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The life history of the stink bug Mecidea minor Ruckes (Hemiptera: Heteroptera: Pentatomidae) was studied in the southern half of New Mexico from January 2005 to December 2007, and the egg and nymphal instars are described. This species was active year-round, occurring on various species of grasses but primarily on Lehmann lovegrass, Eragrostis lehmanniana Nees; grama grasses (Bouteloua spp.); Bermuda grass, Cynodon dactylon (L.); and tobosagrass, Pleuraphis mutica Buckley. Adults and late instars (fourth and fifth) were present during winter. The appearance and abundance of the eggs, nymphs, and adults during the year suggest this species is bivoltine with the possibility of a partial third generation. Instars can be distinguished by differences in morphological features, including body size and presence and relative development of wing pads.
Quantitative analysis of the consumption and use by herbivore pest's of the host plant is a common tool used for studying the interaction between insects and plants. Our goals were to quantify cotton leafworm, Alabama argillacea (Hübner) (Lepidoptera: Noctuidae), larval consumption rate in three cotton, Gossypium hirsutum L., cultivars that produce colored cotton fibers, and the effects of the consumption rate on A. argillacea pupal weight in greenhouse conditions. Larvae consumed a maximum of 0.69–1.03 g of leaf tissue over a 24-h period in all cultivars tested. Total consumption by A. argillacea larvae was highest when fed with ‘BRS 200’ leaves (2.89 g) and the lowest when fed with leaves from ‘BRS Safira’ (2.26 g). The regression analysis showed significant relationships between the quantity of leaf tissue consumed and pupal weights for each cotton cultivar. A. argillacea larvae fed on BRS 200 demonstrated a longer developmental period (14.84 d) than larvae fed on ‘BRS Rubi’ leaves (11.62 d) or BRS Safira (11.14 d). We concluded that BRS Safira presents the best quality food source for A. argillacea, BRS 200 is the worst, and BRS Rubí is intermediate. The longer developmental times of A. argillacea on BRS 200 may allow longer windows of opportunity for the use of biological control agents to reduce the damage caused by this pest and also would complete less generations per phenological cycle of the cotton crop.
Andricus shirakashiiShinji, 1940 and Andricus shirokashicola [sic] Shinji, 1941 (Hymenoptera: Cynipidae) were described from leaf galls on the evergreen oak, Quercus (Cyclobalanopsis) myrsinifolia Blume [Japanese: shirakashi], but their assignment to oak gall wasps (tribe Cynipini) has long been considered enigmatic. These species are in fact inquiline gall wasps that were described as gall-inducing wasps. Because the morphological characteristics of these species are typical of the genus Ufo (tribe Synergini), we transfer A. shirakashii and A. shirokashicola to this inquiline genus. Due to the loss of the type specimens of each species, the neotypes are here designated and the two species are redescribed.
The genus DolichocybeKrantz, 1957 (Acari: Heterostigmatina: Dolichocybidae) is redefined and two new species associated with beetles (Insecta: Coleoptera) are described from Iran: Dolichocybe silvani Rahiminejad & Hajiqanbar n. sp. associated with Silvanus sp. (Coleoptera: Silvanidae) and Dolichocybe varkana Rahiminejad & Hajiqanbar n. sp. associated with Corticeus unicolor Piller & Mitterpacher, 1783 (Coleoptera: Tenebrionidae). It is first record of the association between beetles of the family Silvanidae and Tenebrionidae and mites of the family Dolichocybidae. Also, it is first record of phoresy in the genus Dolichocybe. Chaetotaxy of tarsus I of the genus is discussed, host associations of the dolichocybids with insects are reviewed, and keys to the genera of the family and species of the genus Dolichocybe are presented.
The leafhopper subfamily Mileewinae was previously known in Madagascar from a single species, Ujna flavidipes Distant, also recorded from Seychelles. Study of samples from a recently completed Arthropod biodiversity inventory in Madagascar revealed seven new, apparently endemic species distinguishable based on external and genitalia characters and all referable to the genus Ujna Distant based on the present definition of the genus: Ujna variabilis sp. nov., Ujna bimaculata sp. nov., Ujna affinis sp. nov., Ujna trishula sp. nov., Ujna acuta sp. nov., Ujna alba sp. nov., Ujna rostrata sp. nov. are described and illustrated. Ujna flavidipes Distant is redescribed and illustrated. Three informal species groups are proposed. A key to the males of Ujna from Madagascar is presented. A key to world genera of Mileewinae and a morphological comparison of Ujna with other genera also are provided. Two new placements of genera are proposed: Processina Yang, Deitz & Li is transferred from tribe Cicadellini to Mileewini (Mileewinae) placement n. and Archeguina Young is transferred from Mileewini to Cicadellini (Cicadellinae) placement n.
