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We present a molecular phylogeny of butterflies belonging to the genus Euphydryas s.l., based on partial sequences of 3 mtDNA genes (COI, ND1, and 16S). Euphydryas s.l. has been divided into 4 genera in an earlier revision. The current results show 3 well-supported groups within the genus, corresponding to 3 of the 4 proposed genera. The pair-wise divergences of 1 of the sequences (COI) are on the order of 3% within the 3 groups and 7% between the groups. This level of variation leads us to suggest that the entire group should be considered to be in the genus Euphydryas with 3 subgenera: Euphydryas,Hypodryas, and Eurodryas.
The larva of Loberus impressus LeConte is described based on adult-associated and reared specimens collected from corollas and seed pods of Iris hexagona on the gulf coast of Louisiana. The larva of L. impressus is similar to larvae of Zavaljus brunneus (Gyllenhal) Hapalips prolixus Sharp, Pharaxonotha spp., and Bolerus angulosus (Arrow), the other described larvae within the Xenoscelinae. Larval characters typical for the Loberini that are found in L. impressus include arrangement of integumental granules into rows, frayed and aciculate setae borne on spiny tubercles, and urogomphi spiny or tuberculate and recurved. The tarsungular setae of L. impressus and B. angulosus are single, in contrast to the dual setae present in other described larvae of Languriidae. Larva and adults of L. impressus were common in dried corollas and seed pods of I. hexagona that had begun to split open or had been invaded by Crematogaster ants. Fusarium and Cladosporium fungi were potential sources of food for L. impressus and other fungivorous beetles in the iris seed pods and on corollas.
Phylogenetic analysis of 38 Ips and 7 outgroup species (Orthotomicus spp., Pityogenes spp., Pityokteines sp.) using molecular (mitochondrial cytochrome oxidase I nucleotide sequence), morphological, and behavioral characters revealed Ips to be polyphyletic. The concinnus group, I. concinnus (Mannerheim) and I. mexicanus (Hopkins), was monophyletic and grouped among the outgroup species. The following character states are synapomorphic for these species: procurved sutures of the antennal club, steep elytral declivity, seminal trough of the male genitalia consisting of a single rod, construction of arcuate egg galleries, and laying of multiple eggs per egg niche. Given monophyly, diagnostic characters, and phylogenetic position, a new genus is described for the concinnus group and I. orientalis Wood & Yin.
A new family, genus, and species (Archaeatropidae, n. fam., Archaeatropos alavensis, n. gen., n. sp.) of Psocoptera from Alava Province, Spain, is described and illustrated from Late Cretaceous amber (114 m.y.a.). This new family belongs to the family group Atropetae. The relationships with the family group Atropetae and within Psocatropetae are discussed. We conclude that the Archaeatropidae represents an archaic, extinct lineage of Atropetae and possess some features shared with the Psocatropetae. This reinforces previous hypotheses about the relationships among Atropetae and Psocatropetae. These family groups represent 2 divergent branches arising from a common ancestor. A brief comment on the origin of the hypogean fauna in relation with our findings is made.
Old World Oraseminae were revised recently and a phylogeny proposed; however, nothing was known at that time about the biology or immature stages for genera other than Orasema. The immature stages, habits, and host associations of Timioderus and Orasemorpha are herein described, and a new species of Orasema,O. monomoria, is described based on material reared from a species of Monomorium (Formicidae: Myrmicinae) in Madagascar. Using this new information, the relationships of Old World Oraseminae were reanalyzed. After successive weighting of 48 trees, a set of six trees (length 191, retention index 0.80) was found that matched the earlier hypothesis. To better evaluate behavioral traits of Oraseminae, nine species groups of Orasema from the New World were characterized and included in a separate analysis, resulting in 54 successively weighted trees (length 204 steps, retention index 0.81). Results suggest that a host shift to Pheidole (Myrmicinae) and internal parasitism of the host larva by the first-instar larva, with a later shift to external parasitism of the pupa, are derived for Oraseminae. All Oraseminae deposit eggs into punctures formed in the plant tissue by the ovipositor, but the habit of laying single eggs is plesiomorphic for Orasema and laying multiple eggs is derived for Orasemorpha and Timioderus. The use of an intermediate host for gaining access to the ant host appears to have been derived twice within Oraseminae.
Nicrophorus hispaniola, new species, is described from the Dominican Republic, West Indies, and is distinguished from the known species of the subfamily Nicrophorinae. Preliminary cladistic analyses place this species basal to multiple species groups, which include most of the New World Nicrophorus species. This species has the most narrow range of all the New World Nicrophorus and may deserve conservation attention.
Past taxonomic studies of cockroaches in the genus Paratemnopteryx Saussure (Blattodea: Blattellidae) indicate the presence of different races of P. stonei Roth from cave populations in northeastern Australia. Morphometric analyses were carried out to investigate the morphological variation among individuals from four cave regions, including representatives of each of the races previously noted. Published canonical discriminant analyses, and additional cluster analyses, presented in this article, indicate morphological discontinuities among the populations. In addition, specimens collected from one region, although morphologically similar to P. stonei, are regarded as representing a new species of Paratemnopteryx. To investigate the utility of molecular data at the population and species level for this genus, we sequenced the second internal transcribed spacer (ITS2) region of nuclear ribosomal DNA. Sequences were obtained from 14 individual cockroaches used in the morphometric analyses. The size of the ITS2 gene region was 504–592 bp, with a mean G C content of 52.3%. We found that the ITS2 data supported the existence of at least three races of P. stonei, and the new species of Paratemnopteryx. We concluded that the ITS2 region is useful for taxonomic discrimination at the population and species level within Paratemnopteryx, and can help throw light on the evolution of cave dwelling species.
A new species of fossil grasshopper, Mioedipoda reisereri Stidham & Stidham, is the first insect to be described from the Miocene (15.5 million year old) Buffalo Canyon Formation of west-central Nevada. This fossil is identified as an oedipodine and is the oldest supportable band-winged grasshopper from North America. This species appears to be a primitive oedipodine and is perhaps the sister taxon to extant band-winged grasshoppers.
Platycoelia lutescens Blanchard (Scarabaeidae: Rutelinae: Anoplognathini), a species that occurs in the Andes Mountains of South America, is redescribed. Platycoelia albescens (Bates) and P. baronis (Ohaus) are considered new synonyms of P. lutescens. A lectotype is designated for P. albescens. The use of this species as a food source by the people of the Ecuadorian highlands is discussed.
