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Joseph S. Elkinton, George H. Boettner, Marinko Sremac, Rodger Gwiazdowski, Roy R. Hunkins, Julie Callahan, Susan B. Scheufele, Charlene P. Donahue, Adam H. Porter, Ashot Khrimian, Brenda M. Whited, Nichole K. Campbell
We used pheromone-baited traps to survey the distribution of winter moth, Operophtera brumata (L.) (Lepidoptera: Geometridae), a new invasive defoliator from Europe in eastern New England. The traps also attracted Bruce spanworm, Operophtera bruceata (Hulst) (Lepidoptera: Geometridae), native to North America. We distinguished between the two species by examining male genitalia and sequencing the mitochondrial cytochrome oxidase subunit 1 (COI) gene, the DNA barcoding region. In 2005, we recovered winter moths at sites stretching from eastern Long Island, southeastern Connecticut, all of Rhode Island, eastern Massachusetts, coastal New Hampshire, and southern coastal Maine. At sites further west and north we captured only Bruce spanworm. In 2006, we confirmed that both winter moth and Bruce spanworm are present in Nova Scotia and in coastal Maine, but only Bruce spanworm was recovered in coastal New Brunswick, Canada; Pennsylvania; Vermont; or Quebec City, Canada. In 2007, we collected Bruce spanworm, but no winter moths, in New Brunswick and the interior areas of Maine, New Hampshire, and New York. Winter moth and Brace spanworm differed in the COI sequence by 7.45% of their nucleotides. The prevalence of intermediate genitalia in the zone of overlap suggested that hybridization between the two species may be occurring. To confirm the presence of hybrids, we sequenced the nuclear gene, glucose-6phosphate dehydrogenase (G6PD). We identified six nucleotides that routinely distinguished winter moth and Bruce spanworm, of which three were always diagnostic. We showed that eggs produced by hybridizing the two species in the laboratory contained copies of both species at these six sites. We found that most of the moths collected in the field with intermediate genitalia had winter moth CO1 and G6PD sequences and thus were not hybrids (or at least F1 hybrids). We found three hybrids out of 158 moths with intermediate genitalia in the region where both species were caught. We conclude that hybrids occur in nature, but are not as common as previously reported. Introgression of genes between the two species may still be significant.
Varroa sensitive hygiene (VSH) is a trait of honey bees, Apis mellifera L. (Hymenoptera: Apidae), which supports resistance to Varroa destructor Anderson & Trueman. VSH is the hygienic removal of mite-infested pupa. Bees selectively bred for VSH produce colonies in which the fertility of mites decreases over time. In addition, mite fertility decreases after infested brood is exposed to VSH bees for 1 wk. The purpose of this study was to decide whether the reduction in mite fertility is caused by selective removal of mites that produce offspring. Initially, we monitored changes in a small patch of capped brood during exposure to VSH bees at 2-h intervals through 60 h, which provided a reference for the subsequent experiment. The first test showed that VSH bees uncapped, recapped, and began to remove many pupae in ≈2 h. The approach in the second experiment was to compare the percentage of fertile mites from brood exposed to VSH bees for a 3-h period to the percentage of fertile mites in brood that was protected from hygiene by a screen. There were no significant differences in fertility between mites on pupae that were being removed by the bees and mites on protected pupae. These results suggest that neither egg-laying by foundress mites nor mite offspring are the stimuli that trigger hygienic removal of mite-infested pupae by VSH bees. It may be that hygienic activities such as the uncapping of brood cells inhibits or disrupts reproduction by varroa mites.
Original information on aphidiine braconids attacking aphids feeding on Solanaceae (i.e., Capsicum annuum L., Lycium europaeum L., Lycopersicon esculentum Miller, Solanum spp.) and Cucurbitaceae (i.e., Citrullus vulgaris Schrad., Cucumis spp., Cucurbita pepo L.) plants in southeastern Europe is presented. A total of 13 species are keyed and illustrated with scanning electron micrographs, microscope micrographs and line drawings. The aphidiines presented in this work have been identified from nine aphid taxa. Two hundred four aphidiine-aphid-plant associations are presented, 176 of which are new. The results are discussed in relation to over-all parasitoid-aphid-plant associations in the area.
