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Lee W. Cohnstaedt, Kateryn Rochon, Adrian J. Duehl, John F. Anderson, Roberto Barrera, Nan-Yao Su, Alec C. Gerry, Peter J. Obenauer, James F. Campbell, Tim J. Lysyk, Sandra A. Allan
Effective entomological surveillance planning stresses a careful consideration of methodology, trapping technologies, and analysis techniques. Herein, the basic principles and technological components of arthropod surveillance plans are described, as promoted in the symposium “Advancements in arthropod monitoring technology, techniques, and analysis” presented at the 58th annual meeting of the Entomological Society of America in San Diego, CA. Interdisciplinary examples of arthropod monitoring for urban, medical, and veterinary applications are reviewed. Arthropod surveillance consists of the three components: 1) sampling method, 2) trap technology, and 3) analysis technique. A sampling method consists of selecting the best device or collection technique for a specific location and sampling at the proper spatial distribution, optimal duration, and frequency to achieve the surveillance objective. Optimized sampling methods are discussed for several mosquito species (Diptera: Culicidae) and ticks (Acari: Ixodidae). The advantages and limitations of novel terrestrial and aerial insect traps, artificial pheromones and kairomones are presented for the capture of red flour beetle (Coleoptera: Tenebrionidae), small hive beetle (Coleoptera: Nitidulidae), bed bugs (Hemiptera: Cimicidae), and Culicoides (Diptera: Ceratopogonidae) respectively. After sampling, extrapolating real world population numbers from trap capture data are possible with the appropriate analysis techniques. Examples of this extrapolation and action thresholds are given for termites (Isoptera: Rhinotermitidae) and red flour beetles.
The spittlebugs of the genus EuryaulaxKirkaldy 1906 (Hemiptera: Cercopoidea: Cercopidae) from Australia are revised to include six species: E. angustifasciatus sp. nov. (Western Australia and Northern Territory), E. arctofasciatusLallemand, 1949 stat. rev. [reinstated from synonymy with E. carnifex (Fabricius, 1775)] (Northern Territory), E. carnifex (Fabricius, 1775) (Queensland, Northern Territory, Western Australia and New South Wales), E. kirkaldyi sp. nov. (Northern Territory), E. longiprocessus sp. nov. (Northern Territory and Western Australia), and E. vacuolus (Jacobi, 1928) (Queensland and Northern Territory). Descriptions or redescriptions of the genus and its included species with diagnostic characters are presented together with the dorsal habitus of the adults and structural illustrations of the head, pronotum, forewing, hindwing, and male genitalia. A diagnostic key is provided for identification of the known species in the genus.
A new emerald ash borer (Coleoptera: Buprestidae) ectoparasitoid species, Spathius galinae Belokobylskij & Strazanac (Hymenoptera: Braconidae: Doryctinae), is described from the Russian Far East and South Korea. Molecular evidence supports that Russian and Korean specimens represent a single species and are closely related to two Asian species (S. agrili and S. generosus) that belong to the S. exarator species group. The morphological variation of adult S. galinae and its immature stages, distribution, life history, and relation to similar Asian Spathius species are discussed. The distribution of the new species may indicate this is one of the more cold hardy emerald ash borer parasitoids. A brief review of hymenopteran parasitoids of emerald ash borer and new host record, the first for Atanycolus nigriventris Vojnovskaja-Krieger (Braconidae: Braconinae), is reported.
This paper treats Chinese species of the rove beetle genus AleocharaGravenhorst, 1802, subgenus Aleochara s. str. (Coleoptera: Staphylinidae: Aleocharinae). Four new species are described from China: Aleochara (s. str.) collaris Luo and Zhou, sp. nov. from Sichuan; A. (s. str.) gladiata Luo and Zhou, sp. nov. from Fujian and Guangdong; A. (s. str.) serrulata Luo and Zhou, sp. nov. from Sichuan; and A. (s. str.) similinsularis Luo and Zhou, sp. nov. from Beijing, Heilongjiang, Hubei, Sichuan, and Gansu. Male genitalia and other critical characters are illustrated. A key to adults of Chinese species is provided. All the type specimens of the new species are deposited in the Institute of Zoology, the Chinese Academy of Sciences, Beijing (IZCAS).