Chrysoperla agilis Henry et al. (Neuroptera: Chrysopidae) is a widespread, nomadic lacewing in the carnea group of cryptic species. C. agilis has previously been found only in the warm parts of Europe, western Asia, and a few oceanic islands. Like others of the carnea group, C. agilis is identifiable only by its unique courtship song. Recently, a population with by the C. agilis song was discovered in central Alaska; based on its persistence over several years and its distribution over a wide area near Fairbanks, it seems to be permanent rather than transitory. To assess the relationship of this Western Hemisphere population to C. agilis in the Eastern Hemisphere, we 1) analyzed its courtship song, comparing it to the Eurasian song; 2) compared larval and adult morphology of Alaskan and Eurasian specimens; 3) inferred phylogenetic relationships of Alaskan and Eurasian specimens, by using sequences from the cox2 gene; and 4) crossed Alaskan with European individuals, raising their progeny and analyzing their “hybrid” songs. Alaskan C. agilis generally fell within the range of variation of Eurasian individuals for all acoustic and morphological traits, and their hybrid progeny were also acoustically indistinguishable. Phylogenetically, and despite current geographical isolation, Alaskan individuals clustered with Eurasian C. agilis rather than with Western Hemisphere taxa of the carnea group. We conclude that the Alaskan population is a bona fide member of C. agilis. Examination of the geographical pattern of song variation suggests that dispersal to Alaska took place quite recently in a west to east direction, via eastern Asia and the Bering Strait.
The candezei species group of Neohelota Ohta is revised. Six species are recognized, including one described herein, Neohelota jakli sp. nov., from Indonesia (Sumatra). Helota claudiae Nguyen-Phung, 1985 is placed as junior synonym of Neohelota candezei (Ritsema, 1899), and Helota jocelynae Nguyen-Phung, 1985 as a junior synonym of Neohelota montana (Ohta, 1929). Lectotypes are designated for Helota krugeriRitsema, 1900; Helota margarethaeRitsema, 1900; and Helota mariae Ritsema, 1899. A key for the candezei species group is provided. Figures of protibiae, genitalia, internal sacs, eighth abdominal tergites, and fifth abdominal ventrites are given for all species.
Mayetiola destructor (Say) (Diptera: Cecidomyiidae), the Hessian fly, is distributed across most of the wheat (Triticum aestivum L.)-growing areas of the world and can cause significant yield losses in wheat production. Native to the Old World, Hessian fly reportedly came to the United States in a single introduction during the Revolutionary War and has since spread across North America. Using a nuclear marker, the population structure of North American Hessian fly was examined with regard to collections from the Old World. White intron 1 (wint1) showed insignificant recombination within collections and a large number of informative characters, allowing its use as a phylogenetic marker. Thirty-three alleles of wint1 were identified. Population structure analyses divided the collections into four populations: Middle East, Old World I, Old World II, and New World. More variation was found within populations than between populations, indicating that gene flow exists between local areas. However, shared ancestral characteristics resulted in mixing of Hessian fly collections into more than one population as revealed by the population structure reconstruction. North American and Spanish collections were a mixture of the Old and New World populations. With the sharing of ancestral characters as well as wint1 alleles, this study indicates that the North American lineage may actually be associated to an unsampled location, perhaps northern Europe. If the single introduction hypothesis were correct, then both lineages would have to have been present at the time of introduction.
Among the methods to evaluate field diets of insect predators is frass analysis. The potential of this infrequently used method was explored for determining prey consumption by adult ladybird beetles (Coleoptera: Coccinellidae) in alfalfa, Medicago sativa L., fields. A laboratory experiment revealed that at 20°C, within 48 h after consumption of prey [either pea aphids, Acyrthosiphon pisum (Harris), or larvae of the alfalfa weevil, Hypera postica (Gyllenhal)], almost all prey fragments had been voided by adults of five ladybird beetle species commonly occurring in Utah alfalfa fields. Among the five ladybird beetle species, aphid and weevil fragments were detected in frass of 80–95 and 29–73% of adults, respectively. A second laboratory experiment with adults of the most common of these predators (the introduced Coccinella septempunctata L.) more fully identified and enumerated diagnostic fragments for specific types of prey (aphids, weevil larvae, and conspecific larvae) as they occurred in frass. Frass pellets from the consumption of alfalfa weevil and conspecific larvae most often contained diagnostic cuticle and setae, and less often mandibles and head capsules. Frass from the consumption of pea aphids most often contained antennae and legs, and less often mouthparts, eyes, and tarsal claws. These laboratory results provide a foundation for using and interpreting the results of frass analysis as a technique to assess field diets of aphidophagous ladybird beetles in alfalfa.
