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During exploration for new biological control agents of yellow starthistle, Centaurea solstitialis L. (Asteraceae: Cardueae), in eastern Turkey, we observed four species of broad-nosed weevils (subfamily Entiminae) that are newly associated with this plant: Epiphanops persicus (Chevrolat), Eusomomorphus oligops Daniel, Altonomus modestus (Khnzorian), and Araxia cristofaroi sp. n. Host plants of these species are recorded for the first time. Adults of E. persicus feed on young spines of C. solstitialis capitula (flower heads), whereas A. modestus and A. cristofaroi feed on leaves of C. solstitialis rosettes. Large numbers of E. oligops adults were observed feeding on leaves of both C. solstitialis and Russian knapweed, Acroptilon repens (L.). The genus Araxia Khnzorian is transferred from tribe Brachyderini Schoenherr to the tribe Sciaphilini Sharp, and it is redescribed. Female genitalia of this genus were studied and described for the first time. The new species, Araxia cristofaroi sp. n., is described, illustrated, and compared with the only other known Araxia species: A. mucronata Khnzorian. A taxonomic key discriminating the two Araxia species was developed. The new species differs by having claws that are almost equal in length, thinner and longer protibiae, wider antennal scape, more slender rostrum, and shorter body length. A. mucronata is newly recorded for Turkish fauna.
Approximately 8,900 species of the staphylinid beetle subfamily Pselaphinae have been described, based on adults, but the larvae of only 18 species and 14 genera have been described in sufficient detail for systematic study. The larva of Pselaphophus atriventris (Westwood) (Staphylinidae: Pselaphinae: Pselaphini) is described herein based on a series collected in a pasture habitat in New Zealand. Larvae are distinguished from other described larvae of pselaphines based on the following combination of characters: antennal segment two bearing two trifid setiform sensoria and labrum with irregularly arranged short spines and setiferous tubercles. It is most similar to the larva of Pselaphus heisei Herbst, sharing the following characters: antenna with two subapical branched sensoria, femora tuberculate, and tibiae with ventral row of minute teeth in proximal one third. P. atriventris is introduced to New Zealand and may be widespread in the country in open habitats. Seasonal data indicate that the species is univoltine. Larvae were found during late September–November (early summer), whereas adults are found year-round, but they were most abundant June–December. A list of the described immature stages of Pselaphinae is included.
Curalium cronini, new genus and new species is described on the basis of 16 male specimens from the southeastern United States. The relationships of Curalium are discussed within the context of a phylogenetic analysis for the Heteroptera: Cimicomorpha. Curalium is placed within the Cimicomorpha, primarily on the basis of pretarsal structure, with the ventral arolium being absent and the dorsal arolium existing in the form of a peg-like dorsomedian sensillum. It is further placed in a clade with Joppeicidae and Velocipedidae as the sistergroup of the remaining members of the Cimiciformes, a lineage containing all predatory family-group taxa in the Cimicomorpha other than the Reduvioidea. Curalium uniquely possesses several autapomorphic features, including a collar-like pronotum, novel male genitalia, and enlarged proctiger; other characters which—in combination—contribute to its diagnosis include hemispherical eyes, reduced forewing venation, fusiform antennal segments III and IV, and two-segmented tarsi. Because its placement in any existing family would render the diagnosis of that family meaningless, this novel taxon is placed in the Curaliidae, new family. Color images of whole specimens and extensive line drawings and scanning electron micrographs of morphological details are provided.
This study investigates the zone of overlap and hybridization between a new species in the Allonemobius species complex and Allonemobius socius (Scudder 1877). The new species, Allonemobius sp. nov. Tex was previously misidentified as Allonemobius fasciatus (De Geer 1773). Our survey of genetic variation at 13 allozyme loci shows that the new species differs from A. fasciatus in at least two allozyme loci. A. sp. nov. Tex is distributed mainly in Texas, and it is sympatric with A. socius in some parts of its distribution where the two species hybridize. In addition to the two fixed allelic differences between the two species, there is also a unique allele at a third locus in A. sp. nov. Tex. The proportion of hybrids in the mixed populations where the two species co-occur is always low, resulting in bimodal hybrid index scores. The bimodal distribution suggests that there is reproductive isolation between the new species and A. socius. This reproductive isolation is maintained, at least in part, through conspecific sperm precedence, which also serves as the major barrier to gene flow between A. socius and A. fasciatus.