RESUMEN
Se redescribe a Platycoelia lutescens Blanchard (Scarabaeidae: Rutelinae: Anoplognathini), especie presente en la cordillera de los Andes en Sudamérica. Platycoelia albescens (Bates) y P. baronis (Ohaus) son consideradas nuevos sinonimos de P. lutescens. Se designa lectotipo para P. albescens. Se discute el uso de esta especie como recurso alimenticio en ciertos poblados de los Andes ecuatorianos.
The hive beetle Aethina tumida Murray is a new pest of honey bee colonies in North America. Specimens of A. tumida were collected throughout its current range in the southeastern United States, and from several sites in South Africa. A 1018-bp section of the mitochondrial cytochrome c oxidase I gene was amplified and sequenced in 26 beetles collected from Florida, Georgia, South Carolina, and North Carolina, and in 14 beetles collected from seven sites in South Africa. Mitochondrial DNA variation between all A. tumida samples was <0.8%, which was still considered within the range expected for a single species. The U.S. samples showed two distinct haplotypes, differing by 6 bp (0.6%). Both haplotypes were found across and within several geographic regions, a result consistent with a single introduction into the United States. However, a broad survey of 151 beetles from their new range revealed significant heterogeneity in haplotype frequencies, perhaps resulting from multiple introductions. Although the data do not allow a precise estimate of the point from which A. tumida were accidentally exported from Africa, the close genetic similarity between beetles from the United States and South Africa indicates that studies conducted on beetle physiology, parasites, and pathogens in South Africa will have a direct bearing on populations now found in the United States.
The phylogenetic relationships and divergence times of 25 species of melanopline grasshoppers from western North America were estimated using mitochondrial DNA sequence data from a 1300-bp fragment of cytochrome oxidase I. Although only a few of the >350 species of Melanoplus were studied, the monophyly of the genus and observed sequence divergence suggests the group has radiated within the last 3.5 million years. Much of Melanoplus diversity is concentrated in the montane species groups endemic to the various mountain systems in western North America. Although species divergences correspond to different geologic events, the recency of species origins indicates that older geotectonic events such as mountain uplift were not involved. Sequence divergences indicate that many of the species originated during the Pleistocene, but others apparently originated during the late Pliocene. Although it appears that the diversity of Melanoplus has been generated by both large scale and localized dispersal-vicariance events (i.e., regional and interisland divergences, respectively), such inferences must be made cautiously because the rate of speciation has been high and some of the phylogenetic estimates are consequently uncertain. The short internodes separating some of the species not only restrict phylogenetic resolution, but also increase the probability that the gene genealogy may not accurately reflect species relationships because of lineage sorting. Despite these limitations, the findings of this study indicate that Melanoplus has undergone a recent radiation with rates of speciation comparable to other radiations such as the African cichlids and the drosophilids of the Hawaiian islands.
The yucca moths (Parategeticula Davis and Tegeticula Zeller; Lepidoptera: Prodoxidae) are known for their obligate mutualism with yuccas (Yucca: Agavaceae). Three new species of the previously monobasic Parategeticula are described from Mexico, and the genus is redescribed. The new species P. elephantipella,P. martella, and P. tzoyatlella share highly modified nonpiercing ovipositors with P. pollenifera Davis, a synapomorphy within all Incurvarioidea. Phylogenetic relationships are discussed, with morphological apomorphies mapped. Evidence for early evolution of the distinctive life habits of Parategeticula suggest that the interactions between these moths and their hosts can provide insights into the origin and early diversification of the obligate mutualism.
RESUMEN
Las “palomillas de la yuca” (Parategeticula Davis y Tegeticula Zeller; Lepidoptera: Prodoxidae) son bien conocidas debido a su mutualismo obligado con las yucas (Yucca: Agavaceae). En este trabajo se redescribe el género Parategeticula, previamente considerado monobásico, y se describen tres nuevas especies de México. Las nuevas especies P. elephantipella,P. martella, y P. tzoyatlella comparten la presencia de un ovipositor no cortante, altamente modificado con P. pollenifera Davis, una sinapomorfía dentro de Incurvarioidea. Se discuten sus relaciones filogenéticas y se muestran gráficamente las apomorfías morfológicas sobre un cladograma. Evidencia de la evolución temprana de los distintivos hábitos de Parategeticula sugieren que las interacciones entre estas palomillas y sus hospederos pueden permitir comprender el origen y la diversificación temprana del mutualismo obligado.
Animal taxa meeting in hybrid zones often exhibit partial reproductive isolation. This isolation may result from a variety of causes both before mating (e.g., incompatibilities in courtship behaviors) and subsequent to mating. Understanding the factors effecting reproductive isolation in hybrid zones can offer important insights into the process of speciation and the maintenance of species boundaries. The katydids Orchelimum nigripes Scudder and O. pulchellum Davis (Orthoptera: Tettigoniidae) form 2 hybrid zones in the eastern United States. I carried out breeding studies in the laboratory using animals from pure O. nigripes and O. pulchellum populations in the vicinity of one of these hybrid zones to examine possible modes of postmating reproductive isolation. The number of eggs produced by females mated to heterospecific males was dramatically lower than that of females mated conspecifically, but there was no evidence of any differences in hatch rate or offspring viability between egg clutches from heterospecific and conspecific crosses. Hatch rate, offspring viability, development time, and adult weight of hybrid progenies were all intermediate relative to corresponding values for progenies resulting from the 2 types of conspecific matings, although most of the differences between hybrids and each of the 2 classes of nonhybrid progenies were not statistically significant. The reduced oviposition of heterospecifically mated females suggests that females mated to heterospecific males do not receive the necessary stimulation to trigger oocyte maturation or oviposition behavior. The results reported here show that although some females will mate with heterospecific males, these matings tend to result in substantially reduced reproductive success relative to conspecific matings.
Field observations in the Tucson, AZ, basin reveal that Manduca sexta (L.) has been incorrectly described in the past as a specialist herbivore that oviposits and feeds exclusively on plants in the family Solanaceae. We present evidence that previously unreported, non–solanaceous hostplants are routinely used by M. sexta females for oviposition. These plants permit successful larval development, through to emergence of the next generation of adults. The novel hostplants, 2 species of the genus Proboscidea, belong to the Martyniaceae, a family taxonomically distant from the Solanaceae. Our observations on oviposition and larval feeding were conducted during 2 consecutive field seasons. During the 2nd field season, we counted M. sexta eggs on native hostplants, both solanaceous (Datura wrightii, Regel) and non–solanaceous (2 Proboscidea species), and found higher abundance of eggs on the Proboscidea spp., in approximately a 3:1 ratio. Our results challenge the commonly held view that M. sexta is a specialist exclusively on solanaceous plants.