The suitability for larval development of the alien coconut pest Brontispa longissima (Gestro) (Coleoptera: Chrysomelidae) on the following 15 monocots was investigated. Arecaceae: Cocos nucifera, Trachycarpus wagnerianus; Typhaceae: Sparganium erectum, Typha latifolia; Poaceae: Avena sativa, Echinochloa esculenta, Hordeum vulgare, Oryza sativa, Sorghum bicolor, Zea mays; and Cyperaceae: Carex morrowii, Cyperus alternifolius, Cyperus esculentus, Cyperus serotinus, and Rhynchospora colorata. The larval survival rate to the adult stage was significantly higher when reared on C. esculentus and C. serotinus (95%); however, it was not significantly different compared with C. nucifera (75%). Sixty, 45, 45, and 10% were observed when reared on T. wagnerianus, S. erectum, T. latifolia, and C. alternifolius, respectively. The larval developmental period reared on C. serotinus was as short as on C. esculentus and on C. nucifera up to adult emergence. The fecundity of adults was examined using C. nucifera, T. wagnerianus, T. latifolia, C. esculentus, and C. serotinus as food plants. In these five plants, the females reared on T. wagnerianus started to lay eggs earliest. However, the preoviposition periods on C. esculentus and C. serotinus were not significantly different from those on C. nucifera and T. latifolia. Numbers of eggs laid per female did not differ significantly among these five plants. Our present results suggest that T. wagnerianus, C. esculentus, and C. serotinus can be used as new food plants in addition to C. nucifera and T. latifolia for rearing B. longissima.
Coexistence of competitors may result if resources are sufficiently abundant to render competition unimportant, or if species differ in resource requirements. Detritus type has been shown to affect interspecific competitive outcomes between Aedes albopictus (Skuse) and Aedes aegypti (L.) larvae under controlled conditions. We assessed the relationships among spatial distributions of detritus types, nutrients, and aquatic larvae of these species in nature. We collected mosquitoes, water, and detritus from artificial containers across 24 Florida cemeteries that varied in relative abundances of Ae. aegypti and Ae. albopictus. We measured nutrient content of fine particulate organic matter in water samples as total N, P, and C and ratios of these nutrients. We quantified food availability via a bioassay, raising individual Aedes larvae in the laboratory in standard volumes of field-collected, particulate-containing water from each cemetery. Quantities of detritus types collected in standard containers were significant predictors of nutrients and nutrient ratios. Nutrient abundances were significant predictors of relative abundance of Ae. aegypti, and of larval survival and development by both species in the bioassay. Survival and development of larvae reared in particulate-containing water from sites decreased with decreasing relative abundance of Ae. aegypti. These data suggest that N, P, and C availabilities are determined by detritus inputs to containers and that these nutrients in turn determine the feeding environment encountered by larvae, the intensity of interspecific competition among larvae, and subsequent relative abundances of species at sites. Detritus inputs, nutrients, and food availability thus seem to contribute to distributions of Ae. aegypti and Ae. albopictus in cemetery containers throughout Florida.
Sugarcane (Saccharum L.) in Louisiana is colonized by the sugarcane aphid, Melanaphis sacchari (Zehntner), and the yellow sugarcane aphid, Sipha flava (Forbes). Five commercial sugarcane cultivars, ‘LCP 85-384′, ‘HoCP 91-555′, ‘Ho 95-988′, ‘HoCP 96-540′, and ‘L 97-128′, representing >95% of Louisiana's sugarcane-growing area, were assessed under southern Louisiana field conditions for numbers of the two aphid species. Biweekly sampling during 2007 and 2008 growing seasons indicated cultivar and time effects on aphid frequency. Aphid population peaks occurred during June and July and then crashed. M. sacchari was more abundant than S. flava on almost all cultivars and on all sampling dates during both years of the study. HoCP 91-555 was found to be the most resistant compared with the susceptible Ho 95-988 and L 97-128 cultivars. HoCP 91-555 might be useful in areas of high aphid pressure, and as a source of resistance in cultivar development programs.
