We surveyed a 1,033-bp fragment of the cytochrome oxidase subunit I (COI) sequence to look for a useful diagnostic marker for discrimination between the Japanese cryptic species Chrysoperla nipponensis (Okamoto) (Neuroptera: Chrysopidae) (types A and B) and the commercially introduced Chrysoperla carnea s. str. from Germany. Phylogenetic analysis showed four distinct haplotype groups: one group corresponded to C. nipponensis type B and one group to C. carnea s. str., and the remaining two distinct groups, A1 and A2, corresponded to the same song phenotype, C. nipponensis type A. A2 was linked with the group of C. carnea s. str. and A1 was linked with the group of C. nipponensis type B. Cross-testing between A1 and A2 revealed their reproductive compatibility. Mitochondrial polyphyly within C. nipponensis type A may, therefore, originate from introgression or incomplete lineage sorting. Within the mitochondrial COI region presented here, there were 17 variable nucleotide sites useful for discriminating the four haplotype groups from each other.

Zaprionus is an important drosophilid genus in the Afrotropical region. Here, two new species, Z. burlai n. sp. and Z. tsacasi n. sp., are described from Tanzania and São Tomé, respectively. The two species show incomplete reproductive isolation with Z. tuberculatus Malloch and Z. sepsoides Duda, respectively, with intercrosses producing fertile females but sterile males. The latter two have long been considered sibling species and together with three other species (Z. mascariensis Tsacas & David, Z. kolodkinae Chassagnard & Tsacas, and Z. verruca Chassagnard & McEvey) form the tuberculatus subgroup. The phylogenetic relationships of these seven species of the subgroup were revised in light of mitochondrial (COII) gene sequences and wing morphometrics. Mitochondrial DNA firmly distinguished most of the species, except for a triad of Z. tuberculatus, Z. verruca, and Z. burlai. Wing morphometrics was able to distinguish between closely related species and also indicated the altitudinal origin of each species. Most species can be identified through internal anatomy of the reproductive system (testis and seminal receptacle lengths), and the discovery of the new species with incomplete reproductive isolation may help in understanding the genetic basis of this variation through interspecific hybridization. The molecular phylogeny reconfirmed the Malagasy origin of the subgroup during the Late Pliocene. Colonization of Africa probably involved two independent events during the Pleistocene.

Ceratophysella richardi sp. n. is described from South Carolina, USA. Unusual characteristics of a new species (post antennal organ with posterior lobes not surrounding accessory boss, macrochaetae p₂ on thoracic terga II-III set nearly in line with setae p₁, setae m₂ on thoracic tergum II sometimes present, setae p₁ and p₂ on abdominal tergum IV microchaetae and macrochaetae, respectively, and all body sensilla long) are intermediate between two genera and led the authors to synonymize Mitchellania Wray, 1953 with Ceratophysella Börner, 1932.

In North America, only two species of Neralsia Cameron can currently be considered valid: N. hyalinipennis Ashmead and N. incompleta Jiménez & Pujade-Villar. Claims that Neralsia nigriventris (Kieffer) and N. armata (Say) also should be considered as such are dubious. Here, four new species found in the United States and Canada are described: Neralsia ashmeadi Jiménez & Pujade-Villar sp. nov., Neralsia kiefferi Jiménez & Pujade-Villar sp. nov., Neralsia weldi Jiménez & Pujade-Villar sp. nov., and Neralsia readae Jiménez & Pujade-Villar sp. nov. Their main morphological characters are described and a key is provided so as to distinguish between these North American species.

Zygina rhamni Ferrari (Hemiptera: Cicadellidae: Typhlocybinae) is a mesophyll-feeding leafhopper that infests grapevine, Vitis vinifera L. This leafhopper’s overwintering strategy and the dynamics of its vineyard colonization, relative to the distance between the grapevines and the winter host plants and different grapevine vegetative densities, are described herein. This species shows a facultative heteroecious life cycle. In autumn, it migrates from vineyards to bramble, Rubus gr. fruticosus, and rose, Rosa chinensis Jacquin. On these host plants, females lay eggs that start to hatch at the end of March. Adults that developed on bramble colonize grapevines beginning in May; the leaf fall of rose, which takes place during the first half of April, probably causes the death of unhatched eggs and nymphs. We found that overwintering females can move back to vineyards and lay eggs until early June. The dynamics of vineyard colonization by the leafhopper involved initial concentration in areas close to bramble (May–early July) with subsequent, progressive spread through the vineyards, with concentration in areas of high vegetative density. Leafhopper presence was negligible in areas of vineyards with levels of vegetative density below a certain threshold.