We performed a mark-recapture study to determine rates of change in body mass during maturation of adult free-living Libellula pulchella Drury dragonflies. We captured, weighed, marked, and released 444 individuals (278 females, 166 males) that were 0–5 d old, including 261 that had emerged on the day of initial capture. On subsequent days, we recaptured 87 individuals at least once, and 6 were recaptured more than once. Nearly all new emergents (mean mass = 272 mg) that were recaptured after 1 or 2 d had lost mass (mean change = −29 mg), whereas most individuals recaptured after ≥3 days had gained mass (mean change = 109 mg; mean rate = 18 mg/d). Individuals that were heavier at emergence were much more likely to gain mass and to be recaptured at ages >1 or 2 d, thus suggesting differential survivorship based on size at emergence. Average growth rates of gainers were as high as 57 mg/d over a 5-d period. The sex ratio of newly emerged adults was heavily biased toward females (61%), but males were significantly larger at emergence, were more successful at gaining mass, and the sex ratio of individuals that ultimately gained mass did not differ significantly from 1:1. New emergents had empty guts and minimal fat, and changes in fat and water content explained very little of the average decrease in body mass observed for most new emergents. Overall, our data suggest that L. pulchella dragonflies face severe energy stress during early adult maturation, which strongly affects their demography.
Genetic differentiation among six Florida populations of Diaprepes abbreviatus (L.) was determined using protein and random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) markers. Proteins were separated by electrophoresis and stained with silver stain and for α-naphthylacetate esterase activity. No differentiation was observed among populations when egg proteins were silver stained: α-naphthylacetate esterase activity differentiated five of the six populations. RAPD-PCR data showed significant differentiation among populations, consistent with the hypothesis of three independent introductions of D. abbreviatus into Florida. Our data indicate that D. abbreviatus populations, once introduced, have generally remained in one locality with limited dispersal to new areas.
Brachydeutera sturtevanti Wirth is a shore fly found commonly in a variety of lentic habitats, including ephemeral pools, in the American Southwest and northern Mexico. We conducted field studies and laboratory rearings to elucidate the morphology and trophic ecology of this colonizer species important to newly flooded habitats such as constructed wetlands. The larvae are generally hyponeustic, suspended from the water surface by hydrofuge hairs on the posterior spiracles. All instars exhibit extremely versatile feeding strategies by collecting or scraping algae and detritus from solid substrates, or by bringing their mouthparts to the water surface and creating a vortex to initiate filter feeding. The mouthhooks are modified to form dorsoventrally-flattened plates lined with stout projections that facilitate the versatile larval feeding. The incubation period under laboratory conditions (20–22°C) was 1–4 d; the three stadia lasted 3–5 d each while the pupal period was 6–8 d. The results of a colonization experiment with 15 liter tubs containing distilled water (controls, C), oligotrophic lake water (L), lake water with a tule extract (T), lake water supplemented with the green alga Chlamydomonas (A), or lake water with both a tule extract and algae (TA) illustrated the ability of B. sturtevanti to colonize and complete larval development in habitats varying broadly in food quality. Adults were equally attracted to all treatments and each treatment produced equivalent numbers of puparia. The mean dry weight per puparium formed in each treatment showed an increasing trend of tule extract and algae > A > T > L > C, but dry weights among treatments were statistically equal. These data illustrate the generalist and opportunist nature of B. sturtevanti. The egg, three instars, and puparium are described and illustrated, and a preliminary key to Brachydeutera third instars from North America north of Mexico is given.
Occurrence of Anthocoris tomentosus Péricart, A. antevolens White, A. whitei Reuter, and Deraeocoris brevis (Uhler) in non-orchard habitats is described for areas adjacent to the pear growing regions of Yakima, WA. The four species were found on a number of tree and shrub species, especially willow, cottonwood, oak, alder, aspen, poplar, and bitterbrush. The four predators differed in degree of specialization. A. whitei was found almost exclusively on antelope bitterbrush (Purshia tridentata Pursh), apparently in close association with an unidentified psyllid. The other two anthocorids were more generalized, but differed in occurrence on some tree species. Adult and immature A. antevolens were common on oak, cottonwood, and poplar. Conversely, A. tomentosus was comparatively uncommon on these species, but was more abundant than A. antevolens on the neighboring willows; immatures of A. tomentosus were never recovered from oak. Adult and immature D. brevis were collected from several species not shown to support populations of Anthocoris spp., suggesting that the mirid is more of a generalist than the anthocorids. Anthocoris spp. were rare in apple orchards, whereas D. brevis was common there. A. tomentosus and A. antevolens showed distinct seasonal changes in plant use. Both species congregated on willow catkins beginning in March, but began to appear on summer hosts (oak, cottonwood, alder, aspen, poplar) in May and June. Some of the movement from willow may have been a result of the disappearance of a univoltine psyllid from this host plant. Traps composed of corrugated cardboard were placed at different sites to collect overwintering predators. A. antevolens and D. brevis were more broadly distributed among plant species than A. tomentosus or A. whitei (the latter restricted to pear and bitterbrush). A. antevolens was very abundant in traps collected from poplar and cottonwood, apparently because both tree species are important sources of late-summer prey for this predator. Other miscellaneous Anthocoridae and Deraeocoris spp. were collected while sampling, and lists of these species are provided. Orius tristicolor (White) was common at several sites, and was easily the most abundant anthocorid in overwintering traps at one intensively sampled orchard. This species was particularly abundant in traps placed in peach trees. Overwintering sex ratios of D. brevis, Anthocoris spp., and O. tristicolor were moderately to strongly female-biased.