Phlebotomus argentipes (Annandale and Brunetti) (Diptera: Psychodidae) is the phlebotomine sandfly vector responsible for the transmission of Leishmania donovani (Kinetoplastida: Trypanosomatidae), a parasite capable of transmitting the communicable disease, visceral leishmaniasis (VL) or kala-azar, in the Indian sub-continent. This paper presents the preliminary study on the laboratory-based behavioral responses of P. argentipes females to blood-feeding host and P. argentipes males or male extracts, for mating aggregation and blood feeding.
To search for potential biological control agents of the aquatic weed, Hydrilla verticillata (L.f.) Royle, emerging chironomid adults were collected from aquatic macrophytes sampled between 2007 and 2009 from near shore sites in Lake Tanganyika, Burundi. Initial surveys identified H. verticillata populations at all sampled locations between Bujumbura and Nyanza Lac. Twenty-six (26) species of Chironomidae emerged from collections of four plant species; Hydrilla, Ceratophyllum demersum variety apiculatum (Cham.) Asch., Potamogeton schweinfurthii A.Benn., and Vallisneria spiralis f. aethiopica (Fenzl) T.Durand and Schinz. Twenty-four of the chironomid species were new country records, but none of them represented undescribed species. Dicrotendipes fusconotatus (Kieffer) dominated the chironomid community, comprising 82% of 32,090 reared adults. The six most common species contributed over 96% of the total midge fauna. Most species were uncommon or rare; nine species were represented by 10 or fewer specimens. A species accumulation curve for the 25 chironomid species reared from Hydrilla suggested that our sampling completely describes the community associated with this plant in northern Lake Tanganyika. Quantitative β-diversity values indicated that chironomid communities of the two Hydrocharitaceae species, Hydrilla and Vallisneria, were most similar to each other, even though they have very different growth forms. Chironomids also emerged in greater numbers from the two Hydrocharitaceae than from the other plants. No chironomid species, including Polypedilum wittei Freeman and Polypedilum dewulfi Goetghebuer, two species formerly considered for possible biological control of Hydrilla, were specific to that plant. Polypedilum species emerged from all sampled aquatic macrophytes. No chironomid-caused damage was seen on Hydrilla. African Chironomidae do not appear to be suitable candidates for biological control of Hydrilla.
Dung beetles are important to healthy cattle pasture ecosystems as they provide for nutrient recycling, removal of waste products from the soil surface and assist in the reduction of pestiferous flies. Numerous exotic dung beetles have been accidentally or intentionally introduced to the North American continent and several of these have become established. We surveyed for the presence and distribution of dung beetles on four cattle farms in north central Florida over a 3.5-yr period using cattle dung-baited pitfall traps placed at least every 3 wk. In total, 39 species from 20 genera were identified with a total of 62,320 beetles collected in traps. Although none were intentionally released in Florida, six exotic species were present. Significant differences were observed in species captures among the three most sampled farms, with beetle species dominance patterns differing among the farms. The native species, Onthophagus tuberculifrons Harold, was the most commonly collected species, and both it and the introduced Labarrus pseudolividus Balthasar, had mass emergences. Four of the six most commonly collected species were exotics and included, in order of abundance, L pseudolividus, O. gazella (F.), O. taurus (Schreber), and Euoniticellus intermedius (Reiche).
As the single most important pest of field corn, Zea mays L., throughout most of the Corn Belt, the western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), has undergone repeated selection for resistance to a variety of insecticides that persist widely among Nebraska populations. In this study, we used 11 microsatellite markers to genotype two populations with high levels of resistance to methyl-parathion and aldrin (Polk and Stromsburg), two populations with low and intermediate levels of resistance (Mead and Clay Center) from Nebraska, and one population from outside the Corn Belt (Safford, AZ). The genetic diversity measured by observed heterozygosity (H0) was reduced 15–32% in the highly resistant populations compared with the more susceptible populations in Nebraska. Significant genetic differentiation was detected between the resistant and susceptible populations (Polk and Stromsburg versus Mead and Clay Center) in Nebraska (FST = 0.016) and between all the populations from Nebraska and Arizona (FST = 0.059). The average observed heterozygosities in the populations were positively correlated with insecticide susceptibility based on mortality at diagnostic concentrations of aldrin and methyl-parathion, respectively. These results indicate that the insecticide selection from exposure to aldrin and methyl-parathion may be a contributing factor in shaping the genetic structure of western corn rootworm populations in Nebraska. Factors including isolation by distance and a Wolbachia-induced breeding barrier may have contributed to differentiation of rootworm populations from Nebraska and Arizona.