The banded elm bark beetle, Scolytus schevyrewi Semenov (Coleoptera: Scolytidae), native to Asia, was detected in the United States in 2003, and as of 2011 it is known to occur in 28 states and four Canadian provinces. S. schevyrewi infests the same elm (Ulmus spp.) hosts as the long-established invasive, the European elm bark beetle, Scolytus multistriatus (Marsham). Information on the basic biology of S. schevyrewi in its native range is sparse; thus, we conducted laboratory studies and field studies in Colorado and Nevada. Comparisons of flight and behavioral responses were made with co-occurring S. multistriatus. When Siberian elm, Ulmus pumila L., cut logs (bolts) were allowed to be colonized by wild populations in the field, S. schevyrewi did not differ in emergence density from 10- versus 24-cm-diameter bolts. In the laboratory, S. schevyrewi readily colonized bolts of American elm, Ulmus americana L., but not Chinese elm, Ulmus parvifolia Jacq.; Siberian peashrub, Caragana arborescens Lam.; a cherry, Prunus fontanesiana (Spach) C. K. Schneid.; or Russian olive, Elaeagnus angustifolia L. In Colorado, S. schevyrewi often landed on elm bolts between 12:00 p.m. and 4 p.m.; and near large elm trees, they were captured more frequently on sticky traps at 1.8 and 3.7 m aboveground than higher along the main stem. In Colorado/Nevada, S. schevyrewi initiated flight in April/March and ceased in October/September, whereas S. multistriatus initiated flight in April/May and ceased in October/September. In funnel trap flight assays of semiochemicals in Colorado or Nevada, S. schevyrewi had moderate responses, 3–10-fold greater than unbaited control traps, to Multilure (a commercial lure for S. multistriatus), 2-methyl-3-buten-2-ol (MB) multistriatin, and MB a plant extract that is included in a commercial formulation of Multilure. In contrast, S. multistriatus had a 226–259-fold greater response to Multilure than to the control. Both Scolytus species showed electroantennographic (EAG) responses to MB, racemic multistriatin, and ( )- and (-)-α-inene, with the greatest sensitivity to multistriatin. S. schevyrewi was more responsive to (-)-α-pinene than was S. multistriatus.
Eucryptorrhynchus brandti (Harold) (Coleoptera: Curculionidae) was identified in China and studied in quarantine in the United States as a potential biological control agent for the invasive weed, tree of heaven, Ailanthus altissima (Mill.) Swingle (Sapindales: Simaroubaceae). Studies on its general biology and development, and the most efficacious rearing method were conducted. E. brandti is univoltine. The metathoracic sternite and first abdominal segment are convex in females and concave or flat in males. Females are larger than males. Female and male sagittal measurements averaged 11.50 ± 0.14 (± SEM) and 10.35 ± 0.09 mm, respectively. Transversal measurements averaged 4.22 ± 0.06 and 3.73 ± 0.05 mm for females and males, respectively. Mean weight of females and males were 0.10 ± 0.003 and 0.07 ± 0.002 g, respectively. Females lived longer than males, averaging 66.3 ± 6.8 d and 46.5 ± 7.3 d, respectively. The egg stage averaged 5.0 ± 0.9 d, and the larval stage had six stadia and developed in 110 ± 15.0 d; the pupal stage was 16 ± 7.0 d at 25°C. A method for rearing E. brandti on cut A. altissima billets under quarantine conditions was developed. The most efficient egg-to-adult rearing method involved caging 12 males and 12 females or 24 males and 24 females for 7 d on 23-92-cm-long billets. Duration up to 3 wk after cutting did not affect adult emergence. This information will facilitate laboratory rearing and conducting host specificity tests to determine agent impact on nontarget species.
The lacewings Dichochrysa flavifrons (Brauer) and Dichochrysa zelleri (Schneider) (Neuroptera: Chrysopidae) are considered as important biological control agents, and mass rearing is a prerequisite for their use in biological control programs. We evaluated the effect of Ephestia kuehniella Zeller eggs that are widely used for mass rearing other chrysopids and the nymphs of the aphid Acyrthosiphon pisum (Harris) on the development and reproduction of D. flavifrons and D. zelleri at 25°C and a photoperiod of 16:8 (L:D) h. Preimaginal development of D. flavifrons and D. zelleri was significantly shorter when their larvae were fed on E. kuehniella eggs than on A. pisum nymphs. In D. flavifrons, the intrinsic rate of increase (rm) was higher when larvae were fed on E. kuehniella eggs than on A. pisum nymphs. By contrast, in D. zelleri rm was higher when larvae were fed on A. pisum nymphs than on E. kuehniella eggs. The differences in development and reproduction among the two tested species when their larvae were fed on different prey could be of importance for their mass rearing and use in biological control.
