Current hypotheses on the origin of the fungus–attine ant (Hymenoptera: Formicidae) symbiosis propose, as an ancestral first step in the development of fungal cultivation, fortuitous feeding on fungi growing adventitiously on substrates such as rotting wood, insect parts, seeds stored by ants in nests, regurgitated infrabuccal pellets, free-living soil fungi, or mycorrhizae. However, feeding-deterrent fungi regularly colonize these substrates. De novo feeding on these fungi by the attine ancestor is unlikely because the almost universal presence of mycotoxins on adventitious fungi is a formidable barrier to mycophagy. In addition, there is no evolutionary history of mycophagy in the Hymenoptera. Instead, I propose that attine mycophagy began from opportunistic, selective feeding on wood-colonizing fungi previously “domesticated” by other insects: ambrosia beetles: (Coleoptera: Curculionidae: Scolytinae or Platypodinae); and less likely, woodwasps (Hymenoptera: Siricoidea). Attine ancestors foraged for beetle brood and fungal biomass in the galleries of those insects, which provided the attine ancestor with fungi that were nutritious and nontoxic to insects. The invading ants’ debris (fecal spots, exuviae, meconia, and saliva) possibly allowed the growth of the “good” domesticated fungi in galleries, while ants mechanically eliminated undesirable ones. Feeding on beetle fungi first allowed the development of broad mycophagy in ants, and, later, of the gardening habits. Subsequently, more restricted, specific mycophagy evolved. Only after serious barriers were overcome did incipient mycophagy develop, followed by cultivation. The ambrosia fungi-lined beetle galleries in wood provide one location favorable for this sequence. An analogous progression in mycophagy and incipient fungus manipulation, departing from the omnivore diet has occurred in Megalomyrmex ants that feed parasitically on brood and/or fungus gardens of attines. Colonies of the ancestral attine nested in wood and adopted mated foundress queens after mating flights, and colonies reproduced by budding. Queen adoption by established colonies allowed the chronological continuation of the incipient symbiosis. Mycophagy preadapted the ants to test free-living fungi in wood and soil as cultivars. The fortuitous finding of more adequate lepiotaceous strains in soil allowed the adaptive radiation exhibited in present-day attines. The cultivation, by the primitive attine Apterostigma, of wood-colonizing Basidiomycotina is possibly of ancestral significance.

The Nearctic leafhopper genus Errhomus Oman (Hemiptera: Cicadellidae) exhibits high host-plant selectivity and female brachyptery, which may limit gene flow. Two subgenera, Errhomus (Errhomus) and Errhomus (Erronus), are recognized based on morphological and behavioral differences. We used mitochondrial DNA sequencing to elucidate the phylogenetic relationships among members of the subgenus Errhomus (Erronus). Portions of the NADH dehydrogenase subunit 1 (ND1) and the leucine (CUN) transfer RNA (tRNA-Leu) genes were sequenced and were analyzed with parsimony and maximum likelihood. Our results generally verified the findings of Hamilton and Zack (1999); however, both optimality criteria revealed a paraphyletic Errhomus (Erronus). Errhomus (Erronus) calvus does not seem to be a member of the subgenus Errhomus (Erronus) but seems to be more closely aligned with the subgenus Errhomus (Errhomus). We tested two a priori null hypotheses: 1) that the phylogeny estimated from the molecular data matched a previous phylogeny based on morphology and biogeography from Hamilton and Zack (1999) and 2) that diagnostic characters of the male genitalia (serrated aedeagal processes and triangular aedeagal shaft tip) were synapomorphies that defined major clades. We rejected these hypotheses with both Bayesian tests and parametric bootstraps.

The nuclear gene period is used to reconstruct the phylogeny of Anastrepha, a genus of tephritid fruit flies. Specifically, a region of period termed C3C5 that is located in the dCLK:CYC inhibition domain (CCID) is analyzed. This is the first study using this C-terminal region of the period gene for phylogenetics. Variation in the gene is informative for this genus, and period trees are compared with phylogenies based on mitochondrial and morphological data sets. In general, branches that are supported in the other data sets are recovered in the period tree; moreover, trees built using the period gene support branching patterns previously unresolved with 16S rRNA gene data. Important relationships recovered in the period gene tree include a paraphyletic placement of Anastrepha with respect to Toxotrypana, support for the separation of Anastrepha species groups into two evolutionary sections (with the exception of the pseudoparallela species group), and evidence that several species groups are not monophyletic.