This study reports the results of a survey carried out in the Ucka Nature Park in the northeastern part of Croatia. It reports for the first time a list of species belonging to the family Phytoseiidae from Croatia, as until now, only one species was known from this country. Seventeen species are reported, one of them being new to science. This species belongs to the genus Typhlodromus subgenus Typhlodromus in the subfamily Typhlodrominae: Typhlodromus (Typhlodromus) octogenipilus.
Three new species of the fungus-growing ant genus Myrmicocrypta Fr. Smith are described from Brazil and Peru, all unique within the genus due to their shared character state of erect pilosity. Myrmicocrypta erectapilosa sp. nov. and Myrmicocrypta bucki sp. nov. are otherwise typical for the genus in their small size and effaced, tuberculate sculpture, whereas Myrmicocrypta camargoi sp. nov. is also unique in its large size and pronounced sculpture. M. erectapilosa and M. bucki are closely related but can be distinguished by differences in the frontoclypeal and hypostomal teeth, frontal lobes, mesonotal sculpture, and propodeal spines. All castes (workers, gynes, and males) are described for M. camargoi, workers and gynes are described for M. erectapilosa, and only workers are described for M. bucki. Because the erect pilosity encountered in these species contradicts the state previously considered diagnostic for the genus, that of appressed, spatulate or squamiform pilosity found in all other Myrmicocrypta species, we necessarily discuss the characters that define the genus Myrmicocrypta and review its phylogenetic position within the tribe Attini.
Identifying species boundaries within morphologically indistinguishable cryptic species complexes is often contentious. For the whitefly Bemisia tabaci (Gennadius) (Hemiptera: Sternorrhyncha: Aleyrodoidea: Aleyrodidae), the lack of a clear understanding about the genetic limits of the numerous genetic groups and biotypes so far identified has resulted in a lack of consistency in the application of the terms, the approaches used to apply them and in our understanding of what genetic structure within B. tabaci means. Our response has been to use mitochondrial gene cytochrome oxidase one to consider how to clearly and consistently define genetic separation. Using Bayesian phylogenetic analysis and analysis of sequence pairwise divergence we found a considerably higher number of genetic groups than had been previously determined with two breaks in the distribution, one at 11% and another at 3.5%. At >11% divergence, 11 distinct groups were resolved, whereas at >3.5% divergence 24 groups were identified. Consensus sequences for each of these groups were determined and were shown to be useful in the correct assignment of sequences of unknown origin. The 3.5% divergence bound is consistent with species level separations in other insect taxa and suggests that B. tabaci is a cryptic species composed of at least 24 distinct species. We further show that the placement of Bemesia atriplex (Froggatt) within the B. tabaci in group adds further weight to the argument for species level separation within B. tabaci. This new analysis, which constructs consensus sequences and uses these as a standard against which unknown sequences can be compared, provides for the first time a consistent means of identifying the genetic bounds of each species with a high degree of certainty.
Sexually selected traits are often assumed to convey information to conspecifics about the condition and genetic quality of an individual. However, sexually selected traits also are hypothesized to be among the most rapidly evolving and phenotypically plastic traits in natural populations. When found, such variability can bring into question the reliability of these traits as sexually-selected signals. Here, we examine the expression of a male weapon over multiple spatial and temporal scales in the wild. Specifically, we measured the expression of enlarged hind femora across and within populations of the Neotropical bug Leptoscelis tricolor Westwood (Hemiptera: Coreidae). We found significant variation in the size of this trait across populations and even within a population according to the plant species where adult males were collected. We also found differences in the intercept of the scaling relationship with body size; for a given body size, males in some populations express larger sexually selected traits than males in other populations. These results support the hypothesis that the expression of sexually selected traits is dynamic over space and perhaps time. Such patterns suggest that environmental variation or small amounts of movement across genetically differentiated populations may confound the reliability of information contained in the expression of these traits.
