Tarantula Hawk Research Articles

Dispatches from Bug Cemetery

BUT, ALAS, ALTHOUGH I HAVE ANSWERS, THESE ARE NOT THE ANSWERS THAT RESONATE WITH AN AUDIENCE PREDISPOSED TO EMPATHIZE WITH INSECTS. We are at an outreach event. Any outreach event. Could be an open house. Or the rodeo. Or a scout meeting. It doesn’t matter. They all unfold in the same way. We stand behind cases of brilliant butterflies and tropical beetles, ready to show off the sheen of the morphos’ wings, the antler-like tusks of a lucanid, the unexpected size of a tarantula hawk. We are happy. We even have a peanut-headed lanternfly! Entomology is glorious, of course. We are immersed in wonder. It is the best profession. And we—the staff and students of the University of Texas Insect Collection—are ready to sell it. We field questions about why cockroaches hiss, how bees make their honey, what’s up with all the ladybird beetles in the attic, and why so...

Characterizing the nectar microbiome of the non-native tropical milkweed, Asclepias curassavica, in an urban environment.

In increasingly urban landscapes, the loss of native pollen and nectar floral resources is impacting ecologically important pollinators. Increased urbanization has also brought about the rise of urban gardens which introduce new floral resources that may help replace those the pollinators have lost. Recently, studies have shown that the microbial communities of nectar may play an important role in plant-pollinator interactions, but these microbial communities and the floral visitors in urban environments are poorly studied. In this study we characterized the floral visitors and nectar microbial communities of Ascelpias curassavica, a non-native tropical milkweed commonly, in an urban environment. We found that the majority of the floral visitors to A. curassavica were honey bees followed closely by monarch butterflies. We also found that there were several unique visitors to each site, such as ants, wasps, solitary bees, several species of butterflies and moths, Anna’s hummingbird, and the tarantula hawk wasp. Significant differences in the nectar bacterial alpha and beta diversity were found across the urban sites, although we found no significant differences among the fungal communities. We found that the differences in the bacterial communities were more likely due to the environment and floral visitors rather than physiological differences in the plants growing at the gardens. Greater understanding of the impact of urbanization on the nectar microbiome of urban floral resources and consequently their effect on plant-pollinator relationships will help to predict how these relationships will change with urbanization, and how negative impacts can be mitigated through better management of the floral composition in urban gardens.

Pain and Lethality Induced by Insect Stings: An Exploratory and Correlational Study.

Pain is a natural bioassay for detecting and quantifying biological activities of venoms. The painfulness of stings delivered by ants, wasps, and bees can be easily measured in the field or lab using the stinging insect pain scale that rates the pain intensity from 1 to 4, with 1 being minor pain, and 4 being extreme, debilitating, excruciating pain. The painfulness of stings of 96 species of stinging insects and the lethalities of the venoms of 90 species was determined and utilized for pinpointing future directions for investigating venoms having pharmaceutically active principles that could benefit humanity. The findings suggest several under- or unexplored insect venoms worthy of future investigations, including: those that have exceedingly painful venoms, yet with extremely low lethality—tarantula hawk wasps (Pepsis) and velvet ants (Mutillidae); those that have extremely lethal venoms, yet induce very little pain—the ants, Daceton and Tetraponera; and those that have venomous stings and are both painful and lethal—the ants Pogonomyrmex, Paraponera, Myrmecia, Neoponera, and the social wasps Synoeca, Agelaia, and Brachygastra. Taken together, and separately, sting pain and venom lethality point to promising directions for mining of pharmaceutically active components derived from insect venoms.

A long-term study of male territoriality in the tarantula hawk wasp (Hemipepsis ustulata; Pompilidae) in Central Arizona

Abstract Males of the tarantula hawk wasp Hemipepsis ustulata defend individual trees and shrubs growing on ridges and peaks in the Sonoran Desert of Arizona. Territories occupied by males of this wasp species have been monitored in the Usery Mountains of central Arizona for nearly 4 decades. Although previous research indicated that males abandoned their territories by midday, in this study some territories continued to be occupied until as late as 1600h Mountain Standard Time (MST). Territories held into the afternoon included those that were taken early and late in the flight season and which were most-frequently occupied overall. Individual plants that were most likely to attract territorial males during five previous studies were also the most popular territories in 2016. Likewise, many other features of the territoriality of male tarantula hawks have usually been similar during most of the five previous studies of the wasps, including the tendency of larger males to occupy highly ranked territories ...