The leafmining fly Liriomyza sativae Blanchard is an important polyphagous pest of vegetables crops in the United States and around the world. Phylogeographic analysis of mitochondrial cytochrome oxidase I sequence variation indicates that L. sativae harbors distinct mitochondrial clades suggestive of the presence of cryptic species. Two of the major mitochondrial clades exhibited polyphagy, with members feeding on hosts in at least three plant families. Only one of the major clades was present in introduced populations, causing total mitochondrial variation exhibited by introduced populations to be considerably reduced compared with that observed within the native range.

The Neotropical cicada Fidicina variegata Sanborn is described as a new species. This work validates a name previously assigned to this species and considered a nomen nudum. Comparisons are made to other members of the genus found in Costa Rica. A summary of the biology of the species is provided.

The relationship between fecundity and body size in females of the moth Streblote panda Hübner was studied in laboratory by using both virgin and mated females. Strong relationships among fecundity and pupal weight, adult weight, and forewing length were found. The number of eggs in virgin and mated females was similar; mean egg load (number of eggs per female) was 278.4 ± 8.7 (SE), suggesting that S. panda females eclose with all their eggs fully developed. Larger females were more fecund than smaller ones. Mated females laid eggs soon after emergence without any obvious preoviposition period, and no relationship between female body size and age-specific fecundity or female longevity were found. Male size did not show any effects on egg size or hatchability. Data suggest that determinants of larval development such as temperature and food plant may influence fecundity through their effects on pupal weight and adult body size. All studied reproductive traits are characteristic of the capital breeding strategy.

Blueberry maggot, Rhagoletis mendax Curran, pupae that are exposed to high temperature toward the end of diapause will not develop beyond a specific heat-sensitive stage. The temporal relationship between heat sensitivity and diapause was studied by exposing cohorts of pupae at different stages of diapause to 25:35°C (photoperiod of 12:12 [L:D] h) for 20 d and comparing the length of time to emergence. Results showed that the longest delay in emergence was induced in pupae that were exposed to high temperature <10 d before the completion of diapause. Also, pupae at the heat-sensitive stage exposed to high temperature did not show the increase in respiration rate characteristic of the completion of diapause. The duration of the heat-sensitive stage was studied by keeping pupae at 20°C for different periods of time between two 10-d exposures to 25:35°C. Results showed that a small proportion of the pupae kept at 20°C for 5 d, and all pupae kept at 20°C for 15 d, developed beyond the sensitive stage, indicating that the heat-sensitive stage lasted ≈10 d in individual pupae. The effect of frequency of exposure to high temperature during the sensitive stage was also studied. Data showed that the delay was similar or greater than the total duration of the exposure to high temperature. Exposure to high temperature caused ≈15% of the pupae used in these experiments to remain in a long-term quiescence, with a respiration rate similar to that of pupae in diapause. Potential endocrine causes for this quiescence were investigated by topically applying exogenous 20-hydroxyecdysone on these pupae. Application of the hormone caused 41% of the individuals to develop to the adult stage, suggesting that heat-induced damage to the endocrine system caused the failure to develop. Overall, this study indicates that in the blueberry maggot, during a ≈10-d sensitive stage immediately before the completion of diapause, heat-induced stress on the endocrine system can prolong diapause and delay adult emergence for a period of time similar to the duration of the exposure.

By considering the magnitude of isotope enrichment associated with trophic transfers in biologically important elements such as carbon (¹³C/¹²C) and nitrogen (¹⁵N/¹⁴N), it is possible to infer trophic interactions in systems where direct observations are logistically difficult. Several recent reviews have estimated that consumers become enriched in the heavy nitrogen isotope on the order of 2.3 to 3.4‰ with each trophic transfer. Furthermore, these same reviews have estimated that consumers become enriched in the heavy carbon isotope between 0.4 and 0.5‰ per trophic transfer. Although these estimates have been used to infer trophic interactions in a variety of taxa, the applicability of these estimates for studies of arthropod community ecology is poorly understood. Specifically for insect parasitoid communities, estimates of nitrogen and carbon isotope enrichment from a comprehensive study have yet to be published. Here, we present the results of nitrogen and carbon stable isotope analyses for a suite of hymenopteran parasitoids that attack the gall-making midge, Rhopalomyia californica Felt (Diptera: Cecidomyiidae), on coyote bush, Baccharis pilularis (Compositae), in northern California. Mean carbon enrichment for all parasitoids developing on R. californica was considerably higher than expected, based on recent reviews. In fact, discrimination among trophic levels was possible, based on carbon enrichment values alone. Mean nitrogen isotope enrichment was slightly lower than values reported in recent reviews. However, the variation associated with our estimate of nitrogen enrichment falls well within the range of values reported in the reviews. Mechanisms behind the greater than expected enrichment in carbon are currently unknown and will require further investigation.