Spatiotemporal variation in the species composition, relative abundance, and plant use by cicada nymphs were studied among continuous and fragmented forests and human-modified forestry plantations upon an uplifted reef-karst substrate in tropical East Asia. Nymphal emergence was concentrated in the rainy season but tended to begin earlier, end later, or both, on plantations. Species abundances fluctuated over time and among the types of forests, with greater variation in plantations and fragmented forests. Seven cicada species were present, but the overall similarity in species composition was low among the forest types. Higher mean numbers of species and mean abundances occurred on plantations than in fragmented and continuous forests, but the species heterogeneity was higher in continuous forests and lowest on plantations. Exuviae were found at various heights that were correlated positively with the abundance of exuviae and negatively with the diameter at breast height of trees, whereas coefficients of variation in the height distribution among trees were not correlated with the abundance of exuviae. The plant-use breadth was widest in the cicadas Chremistica ochracea (Walker) and narrowest in Cryptotympana takasagona. Kato, Phtypleura takasagona Matsumura, and Euterpnosia koshunensis Kato, with the other species intermediate, corresponding with their relative abundance. Among-species overlap was generally higher in the continuous forests but declined in forest fragments and plantations. Our results indicated that fragmenting tropical primary forests and creating plantations may generate higher richness and abundance of annual cicadas, but risk the loss of rare or endemic species that show a greater preference for tree species of the primary forests.
Intraspecific geographic variation in morphology and behavior can be indicative of populations that are adapted to local environmental conditions. Heterogeneity in the abiotic environment, such as soil conditions, can be an important driver of local adaptation. In south Florida, mean body sizes in populations of the lubber grasshopper Romalea microptera (Beauvois) (Orthoptera: Acrididae), increase from west to east. We tested how body size variation, population origin, and soil physical characteristics are associated with oviposition depth in the soil. In a laboratory experiment with homogeneous soil conditions, size-corrected oviposition depth (analysis of covariance) differed among three populations: females from a western population oviposited at the shallowest depths; females from an eastern population oviposited the deepest; and a central population oviposited at intermediate depths. A similar pattern also was observed in two field experiments conducted on two additional populations not used in the laboratory experiments. In addition, size-corrected oviposition depth in the field experiments declined with increasing soil compaction for both populations but the decline was significantly steeper for the eastern population. High soil moisture yielded significantly shallower size-corrected oviposition depth only for the eastern population. Female size was positively related to oviposition depth in both field experiments, but the relationship between female size and oviposition depth did not differ among populations (i.e., equal slopes). We suggest that local soil conditions might be an important selection pressure and behavioral cue in determining oviposition depth. Choice of vertical position of the egg pod within the soil is discussed as one possible mechanism by which females can influence offspring viability.
Aspects of the biology of the adult stage of Ufens principalis Owen (Hymenoptera: Trichogrammatidae), an important parasitoid of Homalodisca (Hemiptera: Cicadellidae) eggs in southern California, were studied. The field-based sex ratio of U. principalis was significantly different from 1:1 and was female biased (62% females). Females and males did not differ significantly in size based on measurements of head width and hind tibia length, and these two variables were highly correlated. There was a significant effect of female age on egg load. Females aged 1, 4, and 5 d had significantly higher egg loads than freshly emerged females. There was also a significant positive linear relationship between egg load and hind tibia length. Egg load averaged 37.9 ± 1.1 eggs. Eggs, which measured 207.8 ± 12.2 µm in length, were elliptical with an anterior nipple-shaped constriction. The longevity of adults was significantly affected by temperature and food (1:1, honey/water). Food had a greater effect in prolonging life as temperature decreased from 35.0 to 10.0°C. The most long-lived adults were fed on honey and kept at 10.0°C (20.2 ± 3.3 d). The rate of parasitism was significantly affected by host age, being significantly higher for 0-h-old eggs than for 12-24-h-old host eggs. There was no significant difference in parasitism between 0-h- and 0-6-h-old eggs and between 0–6 and 12-24-h-old eggs.