The larva of Abablemma brimleyana (Dyar) (Noctuidae) is described and illustrated based on ex ova larvae reared on green algae (Protococcus viridis). A last instar Abablemma duomaculata (Barnes & Benjamin), collected from and reared on Physcia, a foliose lichen, and its lichen-encrusted cocoon, as well as a last instar Nigetia formosalis Walker ex ova reared on Protococcus, also are figured. Beating samples of lichens in the thorn scrub that yielded the A. duomaculata larva also produced multiple individuals of Cisthene subrufa (Barnes & McDunnough) (Noctuidae: Arctiinae: Lithosiini) and Glenoides lenticuligera A. Blanchard (Geometridae: Ennominae), both of which were reared to maturity on lichens. Abablemma, presently classified in the Araeopteroninae, is shown to be closely related to Nigetia formosalis, a Scolecocampinae according to Fibiger and Lafontaine. Shared larval and life history characters among the Araeopteroninae Fibiger 2005, Eublemminae Forbes 1954, Hypenodinae Forbes 1954, and Scolecocampinae Grote 1883 are discussed: the similarities between Abablemma, Hypenodes, and other genera suggest that the subfamilial classification for these basal quadrifids has been oversplit. The article concludes with a brief review of lichen and algal feeding in Macrolepidoptera and provides a listing of 38 macrolepidopterans that T.L.M. and D.L.W. have reared from green algae and foliose lichens; included are members of Geometridae: Ennominae (n = 1); and five subfamilies of Noctuidae: Arctiinae (n = 13) (12 of which are lithosiines), Eublemminae (n = 6) (all Metalectra Hübner), Herminiinae (n = 2) (both Zanclognatha Lederer), Scolecocampinae (n = 1), Araeopteroninae (n = 3), Hypenodinae (n = 1), Nolinae (n = 1), and Xyleninae: Elaphriini (n = 10) (all but two of which are Elaphria Hübner).
A new Mexican species of Orizabus Fairmaire (Coleoptera: Scarabaeidae) is described and illustrated. The female of Orizabus fairmairei (Bates) is described by first time. New distributional records are given for Orizabus batesi Prell, Orizabus brevicollis Prell, Orizabus clunalis (LeConte), Orizabus fairmairei (Bates), Orizabus isodonoides Fairmaire, and Orizabus pyriformis (LeConte). A revised key to the species of this genus is presented.
RESUMEN Se describe e ilustra una nueva especie Mexicana de Orizabus Fairmaire. Se describe por primera vez la hembra de Orizabus fairmairei (Bates). Se proporcionan nuevos registros de distribución para Orizabus batesi Prell, Orizabus brevicollis Prell, Orizabus clunalis (LeConte), Orizabus fairmairei (Bates), Orizabus isodonoides Fairmaire, and Orizabus pyriformis (LeConte). Se presenta una clave revisada para las especies de este género.
The analysis of a large census of dung beetles from the southern Alps (108 samples; 85,478 specimens belonging to 59 species) showed that 1) elevation and vegetation type (Mediterranean versus temperate) greatly influenced the assemblage composition, 2) spatial factors have a greater effect than monthly variability, and 3) exposure (north versus south) is a stronger determinant than vegetation structure (grassland-semi-open habitat-forest). Environmental heterogeneity results in different assemblages dominated by related species: Scarabaeinae dominate during spring and summer on south-facing nonwooded habitats; and Aphodiinae dominate from spring to autumn on north-facing slopes and in forests, but on south-facing slopes only in autumn. Scarabaeinae species have similar spatiotemporal distributions; thus, it can be assumed that this subfamily is restricted in space and time by thermal sensitivity. The colonization of high elevations by small tunnelers is due to a few species that have a broad tolerance of environmental conditions. In contrast, the temporal distribution of Aphodiinae is highly segregated, and these beetles occupy a variety of habitats because of their specialization. Analysis shows the distribution of species belonging to different subfamilies is most related to biological requirements rather than interspecific competition.