The current study investigates phylogeographic structure of Zarhipis integripennis (LeConte) (Coleoptera: Phengodidae), a sexually dimorphic beetle with strongly asymmetrical dispersal abilities, to elucidate the spatial and temporal mechanisms of gene flow among populations in southern California. Using DNA sequences of a mitochondrial DNA marker and a nuclear intron in the krotzkopf verkehrt gene we compared the effect of differential dispersal on patterns of genetic structure among Z. integripennis populations across this area. Integrating these data with an ecological niche modeling analysis supported the hypothesis that dispersal between populations with fragmented niche availability was biased toward males and that female movement was limited and based on the availability of contiguous habitat. There was also evidence for historical restrictions to gene flow in the Sierra Pelona region of the Transverse Ranges based on a genetic break in both genes in this region.
The Asiatic rice borer, Chilo suppressalis (Walker) (Lepidoptera: Crambidae), is an important rice, Oryza sativa L., pest in China and difficult to control with conventional pest management. To develop and optimize integrated pest management strategies, efficient and economic artificial diet and rearing protocols are desirable. A new artificial diet based on soybean, Glycine max (L.) Merr., powder and fresh water bamboo, Zizania caduciflora (Turcz.) Hand.-Mazz, was formulated and rearing technique was developed. Fitness parameters including larval development, immature survival, pupal weight, pupation, adult emergence, egg hatchability, and oviposition were measured to evaluate the performance of C. suppressalis fed on the diet over 15 successive generations. C. suppressalis reared on the artificial diet showed better performance with shorter developmental stage, similar larval survival rate and fecundity, and heavier pupae compared with that fed on rice plants and fresh water bamboo. A positive correlation was observed between number of eggs laid per female and number of generations reared on the diet. Larval development time tended to be shortened with successive rearing on the artificial diet. These results indicated that C. suppressalis adapted well to the artificial diet and successive rearing conditions. The diet could serve as a viable alternative to natural host plants for consecutive rearing of the insect. In addition, the diet is inexpensive (US$1.5/1,000 g) and easy to make. The better preserve ability of the diet required only one diet replacement during the rearing process. The successful development of the diet and rearing technique provides a very useful tool for refining stem borer pest management techniques.
Bionomic data usually hold the key for understanding the life history of the target insect species. Here, we provide morphological characteristics of different larval instars of Acanthoscelides macrophthalmus (Schaeffer), a leucaena bruchine beetle species that is a potential biocontrol agent for the notoriously invasive plant Leucaena leucocephala. The scanning electron micrographs of the head capsule, antenna, clypeolabrum, maxilla, labium, leg, spiracle, and anus of the larval stage of A. macrophthalmus also are provided for the first time for this species, with most of the traits reflecting the taxonomic placement of A. macrophthalmus in the genus Acanthoscelides. Successive instars are determined accurately by using a model of the distribution of the width of the larval head capsule. Therefore, the data generated from this study represent baseline information for further biological control programs involving A. macrophthalmus.
The ecological success of invasive ants has been linked to their ability to form expansive supercolonies. In the Argentine ant, Linepithema humile (Mayr), increased productivity and competitive ability of introduced supercolonies in several places, e.g., California and southern Europe, has been linked to high population densities that could have been attained via fusion of nonaggressive and genetically similar nests. Recently, we have found that introduced L. humile colonies in the southeastern United States, which have higher levels of intraspecific aggression and genetic diversity than those in California and southern Europe, sometimes also fuse; yet it is unclear what the longer term consequences of such colony fusion might be. In this study, we examined whether fusion of these southeastern United States L. humile colonies results in larger colonies by recording colony size and productivity in pairs that fused and in pairs that did not fuse. After 6 mo, colonies that fused produced 47% more workers and had twice as many queens as colony pairs that did not fuse. Also, fused colonies had an overall per capita colony productivity (number of brood and workers produced per queen and per worker) comparable to that of nonfused pairs and unpaired controls. Furthermore, all queens contributed to worker pupae production in fused colonies. Thus, fusion of initially aggressive southeastern United States L. humile colonies results in colonies with higher worker number without decreasing per capita productivity. Moreover, offspring contribution by all queens in fused colonies may alter colony genotypic composition resulting in reduced intraspecific aggression that in turn promotes further fusion. This process may be relevant to the establishment of incipient colonies in areas where multiple introductions have occurred.
