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The Mediterranean fruit fly, Ceratitis capitata (Wiedemann), displays lek mating, where searching females actively choose among aggregated males that produce visual, acoustic, and olfactory signals within the tree canopy. Recent studies demonstrated that treated males exposed to the aroma of particular plant compounds (α-copaene) or oils (orange, manuka, and ginger) gain a mating advantage over control, nonexposed males. The goal of this study was to assess the impact of another plant compound, α-humulene, on the mating success of male C. capitata. Prior work showed that α-humulene was not attractive to either sex but elicited a strong electroantennal response in males. Field cage tests showed that males exposed to the aroma of α-humulene obtained significantly fewer matings than control (nonexposed) males as long as 3 d after exposure. Exposed males exhibited lower signaling (pheromone calling) activity than control males, which presumably contributed to their reduced mating success. Despite this lessened activity, the mortality of treated males after chemical exposure was similar to that observed for control, nonexposed males, suggesting that α-humulene was not a toxic or severely debilitating agent.
In many species, male mating success is often influenced by both age and mass. Because mass often increases with age, it can be difficult to disentangle their separate contributions to older male mating success. In species in which age and mass vary independently, it may be possible to determine the influence of mass on male reproductive success. For example, declines in residual reproductive value with age often result in older males increasing their reproductive effort. Mass may have an important influence on this relationship, if having greater mass provides an older male with a larger resource pool to invest in reproductive effort. Here, I evaluated the effect of mass on the reproductive success of males in an insect species in which age and mass are uncorrelated, but mass is highly variable within age classes. Female thornbug treehoppers [Umbonia crassicornis (Amyot and Serville) (Hemiptera: Membracidae)] were given simultaneous choices of younger (22 d) and older (30 d) males under free-choice conditions. Both age and mass contributed to male mating success, but their effects were not additive. Older males had higher mating success than younger males, and among older males, heavier individuals obtained more matings. In contrast, mass did not influence younger male mating success. These findings suggest age and mass interact in their effects, and together provide heavier, older males with a significant mating advantage. Large mass may, therefore, represent an indicator of male courtship performance that is reliably revealed at older ages, which in turn may allow thornbug females to make more effective mating decisions.
The males of many insect species transfer a spermatophore, i.e., a proteinaceous capsule containing sperm, to females during copulation, and this may also function as a nuptial gift. If production of the spermatophore is costly and variations in the quality of females are large, males may strategically allocate their investment based on the quality of the mate to maximize their own reproductive success. We examined the size and protein content of spermatophores transferred to females of different ages and body sizes, and also to water-deprived and water-replete females in the moth Ostrinia scapulalis (Walker). Males transferred a spermatophore of a smaller size or with less protein to older females, smaller females, and water-deprived females. These results indicated that O. scapulalis males manipulated their reproductive investment based on the conditions of the mate. We also demonstrated that older males varied their resource allocation to a greater extent in response to female conditions than younger males. Thus, resource allocation by the males of this species is modulated by both female conditions and the age of the males.
Parasitoid reproduction is often limited by disposable time for accessing hosts or egg availability. In the case of synovigenic parasitoids (which mature eggs during their lifetime), theory predicts that egg limitation is infrequent because they are able to replenish their egg supply throughout life. However, this theory does not contemplate the effect of superparasitism on egg load. If superparasitism is applied as a strategy for modulating offspring sex ratio, as extra eggs are normally deposited in each host, it is to be expected that females experience egg limitation, especially when host density is high. In this article, the effect of host density on egg load, oviposition, and sex ratio in the tephritid parasitoid Diachasmimorpha longicaudata (Ashmead) was investigated. Specifically we analyzed the rate of oviposition per host and adjustments in offspring sex ratio in response to changes in host density and how these affect egg load. Parasitoids maintained a similar rate of oviposition, independent of host densities, except when host density fluctuated between 25 and 5 hosts per day. Females increased their oviposition rate and parasitism when confronted with 5 hosts, after having experienced a density of 25 hosts. Offspring sex ratio was biased in favor of females at high host density and with increasing prevalence of superparasitism. Results suggest that parasitoids have a strategy for maintaining high egg load in order to mitigate egg limitation, and for adjusting oviposition rate and offspring sex ratio with reference to previous oviposition experience.