RÉSUMÉ Dans le sud des Alpes, l’analyse conjointe de nombreux peuplements de bousiers (108 échantillons, 85478 spécimens appartenant à 59 espèces) a montré que: 1) l’altitude et le type de végétation (méditerranéenne ou tempérée) influence fortement la composition des peuplements; 2) les paramètres spatiaux sont plus déterminants que la variabilité temporelle; 3) l’exposition (adret ou ubac) a plus d’importance que la structure de la végétation (pelouse, lande, forêt). L’hétérogénéité environnementale génère des assemblages hautement différenciés d’espèces apparentées: les Scarabaeinae tendent à dominer largement au printemps et en été dans les habitats non forestiers des versants sud; les Aphodiinae sont au contraire très largement majoritaires en versant nord, ainsi qu’en forêt et à l’automne. Les différentes espèces de Scarabaeinae ont des distributions spatio-temporelles très similaires, et on peut supposer que cette sous-famille est, dans son ensemble, limitée dans son extension spatiale et temporelle par la thermophilie des espèces. La colonisation des altitudes supérieures par les Scarabaeinae fouisseurs est le fait de quelques espèces ayant une plus grande tolérance vis-à-vis des conditions climatiques. Au contraire, la distribution temporelle des Aphodiinae est très ségrégée et ces insectes occupent une grande variété de milieux grâce à la spécialisation étroite des espèces. L’analyse montre enfin que la distribution des espèces appartenant aux différentes sous-familles est davantage induite par leurs exigences propres que par d’éventuelles interactions au sein des peuplements, et en particulier la compétition.
Insect herbivores that are tended by ants exhibit a range in host plant use from specialists to extreme generalists. Potential factors that may influence relative suitability of different host plants include the presence or absence of ants and the size of aggregations formed by nymphs feeding on a host. We used a membracid-ant mutualism to test whether presence of ants or aggregation size (from 20 to 320 nymphs per plant) resulted in variable selection for host use by the generalist membracid Publilia modesta (Uhler) (Hemiptera: Membracidae) that feeds on host species Chrysothamnus viscidiflorus (Hook.) Nutt. and Wyethia spp., among others. Survival of nymphs as mid-instars and the percentage of nymphs developing into adults on C. viscidiflorus were greater for nymphs in small than in large aggregations. Survival of nymphs as mid-instars on Wyethia spp. was also greater in smaller aggregations, but the percentage of nymphs developing into adults was independent of aggregation size. The presence of the tending ant, Formica obscuripes Forel, had no effect on the percentage of nymphs developing into adults during this experiment. The survival of membracids on C. viscidiflorus was always greater than survival of membracids on Wyethia spp., regardless of aggregation size or presence of ants; the favored host did not vary in a way that would explain the observed generalized host plant use. C. viscidiflorus was a superior host plant, because it senesced after nymphs became adults, whereas Wyethia spp. senesced early enough that most nymphs died before reaching adulthood.
We describe three specimens from a Late Mississippian (earliest Serpukhovian) pteridosperm (seed fern) Triphyllopteris austrina (Etheridge Jr.) Morris, of probable lyginopterid affinities, which originates from the Sugar Loaf Creek locality of the Sydney Basin, Australia. These specimens provide six examples of folivory assigned to the ichnotaxon Phagophytichnus ekowskiivan Amerom 1966. This damage is the earliest example of folivory in the terrestrial fossil record and probably was produced by a “protorthopteroid” or other basal orthopteroid insect, although a more remote possibility is that the culprit was a diplopod. Three important consequences result from this discovery. First, leaves originated 76 million years (m.y.) before the first indication of their folivory. Second, a temporal lag of 6 m.y. is present between the occurrence of T. austrina folivory and the subsequent earliest appearance of herbivorous insect clades in the body-fossil record that could have caused the damage. Third, once the hurdle of folivory was breached, the overwhelming preference of Paleozoic insect folivores was on a taxonomically diverse, paraphyletic spectrum of pteridosperm hosts.
Culex territans Walker (Diptera: Culicidae) acquires bloodmeals from amphibian hosts. Females overwinter as inseminated adults and exit diapause in New Jersey when spring peepers (Pseudacris crucifer) are calling. We tested the hypothesis that Cx. territans uses amphibian vocalizations as a long-distance attractant. Two thirds of females oriented toward sound across all experiments. Females allowed to orient toward or away from a frog call, bird song, live frog, or control (a plugged in compact disc player) exhibited positive phonotaxis only to the frog call. Females exhibited positive phonotaxis to calls of P. crucifer, Hyla versicolor (northern gray tree frog), Bufo americanus (American toad), and Rana clamitans (green frog), but they were not attracted to calls of R. catesbeiana (bullfrog), R. sylvatica (wood frog), or control. Multiple regression analysis showed that call frequency is the best predictor for phonotaxis, with pulse duration and call amplitude increasing the attractiveness of the source. When exposed to P. crucifer calls at increasing sound intensity levels, females oriented to calls in the range of 50–75 dB, with particle velocities of 0.02–0.3 mm/s, indicating that phonotaxis occurs at distances >5 m from the source.