We studied the biology of Dendroctonus murrayanae Hopkins (Coleoptera: Curculionidae: Scolytinae) in lodgepole pine, Pinus contorta Douglas, in Idaho and Montana. The beetle was not a primary agent of tree mortality. Susceptible host trees were physically damaged, had thin foliage, or were otherwise predisposed to infestation. Beetles attacked individual trees, not in groups, near ground level and at low density. Life stages and their behavior are described. Egg galleries were constructed upward and usually had short spurs. Mating occurred in the egg gallery. Eggs were laid in an elongated group, not in niches, in a shallow excavation along only one side of the egg gallery. Larvae aggregated in a communal chamber, feeding side by side, but separated before pupation. D. murrayanae has four instars. One annual generation is indicated, overwintering as larvae. D. murrayanae occurred in some trees with Pseudips (=Ips) mexicanus (Hopkins), Ips pini (Say), and Hylurgops porosus (LeConte) but seldom with the mountain pine beetle, Dendroctonus ponderosae Hopkins. No natural enemy or commensal insect was observed in brood chambers. A new character on the frons is described and the relationship of D. murrayanae and the spruce beetle, Dendroctonus rufipennis (Kirby), is discussed.

The development, survival, and reproduction of Liposcelis decolor (Pearman) (Psocoptera: Liposcelididae), an important insect pest of infested stored products, were evaluated at eight constant temperatures (20–37.5°C). Female L. decolor had four nymphal stadia, whereas males only had three nymphal stadia. Between 20 and 37.5°C, the female developmental period from egg to adult varied from 46.2 d at 20°C to 16.1 d at 35°C, and the male developmental period from egg to adult varied from 41.8 d at 20°C to 13.6 d at 35°C. Based on a nonlinear model, the lower temperature developmental thresholds of female from egg, first through fourth stadia, and combined immature stages were estimated at 12.22, 16.08, 10.93, 8.88, 12.64, and 13.02°C, the upper temperature thresholds were 42.11, 39.44, 41.27, 40.92, 39.20, and 40.52°C, respectively, whereas the lower temperature thresholds of males ranged from 11.68 to 15.86°C, and the upper temperature thresholds ranged from 40.19 to 42.04°C. The survival rate from egg to adult was 57.3% at 32.5°C, 38.4 at 20°C, and 19% at 37.5°C, respectively. After emergence, the adult had a preoviposition period that ranged from 6.8 d at 20°C to 2.3 d at 35°C. L. decolor produced the most eggs (130.4) at 32.5°C and the fewest (24.7) at 37.5°C. The population reared at 32.5°C had the highest intrinsic rate of increase (0.0609) compared with the populations reared at seven other constant temperatures. The populations reared at 35 and 37.5°C had type III survivorship pattern, whereas populations reared at other temperatures had type I survivorship curve as determined by a Weibull frequency distribution. The optimal range of temperature for L. decolor population growth was 27.5–35°C.