The western flower thrips, Frankliniella occidentalis (Pergande); flower thrips, Frankliniella tritici (Fitch); and tobacco thrips, Frankliniella fusca (Hinds), are abundant, polyphagous species in the southern United States. Paspalum notatum Flugge and Paspalum distichum L. (Poales: Poaceae) are low-maintenance, warm-climate, tolerant grasses that are used for pasture and residential lawns and along roadsides. The potential of P. notatum and P. distichum to serve as sources of the common polyphagous Frankliniella thrips in the southeastern United States was evaluated. The abilities of F. fusca, F. occidentalis, and F. tritici to survive and reproduce on vegetative-stage P. distichum, P. notatum ‘Argentine’, P. notatum ‘Pensacola’, and P. notatum ‘Tifton 9’ were compared in laboratory no-choice tests. Survival of the adults of each thrips species was ≈20% after 12 d on each of the Paspalum treatments. No progeny were produced by F. occidentalis on the U.S. native P. distichum, and the other thrips species produced very few progeny on this host. The number of progeny of each thrips was very low on all P. notatum cultivars. A field survey of the Thysanoptera associated with P. notatum Argentine also was conducted to determine whether the Frankliniella thrips were feeding or reproducing under field conditions. A few male and female adults of F. tritici and F. fusca were noted in the racemes, but larval populations were not observed. Reproducing populations of Caprithrips insularis Beshear and Haplothrips graminis Hood were present in the stems and leaves, and the racemes, respectively. Collectively, the laboratory and field studies revealed that the tested P. notatum cultivars and P. distichum accession are poor hosts for reproduction of the Frankliniella thrips in the southern United States and that the large plantings of these grasses are not serving as sources of pest Frankliniella thrips.
Evaluation of species diversity for highly diverse taxa is extremely time-consuming and costly; thus, there is a need to develop efficient sampling strategies. We established a short-term, efficient sampling scheme to produce samples that represent a full-season sampling of moth assemblages with a high degree of seasonality. We sampled adult moths monthly for the duration of the moth flying season by using light traps in five forest stands in a cool-temperate region in central Hokkaido, northern Japan. From this sample, we generated various subsamples that reduced the sampling period and the number of traps per stand, and tested whether these subsamples provide estimates of species richness, abundance, and species turnover representative of those revealed by the whole season sample. Comparisons between the whole season sample and each subsample indicated that setting one light trap on a night in July and August, which shortened the sampling period to 25% and reduced sample size to 38%, was the most efficient sampling scheme to estimate abundance, species richness, and similarity in the whole season sample. The comparisons also suggest that it is efficient to use rarified species richness as a species richness estimator, and the Bray—Curtis index or Morisita's Cλ for estimating species turnover between sites in moth assemblages.
Drosophila melanogaster (Meigen) (Diptera: Drosophilidae) exhibits several welldefined sleep parameters and a sleep:wake rhythm strength cycle that fragments and deteriorates with age. Because many aspects of functional senescence may be linked to the effects of accumulated oxidative damage, and as several lines of experimental evidence indicate that sleep parameters and sleep:wake rhythm strength may be modulated by oxidative stress in D. melanogaster, it has been postulated that sleep fragmentation is driven, at least in part, by accumulated oxidative damage in this fly. We investigated the contrasting effects of an enriched dietary regime that is likely to exacerbate processes associated with aging and oxidative damage accumulation, and a dietary restriction regime that has been demonstrated to delay the detectable effects of aging-related damage on lifelong sleep and activity patterns in male and female D. melanogaster. We found that female flies on a nutrient-rich dietary regime exhibited stronger sleep:wake cycles than females on a dietary restriction regime and that dietary restriction did not seem to alter the initiation of sleep fragmentation in female or male D. melanogaster.
Previously, we found that the fat body of Aspisoma lineatum Gyll (Coleoptera: Lampyridae) firefly larvae is weakly bioluminescent. This tissue is very different from that of other insect larvae. It is macroscopically distinguished by its color (pinkish and whitish), morphology, and the absence of oenocytes. It is composed of trophocytes that are arranged in groups of globular units covered by a layer of basal lamina. The cytochemistry indicated that the trophocytes have glycoproteins, which are produced by a well-developed rough endoplasm reticulum (RER). Expanded RER cisterns indicated intense protein synthesis by the trophocytes. Lipid droplets are also present in the trophocytes. Charge-coupled device imaging showed that the fat body produces a continuous bioluminescence whose intensity is 2–3 orders of magnitude lower than that of the lanterns, a result that is explained by the lower contents of luciferin and luciferase in the fat body compared with the lanterns. Expression of different luciferase isozymes in the fat body and lanterns is confirmed by bioluminescence spectral and kinetic analyses. Trophocytes were identified as the emitting cells, suggesting that the larval and adult lantern's photocytes may have evolved from fat body trophocytes.
