediate treatment of bee stings should emphasise quick removal, without concern for the method of removal.

Bites and stings of medically important venomous arthropods

About 75% of the world’s animal species are arthropods. While most of these species have no appreciable interaction with humans, a few cause significant medical or agricultural problems. This review is concerned with the small number of medically detrimental species which possess venom that causes morbidity and mortality when humans are bitten or stung. We restrict our discussion to the most important groups of venomous arthropods, the arachnids (spiders, scorpions) and insects of the order Hymenoptera (bees, wasps, ants). These species have a venom apparatus consisting of a gland or pair of glands and a system (fang, sting) meant to inject venom. Beyond the scope of this review are arthropods that employ toxins without delivery systems (i.e. topical noxious repellents) or those which vector disease. This review covers the relevant species worldwide (focusing on North America species), with special reference to the dermatologic expression of the injury. Toxicologically, there is far more diversity in spider venoms than in the venoms of Hymenoptera and scorpions, so that the correct identification of spider bites has special significance. Spiders are rarely correctly identified by bite victims or their physicians and are readily transported by human commerce out of their native range. There are stellar reviews of the toxicology of arthropod venoms and poisons,1,2 as well as an excellent quick guide to bites and stings of arthropods.3

Spiders of the genus Loxosceles (Araneae, Sicariidae): a review of biological, medical and psychological aspects regarding envenomations

Abstract Loxosceles spiders are of concern outside of the arachnological world because their bites can cause occasional necrotic skin lesions and/or systemic complications; these manifestations are known as loxoscelism. Once these spiders became well associated as medical entities, much notoriety was attained through the publication of medical case histories as well as tales of horrific wounds in the general literature. Although most Loxosceles spider bites are unremarkable, require only general supportive care, and often result in excellent outcome, they are an occasional source of severe dermonecrotic injury with long healing times and significant scarring. In rare cases of systemic loxoscelism, serious intravascular, nephrological and/or multi-organ damage can occur, sometimes resulting in death. However, also of concern is that loxoscelism is diagnosed by medical personnel or presumed by the general public in highly improbable scenarios preventing or delaying proper remedy, which can lead to deleterious outcome. Herein, Loxosceles spider biology and medical aspects are reviewed. In particular, an extensive discussion of the distribution of the brown recluse spider, L. reclusa Gertsch & Mulaik 1940, is presented along with life history characteristics, which relate to the medical aspects of the genus. Also presented are manifestations and epidemiology of loxoscelism, misdiagnoses of bites by the medical community, alternative diagnoses confused with recluse spider bites and a discussion of the psychological basis for the proliferation of the myth of loxoscelism by both the general public and the medical community. North and South American species are reviewed because this is where the genus predominates and is the region where the most pertinent research has originated.

A high-efficiency collection device for quantifying sex pheromone volatilized from female glands and synthetic sources

A high-efficiency collection device for sex pheromones volatized from forcibly extruded female glands is described. Filtered nitrogen gas is the carrier and glass wool the adsorbent. Small quantities of distilled carbon disulfide are used to rinse the glass wool. Recovery efficiency of synthetic compounds was usually 90–100%, and a mean of 2.4 ± 0.65 SD ng/min of (Z)-7-dodecenyl acetate was recovered in emissions from individualTrichoplusia ni (Hubner) glands.

An Infestation of 2,055 Brown Recluse Spiders (Araneae: Sicariidae) and No Envenomations in a Kansas Home: Implications for Bite Diagnoses in Nonendemic Areas

Abstract During a 6-mo period, 2,055 brown recluse spiders, Loxosceles reclusa Gertsch and Mulaik, were collected in a 19th-century-built, currently occupied home in Lenexa, KS. We conservatively estimate that at least 400 of these spiders were large enough to cause envenomation. Additional collections from more typically infested homes in Missouri and Oklahoma in 2001 yielded 45 and 30 brown recluse spiders, respectively. Despite these infestations, no envenomations of the inhabitants of these three homes occurred. Considering the levels of infestations with no bites in the homes presented here, nonendemic areas in the United States, which typically lack recluse spider populations and have had zero to few verified specimens of the spider, do not have sufficient numbers of brown recluse spiders to make envenomation a likely scenario. Despite this, physicians from nonendemic recluse areas often diagnose brown recluse bites which, therefore, are unlikely to be correct.

Male-produced aggregation pheromone ofCarpophilus obsoletus (Coleoptera: Nitidulidae).

Males ofCarpophilus obsoletus Erichson produce an aggregation pheromone to which both sexes respond. The pheromone was identified by GC-MS as (2E,4E,6E,8E)-3,5,7-trimethyl-2,4,6,8-undecatetraene (1), which is also a minor constituent of the pheromone blends ofC. hemipterus (L.),C. freemani Dobson, andC. lugubris Murray. The pheromone was synergized in wind-tunnel bioassays by propyl acetate, a “host-type” coattractant. In a dose-response study, 50 pg of1, plus propyl acetate, was significantly more attractive than just propyl acetate. Pheromone emission from groups of 65 males, feeding on artificial diet, averaged 2.2 ng/male/day. Emissions from individual males were larger, averaging 72 ng/day and ranging as high as 388 ng/day. Synthetic1 was tested in a date garden in southern California (500 µg/rubber septum), using fermenting whole-wheat bread dough as the coattractant. The pheromone plus dough attracted significantly more beetles than dough alone (means were 4.2 and 0.0 beetles per week per trap). Captured beetles were 54% females. Field trap catches were highest during the months of July and August.

Behavioral responses of maleHeliothis zea moths in sustained-flight tunnel to combinations of 4 compounds identified from female sex pheromone gland

Each of the four compounds that have been identified from sex pheromone glands ofHeliothis zea female moths was examined for its ability to elicit sexual responses from male moths in a flight tunnel. Males flew upwind to (Z)-11-hexadecenal alone, but greater levels of behavioral activity were evoked with the addition of (Z)-9-hexadecenal to the treatment. Addition of hexadecanal or (Z)-7-hexadecenal to the initial two components had no effect in raising the behavioral response of the males in the flight tunnel whether added singularly at both the normal gland-emission ratio or at varying ratios or in combination at the normal ratio. Live, calling females elicited levels of sexual activity from males not significantly different from that elicited by the mixture of (Z)-11- and (Z)-9-hexadecenal on cotton wicks.

Tracking a medically important spider: climate change, ecological niche modeling, and the brown recluse (Loxosceles reclusa)

Most spiders use venom to paralyze their prey and are commonly feared for their potential to cause injury to humans. In North America, one species in particular, Loxosceles reclusa (brown recluse spider, Sicariidae), causes the majority of necrotic wounds induced by the Araneae. However, its distributional limitations are poorly understood and, as a result, medical professionals routinely misdiagnose brown recluse bites outside endemic areas, confusing putative spider bites for other serious conditions. To address the issue of brown recluse distribution, we employ ecological niche modeling to investigate the present and future distributional potential of this species. We delineate range boundaries and demonstrate that under future climate change scenarios, the spiders distribution may expand northward, invading previously unaffected regions of the USA. At present, the spiders range is centered in the USA, from Kansas east to Kentucky and from southern Iowa south to Louisiana. Newly influenced areas may include parts of Nebraska, Minnesota, Wisconsin, Michigan, South Dakota, Ohio, and Pennsylvania. These results illustrate a potential negative consequence of climate change on humans and will aid medical professionals in proper bite identification/treatment, potentially reducing bite misdiagnoses.