Mariana Bulgarella, Martín A. Quiroga, Gabriel A. Brito Vera, Jonathan S. Dregni, Francesca Cunninghame, Denis A. Mosquera Muñoz, Lucas D. Monje, Charlotte E. Causton, George E. Heimpel
Philornis downsi (Dodge and Aitken) is a bird-parasitic muscid fly native to mainland South America that recently invaded the Galápagos Islands where it is parasitizing Darwin's finches and other land birds. This parasite was previously known only from Argentina, Brazil, and Trinidad and Tobago. The first report of P. downsi from mainland Ecuador is provided, supporting the hypothesis that the invasion route of P. downsi from its native range to the Galápagos Islands includes mainland Ecuador. Four different morphologies of pupal exuviae, which belong to different fly species, were uncovered. Dipteran puparia were found in 20% of naturally occurring nests collected in 2013 and in 27% of nests in 2014 at the two sites in western Ecuador. P. downsi accounted for 74% and 40% of the puparia in 2013 and 2014, respectively. Two new bird host species for the genus Philornis were recorded: the streak-headed woodcreeper (Lepidocolaptes souleyetii) and the fasciated wren (Campylorhynchus fasciatus). The levels of nest parasitism found were much lower than levels reported for the Galápagos Islands. Finally, parasitism of P. downsi by a parasitoid in the genus Brachymeria (Hymenoptera, Chalcididae) is documented. Overall, 9% of fly puparia collected in 2013, and 19% of those collected in 2014, had parasitoid emergence holes.
Cerambycid beetles are abundant and diverse in forests, but much about their host relationships and adult behavior remains unknown. Generic blends of synthetic pheromones were used as lures in traps, to assess the species richness, and phenology of cerambycids in forest fragments in northern Delaware. More than 15,000 cerambycid beetles of 69 species were trapped over 2yr. Activity periods were similar to those found in previous studies, but many species were active 1–3 wk earlier in 2012 than in 2013, probably owing to warmer spring temperatures that year. In 2012, the blends were tested with and without ethanol, a host plant volatile produced by stressed trees. Of cerambycid species trapped in sufficient numbers for statistical analysis, ethanol synergized pheromone trap catches for seven species, but had no effect on attraction to pheromone for six species. One species was attracted only by ethanol. The generic pheromone blend, especially when combined with ethanol, was an effective tool for assessing the species richness and adult phenology of many cerambycid species, including nocturnal, crepuscular, and cryptic species that are otherwise difficult to find.
The planthopper Poekilloptera phalaenoides (L.) (Hemiptera: Flatidae) is a very common species in various regions of Brazil. The aim of this study was to report on P. phalaenoides biology, its behavior, and host plants in agricultural and natural vegetation areas of the Brazilian Cerrado and to relate the bio-ecology of this species with the climatic characteristics of the biome. The study was conducted between 2005 and 2008 in agricultural areas, and areas covered with typical cerrado sensu stricto and cerradão phytophysiognomies (Planaltina, Federal District, Brazil). Weekly field samples were taken to observe the biological stages of P. phalaenoides. Adult population dynamics were studied using light traps. Host plants were observed in natural vegetation areas. P. phalaenoides presented an 11-mo life cycle (egg to adult). The egg stage, which undergoes diapause, lasted ∼6 mo, and the nymphal stage lasted 7 mo. Adults were most abundantly found in October (64.7%). Specimens of P. phalaenoides were observed on nine species of plants; however, all the biological stages were observed only in Maprounea guianensis Aublet, Sclerolobium paniculatum Vogel, and Salacia crassifolia (von Martius) Peyr. Our results suggest that the life cycle and behavior of P. phalaenoides are synchronized with the climatic conditions of the Brazilian Cerrado, with adults present during the rainy season, when oviposition sites are more available, and the immature stages present in the dry season, when they can benefit from lower interspecific competition and a lower incidence of natural enemies. This is the first bio-ecological study conducted on a representative of the Flatidae family in Brazil.