Larval erythraeid mites are common ectoparasites of harvestmen (Opiliones). However, interactions between these mites and hosts in tropical environments have received little attention. In this study, we examined the prevalence and intensity of mite infestations for Neotropical harvestmen from the Caribbean island of Trinidad. Overall, the prevalence of infestation was 9.9%, with significant interspecific variation in the intensity of mite infestation and significant differences in parasitism of hosts between habitats. Harvestmen collected from lowland, crappo-cocorite forest exhibited the highest infestation rates. In our samples, the intensity of infestation varied from 1 to 17 mites per host. Examination by scanning electron microscopy revealed that harvestmen were infested by two taxa of mites, a species of Leptus and another unidentified erythraeid species. Our observations represent the first host records for erythraeid mites parasitizing harvestmen from the families Cranaidae and Manaosbiidae. Mites were found to attach preferentially to the tibia and femur of the leg (175 of 178 observations). In general, the harvestmen of Trinidad exhibited mite parasitism in a fashion similar to temperate species with respect to site of attachment and prevalence and intensity of mite infestation. In the field, we also collected an adult Cynortula sp. (Cosmetidae) that was transporting 30 gravid adults of an oribatid mite (Acariformes, Oribatida, Mixonomata). Cases of mite phoresy upon harvestmen are rare, with our observation representing the first report of phoresy by an oribatid mite upon a harvestman and the first documentation of mite phoresy upon harvestmen in the Caribbean.

The intrinsic rate of increase (r_m) was estimated for Proprioseiopsis asetus Muma (Acari: Phytoseiidae) on pollen and two prey species at 35°C. Cattail, Typha latifolia L., pollen and Frankliniella occidentalis (Pergande) were equally favorable as food and superior to Tetranychus urticae Koch. More females were produced in a shorter time when P. asetus was fed F. occidentalis or pollen; however, survivorship was longer when the predator was fed T. urticae. On an F. occidentalis diet, calculated r_m values ranged from 0.2789 to 0.2925. The net reproductive rate was lower on a diet of T. urticae (6.48) than on pollen (9.76) or on F. occidentalis (21.39). The finite rate of increase was lower on T. urticae (1.1868) than on pollen (1.3274) or F. occidentalis (1.3398). The mean generation time was similar on the three diets. That the data reported here were collected at 35°C makes it remarkable. P. asetus may have great potential as a biological control agent of arthropods, especially thrips under climatic conditions of high temperatures such as in protected culture.

The mining flies Thrypticus truncatus Bickel & Hernández and Thrypticus sagittatus Bickel & Hernández (Diptera: Dolichopodidae) are being evaluated as biological control agents for the water hyacinth, Eichhornia crassipes (Martius) Solms-Laubach (Pontederiaceae). The behavior of adults and larvae of these species was studied in the laboratory and in several water courses of the Paraná River basin, Argentina. The larvae feed on sap from feeding points scraped in the vascular bundles in the petioles of E. crassipes. Pupation occurs in a chamber dug near one of the mine’s openings. External morphology of larvae and pupae, larval cephalic skeleton, and tracheal system are described. The pupae of both species have the ventrally flattened profile of the Medeterinae, with a transverse serrate ridge divided by a notch at the apex of the head. The mines, described herein in detail, constitute the microhabitat where the larvae live throughout their development, and obtain food and protection. Both species are active and reproduce on water hyacinth from spring to the end of fall, and overwinter as larvae inside the mines in the petioles. No morphological or behavioral differences were evident between the immature stages of these species, except in the apical ridges of the pupae. Both species seem to occupy the same niche on the plants.

RESUMEN Las moscas minadoras Thrypticus truncatus Bickel & Hernández y Thrypticus sagittatus Bickel & Hernández (Diptera: Dolichopodidae) están siendo evaluadas como agentes para el control biológico de la maleza acuática Eichhornia crassipes (Martius) Solms-Laubach (Pontederiaceae). Se realizaron observaciones de comportamiento de adultos y larvas de estas especies, en laboratorio y en diversos cuerpos de agua de la cuenca del Río Paraná, en Argentina. Las larvas se alimentan de savia a partir de orificios de alimentación roídos en los haces vasculares de los pecíolos de E. crassipes. Ellas desarrollan toda su vida dentro de la mina hasta empupar en una cámara construida en un extremo de la misma. Se describen la morfología externa de larvas y pupas, el esqueleto cefálico y el sistema traqueal de las larvas. Las pupas poseen el perfil plano de las Medeterinae, con una estructura serrada dividida por una hendidura transversal en el ápex de la cabeza. Se describe la estructura de la mina, la que constituye el micro hábitat donde las larvas obtienen alimento y protección. Ambas especies están activas y se reproducen sobre E. crassipes desde primavera hasta fin del otoño y sobreviven durante invierno como larvas dentro de los pecíolos de E. crassipes. No se encontraron diferencias morfológicas ni de comportamiento entre las larvas de ambas especies, excepto en el serrado apical de las pupas. Ambas especies parecen ocupar el mismo nicho sobre la planta.