Cheiracanthium inclusum (Hentz) (Araneae: Miturgidae), a spider that is common in cotton, Gossypium hirsutum L., foliage, was tested for the impact of consumption of cotton pollen on its survival and development under conditions of prey limitation. Immature C. inclusum readily consumed cotton pollen grains that were pierced, crushed, and macerated with the mouthparts while being extraorally digested. When reared on a diet of cotton pollen alone, spiderlings survived 178% longer than those given only water (14.45 versus 5.2 d). When provided with a prey-limited diet (Five eggs of Helicoverpa zea, a favored prey) access to cotton pollen improved the likelihood of spiderlings molting to the second instar from 0 to 22%. This increased from 60 to 84% for spiderlings provided with 10 eggs plus access to pollen. Addition of cotton pollen also extended the survival of spiders fed five or 10 eggs. Supplemental consumption of pollen seems adaptive for this spider and may lead to increased survival and retention of spiders in cotton fields.
Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae) is an invasive vector of Xylella fastidiosa, the causal agent of Pierce's disease of grapevines (Vitis vinifera L.). Transmission efficiency of X. fastidiosa to grapevines by H. vitripennis originating from two geographically separated populations in California (Riverside and Bakersfield) based on gender and age was evaluated. To evaluate transmission efficiencies among groups, insects were given a 96-h acquisition access period on infected grapevines and caged in groups of five on healthy grapevines for a 72-h inoculation access period. At the conclusion of tests, polymerase chain reaction determined that a mean ± SD of 0.98 ± 1.02 X. fastidiosa-positive H. vitripennis were present on each grapevine and that 29% of test plants were infected. Acquisition and retention of X. fastidiosa was not affected by vector origin, gender, or age. The probability that a grapevine was infected 12 wk after the inoculation access period increased with the number of X. fastidiosa-positive H. vitripennis per plant. Gender had no effect on inoculation success and main effects of insect origin and age on inoculation success were minor. Collectively, the result indicated that H. vitripennis origin, gender, and age did not affect acquisition and retention of X. fastidiosa and had only minor effects on inoculation success under laboratory conditions. Accordingly, rates of pathogen spread in the field are more likely to be affected by local biotic and abiotic factors that differentially affect H. vitripennis abundance and movement based on origin, gender, and age than inherent differences in transmission efficiencies among these groups.
We tabulated plant species that served as floral hosts of adult beetles as reported by Charles Robertson in his 33-yr data set of flower-visiting insects of central Illinois. Robertson listed 153 species of beetles (28 families) that visited 141 species of plants (44 families), most of which were in the Asteraceae. The most common beetle species were the cantharid Chauliognathus pennsylvanicus (De Geer), the chrysomelid Diabrotica undecimpunctata Mannerheim, and the scarab Trichiotinus piger (F.). Most of the beetle species (81%) were observed on five or fewer plant species. In general, non-native plant species were associated with fewer beetle species than were native plant species. Nevertheless, plant species that had the greatest diversity of beetle visitors were the non-native umbellifer Pastinaca sativa L. and the native rose Aruncus dioicus (Walter) Fernald variety vulgaris (Maxim). These findings may find application in guiding research on insect ecology and behavior, for selecting plant species in ornamental landscapes that will foster populations of native beetle species, and for identifying plant species that may be used in agricultural settings to improve pollination or biological control services.
Although the phylogenetic relationships of Apis species (Hymenoptera: Apidae) have been generally accepted, genetic variation within most species and some new possible species' status have not been studied in detail. In this study, we surveyed the genetic variation of mitochondrial DNA sequences in Apis species from China and investigated the phylogeography of Apis dorsata F. in China and neighboring Asian areas. The phylogeny of Chinese Apis species was consistent with the generally accepted Apis phylogeny, and a substructure within A. dorsata was suggested. Furthermore, results of analysis of molecular variance revealed significant genetic structuring of A. dorsata between Hainan Island and China mainland. When compared with neighboring Asian areas, Chinese A. dorsata grouped with one A. dorsata sample from Palawan Island of Philippines and two samples from Malaysia. Another two samples from Malaysia clustered with one Nepalese sample and the cluster from Thailand also was supported. These results support the hypothesis that glaciations and deglaciations during the Pleistocene could have greatly influenced the distribution and divergence of A. dorsata in China and Southeast Asia. In addition, the species status of Apis dorsata breviligula Maa and Apis dorsata binghami Cockerell were supported in our study and genetic variation may exist in Apis laboriosa Smith despite of limited natural distribution.