Laboratory feeding trials were conducted with 40 adult Calosoma sayi DeJean (Coleoptera: Carabidae) over a 19-wk period, by using as food either the larval, prepupal, pupal, or adult stages of the fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae). The mean survival period of the beetles maintained on the separate fall armyworm stages was 122 d (larvae), 75 d (prepupae), 57 d (adults), 34 d (pupae), and 31 d (no food). All beetles offered food weighed less at death than at the beginning of the experiment, even though the percentage of gain in body weight during the experiment ranged from 25% (pupae) to 40% (prepupae). Those denied food gained no weight and lost >19% body weight before death. The only significant difference between the sexes was in the percentage of body weight gained (female, 39%; male 26%). These results are compared with other studies and their significance is discussed.
The effects of corn stunt spiroplasma (CSS), Spiroplasma kunkelii, on survival of corn leafhopper Dalbulus maidis (Delong & Wolcott) (Hemiptera: Cicadellidae), exposed to parasitism, fungal disease, or predation were investigated in the laboratory. Adult corn leafhoppers with or without CSS were exposed separately to parasitism or predation by Gonatopus bartletti, a parasitoid that acts also as a predator, or to infection by Metarhizium anisopliae, a pathogenic fungus, to evaluate the effects of CSS on corn leafhopper survival confronted with these natural enemies. CSS alone did not affect corn leafhopper survival, but differentially mediated survival of leafhoppers exposed to parasitism or predation by G. bartletti, or infection with M. anisopliae. CSS did not affect the survival of corn leafhoppers parasitized by G. bartletti: Survivorship of leafhoppers carrying CSS and parasitized by G. bartletti was ≈9%, whereas in the absence of CSS and parasitized it was ≈17%, but the difference was not significant. Similarly, CSS did not affect the survival of corn leafhoppers infected with M. anisopliae: Survivorship of leafhoppers carrying CSS and infected with M. anisopliae was ≈64%, whereas in the absence of CSS and infected with M. anisopliae it was ≈73%, but the difference was not significant. In contrast, CSS reduced the survival rate of corn leafhoppers exposed to predation by G. bartletti, though the effect was mediated by the incubation period of CSS. Corn leafhoppers exposed to predation and carrying CSS for 10 or 20 d had significantly lower survivorship rates, ≈54 and ≈47%, respectively, compared with those of leafhoppers carrying CSS for 2 d or free of CSS, ≈91 and ≈78%, respectively. The lower survival rate of corn leafhoppers carrying CSS and exposed to predation by G. bartletti, particularly of leafhoppers with longer CSS incubation periods, together with the lower survival rate of CSS in leafhoppers parasitized by G. bartletti documented in earlier studies, are suggested as factors limiting the abundance of the vector and plant pathogen in their shared area of origin.
Studies of interactions between imported fire ants and other ant species (Hymenoptera: Formicidae) have generally addressed populations in open areas where imported fire ant densities are highest. Forest habitats harbor a different assemblage of ant species and interactions between ant species in forests are occurring under different environmental conditions. We have asked three questions about the distribution of hybrid imported fire ants and native ant species in a Mississippi forest: 1) Is their distribution influenced primarily by interspecific competition or by local conditions? 2) Are the communities at locations with and without hybrid imported fire ants different? and 3) Which native ant species are using the same resources as hybrid imported fire ants? To answer these questions, ant species were collected at baits, along with the metrics for a set of local conditions, over a representative sample of forest habitats. Data were analyzed using permutation tests comparing the observed characteristics of the ant community to those expected by random processes. The community of ant species collected at baits was not structured competitively and their distribution was strongly associated with the distribution of local conditions. The assemblage of ant species was different at locations with hybrid imported fire ants from the assemblage at locations without them, but the two groups of locations were equal in richness when samples were standardized by rarefaction. Of the 28 species collected, 14 occurred with hybrid imported fire ants. One species, Aphaenogaster carolinensis Wheeler, was negatively associated, and another, Monomorium minimum (Buckley), was positively associated with hybrid imported fire ant occurrence.