The ultrastructure of the first segment of the four-segmented Malpighian tubules of Cenocorixa bifida Hungerford (Hemiptera: Corixidae) is described. The first segment of each of the four tubules empties proximally into the midgut—hindgut junction. Its squamous epithelium is composed of a single layer of binucleated cells containing two types of mitochondria. The cells rest on a prominent basal lamina and possess short, shallow, widely spaced basal plasma membrane infoldings closely associated with large mitochondria and a few short blunt microvilli devoid of mitochondria projecting into the lumen. In sharp contrast, the fourth segment cells that are secretory in function, display numerous, long basal membrane infoldings that penetrate deeply into the cytoplasm and numerous long microvilli at the luminal border. The cytoplasm of the first segment cells contains dense bodies, small mitochondria, microtubules, vesicles, and vacuoles and is rich in smooth endoplasmic reticulum, giving rise to clear vacuoles, but rough endoplasmic reticula and Golgi apparati are sparse. The apical plasma membrane is covered with glycocalyx and displays coated pits pinching off coated vesicles. The apical cytoplasm displays numerous vesicles containing fine granular material, smooth vesicles, dense tubules, large vacuoles, primary lysosomes, and multivesicular bodies. The lateral plasma membranes are linked by extensive junctional complexes each composed of an apical smooth septate junction, intercalated gap junctions, and a basal heterocellular scalariform junction. The contrast in ultrastructural features between of the first segment and fourth segment cells suggests that the first segment is involved in reabsorption than secretion of inorganic and organic solutes.
The longicorn beetles Leptura arcuata Panzer and Leptura aethiops Poda (Coleoptera: Cerambycidae) are predominant pollination beetles in Eurasia and North America. To further elucidate the mechanism of mate and host location, the type, number, and distribution of antennal sensilla of both species of the longicorn beetles were studied using scanning electron microscopy. The filiform antennae of both sexes of the both species consist of the scape, pedicel, and nine flagellomeres. Based on their morphology, three types of sensilla chaetica, one type of sensilla trichodea, four types of sensilla basiconica, and Böhm bristles were distinguished on the antennae in both sexes. No significant sexual differences in the types, numbers, and distribution of the antennal sensilla were found on the antennae, except for the number of sensilla basiconica type 2. The average number of sensilla basiconica type 2 on the antennae of the males was significant greater than that on the antennae of the females. Based on the ultrastructure we postulated that this type of sensillum on the male beetle's antennae should be responsible for the reception of the sex pheromone produced by the female beetle. The putative functions of other sensillar types also are discussed with reference to their morphology, distribution, and ultrastructure.
The complete mitochondrial DNA (mtDNA) sequence of the oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae), has been identified. The mtDNA (15,717 bp) of G. molesta encodes 13 putative proteins, two rRNAs, and 22 tRNAs. Analysis of nucleotide composition of the genome indicates high A T composition (80.74%), which results in biased codon use and richness in specific amino acids of mitochondrial proteins. All protein-coding genes are initiated by ATN codons except for COI, which is initiated presumably by CGA codon. Except tRNASer (AGN), the remaining 21 tRNAs form a typical cloverleaf structure. An intergenic space between tRNASer (AGN) and ND1 contains a lepidopteran-characteristic sequence (ATACTAA). The control region, rich in A T, harbors several sequence characteristics shared by lepidopteran species, such as the motif ATAGA followed by 5′ poly T stretch and 3′ poly A stretch at just upstream of tRNAMet. The phylogenetic analysis, using whole mtDNAs, showed that G. molesta is clustered with other tortricid species, in which lepidopterans form a monophylogeny on the basis of Papilionoidea.