To monitor aphid parasitism by Aphelinus hordei (Kurdjumov) and Aphidius colemani Viereck, we developed specific ribosomal DNA markers to distinguish them from several other cereal aphid parasitoid species and two important host species, the Russian wheat aphid, Diuraphis noxia (Mordvilko), and the greenbug, Schizaphis graminum (Rondani). Ribosomal DNA sequences for the internal transcribed spacer 2 (ITS2) were first cloned and sequenced from A. hordei,A. albipodus Hayat & Fatima, A. asychis Walker, A. varipes (Foerster), A. colemani, D. noxia, and S. graminum. We designed specific primers based on the ITS2 sequences. Polymerase chain reaction (PCR) amplification of wasp and aphid DNA using these primers, followed by agarose gel electrophoresis, successfully distinguishes A. hordei and A. colemani from all three other Aphelinus species and two aphid species. A 411-bp nucleotide fragment and a 571-bp fragment were amplified only from A. hordei and from A. colemani, respectively, and no such fragments were amplified from any other wasp species or aphids. DNA could be detected at a level as low as 10−3 adult wasp equivalent for A. hordei and 5 × 10−4 adult wasp equivalent for A. colemani. The DNA of both species was detectable in parasitized D. noxia 24 h after initial contact with adult parasitoid pairs.
Chilo partellus (Swinhoe) and Chilo orichalcociliellus Strand (Lepidoptera: Crambidae) are gramineous stem borers that occur sympatrically in the southern coastal area of Kenya. Evidence over a 30-yr period indicates that the indigenous stem borer, C. orichalcociliellus, is being gradually displaced by the exotic stem borer, C. partellus. Comparative laboratory studies were conducted in several large-stemmed grasses to examine factors that may be involved in the displacement of C. orichalcociliellus, and to examine other possible effects of the invasion of C. partellus into Kenya. C. partellus had a higher fecundity than C. orichalcociliellus at 25 and 28°C, but not at 31°C. In addition, more C. partellus than C. orichalcociliellus eggs survived to the first instar. C. partellus larvae developed faster than C. orichalcociliellus in maize and sorghum. In this shorter developmental time, C. partellus consumed more maize than C. orichalcociliellus, but both species consumed equal amounts of sorghum. On a daily basis, C. partellus consumed more maize and sorghum than C. orichalcociliellus. A few C. orichalcociliellus survived to the pupal stage in napier and guinea grasses, whereas no C. partellus survived. The shorter developmental period of C. partellus may give this species a competitive advantage over the slower developing C. orichalcociliellus. However, the ability of C. orichalcociliellus to complete development in two native grasses in which C. partellus did not survive may provide a refuge that has allowed C. orichalcociliellus to escape extirpation from the coastal area of Kenya.
In 1995 and 1996, Lepidoptera larvae of 13 families were sampled by pruning foliage from canopies of maple, hickory, red oak group, white oak, and chestnut oak. The families were Arctiidae, Geometridae, Hesperiidae, Lasiocampidae, Lycaenidae, Lymantriidae, Noctuidae, Notodontidae, Nymphalidae, Papilionidae, Saturniidae, Sphingidae, and Thyatiridae. Samples were collected from 18 plots (each 200 ha), nine in the George Washington National Forest in Virginia and nine in the Monongahela National Forest in West Virginia. Sampling seasons were from May to mid-August; foliage samples were collected each week. The occurrence of Lepidoptera on host trees within the two forests was compared. A total of 131 species of caterpillars representing 13 families was collected. Most larvae were Noctuidae (47 species) and Geometridae (44 species). Of 6,743 larvae collected over both years, 57% were gypsy moth, Lymantria dispar (L.). The population of this species collapsed during the second year of the study because of the fungus Entomophaga maimaiga. Other particularly abundant species in both forests were Acronicta ovata Grote, Hyphantria cunea (Drury), Polia latex (Guénée), Melanolophia canadaria (Guénée), Alsophila pometaria (Harris), and Nadata gibbosa (J.E. Smith). Some species were found only in one forest. Larval richness and abundance were higher in May and August and the lowest numbers occurred in June and July. Abundance and richness were different for the 2 yr. Population shifts may be directly related to weather conditions or indirectly related through the effects of temperature or rainfall patterns on natural enemies, foliage chemistry, or other factors. The number of species of caterpillars collected from the host tree groups was 62 on maple, 77 on hickory; 76 on the red oak group, 75 on chestnut oak, and 66 on white oak. The abundance of larvae ranged from 14.8% collected on maple to 25.4% collected on the red oak group.
The processes involved in the induction and termination of facultative larval diapause in the parasitoid Colpoclypeus florus (Walker) was investigated in the laboratory. Larval diapause in C. florus is under maternal control. Photoperiod is the major factor governing the induction of larval diapause in C. florus. The pupa of the maternal generation is the most sensitive stage though the adult is also sensitive. Adult sensitivity increases with age, in particular at low temperatures. Photoperiod has no effect on the developing larva. The critical photoperiod for diapause induction for parasitoids maintained throughout the life cycle at 15 and 20°C was found to be 15 and 13.5 h, respectively. No diapause was induced at 25°C at any photoperiod examined. A chilling period of >5 wk is a prerequisite for diapause termination. After 8 wk at 5°C, all diapausing larvae pupate within 20 d whether held under short or long daylength. Chilling temperature and duration of chilling significantly affected diapause termination. Diapause development proceeds rapidly as chilling period increases and temperature decreases. The role of diapause in the biology of this parasitoid is discussed.
Different larval stages of Microplitis rufiventris Kokujev were exposed to a sublethal dosage (0.4 ppm) of Lefenuron [N-{2, 5-dichloro-4-(1, 1, 2, 3, 3, 3-hexafluoropropoxy)-phenylaminocarbonyl}-2, 6-difluorobenzamide] or Lefenuron (0.2 ppm)/Deltanet (0.2 ppm) [O-n-butyl Ō-(2, 2-dimethyl-2, 3-dihydrobenzofuran-7-yl)-N, N′-dimethyl-N-N′-thiodicarbamate] by feeding treated artificial diets to parasitized Spodoptera littoralis (Boisduval) larvae to evaluate the effects on the reproductive potential of developing parasitoids. Lefenuron treatments caused a reduction in the reproductive ability of either the host insect or its parasitoid. Ovaries of parasitoid females (1 d old) emerging from Lefenuron/Deltanet treatments contained more ova than those from either Lefenuron-treated or control females. Experienced (ovipositing) females from Lefenuron/Deltanet treatments deposited significantly more eggs and contained, at death, more remaining mature oocytes in their calyx and egg reservoirs. The combination of a carbamate insecticide (Deltanet) and chitin-inhibiting growth regulator (Lefenuron) may enhance the reproductive ability of insect parasitoids and may provide a potential means for developing more effective biological control methods against insect pests.