The abundance, diversity, and spatial distribution of the weevil fauna (Coleoptera: Curculionidae) of leaf litter were compared between primary and successional cloud forests at the Biological Reserve Cerro Huitepec in the highlands of Chiapas, Mexico. In total, 2,102 individuals and 57 species of Curculionidae were collected and identified, of which >90% represented undescribed species. Total weevil densities averaged 8.51 ± 9.04 individuals per 0.5 m2 of leaf litter. Estimates of the total number of leaf litter weevils in the reserve were >20 million. Data suggest that even small fragments of cloud forest (<10 ha) may maintain viable populations of the more common species of leaf litter weevils for extended periods. However, because of their low powers of dispersion and their high levels of endemism, leaf litter weevils, and presumably other leaf litter insects, are particularly vulnerable to extinction when whole forest fragments are lost or when recent climate changes push cloud forests to higher elevations.
We describe the richness, abundance, and ecological characteristics of bees in community gardens located in heavily developed neighborhoods of the Bronx and East Harlem, NY. In total, 1,145 individual bees, representing 54 species (13% of the recorded New York State bee fauna) were collected over 4 yr. The nesting habits of these species include bees that nest in cavities (33% of species), hives (11% of species), pith (1.9% of species), wood (1.9% of species), or soft/rotting wood (7.4% of species) substrates. Soil-nesting individuals were relatively rare (25% of individuals), perhaps due to a lack of proper soils for nesting sites. Parasitic species were scarce (5.6% of species, 2.6% of individuals), most likely because of an absence or rarity of host species. Overall, exotic species were abundant and constituted 27% of the total individuals collected and 19% of the identified species. We compare these results to several bee faunal surveys in New Jersey and New York State, including newly reported species lists for Central Park and Prospect Park in New York City. Relative to other studies, bee richness of the urban gardens is reduced and composition is biased toward exotic and cavity-nesting species. Nevertheless, despite their small size and location within highly urbanized areas, urban community gardens harbor a diverse assemblage of bees that may provide pollination services and opportunities for ecological exposure and education.
The midgut of Acheta domesticus L. (Orthoptera: Gryllidae) is composed of anterior and posterior parts. Midgut epithelium has columnar digestive cells and regenerative cells, the latter of which form regenerative crypts. Differences at the ultrastructural level between digestive and regenerative cells of the anterior and posterior midgut are described. Processes of degeneration and regeneration are more extensive in the posterior midgut, where entire groups of the digestive cells undergo necrosis, whereas only individual degenerating cells are observed in the anterior midgut. Regenerative cells, which occupy the basal regions of regenerative crypts, proliferate intensively, and they are the stem cells of the midgut epithelium. The cells situated in the apical part of the regenerative crypt assume an epithelial character and differentiate into epithelial cells. Those digestive cells that degenerate separate from the basal lamina and are lost. Regeneration in this species proceeds in a continuous manner.
Microdissection and transverse semithin sections were used to perform a light microscopy survey of the gross morphology and cellular anatomy of the alimentary canal, respectively, of Lygus hesperus Knight, a key pest of cotton (Gossypium hirsutum L.), alfalfa (Medicago sativa L.), and other crops. The gross morphology of the alimentary canal showed a relatively unadorned tube compared with other hemipterans, with variably shaped compartments and one small diverticulum. However, the epithelial cell anatomy of the gut was relatively complex, with the midgut having the most diverse structure and cell types. The midgut was typical of the “Lygus-type gut” seen in the older literature, i.e., it consisted of three major regions, the first (descending), second (ascending), and third (descending) ventriculi, with different variants of three major epithelial cell types in each region. Our light microscopy (LM) study suggests that the three cell types are nondifferentiated regenerative cells (which sparsely occurred throughout the midgut but were abundant in the anterior region of the first ventriculus), endocrine cells, and columnar cells. Although the Lygus gut cells strongly resemble those cell types seen in other insects, their identification should be confirmed via transmission electron microscopy to be considered definitive. These cell types differed in the size and opacity of vesicles, geometry of cell surface in the gut lumen, and size, shape, and concentration of brush-border microvilli and location within the gut. Comparison of gut structure in L. hesperus with that of other hemipterans, especially in relation to hemipteran phylogeny and feeding strategies, is discussed.