Previous inventories of the diversity of lepidopteran symbionts have been limited to Eubacteria. We conducted a microbial survey of Calyptra thalictri Borkhausen (Lepidoptera: Noctuidae) by using polymerase chain reaction (PCR) primers for 16S rRNA sequences for Eubacteria, and primers for Archaea, fungi including yeast-like organisms, Microsporidia, and Wolbachia. Heads and abdomens of adult males of this fruit-piercing and blood-feeding moth were assayed separately. High-fidelity PCR and subsequent DNA analyses indicated that at least five microorganisms belonging to the α-, β-, and γ-Proteobacteria were present. Two eubacterial sequences, related to a Klebsiella sp. and a Sinorhizobium sp., were detected in the abdomens of all nine individuals sampled, and three additional sequences, two related to species in the genus Alcaligenes and one related to a Rhizobium sp., were found in some of the abdominal samples, suggesting all five could be associated with abdominal structures. No Archaea, fungi including yeast-like organisms, Microsporidia, or Wolbachia were detected. These results document the first microbial associates in a fruit-piercing and blood-feeding moth.

More than four decades have passed since the completion of the checklist by Moser and Blum (1960) of the ants of Louisiana. This research represents a significant contribution to and an update of their work. This report is the first-ever comprehensive assessment of the formicid fauna of Louisiana. One hundred thirty-two species from 40 genera and nine subfamilies were found. Information on how Louisiana ant fauna compares to that of adjacent states and Nearctic fauna are provided. Interesting results include the identity of exotic and pestiferous species, missing species, species lost, and previously unreported species.

As suburban landscapes expand, it is critical to understand their capacity to support wildlife. Pollinators, specifically bees (Hymenoptera: Apoidea: Anthophila), are to some degree compatible with urbanization and may be able to exist in suburbs in diverse assemblages. We surveyed 21 residential gardens for bees in Westchester County, a suburban area immediately north of New York City. From a sample of 1,675 individuals, we documented 110 species, of which 95% were native, 50% were solitary, and 93% were polylectic. In terms of abundance of specimens, eusocial (50% of specimens), native (97%), and polylectic (98%) bees were dominant. Contrary to our expectation, based on previous bee surveys in urban landscapes, the bee community documented was not depauperate in either soil-nesting or parasitic species (65 and 19% of species, respectively), nor was it enriched in exotic species (6% of species). Instead, the assemblage resembled the richer bee fauna documented at a 1,520-ha research preserve (forest) located in the same region, although certain specialist (oligolectic) and/or forest-associated species were absent. These results suggest that suburban landscapes in eastern North America have the potential to host relatively diverse and intact bee communities.

Several studies suggest the possibility that non-native lady beetles may have replaced native lady beetles in some agricultural habitats. There is relatively little information, however, about lady beetle species composition outside of agricultural habitats. Evans (2004) suggested that native species have retreated to nonagricultural habitats in response to the arrival of non-native lady beetles (habitat compression hypothesis). To test this hypothesis, a survey of lady beetles was conducted in 2004 and 2005 in different habitats in Maine. From May to October, lady beetles were sampled in a variety of agricultural and nonagricultural habitats. In total, 3,487 and 2,903 lady beetles were collected in 2004 and 2005, respectively. Non-native lady beetles were found in a variety of habitats, including the habitats that would have likely served as a refuge for native species if the habitat compression hypothesis applied to the surveyed areas. Native species were found in a higher proportion in agricultural habitats compared with nonagricultural habitats and in very low numbers in all of the habitats surveyed. Hippodamia tredecimpunctata tibialis (Say) and Coccinella transversoguttata Brown, the two native species that were once dominant here, made up only 1.09 and 0.07% of the total lady beetles collected, respectively. In this survey, we failed to detect evidence that native lady beetles have retreated to nonagricultural habitats in response to the arrival of non-native lady beetles.