Studies on the effects of perfluorooctane sulfonic acid (PFOS) exposure on terrestrial invertebrates are very scarce. Here, we quantified the effects of PFOS on the number of offspring for two generations of Drosophila hydei Sturtevant 1921 (Diptera: Drosophilidae) reared in the laboratory. The first generation was exposed to a range of PFOS concentrations from 5 to 5,000 ng/ml and a control through their diet. For the second generation, offspring of the 50 ng/ml PFOS treatment and the control were further reared in a PFOS-free environment. For the first generation, the number of offspring decreased with increasing levels of PFOS contamination. Although the second generation was not exposed to PFOS, we still observed a reduction in the number of offspring when the parental flies were exposed to 50 ng/ml PFOS. The results of the current study indicate that the sensitivity to PFOS of D. hydei is several magnitudes higher than of the other terrestrial invertebrate species tested so far. This sensitivity falls within the concentration range detected in its natural food.
The development, survival, and reproductive output of the armored scale Rhizaspidiotus donacis Leonardi (Hemiptera: Diaspididae) were determined as part of an evaluation of this scale for biological control of giant reed, Arundo donax L. Scale crawlers produced by females collected in southern France and Spain lived for less than two d in the absence of a host. On A. donax shoots held under a diurnally variable temperature regime (15–26°C), crawlers settled on leaf collars and axillary stem bases and completed the first instar within 14 d. Winged adult males emerged within six wk and lived 1.7 d in vials. Immobile adult females were observed 75 d after crawler release. Development time to adult was reduced 15% in males and 28% in females when scales were reared at a constant temperature of 26°C. Survival from crawler to adult was 20–25%. The generation time for laboratoryreared females was 170d and their average life span was 203 d. Females from field collections produced an average of 85 live crawlers, 2.7-fold more than did colony-reared females. Across 31 field collections, female size was correlated to the percentage of scales that were reproductive. However, among eight collections from two Spanish sites, size varied but was not correlated to reproductive success. Peak reproduction from field collections occurred between November and March, and the scale completed two generations per year. Biological information about R. donacis will aid production, release, and field evaluation of this scale for biological control of invasive A. donax in North America.
This study evaluates characteristics commonly used to define insect quality or fitness by using a complement of three species of tephritid fruit flies (Diptera: Tephritidae) obtained from cryopreserved embryos. Anastrepha ludens (Loew), Anastrepha suspensa (Loew), and Ceratitis capitata (Wiedemann) were used to assess embryo to adult emergence and adult longevity, flight ability, mating ability, fecundity, and genetic variability after cryopreservation. With the three species tested, embryo survival was reduced by 50–70% whereas adult eclosion seemed unaffected by cryogenic treatment. Laboratory cage survival of cryopreserved A. ludens paralleled that of controls when tested with or without food and water posttreatment. With C. capitata, field cage survival was also similar when the adult progeny of cryopreserved parents was compared with that of untreated flies of the same age. Assessment of flight ability of cryopreserved A. ludens over a 19-d period by using a flight mill showed no statistical difference when compared with the untreated groups over the same time period. Flight ability within field cages for newly emerged progeny of cryopreserved C. capitata also mirrored that of the controls. Observed matings occurring within laboratory cages containing equal numbers of A. ludens males and females did not differ from comparable control groups. Furthermore, male progeny obtained from cryopreserved C. capitata parents competed equally with untreated males for mates while housed in field cages. A laboratory analysis of fertility and fecundity of A. suspensa revealed that males mated with control females were unaffected by cryopreservation as embryos, whereas cryopreserved females exhibited a significantly reduced fecundity when mated with control males. The fecundity of C. capitata progeny of cryopreserved parents also did not differ from control levels while caged under laboratory conditions. A random amplified polymorphic DNA assay of the genetic diversity of A. ludens comparing cryopreserved males with control males showed that the coefficient of similarity was ≥85%. This study indicates that embryo cryopreservation had little or no effect on the reproduction, longevity and flight of the species tested and can be used to support maintenance of insect stocks and control programs supported by the mass-rearing process.