Tethered females of the common cattle grub, Hypoderma lineatum (Villers), were allowed to oviposit on Hereford calves. The diameters of hairs selected for oviposition were compared with the diameters of randomly sampled hairs from the back of each animal. Also, the number of eggs attached to a hair was compared with the diameter of the hair to which they were attached. The mean diameter of hairs selected for oviposition was 0.07 ± 0.002 mm, whereas the mean diameter of randomly sampled hairs was 0.04 ± 0.001 mm. These means were significantly different, demonstrating that H. lineatum females rejected the more abundant narrow diameter hairs in favor of the relatively scarce larger diameter hairs during oviposition. The number of eggs deposited per hair increased linearly with increasing hair diameter, again demonstrating a propensity for selection of large diameter hairs during oviposition. Measurements of the circular area formed by the opposing, concave, hair grasping surfaces of the 9th sternites and 10th tergites resulted in a mean diameter of 0.10 ± 0.01 mm, conforming to the diameter of the largest hairs selected during oviposition. The possible selective advantages driving hair selection by H. lineatum are discussed as well as characteristics related to hair suitability and ovipositor tip morphology.
A method is presented to quantitatively score the degree of ovarian maturation in a predacious pentatomid with asynchronous follicle development. The effects of artificial diet and mating status on ovarian maturation rates were examined. Ovarian scores were not influenced by mating status but were significantly lower in females fed the artificial diet. Ovarian follicles start forming when females are 2.3 d old, reaching a peak at 4.5 d. In controls, the rate of new follicle formation decreases after the onset of vitellogenesis. By 4.5 d, all control ovarioles contained at least 1 vitellogenic follicle, and by 9.5 d all ovarioles had chorionated follicles. In contrast, females fed the artificial diet had 40% of the ovarioles with a vitellogenic and chorionated follicle at 10.5 d of age. Mating started when females were 3.5 d old and correlated with the start of vitellogenesis. Two peaks in mating were observed, one at 4.5 d and the other at 9.5 d. Regulatory mechanisms for oogenesis are discussed.
Development of the 1st-instar (L1) of the spruce budworm, Choristoneura fumiferana (Clemens), was studied at different temperatures under laboratory conditions. The development process was divided into different phases based on 4 distinct events observed during L1 development: hatching of L1, construction of hibernacula, excretion of green pellets, and molt. The green substance in newly hatched L1 was found to be proteinaceous. The proportion of L1 that successfully completed development at various temperatures indicated that the optimal temperature range for L1 development was between 18 and 27°C. Larval mortality, particularly at low temperatures, occurred mainly before construction of hibernacula and excretion of green pellets. Low temperatures had a weak effect on development time from larval hatching to construction of hibernacula, but the duration of subsequent development periods were substantially increased under these temperatures. Temperature threshold (TT ≈ 6°C), degree-day requirement (DD ≈ 87), and other developmental parameters were estimated.
We found evidence of a symbiotic relationship between Fusarium solani (Martius) and Hypothenemus hampei (Ferrari). Females of H. hampei colonizing coffee beans infested with F. solani produced significantly more progeny than those colonizing sterile beans. Beans infested by F. solani had significant amounts of ergosterol, which was not present in sterile beans. Fecundity and survival of H. hampei was positively correlated with the content of ergosterol in their diet. Other evidence of symbiosis includes the presence of F. solani spores caught in cuticular protuberances, known as asperites, on the pronotal area of female H. hampei. The asperites are flat and arranged in a radial pattern presenting a pronounced inclination directed to the center of this radial pattern which originates at a protuberance on the pronotal area. The asperites appear to increase the chances of fungal deposition on the pronotum when female beetles bore into infested coffee beans. The existence of a mutualistic association between H. hampei and F. solani and the role of the pronotal structures as primitive mycangia are discussed.
Laboratory experiments investigated the effects of mating status and wasp density on frequency of superparasitism, development time, longevity, and fecundity of offspring of the egg parasitoid Tiphodytes gerriphagus Marchal. When individual females searched a patch over a 24-h period the number of probes per egg from mated wasps was higher than that from unmated wasps, but there was no difference in number of larvae found per egg during dissections. When groups of 5 females searched a patch together, both number of probes per egg and number of larvae per egg increased significantly compared with that of individual females. Superparasitism occurred most frequently when eggs were simultaneously exposed to 5 females, and mated groups of females superparasitized more frequently than unmated groups (frequencies of 78.1 and 62.9%, respectively). Development time of wasps in superparasitized eggs was longer than that of wasps in singly parasitized eggs. Longevity of adult male parasitoids was not affected by having come from superparasitized eggs, but female longevity was decreased significantly. Mated and unmated females showed no significant differences in fecundity, regardless of whether they had emerged from superparasitized or singly parasitized eggs.
The twospotted leafhopper, Sophonia rufofascia (Kuoh & Kuoh), is an inadvertently introduced insect that has become a pest in Hawaii’s diverse ecosystems. In this study, laboratory and field experiments were conducted to examine mating, oviposition, and egg and nymphal development of S. rufofascia. In the laboratory at 23 ± 1.5°C, adult S. rufofascia did not mate until 7–9 d after eclosion; the proportion of mating pairs increased from 10 to 100% as age increased from 9 to 15 d. A complete mating process in S. rufofascia consisted of mounting, back-to-back copulation, and postmating rest phases, which lasted for a mean ± SE period of 0.7 ± 0.04, 64.7 ± 1.20, and 3.5 ± 0.39) min, respectively. When caged on individual shoots of host plants (ti, Cordyline terminalis L. and guava, Psidium guajava L.) growing outdoors, adults did not lay eggs until the second week after emergence. The oviposition period lasted 8–9 wk, and the weekly oviposition rate peaked 4–5 wk after emergence (9.8 ± 2.9 eggs per female on ti; 8.1 ± 0.9 eggs per female on guava). There was no significant difference in the total number of eggs laid per female on guava versus ti plants. Under outdoor ambient conditions, eggs of S. rufofascia did not begin to hatch until 4 wk after oviposition, and the peak rate of hatch occurred 6 wk after oviposition. Newly hatched nymphs took a mean of 56.9 ± 2.8 d on guava and 47.2 ± 1.7 d on ti plants to complete development to the adult stage. These results indicate that S. rufofascia may take 3–4 mo to complete a single generation during fall and winter in Hawaii. Because of the 2-mo oviposition period of adults and the large variation in the developmental time of eggs and nymphs, S. rufofascia is likely to have overlapping generations in Hawaii.