Neoleucinodes elegantalis (Guenée) (Lepidoptera: Crambidae) is a major pest of fruits in the family Solanaceae in the Western Hemisphere. The objectives of this study were to determine whether life zone or host plant explained morphological variation in females, and if so, if there was evidence of sexual selection driving diversification in this species. We collected larvae feeding on cultivated (Capsicum annuum L., Solanum betaceum Cavanilles, Solanum lycopersicum Lamarck, Solanum melongena L., and Solanum quitoense Lamarck) and wild species (Solanum atropurpureum Schrank, Solanum acerifolium Dunal, Solanum crinitum Lamarck, and Solanum hirtum Vahl) of Solanceae in Colombia. The genitalia traits of 547 reared females were measured and correlations with host plant fruit size were estimated. Six female genitalia morphological characters, apophysis posterioris, apophysis anterioris, ostium bursae, ductus bursae length, corpus bursae, and the seventh abdominal segment were measured. Principal component analysis and cluster analysis classified individuals based on female morphological similarity and clustered them into four main groups according to host plant: 1) S. aceriflolium; 2) S. quitoense, S. lycopersicum, C. annuum and S. hirtum; 3) S. atroporpureum; 4) S. melongena, S. crinitum and S. betaceum. In this unique study, we found that variation in female genitalia size is directly correlated with the size of its host fruit, which suggests a mechanism for reproductive isolation and divergence of the four host races. Ours is one of the first studies that shows female genitalia morphology is correlated with species of host plants and represents a valuable contribution to the study of sexual selection in the evolution of insects.
Most research examining mosquito larval nutrition has focused on fungi, bacteria, and particulate organic matter. Fungi and bacteria, however, may be nutritionally insufficient to support larval growth. We predicted that the presence of protozoans would have a positive additive effect on larval growth and survival compared with when they were absent. We conducted a laboratory experiment where larval performance (Experiment 1) of two species of container mosquitoes [Culex coronator (Dyar and Knab), Aedes albopictus (Skuse)] was compared under two food environments (bacteria and bacteria with protozoans, each with an artificial diet). We also conducted a laboratory experiment where larval survival (Experiment 2) of three species [C. coronator, Culex quinquefasciatus (Say), and A.albopictus) was compared between the same two food environments without the addition of the artificial diet. In Experiment 1, survival was significantly different between species, with no significant difference between food treatments. Specifically, A.albopictus exhibited significantly higher survival compared with C. coronator, regardless of treatment. There were no significant differences in male or female mass and the development time between each treatment for either species. For Experiment 2, there was a significant difference between species, but no difference between treatment levels. Again, A. albopictus had higher survival compared with C. coronator and C. quinquefasciatus. We found little evidence of a unique nutritional role of protozoans for mosquitoes in either experiment, although it remains to be seen if protozoans may help mosquitoes meet specific requirements not examined in the general life history traits we measured.
The fivespotted gamagrass leafhopper, Dalbulus quinquenotatus DeLong & Nault (Hemiptera: Cicadellidae), is a sister species of the common and widespread leafhopper pest of maize in the New World, Dalbulus maidis (DeLong). In the course of a survey of egg parasitoids (Hymenoptera: Mymaridae and Trichogrammatidae) in Jalisco, Mexico, using sentinel eggs of D. quinquenotatus on its principal host plant, Tripsacum dactyloides (Poaceae), three species have been discovered and reported for the first time as its egg parasitoids: Anagrus (Anagrus) naulti Triapitsyn & Moya-Raygoza sp. n. (Mymaridae), which is newly described and illustrated, and also Paracentrobia sp. near subflava (Girault) and Pseudoligosita sp. near longifrangiata (Viggiani) (Trichogrammatidae), on which taxonomic comments and illustrations are provided. Paracentrobia sp. was the most common and abundant egg parasitoid, occurring in 36.9% of the rearings, and A.naulti was reared in 18.2% of the samples; the latter has a much shorter life cycle than the former species. Only a few Pseudoligosita sp. have been found in 1.3% of the samples.
The process of domestication and geographic origins of the cochineal insect (Dactylopius coccus Costa) has remained largely unstudied despite its importance as a global food colorant commodity. Ecological evidence supports Oaxaca Mexico as the geographic origin of this species. Other recent genetic studies have been inconclusive. Here, we fill in the remaining gaps in the ecological record and look for corroboration from mtDNA markers as to the origin of this species. We use three mtDNA genes (CO1, tRNA-Leucine, and CO2) spanning 1294 bp, along with climate niche modeling of Holocene and Pleistocene cochineal distributions. We find the center of origin of D. coccus to be Oaxaca Mexico based on mtDNA data and climate niche modeling. Further meta-genomic data are needed to rule out selective sweeps from past and present endosymbionts for these results to be definitive.