Amino acids are important to all animal life. Termites rely mainly on microorganisms to retrieve these nitrogen sources from their food. One naturally occurring amino acid, m-tyrosine, has been reported to be toxic to bacteria and weeds. Its direct effects on termite survival are unknown however. Both no-choice and choice bioassays using five different doses of m-tyrosine were conducted to determine the feeding response and survival of Formosan subterranean termites, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae), in the laboratory. In no-choice tests, although all doses of m-tyrosine tested reduced filter paper consumption, only the highest dose tested (0.05 M) had significantly lower consumption compared with the control. This dose also caused significantly high termite mortality. In a five-choice bioassay, all doses of m-tyrosine tested reduced filter paper consumption significantly compared with the control. No mortality was observed in the choice tests, and very little feeding of filter paper treated with m-tyrosine occurred. From these experiments, we conclude that m-tyrosine is toxic to Formosan subterranean termites and acts as a feeding deterrent, and therefore, may be a promising wood preservative.

The antennal receptors of Sirex noctilio F. (Hymenoptera: Siricidae) were examined using scanning and transmission electron microscopy. Male and female antennae share five sensillum types: Böhm bristles, sensilla chaetica, sensilla basiconica, sensilla ampullacea, and uniporous contact chemoreceptors. Contact chemoreceptors make up ≈85 and 78% of the total sensilla on male and female antennae, respectively. On the most proximal flagellomere of the antennae, contact chemoreceptors are located in a shallow depression on the ventral surface. The number of contact chemoreceptors increases toward the distal end, covering two thirds of the circumference of each flagellomere. Contact chemoreceptors seem to be innervated by two sensory dendrites that terminate near the tip. In longitudinal section, a single subterminal pore is seen to be associated with each sensillum. Males had significantly more uniporous sensory pegs than females on the proximal half of the antennae. These receptors may play an important role in mate identification, suggesting that a female-released contact pheromone may be used by this insect. The putative function of these sensilla types is discussed.

The antennal sensilla of the emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), were examined using scanning and transmission electron microscopy. Male and female antennae have a scape, pedicel, and nine flagellomeres. Both male and female antennae share five sensillum types: sensilla chaetica (mechanoreceptors), three types of sensilla basiconica (olfactory), and uniporous gustatory/taste sensilla. Apical depressions containing large sensory fields of uniporous sensilla were seen on the eight most distal flagellomeres of both sexes. Counts of sensillum types showed that males possessed significantly more uniporous sensilla than females. We hypothesize that antennal contact is important for mate recognition by male A. planipennis. The distal apices of the eight outer flagellomeres were seen to have “tufts” composed of two types of sensilla basiconica. A third type of sensilla basiconica was observed within the perimeter of the uniporous sensory fields. The structure and putative function of each sensillum type are discussed.

Fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is a major economic pest throughout the Western Hemisphere. There exist two morphologically identical but genetically distinct strains (corn-strain and rice-strain) that differ in their host plant preferences. These strains can be distinguished by polymorphisms in the mitochondrial cytochrome oxidase I gene. There is also a tandem-repeat genetic element called FR that is found in large sex-linked clusters primarily in the rice strain, as characterized by sampling of fall armyworm populations in the southeastern United States. It was recently shown that the FR element is also present in Brazil, where it exhibits a similar strain-biased distribution. In this article, the analysis of FR was extended to populations in southern Texas, one of the principle overwintering locations for fall armyworm that infests the continental United States. DNA sequence analysis and an optimized polymerase chain reaction (PCR)-based method demonstrated that FR sequences are present in Texas and show the same distribution pattern as observed in Florida. The distribution of FR in Florida has remained relatively unchanged over a 4-yr period, suggestive of polymorphic equilibrium and the existence of at least partial barriers to the generation of interstrain hybrids. The implications of these findings on our understanding of interstrain mating behavior and the utility of the modified detection method to study fall armyworm populations are discussed.