Although a large amount of data have been published in past years on the taxonomic status of the Anastrepha fraterculus (Wiedemann) species complex, there is still a need to know how many species this complex comprises, the distribution of each one, and their distinguishing features. In this study, we assessed the morphometric variability of 32 populations from the A. fraterculus complex, located in major biogeographical areas from the Neotropics. Multivariate techniques for analysis were applied to the measurements of 21 variables referring to the mesonotum, aculeus, and wing. For the first time, our results identified the presence of seven distinct morphotypes within this species complex. According to the biogeographical areas, populations occurring in the Mesoamerican dominion (Mexico, Guatemala, and Panama) were clustered within a single natural entity labeled as the “Mexican” morphotype; whereas in the northwestern South American dominion, samples fell into three distinct groups: the “Venezuelan” morphotype with a single population from the Caribbean lowlands of Venezuela, the “Andean” morphotype from the highlands of Venezuela and Colombia, and the third group or “Peruvian” morphotype comprised the samples from the Pacific coastal lowlands of Ecuador and Peru. Three additional groups were identified from the Chacoan and Paranaense sub-regions: the morphotype “Brazilian-1” was recognized as including the Argentinean samples with most pertaining to Brazil, and widely distributed in these biogeographical areas; the morphotype “Brazilian-2” was recognized as including two samples from the state of Sao Paulo (Ilha-Bela and São Sebastião); whereas the morphotype “Brazilian-3” included a single population from Botucatu (state of Sao Paulo). Based on data published by previous authors showing genetic and karyotypic differentiation, as well as reproductive isolation, we have concluded that such morphotypes indeed represent natural groups and distinct taxonomic entities.
Fruit flies (Diptera: Tephritidae) are among the most important pests of fruits and vegetables. In this study, the typology, number, size, and distribution pattern of sensilla on tarsi and ovipositors of six fruit fly species, including Bactrocera Cucurbitae Coquillett, Bactrocera diaphora (Hendel), Bactrocera dorsalis Hendel, Bactrocera minax (Enderlein), Bactrocera scutellata (Hendel), and Bactrocera tau (Walker), were analyzed by scanning electron microscopy techniques. The tarsi of these six fruit fly species are equipped with three types of trichoid sensilla (1, 2, and 3), chaetica sensilla, and basiconic sensilla. Two types of sensilla, trichoid sensilla (4 and 5) and campaniform sensilla, are identified on the ovipositors of the female fruit files. In addition, the possible functions of these sensilla are discussed in light of previously published literature, and the trichoid sensilla (1, 2, and 3) on the tarsi, and trichoid sensilla (4 and 5), as well as campaniform sensilla on the ovipositors are considered as mechanoreceptor. The basiconic sensilla might have an olfactory function, and the chaetica sensilla were suggested as a mechano- or olfactory / gustatory neurons. Future functional tarsi and ovipositors morphology and electrophysiological of tarsi and ovipositors studies are needed to confirm these proposed functions.
The multicolored Asian lady beetle, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), is an invasive species in North America that has a low susceptibility to indigenous natural enemies. We investigated the role of the immune system of H. axyridis in its resistance to North American population of the hymenopteran parasitoid Dinocampus coccinellae Schrank. An ultrastructural study of adult H. axyridis hemocytes under electron and light microscopy identified five different cellular types: plasmatocytes, granular hemocytes I, granular hemocytes II, oenocytoids, and spherule cells. Only granular hemocytes II and plasmatocytes are involved in the nodulation of bacteria and encapsulation of parasitoid eggs. Injection of Sephadex beads in H. axyridis adults induces an innate immune response and results in complete encapsulation of ≈28% of the beads after 24 h and 81% after 5 d. When H. axyridis was parasitized by D. coccinellae, we observed a decrease in the encapsulation response, and this pattern was inversely related to the number of parasitoid eggs in the H. axyridis hemolymph. The injection of polydnaviruses by D. coccinellae females and the multiple target hypotheses could both explain the encapsulation rate decreasing with increasing parasitoid egg load. Our results suggest that the immune system of H. axyridis could favor its escape from internal developing natural enemies indigenous to North America.