Venom from the pupal endoparasitoid Pimpla turionellae L. (Hymenoptera: Ichneumonidae) contains a mixture of biologically active components, which display potent paralytic, cytotoxic, and cytolytic effects toward hosts. Here, we further investigate whether parasitism or envenomation by P. turionellae alters hemocyte numbers of its host Galleria mellonella L. (Lepidoptera: Pyralidae). Total hemocyte counts declined sharply in pupae and larvae of G. mellonella exposed to P. turionellae. These same cellular responses occurred when wasp venom was artificially injected into hosts, suggesting that venom alone induces cytotoxicity in hemocytes. Analysis of the differential hemocyte counts in untreated pupae and larvae revealed that more than half of the circulating hemocytes were granular cells followed by plasmatocytes. Parasitism reduced the number of granular cells while increasing the number of plasmatocytes. This trend was most evident at 4 h postparasitism, and a similar trend was observed with the artificial injection of high (but not low) doses of venom. When isolated larval hemocytes were exposed to a LC99 dose of venom, a differential response was observed for granular cells versus plasmatocytes. Both types of cells displayed some formation of vacuoles within the cytoplasm within 15 min posttreatment. However, the degree of vacuole formation was much more extensive in granular cells at later time points than for plasmatocytes, and granular cells seemed much more susceptible to venom as evidenced by cell death.
Fall armyworm, Spodoptera frugiperda (J.E. Smith), is a significant agricultural pest in the United States, affecting most notably sweet corn, Zea mays L., and turfgrass. Two strains exist that differ physiologically and behaviorally but are morphologically indistinguishable. Polymorphisms within the fall armyworm Triose phosphate isomerase gene (Tpi; EC 5.3.1.1) were characterized and used to develop a polymerase chain reaction-based method for discriminating fall armyworm strains. The Tpi markers were used in multilocus analysis to estimate interstrain hybrid frequency and their distribution in populations from the United States and Brazil. The results were compared with previous studies using different marker combinations to test hypotheses about interstrain mating behavior and to explain earlier observations of unusual strain distribution patterns. The importance of understanding the frequency and consequences of interstrain hybridization to deciphering the mechanism of strain divergence and the distribution of fall armyworm subpopulations in different habitats are discussed.
Three mantid species, Tenodera aridifolia (Stoll), Hierodura patellifera (Serville), and Statilia maculata Thunberg, of varying body size and habitats, exhibited defensive reactions when faced with a natural enemy, the Japanese skink, Takydromus tachydromoides (Schlegel). Defensive reactions were analyzed as primary or secondary defenses for all stages. Of the primary defenses, the cryptic reaction was the main defensive reaction: mantids lowered the prothorax and simultaneously stretched the prothoracic legs, the antennae were arranged forward, and the abdomen was sometimes extended posteriorly. The frequency of the subcryptic reaction as a primary defense tended to increase with more advanced developmental stage. The primary defensive strategy switched at specific developmental stage and also depended on the distance between the prey mantid and the natural enemy. In some instars, T. aridifolia and H. patellifera displayed the cryptic reaction when the mantid—foe distance was long, whereas they displayed the subcryptic reaction when the mantid—foe distance was short. However, S. maculata did not switch defense strategies based on the mantid—foe distance. The secondary defenses of young instar nymphs of T. aridifolia and H. patellifera were primarily defensive reactions, whereas the frequency of aggressive reactions tended to increase with developmental stage. S. maculata did not display aggressive reactions during any stage. We concluded that the primary and secondary defenses used by mantids depend on the developmental stage and mantid—foe distance. Moreover, three mantid species that vary in both body size and habitat showed different defensive reactions when faced with a natural enemy.
Adult Lygus hesperus Knight (Hemiptera: Miridae), major crop pests of the south-western United States, can mate repeatedly during their lives, potentially enhancing the lifetime fitness of both sexes. However, the periodicity of mating and its regulation in this species is poorly understood. In this study the postmating refractory period for both sexes is described. Males were found to have a median delay of 24 h, which seems to be the minimum time needed to refill the accessory glands and produce another viably sized spermatophore. The median refractory period in mated females was 5 d, but sometimes lasted longer than 2 wk. The loss of sexual receptivity in mated females, at least for the first 24 h, seems to be induced by males; spermatophore homogenates injected directly into the abdomen of virgin females reduced their sexual receptivity. The total duration of female refractoriness may be dictated by the starting size of a spermatophore and the rate at which it degrades.
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