Predatory Behavior of Long-Legged Flies (Diptera: Dolichopodidae) and Their Potential Negative Effects on the Parasitoid Biological Control Agent of the Asian Citrus Psyllid (Hemiptera: Liviidae)

Summary Apparently because of mulch buildup and abstinence from pesticide use, an organically managed citrus grove in Vero Beach, Florida, can support large populations of long-legged flies (Diptera: Dolichopodidae) that impose predation pressure on inundative releases of Tamarixia radiata (Waterston) (Hymenoptera: Eulophidae) parasitoid wasps to control the Asian citrus psyllid (Hemiptera: Liviidae). During peak activity, flies on wing characteristically hawk wasps in mid-air as the wasps are sprinkled from shipment containers onto the leaves of citrus plants. Flies on leaves enter into entrained scramble competition for prey by systematically “canvassing” upper leaf surfaces in rapid, jerked movements and, albeit infrequently, attack and eat wasps when encountered during this behavior.

Experimental Flights Using a Small Unmanned Aircraft System for Mapping Emergent Sandbars

The US Geological Survey and Parallel Inc. conducted experimental flights with the Tarantula Hawk (T-Hawk) unmanned aircraft system ( uas ) at the Dyer and Cottonwood Ranch properties located along reaches of the Platte River near Overton, Nebraska, in July 2013. We equipped the T-Hawk uas platform with a consumer-grade digital camera to collect imagery of emergent sandbars in the reaches and used photogrammetric software and surveyed control points to generate orthophotographs and digital elevation models ( dems ) of the reaches. To optimize the image alignment process, we retained and/or eliminated tie points based on their relative errors and spatial resolution, whereby minimizing the total error in the project. Additionally, we collected seven transects that traversed emergent sandbars concurrently with global positioning system location data to evaluate the accuracy of the uas survey methodology. The root mean square errors for the elevation of emergent points along each transect across the dems ranged from 0.04 to 0.12 m. If adequate survey control is established, a uas combined with photogrammetry software shows promise for accurate monitoring of emergent sandbar morphology and river management activities in short (1–2 km) river reaches.

Territorial Preferences of the Hilltopping Wasp Hemipepsis ustulata (Pompilidae) Remain Stable from Year to Year

Males of the tarantula hawk wasp Hemipepsis ustulata defend individual trees and shrubs on mountaintops in central Arizona where they wait for arrival of sexually receptive females. Each spring, a new generation of males comes to prominent hilltops to compete for mating territories. In 4 of 5 years during 1997–2007, in which the same Arizonan peaktop was censused regularly, behavior of males was similar with respect to such things as total number of plants occupied by territorial males, average number of days in which site-faithful males returned to their territories, and mean maximum days of residency at those select sites that attracted at least one male for a period of ≥2 weeks. Territories that regularly attracted males in one year did so in other years as well; territories that were infrequently occupied in one year were defended only occasionally, if at all, in other years. Even in the year (1998) when an unusually large number of plants were selected as perch territories by male wasps, preferred sites (those most consistently occupied over the flight season) remained the same as in the more typical years. Perhaps because the position and relative conspicuousness of the slow-growing mature trees and shrubs on hilltops remains the same from year to year, perch preferences of males also remain constant over long periods.

The Behavioral Significance of Male Body Size in the Tarantula Hawk Wasp Hemipepsis ustulata (Hymenoptera: Pompilidae)

AbstractLarge males of the tarantula hawk wasp Hemipepsis ustulata appear to have an advantage in the competition for mates. Large males are more likely to acquire perch territories used to scan for incoming receptive females and territorial males appear more likely to mate than non‐territorial males. In addition, among the males that do secure a mate, those that intercept a female on a territory are larger than those that do so elsewhere. Despite the mating advantages apparently enjoyed by larger males of this species, average male size has remained essentially constant over the last 25 yr. Moreover, larger males are not seen to employ certain competitive tactics that might otherwise enhance their reproductive success. Thus, larger males did not preferentially visit the most popular landmark territory compared to a site that attracted fewer visitors overall. Nor were larger males more likely to return to potential territories after marking, capture, and release, either immediately or on a subsequent day. Finally, although large males made up a significantly greater proportion of the males captured at two territories as the 2005 flight season progressed, over all the years of the study, receptive females have not been concentrated in the latter part of the flight seasons.