The efficacy of sterile insect technique (SIT) depends on successful mating of released males with wild females. If the time of mating in a day of mass-reared and released males differs from those of wild females, the efficiency of SIT decreases. Therefore, understanding the molecular mechanisms controlling mating time of the target pests is particularly important for SIT. The period (per) gene, which has been considered as a key clock gene controlling the mating time of the melon fly, Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae), was cloned from two strains having different times of mating during the day. DNA sites varied in the 5′ and 3′ untranslated regions and at synonymous sites, although protein sequences were identical. We also provide phylogenetic relationships among PER protein sequences of dipteran species including several tephritid pest species. The functional domains of PER in the melon fly are very similar to those in other tephritid species. A luciferase reporter assay showed that the melon fly PER can functionally complement that of Drosophila melanogaster (Meigen). The results implicate that the major genetic cause of the difference in circadian periods, and thus in reproductive isolation, is probably one or more other clock gene(s). Thus, the series of studies may provide a novel factor concerning genetic quality control of mass-reared insect pests for SIT, which depends on successful mating of released males and wild females.

The entire mitochondrial genome of the bristletail Pedetontus silvestrii (Mendes) (Archaeognatha: Machilidae) was sequenced. The genome is 15,879 bp and bears the standard set of genes common to all arthropods. Genome features like nucleotide composition and codon use are compared with three other bristletails. The gene trnQ was inverted compared with the order in other hexapods. The major noncoding region (the A T-rich region or control region) between the small ribosomal subunit (rrnS) and the trnI gene includes one extensive repeat region, which has two tandem repeats of a 128-bp sequence. A T content is higher than in other known species of Archaeognatha and Zygentoma but is similar to that in Collembola and Pterygota.

Honey bees (Apis mellifera L.) (Hymenoptera: Apidae) have been selectively bred for varroa-sensitive hygiene (VSH), which is the removal of pupae that are infested by Varroa destructor Anderson & Trueman from capped brood cells. This hygienic behavior is a complex interaction of bees and brood in which brood cells are inspected, and then brood is either removed or recapped. Previous work has shown that VSH bees uncap and remove significantly more varroa-infested worker pupae than nonhygienic bees do, but nothing is known about the reactions of VSH bees to mite-infested drone brood. This study compared the reactions of VSH bees with mite-infested worker and drone brood in a laboratory test and a field test. VSH bees inspected brood cells containing mite-infested pupae of both types of brood, but they removed significantly fewer mite-infested drone pupae than mite-infested worker pupae after 1 wk. This result suggests that mite populations in VSH colonies could increase more rapidly when drone brood is available. Additionally, the percentages of uncapped pupae and uncapped mite-infested pupae were positively correlated to the natural infestation rate of brood after a 24-h exposure, but not after an exposure of 1 wk. This result suggests that the rate of uncapping brood by hygienic bees may depend on the infestation rate, which gradually decreases with longer exposures to bees that remove mite-infested pupae from capped brood.

Ants use a variety of navigational mechanisms in homing, including pheromone trails, landmarks, compasses, and visual “snapshots” of the landscape. In many cases, an ant has more than one of these information types available and may give priority to one mechanism over the others. We investigated how the ant Formica podzolica Francoeur makes use of polarized light during the initial stages of homing. When ants were displaced to an unfamiliar area, they spent significantly more time in the 90° arc centered on their perception of the direction to the nest. This preference was eliminated by modifying the ants’ view of the sky with a polarizing filter, suggesting that F. podzolica use polarized light information. However, the displacements also showed that the ants make use of nest-specific information (possibly landmarks or snapshot matching) to recalibrate their homeward paths. When confronted with incompatible orientation information from polarized light in the sky and landmarks, the ant seems to reorient using landmarks, overriding the information from polarized light.

The invasive container-dwelling mosquito Aedes albopictus (Skuse) shows modest behavioral responses to water-borne cues from predatory Corethrella appendiculata Grabham in North America. We investigate whether Ae. albopictus adjust their antipredatory responses to be proportional to size-dependent risk of predation. Fourth-instar Ae. albopictus attain a size refuge from C. appendiculata predation, and we compared the responses of second- and fourth-instar Ae. albopictus to cues from C. appendiculata predation. More vulnerable second-instar larvae showed a larger change in behavior in response to predation cues than did less vulnerable fourth-instar larvae, indicating threat-sensitive behavioral responses by Ae. albopictus.