Females of the oriental fruit fly, Bactrocera dorsalis (Hendel), show a strong mating preference for males that have fed previously on methyl eugenol, a compound occurring naturally in various plant families. The current study compared fecundity and fertility (proportion of eggs hatching) of individual females mated to methyl eugenol-deprived males (control) or methyl eugenol-fed males (treated). Based on data collected over an 8-wk period, no differences were detected in female survival, fecundity, or fertility between females mated to control or treated males. In a second experiment, female remating frequency was monitored, and the fecundity of singly versus multiply mated females was compared. Approximately 50% of females remated over 8 wk, and multiple maters laid significantly more eggs than did single maters. Possible explanations for the female preference for methyl eugenol-fed males and the difference in fecundity observed between singly and multiply mated females are discussed.
In cricket calling songs, pulse rate is often the feature that allows females to home on the songs of conspecific males while ignoring those of other species. A previous study of the sibling species Gryllus rubens Scudder and G. texensis Cade & Otte from western Florida showed unexpected effects of developmental conditions and parental generation on the pulse rates of their songs. The current study tested for these and other effects in G. rubens from Gainesville, FL, and G. texensis from Dallas, TX. In both species, sibships from different field-fertilized females differed significantly in the effects of rearing environment on the pulse rates of their songs. Tests for effects of nymphal diapause and adult age were negative. Hybrids between the two species produced pulse rates intermediate to the rates of the control crosses. Males of G. rubens reared at 32°C produced faster pulse rates (at a standard temperature) than those reared at 25°C. Furthermore, pulse rates of field-collected males in this study and of field-collected and laboratory-reared males in the previous study increased in rough proportion to the known and estimated temperatures during nymphal development.
The feeding behavior of the whitefly Bemisia tabaci (Gennadius) was monitored using the electrical penetration graph (EPG) technique during the transmission process of tomato yellow leaf curl geminivirus (TYLCV). The behavior of individual viruliferous whiteflies was recorded on two-leaf stage tomato test plants (Lycopersicon esculentum Mill ‘Riofuego’). A total of 213 whitefly individuals was recorded on single test plants during an inoculation access period that ranged from 3.5 to 14 h. Recordings were classified into 4 categories depending of the waveforms observed: group I, including only waveform C (pathway), was associated with a residual 2.4% TYLCV transmission efficiency; group II, showing stylet pathway and a single E(pd)1 waveform, was associated with a 7.4% transmission efficiency; group III, showing stylet pathway and a single E(pd)1 E(pd)2 waveform, achieved a 23.4% transmission efficiency; and finally group IV, showing pathway followed by several E(pd)1 E(pd)2 waveforms, was associated with the highest transmission efficiency (37.5%). A total of 16 different behavioral variables was introduced into a stepwise-backward logistic regression model to determine the variables most related to TYLCV inoculation. Among them, the total duration of E(pd)1 was the most significant variable associated with virus inoculation by B. tabaci (P = 0.002, positive relationship). In addition, the regression analysis indicated a strong positive relationship (P = 0.005) between transmission efficiency and total number of E(pd)1 (t = 4.39, β = 0.45 ± 0.10, r = 0.87), and total duration of waveform E(pd)1 (P = 0.05) (t = 4.00, β = 0.02 ± 0.004, r = 0.94). The minimum phloem contact E(pd)1 threshold period observed for successful inoculation of TYLCV by B. tabaci on tomato plants was 1.8 min. Implications of these results for persistent virus transmission by whiteflies are discussed.
We tabulated flowering plant species visited by 151 species of parasitic Hymenoptera. These data were extracted from records of C. Robertson who collected >15,000 insect visitors of flowering plants in central Illinois during a 33-yr period. Species diversity of parasitoids was highest on plant species of the Apiaceae and Asteraceae. The most abundant parasitoids were 2 tiphiid and a scoliid species. Parasitoid species in 6 dominant families (Ichneumonidae, Braconidae, Chrysididae, Tiphiidae, Pteromalidae, and Eucoilidae) showed similar preferences for 10 plant species. Most parasitoid species visited a limited range of host plants, which may have implications for conservation biological control and conservation biology.
The burying beetle Nicrophorus americanus Olivier is an endangered species known to occur in disjunct populations in 6 states. Parsimony and maximum likelihood analysis of the nuclear ribosomal DNA first internal transcribed spacer (ITS1) sequences from 10 Nicrophorinae species revealed N. americanus to form a distinct clade with N. orbicollis Say. Genetic variation within and among 5 N. americanus populations, collected from South Dakota, Nebraska, Oklahoma, Arkansas, and Rhode Island, was studied. Ribosomal DNA ITS1 sequences from 14 beetles revealed 48 polymorphic and 20 informative nucleotide sites. N. americanus genetic divergence was between 0.16 and 4.76%. We found little evidence that these 5 populations have maintained unique genetic variation. No nucleotide sites were found that were diagnostic for any of the 5 populations examined, indicating that these populations may not be necessarily treated as separate, independent objects of conservation. However, further genetic investigation is warranted before translocations are attempted among the remaining populations of the American burying beetle.
Four hydrolases and five oxido-reductases were examined using native stacking polyacrylamide gel electrophoresis. Homogenate of Russian wheat aphid, Diuraphis noxia (Mordvilko), bird cherry-oat aphid, Rhopalosiphum padi (L.), ‘Arapahoe’ (aphid-susceptible) and ‘Halt’ (aphid-resistant) wheat, Triticum aestivum L., and powdery mildew–infected Erysiphe graminis DC. ex Merat f. sp. tritici Em. Marchal, Arapahoe wheat leaves were assayed for enzyme activities. Pectinesterase, polygalacturonase (or pectinase), cellulase, and amylase activities were examined in the hydrolase group. Catalase, peroxidase, catechol oxidase, superoxide dismutase, and ascorbate oxidase activities were examined in the group of oxido-reductases. The two aphid species had the same hydrolases but different oxido-reductases. Although pectinesterase and cellulase enzymes were present in D. noxia and R. padi, the banding patterns were different. Polygalacturonase and δ-amylase were not detected from either aphid species. In the oxido-reductase group, catalase was detected from D. noxia, wheras peroxidase was detected from R. padi. Superoxide dismutase and ascorbate oxidase activities also were detected from both aphids. Enzyme assays using aphid head tissue that included salivary glands but excluded aphid foregut supported the enzyme assays using whole aphids. Peroxidase activity was detected from the salivary tissue of R. padi, but not D. noxia, and catalase activity was detected from D. noxia salivary tissue, but not R. padi. We suggest that the salivary enzyme difference between the 2 aphid species (i.e., catalase and peroxidase) is important in the type of damage symptom formation on susceptible wheat plants.