Within the North American Lycaeides (Hübner) fauna, there are at least three major lineages that exhibit extensive morphological and ecological variation, especially at suture zones where these lineages meet. We examined male genitalic morphology in Lycaeides populations spanning much of North America to evaluate the current taxonomy and to address questions about the patterns of morphological variation at suture zones and potential evolutionary processes responsible for the patterns. Our genitalic measurements were based on those of V. Nabokov who revised North American Lycaeides taxonomy in the 1940s. Canonical discriminant analysis validated Nabokov’s original species designations, but it did not support many of his subspecific designations. Populations at a suture zone in the Great Lakes region are similar to populations on the east side of this zone. Populations at a western suture zone in the Sierra Nevada and adjacent ranges exhibit intermediate morphology between lineages on either side of this suture zone. We tested the hypothesis that contemporary gene flow contributes to the patterns of morphology in suture zones by testing for the increased variance in quantitative traits that is expected in a hybrid swarm. Based on a comparison of variances from populations within and outside of these suture zones, there is no evidence of current hybridization between lineages, with the sole exception of the population sample from the White Mountains of eastern California. The intermediate morphology and the general absence of increased variance within western suture zone populations imply that hybridization may have been important in the evolution of North American Lycaeides.
Antennal morphology, types of sensilla, and their distribution have been investigated in Talponia batesi Heinrich (Lepidoptera: Tortricidae) by using scanning electron and light microscopy. T. batesi antenna is filiform and segmented in both sexes, consisting of the three usual components: scape, pedicel, and flagellum. Antennal length was greater in females than in males. Five types of sensilla were identified on the antennae of both sexes: trichodea, chaetica, styloconica, coeloconica, and auricillica. All types of sensilla were present on the ventral side of the antenna, and sensilla coeloconica and auricillica also were found on the dorsal side. The sensilla trichodea were the most numerous sensilla on the antennae. There was sexual dimorphism in the antennae of T. batesi. The male antennae had more trichodea sensilla than female antennae. The sensilla observed in this species also have been reported in other Tortricidae.
Cotesia vestalis (Haliday) (Hymenoptera: Braconidae) is one of the most important biological control agents of the diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae). Immature development of C. vestalis was studied by dissecting parasitized hosts in the laboratory at 25 ± 1°C and 60–65% RH. Results showed that the egg matured in 2 d. Larvae seemed to have three instars; the first two larval instars molted inside the host, and the third instar emerged from the host to spin a cocoon. The first, second, and third instars lasted 2, 5, and 1 d, respectively. The first instar is transparent and caudate-mandibulate with a large head, distinct mandibles, and a caudal projection. The second instar is semitransparent with an anal vesicle. The third instar larva is yellowish green and the body is slightly curved. The pupa develops for 5 d and is bright yellow with transparent antennae, wings, and legs. All stages were fully documented with microscopic photos.
Amplified fragment length polymorphism (AFLP) fingerprints were used to characterize the population genetic structure and gene flow of the oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae), for the first time in the major stone-fruit growing regions in South Africa. Populations were collected from six different regions and compared with each other. Furthermore, intraregion gene flow was determined by sampling more extensively from farms and orchards within two of these six regions. Five selective AFLP primer pairs generated 250 fragments. Phylogeny analysis clustered populations from the six regions into two main groups, although those situated close together geographically were not necessarily closely related genetically. Over local scales, populations collected from closely situated orchards (<1 km) could be distinguished. It seems that G. molesta was introduced at least twice into South Africa and that although moth dispersal over local scales may be limited, leading to the formation of localized populations, factors such as movement of fruit, bins, and nursery material among areas also may have helped extend the range of this insect in South Africa. These results provide important information on the population genetics of G. molesta for the design and implementation of sustainable pest management strategies, such as the management of insecticide resistance, which is influenced by insect dispersal.