Venom and the Good Life in Tarantula Hawks (Hymenoptera: Pompilidae): How to Eat, Not be Eaten, and Live Long

Abstract Tarantula hawk wasps in the genera Pepsis and Hemipepsis are conspicuous elements of Southwestern U. S. and the Neotropics where they often appear oblivious to potential predators while they actively forage for nectar or search for prey. Tarantula hawks produce large quantities of venom and their stings produce immediate, intense, excruciating short term pain in envenomed humans. Although the instantaneous pain of a tarantula hawk sting is the greatest recorded for any stinging insect, the venom itself lacks meaningful vertebrate toxicity. The respective lethalities of 65 and 120 mg/kg in mice for the venoms of Pepsis formosa pattoni and P. thisbe reveal that the defensive value of stings and venom of these species is based entirely upon pain. This pain confers near absolute protection from vertebrate predators. The pain also forms an enabling basis for the evolution of aposematic coloration, aposematic odor, and a huge mimicry complex involving most species of tarantula hawks and numerous flies,...

Success in territorial defence by male tarantula hawk wasps Hemipepsis ustulata: the role of residency

1. Some male tarantula hawk wasps Hemipepsis ustulata defend landmark shrubs growing on mountain tops, while others only visit a succession of territory sites, generally fleeing from territorial males. To determine whether residency asymmetries contribute to the short duration of most interactions between territorial males and visiting intruders, established residents were held captive for varying periods while other males replaced them at their territories.2. Replacement males immediately assumed resident status and began to defend the shrubs and trees with success against non‐resident intruders, many of which were larger. Interactions between replacements and non‐resident intruders rarely escalated into pursuits leading to ascending flights.3. In contrast, when the original resident was released, its subsequent encounter with the replacement male almost always resulted in one or more ascending flights, even when the replacement had been on territory for less than 10 min. The longer the period of territory occupation by replacements, the longer on average the interaction and the more ascending flights, showing that the duration of time on a territory affects male motivation to defend the site. Despite strong resistance from long‐term replacements, however, returning residents almost always regained their territories.4. The strong residency effect in H. ustulata may be an adaptive proximate control mechanism for male behaviour that arises because established residents typically have high resource holding power, which makes them difficult to displace.

Territory Preferences and Intensity of Competition in the Grey Hairstreak Strymon melinus (Lepidoptera, Lycaenidae) and the Tarantula Hawk Wasp Hemipepsis ustulata (Hymenoptera, Pompilidae)

Males of the tarantula hawk wasp Hemipepsis ustulata and the grey hairstreak butterfly Strymon melinus have independently evolved highly similar reproductive tactics. Males of both species perch in and defend certain palo verde trees growing on ridgetops in central Arizona. The most popular trees, judging from frequency of occupation and frequency and duration of male-male aggressive encounters, are the same for both species. For both insects, most interactions between a territorial male and an intruder end quickly with the departure of the intruder. In the tarantula hawk, long aerial duels can be experimentally induced by capturing a resident male and then releasing him after a new male has taken control of his perch tree. Female tarantula hawks and female hairstreaks occasionally visit perch territories; although the data are scant, they suggest that females most often come to the territory location that males prefer. INTRODUCTION Many unrelated insect species use hilltops as mate-encounter sites (Shields, 1967). For example, over the course of a spring day in central Arizona, one can find males of several species of flies, wasps and butterflies perched on or patrolling near prominent shrubs and trees on hilltops that rise steeply from the surrounding desert plain. Among the hilltoppers are a large cuterebrid bot fly (Alcock and Schaefer, 1983), the California patch, a nymphalid butterfly (Alcock, 1985), two lycaenid butterflies, the great purple hairstreak and the grey hairstreak (Alcock, 1983a; Alcock and O'Neill, 1986), and a pompilid wasp (Alcock, 1979, 1981, 1983a). Males of all these insects are territorial. They defend perching sites on or near certain palo verde trees (Cerdidium microphyllum) that grow on the tops of ridges and hills. Although the palo verdes found on the highest points on ascending ridges seem to be the most consistently occupied by territorial hilltopping insects, other locations all along the backbone of a ridge are also claimed at times. Differences in the frequency with which individual trees are occupied provide a way to measure the preferences of hilltopping males for particular perches. Frequency of occupation data collected over several years for the tarantula hawk wasp Hemipepsis ustulata and the great purple hairstreak Atlides halesus have revealed that: (1) the same trees are claimed year after year by different generations of males of the two species; (2) the perch rankings remain much the same from year to year within a species, and (3) the wasp and hairstreak rank the trees in a similar manner, occupying the same few trees most consistently during their flight season (Alcock, 1983b). The question is, are the detailed behavioral similarities between Hemipepsis ustulata and Atlides halesus an exceptional case, or is convergence among territorial hilltopping insects widespread? We explored this question by comparing the tarantula hawk with another butterfly, Strymon melinus, a hairstreak that is not particularly closely related to A. halesus. Alcock and O'Neill (1986) established that males of both species perch in certain ridgetop palo verdes and that chases and ascending spiral flights between residents and conspecific intruders occur in both wasp and butterfly. This paper examines whether the wasp and butterfly also share similar perceptions of territory quality, which we measured by examining: (1) the frequency of occupation of palo verdes growing on 'Present address: Department of Entomology, Montana State University, Bozeman 59717.