The utility of the cytochrome oxidase I gene barcode region for diagnosis of the Mediterranean fruit fly, Ceratitis capitata (Weidemann), is evaluated using African fruit fly collections. The method fails to discern C. capitata from its close relative Ceratitis caetrata Munro, based on genetic distances, parsimony networks, or nucleotide diagnostic characters observed in the DNA barcode sequences. When treated as a single taxon, it is possible to discern the C. capitataC. caetrata lineage from other Ceratitis species. Levels of intraspecific diversity vary within the genus Ceratitis and multiple copies of the mitochondrial gene are reported for Ceratitis cosyra (Walker). The DNA barcoding method based on genetic distance is compared with a molecular identification method using restriction fragment length polymorphism. The DNA barcode and restriction fragment-length polymorphism methods provide similar identification results, but the DNA sequence information is more suitable for quantitative analysis of the information.
Fall armyworm is a significant agricultural pest in the Western Hemisphere and an important system for studying Lepidopteran migration and speciation. Critical to these investigations are methods that can differentiate between two morphologically indistinguishable strains that differ in their choice of plant host. In a previous study, haplotypes of the fall armyworm Triose phosphate isomerase gene (Tpi; EC 5.3.1.1) were shown to be effective indicators of strain identity. However, the method had technical complications that made it expensive to apply on the scale needed for most population studies. The focus of this paper was to develop a more efficient and cost-effective procedure. By combining polymerase chain reaction (PCR) amplification and restriction enzyme digestion, a strain-specific polymorphism in the fall armyworm Tpi locus can be characterized from single specimens without the need of DNA sequencing. This method was more accurate under some circumstances than COI haplotyping, the current method of choice for population studies. The modified Tpi method was used to expand upon previous indications that interstrain hybridization occurs asymmetrically, to confirm observations of seasonal periodicity in the proportions of the two strains infesting Florida cornfields, and to demonstrate that certain instances where strain specificity to their host plants appeared to be compromised were because of variability in the association of the COI markers to strain identity. The results indicate that the application of both Tpi and COI analyses to the study of fall armyworm populations is now practical and should facilitate the mapping and study of fall armyworm subpopulations in the United States.
Spatial genetic variability of the fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), was studied by collecting samples from 31 locations in the United States, Argentina, Panama, and Puerto Rico, and then using amplified fragment length polymorphism to detect genetic variation. Analysis of molecular variance showed significant genetic variation in fall armyworm among all (28%) sample locations and individuals within (71%) sample locations; genetic variation of fall armyworm was minimal between sample locations grouped into regions. The pairwise fixation index (FST) comparisons showed significant genetic differentiation (0.288) among the 31 locations. However, dendrograms of results from cluster analysis did not provide support of a high level of genetic structuring among regions. The isolation by distance analysis for all sample locations showed the absence of significant correlation between genetic dissimilarity and geographic distance except for fall armyworm samples collected within Argentina. Moreover, the estimate of modest gene flow (Nm >1) may prevent gene fixation within regions. These results indicate that fall armyworm shows little genetic differentiation and high genetic diversity over its range, important information for the development of management strategies and monitoring the development of resistance to management techniques.
The Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann), exhibits a lek mating system characterized by intense female choice apparently based on male courtship performance. However, recent observations showed that receptive females are aggressive toward one another and compete for access to displaying males, suggesting that the traditional view that sexual competition in the medfly is restricted exclusively to males may not be accurate. The current study further examines the accepted view of the medfly mating system by investigating the possibility that males discriminate among potential mates on the basis of female age. In field cage trials, we scored matings for males presented with virgin females of different ages. Young females were mated more frequently than old females, and additional tests revealed that this pattern did not reflect age-dependent variation among virgin females in mating propensity or response to male signaling. Although the experimental environment was artificial in simultaneously providing males with young and old virgin females, the existence of nonrandom mating nonetheless was unexpected given the accepted view that, given limited mating opportunities, male medflies will copulate indiscriminately with available females. Fecundity, fertility, egg-to-pupal yield, and longevity were compared among females of different ages to assess the potential reproductive benefits gained by males via age discrimination among potential mates. Young females (10–15 d old) had significantly higher fecundity, fertility, and egg-to-pupal yield than old females (35–40 d old), and consequently male choice for young females appears to confer substantial fitness benefits.
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