Leif D. Deyrup

Biology of the Parasitoid Melittobia (Hymenoptera: Eulophidae)*

As parasitoids upon solitary bees and wasps and their nest cohabitants, Melittobia have an intricate life history that involves both female cooperation and variably expressed male siblicidal conflict. Inter- and intrasexual dimorphism includes blind, flightless males and (probably nutritionally determined) short- and long-winged females. Thought to be highly inbred, Melittobia do not conform to local mate competition (LMC) theory but exhibit simple forms of many social insect traits, including overlapping adult generations, different female phenotypes, close kinship ties, parental care, and altruistic cooperative escape behaviors. Most host records and research findings are based on only 3 species--M. acasta, M. australica, and M. digitata--but any of the 12 species could have pest potential due to their polyphagy, explosive population growth, cryptic habits, and behavioral plasticity. Readily cultured in the laboratory, Melittobia offer considerable potential as a model for genetic, developmental, and behavioral studies.

Effects of gustatory nerve transection and regeneration on quinine‐stimulated Fos‐like immunoreactivity in the parabrachial nucleus of the rat

The distribution of quinine‐stimulated Fos‐like immunoreactivity (FLI) in several subdivisions of the parabrachial nucleus (PBN) known to be responsive to gustatory stimulation was examined in rats in which the chorda tympani nerve (CT) and/or glossopharyngeal nerve (GL) was transected (Experiment 1) and in rats in which the GL was transected with regeneration promoted or prevented (Experiment 2). We confirmed previous findings in the literature by demonstrating that rats intraorally infused with 3 mM quinine showed a robust population of FLI in the waist area and the external lateral (EL) and external medial (EM) subdivisions of the PBN (Yamamoto et al. [ 1994 ] Physiol Behav 56:1197–1202; Travers et al., [ 1999 ] Am J Physiol 277:R384–R394). In the waist area, only GL transection significantly decreased the number of FLI‐neurons elicited by intraoral infusion of quinine compared with water‐stimulated controls. In the external subdivisions neither neurotomy affected the number of FLI‐neurons. The effect of GL transection in the waist area was enduring for rats in which the GL did not regenerate (up to 94 days), but regeneration of the GL after 52 days restored quinine‐stimulated FLI to control values. In these same GL‐transected animals, there were parallel decreases in the number of gapes elicited by intraoral quinine stimulation that recovered, but only subsequent to regeneration of the GL. These data provide support for the role of the waist area in the brainstem processing that underlies oromotor rejection behaviors and also help substantiate the hypothesis that the CT and GL are relatively specialized with regard to function. Moreover, when the quinine‐induced pattern of neural activity in the second central gustatory relay, as assessed by FLI, is substantially altered by the loss of peripheral gustatory input from the GL, it can be restored upon regeneration of the nerve. J. Comp. Neurol. 465:296–308, 2003.

A simple technique for milking the venom of a small parasitic wasp, Melittobia digitata (Hymenoptera: Eulophidae).

We describe a simple method for obtaining good a quantity of pure venom from a small parasitoid wasp, Melittobia digitata. Crushing the insects head causes venom to be extruded from the ovipositor that dries rapidly as it is collected onto an insect pin. This technique may be applicable to other parasitic Hymenoptera.

Cooperative chewing in a gregariously developing parasitoid wasp, Melittobia digitata Dahms, is stimulated by structural cues and a pheromone in crude venom extract

To disperse after mating, female Melittobia digitata Dahms (Hymenoptera: Eulophidae) tunnel through the walls of their host’s nest. We found that M. digitata use chemical and structural cues to identify locations for chewing exit holes. An experimental combination of milked venom and artificial pits on the inner surface of rearing containers elicited a stronger response than either stimulus alone. We suggest that the venom-associated cue may be a pheromone that facilitates mutual attraction, aggregation, and focused chewing, and that these behaviors may have arisen from behaviors associated with the initial stages of host attack. This apparently cooperative behavior promises insights into the possible evolutionary origins of components of eusocial behavior.

Increased male sex ratio among brachypterous progeny in Melittobia femorata, a sib-mating parasitoid wasp (Hymenoptera: Eulophidae)

Abstract Melittobia are gregarious ectoparasitoid wasps that primarily attack various solitary bees and wasps. Characterized by high levels of inbreeding and an extremely female‐biased sex ratio, these wasps appear to satisfy Hamiltons criteria for local mate competition. However, previous studies of sex ratio have failed to take into account an important aspect of Melittobia life history, namely that every clutch represents the combined reproductive output of the initial foundress female plus as many as 37 non‐disperser short‐winged daughters. Melittobia femorata Dahms is unique among the 13 species of Melittobia in that adults emerge as two temporally distinct clutches. While the overall sex ratio of the combined progeny from both clutches (0.025 ± 0.01) is typical for that for other Melittobia species (between 0.02 ‐ 0.04 for single foundress cultures of the five other species included in this study), the sex ratio for the brachypterous first clutch of M. femorata from field‐parasitized hosts averaged about 10 times greater (0.303 ± 0.10). Laboratory experiments with single foundress M. femorata cultures on the same host species (Trypoxylon politum Say) maintained at 25°C or 30°C produced smaller first clutch sizes compared to the field‐infested hosts. While the number of brachypterous first clutch daughters was similar, significantly reduced first clutch sex ratios relative to field‐parasitized hosts (0.07 ‐ 0.10) were due to significantly fewer males being produced. Possible reasons for these differences and the elevated first clutch sex ratio in this species are discussed.