Trypsin-like, chymotrypsin-like, aminopeptidase and carboxypeptidase A and B were detected in the midgut of adult female Anastrepha suspensa (Loew). Based on specific substrates and inhibitors, endoproteinases were demonstrated to be serine proteinases in which trypsin-like enzyme seemed to be the major digestive enzyme. These proteinases had alkaline pH optima, pH 7.5–9. All determined proteinase activities in the midgut were reduced to different degrees in the first few days after newly emerged flies were treated for 24 h with 0.2 and 0.5% sodium tetraborate. The 0.5% concentration caused greater reductions. These reductions in proteinase activities were not the result of direct enzyme inhibition.
Determining the sex of boll weevil adults is complicated by the lack of a discreet, gender-specific, externally visible character. However, the posterior edge of the male’s 8th tergite is distinctively notched and can be revealed by gentle probing. Although completely accurate as originally described 35 yr ago, this method has not gained wide acceptance because of the perception that it is too slow for processing large numbers of weevils, and because the original illustrations are not entirely adequate. Here we illustrate the tergal-notch method of sexing with photographs and interpretive drawings. This method is quickly learned and fast enough for most applications. Experienced users in our laboratories routinely sex 200–300 weevils per hour. The common alternative technique of sexing by relative snout characteristics is only 88–90% accurate.
The eggs of 10 species of stink bugs found on cotton or soybeans are described, including size, chorion, and number and length of the micropylar processes; electron micrographs are provided for each species. In addition, egg size and length of the processes are compared among the species. Eggs of Acrosternum hilare (Say) and Thyanta custator accerra McAtee were the largest and smallest, respectively. Eggs of Podisus maculiventris (Say) had the longest micropylar processes, followed by those of Piezodorus guildinii (Westwood). The smallest processes were those of T. c. accerra. The number of micropylar processes ranged from 19 in P. maculiventris to 79 in Oebalus pugnax (F.). In addition, to these characters, the number of eggs per egg mass and the North American distributions of each species is given. Finally, a key is presented for identification of the pentatomid eggs found on cotton and soybeans in the southeastern United States.
The orbicula (manubrium) is a dorsal sclerite between the tarsal claws in the Hymenoptera. Its detailed external morphology was surveyed throughout the order using scanning electron microscopy. Four types of presumed mechanosensory sensilla were found: two sensilla trichodea and two sensilla campaniformia. Variation in number, shape, orientation, and associated structures are discussed in the light of current phylogenetic hypotheses. There are generally two sensilla trichodea A on each orbicula, and this is a putative synapomorphy for all of Hymenoptera excluding the Xyelinae. The presence of a single sensilla trichodea A with a marked socket is postulated as a synapomorphy for the Chalcidoidea, Mymarommatidae, Diapriidae, an undescribed New Zealand family of Proctotrupoidea, and possibly Ceraphronidae. Arrangement of the sensilla trichodea B in a single row supports a putative clade comprising the Chalcidoidea, Mymarommatidae, Ceraphronidae, Cynipoidea, Diapriidae, Platygastridae, and the undescribed New Zealand family. Presence of a spur at the base of the sensilla trichodea B is a putative synapomorphy for the Chalcidoidea and the undescribed New Zealand family. Possession of sensilla campaniformia type B suggests a clade comprising Chalcidoidea, Diapriidae, and Scelionidae.
Although there is often an isometric relationship between the size of nongenital parts and body size, data on insects and spiders indicate that male genitalic size is only slightly influenced by variation in body size. Eberhard et al. (1998) interpreted the low influence of body size on genitalic size as evidence of stabilizing selection based on cryptic female choice. Data on this aspect of sexual selection are rare. We compared the variation in genitalic size with the variation in elytra length as an indicator for body size in the males of two mordellid beetle species, Mordellistena weisei Schilsky and M. bicoloripilosa Ermisch (Coleoptera: Mordellidae), to find additional indications of stabilizing selection on genital traits. The slopes of the allometric regressions between paramere size and elytra length were <1 for left and right parameres in both species, and significantly less in three of the four comparisons. There was no significant correlation between elytra length and genitalic size in either species and the coefficient of variation was similar for paramere size and elytra length. Although there is no unequivocal proof for the existence of cryptic female choice, the results reinforce the evidence in favor of stabilizing selection on genitalic size.
Larvae of closely related parasitoid taxa often lack morphological differences that can be used for species level identification. Determining the parasitoid species present in a host population may require rearing, often a time-consuming process. To monitor field parasitism rates by several species of Peristenus wasps (Hymenoptera: Braconidae) that are natural enemies of Lygus (Heteroptera: Miridae), we have developed a two-step molecular approach. Polymerase chain reaction (PCR) of the COI gene with wasp-targeting primers is performed on DNA extracted from a Lygus nymph and the parasitoid larva (if any) therein. A positive reaction indicates parasitoid presence. A restriction digest of the PCR product then indicates which parasitoid species is present among known alternatives, and a diagnosis is achieved in days rather than weeks or months.
The heat shock response as revealed by heat inducible puffing and protein patterns, as well as the localization of the major heat shock genes on the salivary gland polytene chromosomes of the olive fruit fly, Bactrocera oleae (Gmelin), a major agricultural pest, have been studied. After in situ hybridization of specific DNA sequences to the polytene chromosomes of B. oleae, the loci of the major heat shock genes hsp70, hsp83, and a putative hsp68 were detected. The two latter genes gave unique signals, and hsp70 hybridized to two adjacent discrete bands. Eight puffs were induced after heat shock, two of which were found to be the loci of the hsp70 and hsp83 genes. The newly synthesized polypeptides from the salivary glands of B. oleae, after gradual temperature elevation from 25 to 42°C, were analyzed in denaturing acrylamide gels. The most heat inducible polypeptides were found to exhibit relative electrophoretic mobilities of 83, 70, 69, 27, 26, and 23 kDa. The thermotolerance of B. oleae assumed by the above results is discussed in comparison with that observed in Drosophila species.