Males of many species guard their mates to prevent rivals from usurping paternity of the potential offspring. Environmental conditions, such as temperature, may affect a male’s ability to guard a female effectively and consequently the amount of sperm competition that occurs. We tested whether temperature and light affected mating behavior in laboratory experiments on the Japanese beetle, Popillia japonica Newman, a species in which males guard females for minutes to many hours after mating. When tested in groups, under conditions of high temperature and high light, males guarded females for shorter periods of time and males and females both mated with more different individuals. The number of mating pairs observed at any one time, however, was lower under conditions of relatively high temperature and light, which agrees with field data and is likely due to a combination of shorter pair durations and a period of time between successive mates. Contests for females were rare, which indicates that these patterns were due to changes in the behavior of the male and/or female of the pair. To tease apart male versus female roles in these patterns, single males were given dead females for copulation and guarding. When single males mated with the dead female, light and temperature still affected guarding behavior (e.g., the shortest durations were under conditions of relatively high temperature and light), indicating that males play a major part in determining the duration of mate guarding, probably due to a change in the costs the males are incurring. However, the patterns in the dead female experiment were not identical to the patterns in the group experiment, implying that female behavior also plays a role in guarding time. Our results demonstrate that environmental conditions can have a major effect on sperm competition risk and suggest that males would benefit greatly from being able to mitigate, either morphologically, physiologically, or behaviorally, the impact of those conditions.

Using natural venom collected from the red imported fire ant, Solenopsis invicta Buren, we determined the dose of venom necessary to kill 50% of the workers (LD₅₀) of Argentine ants, Linepithema humile (Mayr), and several other ant species that the fire ant may encounter in California. Of the species tested, the Argentine ant was most susceptible to the venom. On a weight-adjusted basis the red imported fire ant was 330 times more resistant to the venom than the Argentine ant. In addition, the native southern fire ant, Solenopsis xyloni McCook, was significantly more susceptible to the venom than S. invicta. Formica perpilosa Wheeler was most resistant to the venom when the LD₅₀ was not adjusted for weight, requiring a dose 684 times higher than that of the Argentine ant. When we tested synthetic venom (solenopsin A, which is the main component of S. xyloni venom) against the Argentine ant, the LD₅₀ value was unchanged. However, both S. invicta and S. xyloni were ≈6 times more susceptible to the synthetic compound than to natural venom. Therefore, S. invicta venom is less toxic to fire ants while being just as toxic to Argentine ants as the simpler, more primitive venom of S. xyloni. Fire ant gaster flagging and venom dabbing applies enough venom to the Argentine ant to be lethal and may help explain the superior interference competition shown by the red imported fire ant.

Mating behaviors of the predaceous spined soldier bug, Podisus maculiventris (Say) (Pentatomidae: Asopinae), were observed, and vibrational signals used in intraspecific communication were recorded and analyzed. Only males produced vibrational signals, using three different vibrational modes: vibration of the abdomen, percussion with the front legs, or tremulation of the body. When recorded on a nonresonant substrate (a loudspeaker membrane), the mean dominant frequency of signals produced by abdominal vibration varied between 90 and 140 Hz, and of tremulatory signals between 8 and 22 Hz. Percussion signals were broad-band, with the dominant frequency ≈97 Hz and lower amplitude spectral peaks between 1,500 and 3,000 Hz. In the courtship phase of mating behavior, males emitted pulse trains composed of an abdominal vibration after a tremulatory pulse. Females stimulated by signals of abdominal vibration and composite signals expressed searching behavior and orientation toward the source of vibration, whereas no specific reaction to tremulatory signals was observed. Observations of mating behavior and playback experiments showed that the abdominal vibration signals had both long range calling and short range recognition functions. Tremulatory signals were emitted at close range and were essential for copulation to occur. The sequences of fast and repeated percussion signals were emitted both as individual signals during calling and courting or between vibratory and tremulatory pulses. However, unlike the other vibrational signals, percussion did not seem to be emitted in a particular behavioral context, and its possible function in eliciting responses from females is unclear.