Ant Species in the Diet of a Florida Population of Eastern Narrow-Mouthed Toads, Gastrophryne carolinensis

Abstract Gastrophryne carolinensis (Eastern Narrow-mouthed Toad) is known to be an ant specialist, but prey identification has rarely progressed beyond family level. There are no prey records from Florida scrub, a rare upland habitat type. This study identifies species of 4859 individual ants retrieved from stomachs of 146 G. carolinensis collected in Florida scrub. All toads had consumed ants; ants comprised about 95% of all food items. Forty-three species of ants were recorded. About 77% were various species of Pheidole or Nylanderia. The ants consumed were mostly small (4 mm or less in length) and nocturnally active. Species that were eaten belong to ant genera known to contain venoms, chemical repellents, or other organic substances in exocrine glands. This finding suggests the possibility that Narrow-mouthed Toads have opportunities to sequester exocrine secretions of ants, in the manner of some other anurans. The diversity of ant species consumed by G. carolinensis suggests that this species might be able to subsist on disturbed-site ants, including exotic species such as Solenopsis invicta.

The Diversity of Insects Visiting Flowers of Saw Palmetto (Arecaceae)

ABSTRACT A survey of insect visitors on flowers of Serenoa repens (saw palmetto) at a Florida site, the Archbold Biological Station, showed how nectar and pollen resources of a plant species can contribute to taxonomic diversity and ecological complexity. A list of 311 species of flower visitors was dominated by Hymenoptera (121 spp.), Diptera (117 spp.), and Coleoptera (52 spp.). Of 228 species whose diets are known, 158 are predators, 47 are phytophagous, and 44 are decomposers. Many species that visited S. repens flowers also visited flowers of other species at the Archbold Biological Station. The total number of known insect-flower relationships that include S. repens is 2,029. There is no evidence of oligolectic species that are dependent on saw palmetto flowers. This study further emphasizes the ecological importance and conservation value of S. repens.

Flower Visitation by Adult Shore Flies at an Inland Site in Florida (Diptera: Ephydridae)

Shore flies (Ephydridae) are small acalypterates whose larvae are usually aquatic or semiaquatic. Adult feeding habits are varied and known for only a small proportion of species. Most adults consume algae or bacterial slurries, but some are predators on smaller arthropods, scavengers, or nectar feeders (Wirth et al. 1987). At the Archbold Biological Station in south-central Florida some adult ephydrids occur regularly on flowers. These species and their floral hosts are listed below. The Archbold Biological Station (ABS), located in Highlands County, is near the south end of the Lake Wales Ridge, a distinctive sandy upland. During the rainy season (Jun-Oct) low areas on the Ridge accumulate water in extensive shallow ponds, more than 150 of which occur on the ABS. These ponds usually dry up in winter and spring. Their drying shores become zones of biological hyperactivity as oxygen becomes more available for plants and animals, stranded aquatic organisms die, algae become concentrated, and nutrients are released. Such edges are ideal for a variety of shore flies. Drying ditches and a permanent lake also produce ephydrids. About 45 species of ephydrids are known from the ABS, but there are probably many additional species. Only a small number of species are known to visit flowers at the ABS. Specimens were collected with nets and aspirators from open flowers over a period of about 20 years. Over 150 species of plants were examined, of which only a small proportion attracted ephydrids. Only 1 or 2 representative specimens of each species were mounted from flowers of a single species of plant on a single day. These specimens are in the collection of the Archbold Biological Station. Most specimens were identified by the senior author, using taxonomic guides and ABS reference specimens identified by Willis Wirth, Wayne Mathis, and J. R. Vockeroth, all of whom examined the ABS ephydrid collection. Plants were identified by the senior author.

Host Preference and Utilization by Melittobia digitata (Hymenoptera: Eulophidae) in Relation to Mating Status

Host preferences of virgin and mated females of Melittobia digitata Dahms were compared in the laboratory using pupae of the flesh fly Neobellieria (=Sarcophaga) bullata (Parker) as hosts. When simultaneously offered two hosts, virgin females used only one of the hosts more often than mated females did. However, the unused second host developed to adulthood significantly less often than did controls, suggesting that the female stung and paralyzed it. Because virgin females lay only a few eggs that always develop into males which utilize very little of the host resource, this behavior seems adaptive in that potential hosts remain available, but developmentally arrested, for later full exploitation by the same female (now mated by her offspring). An additional implication of these results is that females can discriminate one flesh fly host from the other, and choose to avoid oviposition on both.

Colletes francesae, a New Species of Colletid Bee (Hymenoptera: Colletidae) Associated with Sideroxylon tenax (Sapotaceae) in Florida Scrub Habitat

ABSTRACT Colletes francesae, new species, is described and differentiated from other Colletes species. All specimens were collected from Florida scrub habitat on the Lake Wales Ridge in Peninsular Florida, an area known for arthropod endemism. Colletes francesae is oligolectic, at least locally, on a shrub of the genus Sideroxylon. Specimens of C. francesae are currently known from 5 protected sites; its conservation status is uncertain.