The citrus red mite, Panonychus citri (McGregor) (Acari: Tetranychidae), has a world-wide distribution and is the most important citrus (Citrus spp.) pest in many countries, including Japan, Spain, and China. To characterize the population genetic structure of the citrus red mite, the genetic variation in 15 populations from three citrus-planting regions of China (citrus belt of upper and middle reaches of Yangtze River [UMYR], citrus base of Yungui Plateau [YGP], and citrus belt of South China [SC]) was investigated using the ribosomal internal transcribed spacer (ITS) 1 region. These populations were characterized by high genetic diversity. Neutrality tests, mismatch analysis, and star-like network strongly supported the population expansion. Analysis of molecular variance (AMOVA) showed that no significant population genetic structure existed among UMYR, YGP, and SC. However, a significant global φ;ST and the genetic structure were found between (UMYR YGP) and SC. Pairwise φ;ST values between most populations were not significant, and a high gene flow was found among some geographically distant populations. The significant influence of host plants on the genetic structure of P. citri populations was found by the AMOVA for five host-related groups. In addition, the Mantel test revealed that geographical isolation was a factor responsible for the genetic differentiation. Therefore, our current observed population structure of P. citri can be contribute to several factors together, i.e., ongoing gene flow, the retention of ancestral polymorphisms, and natural selection (e.g., host plants, acaricides).
The genetic basis by which insects adapt to novel host plants is poorly understood, in part because genetic changes that accompany host-range expansions often cannot be distinguished from those that occurred well after the shift. We examined the inheritance of traits mediating rapid adaptation to a poor host by the seed beetle Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae: Bruchinae). For an Asian beetle population, larval survival in lentil, Lens culinaris Medikus, was initially ≈1%, but three separate mass-selection experiments produced lines with >80% survival in <20 generations. Each lentil-adapted line (L1–3) was then crossed with the ancestral line (M) from which it had been recently derived. Survival in the parental lines was extremely divergent: >90% in all L lines versus 0% in the M line. Survival of reciprocal F1 and F2 progeny suggested additive (intermediate) inheritance, with a small dominance deviation toward the M-line parent (in the L1 cross) or the L-line parent (in the L2 and L3 crosses), and no evidence of sex-linkage or cytoplasmic effects. Progeny from backcrosses to the M line survived at a much lower rate than would be expected by additive inheritance, but the survival of L1-backcrossed progeny was consistent with simple additivity. A potential explanation for this asymmetry is that larvae deriving 75% of their genes from the M line only rarely reach a threshold of enzymatic activity needed to detoxify lentil seeds. Two other fitness components, egg-to-adult developmental time and adult mass, also were intermediate in hybrids, but quantitative comparisons were precluded by a lack of M-line adults emerging from lentil. Additive expression of initially rare alleles can account for rapid colonization of a marginal host.
An existing microsatellite genotype database has been used for several years in population genetic assignment analyses of boll weevils, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae), captured in eradication zones. It is important to update it in case of changes in genotype frequency at any of the locations over time. Such changes at neutral loci could be caused by drift, immigration, or population bottlenecks. We examined allele frequency distribution for 10 microsatellite loci to determine genetic differentiation among 10 boll weevil populations sampled from Texas and Mexico in 2009. In addition, temporal changes in genetic composition were examined in the eight populations for which samples were available from previous years. Substantial levels of spatial genetic structure were observed, with the 10 populations clustering as four major groups. Pairwise FST estimates in 2009 samples ranged from 0.001 (College Station-Cameron) to 0.492 (College Station-Ojinaga). There was little change in genetic profiles over time at four of the eight locations. Thus, for those four locations, genotype and allele frequency data can be pooled over the two sample dates, which will provide greater statistical power in future population assignment tests. However, genetic profiles changed substantially at Ojinaga, and to a lesser extent at Uvalde, Cameron, and Rosales, so the 2009 genotype data should be substituted in future analyses. Finally, populations from two new locations, Brownsville and Lockhart, TX, were sampled, genotyped, and added to the database. The addition of Lockhart is particularly important given its surprisingly high differentiation from the relatively nearby populations of Cameron and Uvalde.
Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) is a Neotropical moth that has diverged into corn, Zea mays L., and rice, Oryza sativa L., host strains because these plants are their most frequently used hosts. The corn strain also has been found in cotton, Gossypium hirsutum L., and sorghum, Sorghum bicolor (L.) Moench, and the rice strain in small grasses and pasture grasses. Studies of the reproductive isolation between these two strains have provided ambiguous results from populations in the United States. In Colombia, we tested pre- and postzygotic isolation in these strains. Both strains showed postzygotic isolation for several life-history traits, including number of egg masses, number of larvae, number of females, pupal developmental time, female and male longevity, and female and male pupal weight. We observed a reduction of the number of hybrid females and a reduction in fertility in hybrids in S. frugiperda. These results suggest the possibility of Haldane's rule. Heterosis in the F1(2) and F2(1) generations was observed for number of larvae and adult longevity. This line presented a high standard deviation, suggesting instability in this cross. A possible effect of the X chromosome may explain the reduction in viability and sterility in F1 hybrids of host strains of S. frugiperda. No temporal isolation was observed between the corn and rice strains. Differences in longevity between corn and rice strains might be another form of temporal isolation between these strains, because differences in adulthood time might reduce the encounters between them and thus hybridization.