Convergent Evolution in Perching and Patrolling Site Preferences of Some Hilltopping Insects of the Sonoran Desert

Males of the pompilid wasp, Hemipepsis ustulata, defend palo verde trees on mountain ridges in the Sonoran Desert. The preferences of the wasps for different trees on one ascending ridge remained essentially the same over four spring flight seasons. The wasps preferred large trees high on the ridge. Other insects unrelated to the wasp behaved similarly and focused their territorial or non-territorial mate-searching on or near the same sites most preferred by the wasps. Convergent preferences of hilltopping male insects may reflect the capacity of the compound eye of insects to detect some distant landmarks more easily than others. The prominent ridges that rise from the upland Sonoran Desert of central Arizona attract a diversity of insects, including tarantula hawk wasps, various butterflies, and bot flies. In the spring months males of these hilltopping species patrol or perch in or near conspicuous palo verdes (Cercidium microphyllum) growing on the backbone of the ridges. There they await the arrival of receptive females. Males of some species defend their patrolling or perching locations; in other species males exhibit little or no aggression toward conspecifics. But whether territorial or not, hilltopping males are not distributed evenly along ascending mountain ridges. Previous studies (Alcock, 1981, 1983a,b; Alcock and Schaefer, 1983) of three territorial members of the hilltopping complex (a pompilid wasp, Hemipepsis ustulata; a hairstreak butterfly, Atlides halesus; and a rodent bot fly, Cuterebra sp.) have documented that: (1) certain locations are much more likely to be occupied than others by territorial males, (2) territorial preferences appear to be stable from year to year, and (3) different species have similar preferences for available territory sites. The purpose of this report is (1) to provide new data on the year to year stability of territorial preferences of the wasp Hemipepsis ustulata, (2) to identify the key parameters of perch sites that determine their relative attractiveness to the wasps, and (3) to present new evidence showing that other species, both territorial and non-territorial, rank available mate- locating sites along a ridge in much the same order as the wasp.

Consistency in the relative attractiveness of a set of landmark territorial sites to two generations of male tarantula hawk wasps (Hymenoptera: Pompilidae)

Males of the tarantula hawk wasp Hemipepsis ustulata defend conspicuous palo verde trees on mountain ridges. A comparison of data from two flight seasons (1981 and 1980) reveals that the preference rankings of males for a set of perennial territories on one ridge remained highly consistent from generation to generation. This is the first thoroughly documented demonstration for insects that landmarks used as mating encounter sites retain the same relative attractiveness from year to year. The stability of male preferences is indirect evidence that access to females is related to the ability to acquire high-ranking territories. Moreover, in both years, (1) the flight season was 2.5 to 3 months long, (2) the range of body sizes in this highly variable species remained the same, and (3) the ratio of territorial males to non-territorial patrollers was constant. A key difference was a strong reduction in the total number and density of males found in the study site in 1981. The wasps responded to the decrease in competition for perch territories by failing to occupy some low-ranking sites that were taken in 1980.

Tarantula versus tarantula‐hawk: A study in instinct

Tarantula versus tarantula‐hawk: A study in instinct