We used mitochondrial 16S ribosomal DNA (16S rDNA) and microsatellites to study genetic diversity and population structure of the gray sunflower seed weevil, Smicronyx sordidus LeConte (Coleoptera: Curculionidae). A 400-bp fragment of mitochondrial 16S rDNA was amplified and sequenced from weevils collected from 20 geographic populations. Thirty-three unique mitochondrial DNA sequences (haplotypes) were identified based on 62 polymorphic sites. Sequence divergence among haplotypes ranged from 0.2 to 3.68%. Four of 33 haplotypes were shared among populations, but most (88%) were found in only one population. No geographical disjunctions could be correlated with cladogenesis shown by phylogenetic reconstruction of unique haplotypes. Haplotype 33 from Texas separated from a major clade composed of other gray and red sunflower seed weevil haplotypes. Analysis of molecular variance results revealed that most of the genetic variation observed in gray sunflower seed weevils was due to variation within populations. Nested clade analysis showed two main clades with significant geographic structure. Contiguous range expansion seemed to be the main mechanism of increased variation within the species. Significant differences were found in analyses of five polymorphic microsatellite loci in four geographically separated field populations from which multiple individuals could be collected from wild sunflowers. More genetic divergences occurred among weevil populations collected from sunflowers along the east-west axis than among weevil populations collected on a north-south axis. The overall results are consistent with current theories concerning the origin of the cultivated sunflower in central United States. The population represented by haplotype 33 from Texas is likely a new species that evolved independently.
Life history parameters and reproductive behaviors of the harlequin bug, Murgantia histrionica Hahn (Heteroptera: Pentatomidae), were determined. Total developmental time from egg to adult was ≈48 d. After a sexual maturation period of ≈7 d, both sexes mated repeatedly, with females laying multiple egg masses of 12 eggs at intervals of 3 d. Adult females lived an average of 41 d, whereas adult males lived an average of 25 d. Courtship and copulation activities peaked in the middle of the photophase. In mating experiments in which mixed sex pairs of virgin and previously mated bugs were combined in all possible combinations, the durations of courtship and copulation by virgin males were significantly longer with both virgin and previously mated females than the same behaviors for previously mated males. When given a choice between a virgin or previously mated female, previously mated males preferred to mate with virgin females, whereas virgin males showed no preference for virgin over previously mated females. Analyses of mating behaviors with ethograms and behavioral transition matrices suggested that a primary reason for failure to copulate by virgin males was the incorrect rotation of their pygophores to the copulation position, so that successful alignment of the genitalia could not occur.
Mating preferences, including the proximate mechanisms of preferences, have not been well studied among parasitoid wasps. In the parasitoid wasp Spalangia endius Walker (Hymenoptera: Pteromalidae), males chase after both mated females and virgin females equally. Not until contact or near contact are males more likely to retreat from mated females and hence less likely to mount them. This study used a behavioral perspective to test several hypotheses about the proximal cause of such retreats. Retreats do not seem to be a response to aggressive physical behavior by mated females. Male retreats also were not just a response to female motion; females were not consistently moving or consistently still before male retreats. Retreats were not simply a response to antiaphrodisiac pheromone on the surface of mated females; males did not avoid mounting dead females. If a pheromone is involved, females seem to be actively releasing it, in contrast to the antiaphrodisiac surface pheromones known in other hymenopterans. The mated female’s head and thorax, but not her abdomen, were essential to unattractiveness at the mounting stage of mating.
The substrate-borne vibrational songs produced by phytophagous stink bugs of the genus Chlorochroa (Heteroptera: Pentatomidae) were recorded and compared. Sex- and species-specific vibrational songs were recorded from both sexes of three stink bug species of agricultural importance, the congeners Chlorochroa uhleri Stål, Chlorochroa sayi (Stål), and Chlorochroa ligata (Say). The temporal and spectral characteristics of the songs were determined, along with the context in which they were produced relative to contact between signalers and receivers. Vibrational communication started with production of the calling song by C. ligata females (FS-1), and by males of C. uhleri (male song [MS]-1) and C. sayi (MS-1). Males of all three species produced courtship songs (MS-2), whereas only C. ligata and C. sayi produced rivalry songs. Copulatory songs were produced by all three species, but they could not be attributed to either sex. Several of the songs share similarities in their fine-scale time units that seem to be rearranged either temporally or by behavioral context in generating songs associated with different behavioral functions. The relationship of the Chlorochroa spp. songs to the songs of other stink bug species is discussed.
The twospotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae) aggregates on its host plant until mated females collectively disperse by walking to a new colony. Some females disperse singly and found new colonies. I experimentally investigated the role of trails in collective and solitary behaviors and found that dispersing females simply follow the trails left by preceding females. This behavior seemed to induce an amplification process, resulting in aggregation at a new colony. A solitary female readily joined a trail made by other females if she came upon one. Otherwise, a female should encounter her own trail at a new feeding site and automatically establish a colony, presumably by following her own trail. Thus, the collective and solitary behaviors that constitute the basic structure of the T. urticae colony life cycle seem to be induced by one rule: follow a trail.
Observations and comparative data are presented on the acoustic signals of three sharpshooter (Hemiptera: Auchenorrhyncha: Cicadellidae: Cicadellinae) species native to North America. The acoustic signals of the glassy-winged sharpshooter, Homalodisca vitripennis (Germar), native to the southeastern United States, are compared with two smaller sharpshooters native to the western United States, Homalodisca liturata Ball and blue-green sharpshooter, Graphocephala atropunctata (Signoret). Each sharpshooter is a known vector of the plant pathogenic bacterium Xylella fastidiosa Wells et al. Male acoustic signals from all three species and female signals from H. liturata and G. atropunctata were recorded from host plant substrates. The H. vitripennis calls were recorded in the evening and morning, whereas H. liturata and G. atropunctata were recorded in the afternoon. Each species has a characteristic acoustic signal of which the male call structure is most complex in H. vitripennis and simplest in H. liturata. Male–female acoustic duets in H. liturata and G. atropunctata were recorded, and distinct differences were found in the reply latencies between male and female calls in these species.
Oecanthus niveus (Gryllidae: Oecanthinae), a tree cricket species, inhabits the Tehuacán Valley, Mexico, year-round. Solitary males radiate calling songs that attract receptive females. The calling song is composed of discrete trains of five pulses with regular intertrain intervals. The courtship and mating behaviors are similar to other tree cricket species. In this study, we evaluated 1) the relationship between male body size and train duration, and the train period of its calling song; 2) female choice by exposing females to contrasting trains and train periods of the calling songs; and 3) the predation risk associated with the song patterns preferred by females. We hypothesized that 1) there is a significant relationship between male body size with train duration and the train period of calling songs, 2) females prefer song patterns associated with larger males, and 3) that a high predation risk is associated with these patterns. In line with our hypotheses, we found a significant relationship between male body size and song patterns. Females preferred calls with a train duration corresponding to a male 11% larger than an average male of the population. Nevertheless, no increase in invertebrate predation was detected in a field experiment for this song pattern. The train duration of the song is a reliable indicator of male size that does not have associated predation costs. Females may obtain direct or indirect benefits, or both, as a result of their mate choice preferences.
Nicrophorus beetles reproduce by burying small vertebrate carcasses underground in a brood chamber. All stages of the phoretic mite Poecilochirus (Mesostigmata: Parasitidae) associate closely with Nicrophorus beetles by clinging to them for transportation and by reproducing in the beetles’ brood chamber. Presumably, the fitness of phoretic mites is affected by the ability of their beetle host to successfully locate and bury a carcass. Previous studies have shown that thermoregulation during flight, competitive ability, burying speed, and burial depth are all positively correlated with adult beetle body size. This study, conducted in the Rocky Mountains of southwestern Colorado, addresses whether deuteronymph mites discriminate among male Nicrophorus investigator Zetterstedt (Coleoptera: Silphidae) hosts based on beetle body size, a proxy for beetle condition. We found that the number of phoretic mites on wild-caught male N. investigator beetles was positively correlated with beetle body weight and other measures of adult beetle body size. Laboratory trials with pairs of N. investigator beetles also demonstrated that deuteronymph mites preferentially associate with larger beetle hosts. A test to determine whether mites select hosts based on nutritional status was inconclusive. These results suggest that deuteronymph mites discriminate among adult male Nicrophorus based on body size, which is consistent with a choice that would benefit the mite. The precise mechanism by which mites detect size is not known, but it is most likely chemical.
Foraging behavior has been extensively studied in harvester ants (Hymenoptera: Formicidae); however, there is little information about the determinants of foraging success. We developed a path analysis model to quantify the functional relationships among the components of foraging at the colony level (onset, duration, number of foragers) and foraging success. Variation in the onset of foraging among colonies directly influences the amount of time a colony has available for foraging, and contributes substantially to the total biomass of food retrieved. This difference in foraging effort provides a causal explanation for previously observed differences in colony growth rates.
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