Diabroticite corn rootworms are significant maize, Zea mays L., pests that have evolved resistance to cultural and chemical management methods. Transgenic maize synthesizing a rootwormtoxic protein originating from the bacterium Bacillus thuringiensis Berliner is an important new management technology. Its use requires a refuge of nontransgenic maize to delay evolution of resistance by generating susceptible beetles capable of copulating with any resistant individuals surviving on the transgenic crop. The evolution of such resistance may concurrently influence a variety of fitness-related characters. Here, we examined multiple mating by female Diabrotica barberi Smith & Lawrence (Coleoptera: Chrysomelidae) in relation to the following fitness-related traits: female longevity, fecundity, and body size of males and females at the first copulation. For the first copulation, large and small males were reciprocally paired to large and small females for comparison with average-sized beetles. Once-mated females were then maintained under conditions conducive to oviposition and paired with averaged-sized males at weekly intervals until death. Although female age at second copulation varied significantly with size category, female age at first copulation, longevity and fecundity did not. Females that mated multiple times lived longer and laid more eggs than did those that mated once. The results suggest that resistance management models may need to consider those females deriving fitness benefits from a second mating.
In grass-infecting Epichloë (Ascomycetes: Clavicipitaceae) fungi, the transfer of spermatia for fungal fertilization depends on an insect vector: flies of the genus Botanophila (Diptera: Anthomyiidae). The flies use the fungal stroma, a spore-producing fungal structure surrounding the grass inflorescence, for laying eggs and as a food source for both adults and larvae. This fly—fungus interaction is generally regarded as obligatory and mutualistic. Two Botanophila taxa were noted among four populations of the nonagricultural grass Puccinellia distans (L.) Pari, that were infected with the fungus Epichloë typhina (Pers.) Tul. However, during the 7 yr of field observations, Botanophila flies were present every year in only one population of P. distans. The number of eggs per stroma ranged from zero to four and differed with year and site. Overall, eggs (or larvae) were observed on only 132 (19.2%) of the 687 stromata examined during the survey, with one (13.8%), two (4.5%), or more than two (0.9%) per stroma. However, 90.8% of the examined stromata were fertilized and produced perithecia, suggesting that other mechanisms or vectors of spermatia were responsible for fertilization.
The dispersal of the nest parasite Crataerina pallida Latreille 1812 (Diptera: Hippoboscidae), between nests of their common swift, Apus apus (Aves: Apodidae), hosts is reported for the first time. Adult parasites were marked, and their presence in other nests determined. More than 10% of marked parasites were found in nests other than those in which they were originally marked, indicating that such dispersal is frequent. Because the supposed lack of dispersal of this parasite between common swift hosts that are unrelated has been used to account for its apparent avirulence upon hosts, this discovery has important implications for understanding of this host—parasite system and parasitic virulence. New explanations accounting for its apparent lack of virulence may be required. The results of this preliminary study indicate avenues for more in-depth research of this and other host—parasite systems.
If typical host plants are absent, some herbivorous insects “dump” eggs on unsuitable substrates, even though this can cause complete larval mortality and reduced maternal life span. In the seed beetle Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae: Bruchinae), the tendency to dump eggs varies genetically both within and between populations. A previous study hypothesized that egg-dumping behavior facilitates host-range expansions, and suggested that such expansions have served to maintain “dumper” genotypes in beetle populations. We tested this hypothesis in two experiments. For both African and Asian beetle populations, full-sib females from >60 families were split among three treatments: no seeds, a less-preferred novel host, and a preferred host. Within each population, we found no correlation among families between the tendency to dump eggs and the tendency to accept the novel host. We also compared egg dumping between selection lines that had adapted to a novel host and a line that had remained on the ancestral host. Females from lines that had evolved greater acceptance of the novel host did not dump more eggs if hosts were absent. Thus, neither experiment supported the host-range expansion hypothesis. Egg distributions on the preferred host in the first experiment provided weak support for a more proximate explanation: family-level variation in the tendency to dump eggs is inversely related to the tendency to avoid superparasitism of seeds. Such a relationship is also evident in comparisons between populations. Given the considerable short-term costs of egg dumping, we suggest that the host-range expansion hypothesis requires unrealistically high frequencies of host deprivation and subsequent host shifts in C. maculatus.
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