Dichroplus elongatus (Giglio-Tos) is a phytophagous grasshopper widely distributed in Argentina. In the current work, the genetic variation and phylogeography of this species was studied with mtDNA techniques. In total, 171 individuals from northwestern (Las Yungas province) and eastern (Espinal and Pampeana provinces) Argentina populations were analyzed using restriction fragment-length polymorphism. The number of substitutions per site between pairs of haplotypes ranged from 0.65 to 3.84%. The neighbor-joining phenogram yielded two main groups; one clusters together the haplotypes restricted to the east and the other the haplotypes restricted to the northwestern region. Phylogenetic consensus unrooted tree among mtDNA haplotypes allowed us to propose the ancestral haplotype, which occupies the central position of the network. The unweighted pair-group method with arithmetic average dendrogram from nucleotide divergence among populations showed that populations are roughly grouped according to their geographic distribution. There was a significant heterogeneity of the mtDNA distribution when populations from all three biogeographic provinces were compared. The distribution patterns of mtDNA variation observed in D. elongatus may be explained by isolation by distance when referring to the main biogeographic provinces. In Las Yungas and Pampeana provinces, ecological factors seem to have contributed to the genetic differentiation among populations.
The predatory bug Anthocoris nemoralis (F.) is a common species native to Europe that has become established in several areas of North America. The objectives of this study were to determine whether North American and European insects differed in aspects of mating activity and reproduction. We compared mating preferences, mating propensities, and some life history traits between a European (England) and North American (San Francisco Bay area) population of A. nemoralis; the North American population colonized the source locale apparently between 10 and 30 yr ago. In no-choice and choice assays, the insects showed no preference for mating with insects from the same source population. Both types of assays indicated that insects from the two sources differed in mating propensities: UK females were less likely to mate during a 30-min assay than females from California (irrespective of male source); and California males were less likely to mate than males from the UK (regardless of female source). More than 80% of mated females matured ovaries from all population crosses. Copulation duration was shorter in pairings involving California males (13.8 min) than matings involving UK males (16.9 min). The preoviposition period averaged ≈3 d for females from both populations. Insects of both sexes from both populations were able to mate within 24–48 h of adult eclosion. Younger males of both populations copulated longer and were less likely to prompt ovarian maturation in the female than older males. Several characteristics of A. nemoralis, including its generalist feeding habits, rapid maturation, short preoviposition period, and low levels of mating discrimination may help explain why this species has been successful in colonizing new geographic areas.
John G. Stoffolano, Elizabeth Y. Gonzalez, Marilyn Sanchez, Joann Kane, Kenneth Velázquez, Aida L. Oquendo, Gabrielle Sakolsky, Peter Schafer, Chih-Ming Yin
Size variation occurs in natural populations of the black blow fly, Phormia regina (Meigen); head width varied from 2.25 and 1.89 mm to 3.68 and 3.72 mm for males and females, respectively. Using these values as a guide, small flies were produced in the laboratory by early removal of larvae from the rearing medium. Mating experiments, pairing flies of various size categories, showed that when small males mated with large females the percentage of successfully inseminated females was significantly reduced compared with the other combinations (42% versus 73–89%). Previous work led us to suspect that small males might have small aedeagi and therefore have a problem in successful sperm transfer when they mate with large females. Measurement of aedeagus size and head width showed that in wild flies the size of the aedeagus is positively correlated with body size.
Laboratory experiments using small artificial streams were performed on 3rd-5th instars of the net-spinning caddisflies Hydropsyche sparna (Ross), H. betteni Ross, H. morosa (Hagen), and H. slossonae (Banks) to examine the effects of suspended particle transport on their behavior, drift, and mortality. Larvae were exposed to suspended particles 0.4–500 μm in diameter at suspended concentrations between 667 and 6000 mg/liter for 24 h. Water velocity was held constant at 23 cm/s in all experiments to eliminate the confounding effects of flow on net-tending. Drift and mortality rates were also measured but did not occur in the experimental or control populations. Four net-tending behaviors occurred that varied in the degree of filter net modification. One behavior was to clean the net of particles and leave it intact. Three other behaviors, involving modification of the filter net strands, were detachment of one side, cutting a hole in the middle of the filtering surface, and total removal of the net. For particles >64 μm in diameter, the frequency of net modification increased with increased particle size and load. Intraspecific differences in net-tending behaviors occurred in only 1 instance, and there were no interspecific differences. We speculate that H. sparna individuals modify their nets to change the local hydrology and therefore prevent excessive fine particle transport into their retreats. Observed net-tending behaviors might represent adaptations to frequent exposures to suspended sediment transport. Fine suspended particle transport of the duration and magnitude studied represents a sublethal disturbance to hydropsychids.
To date, social nesting has been relatively unknown in the bee family Colletidae. Same-generation females of the bee Amphylaeus morosus Smith frequently share tubular nests where only 1 brood cell can be provisioned at a time. In montane eucalypt forests of southern Australia, A. morosus nests are constructed within naturally excised fronds of the rough tree fern, Cyathea australis. In these habitats, the species is univoltine with adult eclosion occurring in late summer. Dispersal from overwintering nests and new nest initiation begins in spring, and all new nests contain only 1 adult female. However, a significant proportion of old, reused nests during the brood-rearing phase contain 2 or 3 adult females that are mated with mature ovaries (≈23% of all inhabited nests). Per capita brood production was statistically higher in reused versus new nests, probably because the former start their cell provisioning earlier. Per capita brood production was not statistically higher in two- versus one-female reused nests, although there were trends in this direction and earlier adult female mortality may have obscured end-of-season patterns. Brood parasitization by a gasteruptiid wasp (Gasteruption sp.) was statistically higher in new nests than two-female reused nests, but only marginally higher in one- versus two-female reused nests. Average relatedness among adult females in multifemale nests was quite low (r = 0.26 ± 0.06 SE). Hence, kin selection is unlikely to be a major factor selecting for cooperative nesting in this species. Cell provisioning patterns in A. morosus could lead to nestmates conflicting over foraging effort and reproduction. No evidence for reproductive division of labor or foraging specialization among nestmates was found, however, and their relative body sizes, ovary sizes, and wing wear were not significantly different from statistical expectation. Therefore, sociality in A. morosus probably results from the benefits of sharing a valuable resource (i.e., a preexisting nest) and avoiding dispersal costs, rather than cooperation per se. Nevertheless, the prospects for nestmate cheating are high. High-resolution genetic studies could determine if the apparent lack of reproductive skew, based on dissection data, reflects brood maternity. Sociality in A. morosus provides an ideal opportunity to investigate reproductive skew theories.
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