Hosts, pattern of seasonal emergence and flight, and distribution of the palearctic moth Pasiphila rectangulata (L.) (Lepidoptera: Geometridae) were examined in the upper northeastern United States. Larvae developed on 29 hosts in three genera (Amelanchier, Malus, and Pyrus) in the Rosaceae. At Hamden, CT, larval density was significantly higher on ‘Delicious’ and ‘McIntosh’ apple, Malus domestica Borkhausen, than on ‘Bartlett’ pear, Pyrus communis L. Larvae were absent from ‘Napoleon’ sweet cherry, Prunus avium L.; ‘Shiro’ Japanese plum, Prunus salicina Lindley; and ‘Stanley’ European plum, Prunus domestica L., which grew in the same orchard as the infested apples and pear. In the Hamden orchard, moths were captured in emergence traps beneath apple trees over 12–15 d between late May and mid-June in 1999–2001. In 2000 and 2001, emergence was earlier for males than females, and in all years the sex ratio did not depart significantly from 1:1. Based on captures at a mercury vapor light-trap in 2000 and 2001, the adult flight lasted 1 mo between late May and late June, with the mean date of capture being statistically equal for the sexes. In 2001, more males than females were captured. The distributional range of P. rectangulata in the northeastern United States includes the New England states, extreme eastern New York, and northernmost New Jersey; specimens collected in Connecticut, New Jersey, New York, and Vermont represent new state records. The biology of univoltine P. rectangulata is similar in Europe and the northeastern United States, although the moth apparently has a broader range of larval hosts in Europe.

Hawaiian crickets in the genus Laupala Otte have emerged as a model system in the study of several evolutionary processes, such as the differentiation of signaling phenotypes, the evolution female preferences, and the phylogeographic patterns of speciation. However, very little is understood concerning the basic biology of species within this genus. Here, we document the postembryonic timing of developmental events in two closely related Hawaiian crickets in the genus Laupala. Laupala kohalensis Otte and Laupala paranigra Otte are closely related, exhibit widely divergent pulse rates of the male calling song, and are members of a rapid, recent, and extensive diversification of Hawaiian crickets. In this article, we used morphometric image analysis of developing individuals, from hatching through to adult maturation, to delineate instars in each species. We found that instar duration was consistent across both species, but the number of juvenile ecdysis events differed. L. kohalensis consistently exhibited eight instars. In contrast, L. paranigra exhibited a maximum of seven instars; moreover, half of the individuals experienced only six instars before maturation. A molecular mechanism linking the evolution of song pulse rate and developmental rate is discussed.

We studied four populations of the pierid butterfly Eucheira socialis Westwood, located in the Mexican states of Sinaloa, Durango, Mexico, and Oaxaca. We found extreme geographic variation in spermatogenic abnormalities, including a variable number of chromosomes, irregular pairing of chromosomes, lagging chromosomes in metaphase I, lagging chromosomes in anaphase I, the production of micronuclei, and the failure of some spermatids to condense before maturation. We also present evidence suggesting the production of aneuploid sperm. These abnormalities correlate with previously reported male biases in the primary sex ratio of two of these populations. The population with the greatest bias in sex ratio also exhibited the highest frequencies of spermatogenic abnormalities. Because butterflies have female heterogamety and Eucheira females are XO, a possible mechanism linking the sex ratio biases and these abnormalities is nondisjunction of the X chromosomes during spermatogenesis, yielding disomic X sperm. We conclude that the most parsimonious explanation for the meiotic abnormalities in E. socialis is the presence of supernumerary chromosomes, which are associated with sex ratio biases in other systems.

We studied attraction of Vespula germanica (F.) by conspecifics and food. By confining different numbers of wasps in containers, we showed that wasp attraction is density-dependent. Attraction to the containers persisted when the wasps were removed, suggesting that wasps leave an odor trace. Moreover, we demonstrated that conspecific attraction is not seasonal and that thorax extracts are attractive. Conversely, cat food bait attractiveness varied during the season. Third, we studied the predatory behavior of V. germanica wasps to determine whether the attraction elicited by conspecific wasps is due to cannibalistic behavior. Finally, we showed that attraction to food varied seasonally, unlike conspecific attraction. We believe these experiments are useful for improving control methods of this pest that severely affects northwestern Patagonia by the utilization of specific and stable toxic baits.