After more than a century since the description of the coffee berry borer, Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae), and dozens of scientific articles on the basic biology of the insect, there is still debate on the number of female larval instars. This article analyzes the metamorphosis of H. hampei females through direct observations during its entire biological cycle in the laboratory, together with scanning electron microscope photos. Also, the size of the head capsule of wild larvae and prepupae was analyzed with Dyar's rule and a discriminant analysis was conducted. Only two instars were observed during H. hampei metamorphosis up to the adult stage. Contrasting morphological changes in the larvae occurred when they transformed into prepupae, with no previous ecdysis. The statistical analysis revealed that the width of the cephalic masses form two significantly distinct groups before transformation into pupa, confirming that the prepupal stage forms part of the second larval instar.
The external morphology and internal anatomy of the compound eyes of the adults of the rice spittlebug Callitettix versicolor (F., 1794) (Insecta: Hemiptera: Cercopidae) are described for the first time with light, scanning, and transmission electron microscopy observations. The eyes of C. versicolor are of the apposition type and each eye consists of ∼2,042 ommatidia. Each ommatidium is composed of a plano-convex corneal lens, a eucone-type crystalline cone, eight retinular cells, two primary pigment cells, and an undetermined number of secondary pigment cells (probably six). The rhabdomeres of the eight retinular cells form a centrally fused rhabdom surrounded by palisades. The distal end of the rhabdom is funnel shaped around the proximal region of the crystalline cone. The microvilli of the rhabdom are arranged in orthogonal directions suggesting polarization sensitivity. With a small F-number of 1.48 and a large interommatidial angle Δφ; of 7.7°, the eye possesses high light sensitivity but low spatial resolution. With a large ommatidial acceptance angle Δρ of 11.6°, the eye can merely form a burred image of its surroundings, but the ratio Δρ/Δρ of 1.5 indicates that the eye can provide a relatively good contrast.
Myllocerus undecimpustulatus undatus Marshall (Coleoptera: Curculionidae), also known as the Sri Lankan weevil, is becoming a major pest of ornamentals and tropical fruit trees in the southern states of United States, especially in Florida. Recent findings of this species in Florida citrus groves justify research into their biology and ecology. Identification of semiochemicals involved in their behavioral and chemical communication will help to develop insect control strategies. We studied morphological and sexually dimorphic characters of this species as an aid to rapid separation of sexes for studies aiming to identify semiochemicals that may be of value in management. Female weevils collected from the field in southeastern Florida were significantly larger than males in length of head, abdomen, and overall length. Females weight was approximately twice that of males. No significant differences in the distance between procoxal or mesocoxal articulations observed between males and females. But the distance between the metacoxal articulations was significantly higher for females than males. All measures of female elytra were significantly greater than those of male elytra. Females, but not males, have a characteristic black—gray marking extending from the ventral mesosternum to the second abdominal segment. Scanning electron microscopic images revealed that females had fewer ovate-to-obovate scales in this region of characteristic black—gray marking and more plumose scales compared with males. Deposition of white cuticular hydrocarbons in this region was less dense on females compared with males. These characters proved sufficient to separate sexes 100% of the time in a blind test and should allow researchers to develop an accurate gestalt to separate males and females of the Sri Lankan weevil.
Dicyphus agilis Uhler (Hemiptera: Miridae) is reported for the first time in Colombia, and it is associated with Sparmannia africana L. (Malvales: Malvaceae) and in urban and Nicotiana tabacum L. (Solanales: Solanaceae) in rural areas as a predator of aphids. This study describes the external structure, genitalia, and morphometry of the most prominent structures of males and females of D. agilis. Adults of this insect were collected from tobacco fields at Municipality of San Gil, Santander, Colombia. Morphological characteristics of D. agilis were: body oblong-elongated, small head, reniform compound eyes, rostrum and antennae with four segments, thorax punctate, femur with six dark spots, elongated tibia, tarsus with two tarsomeres; male genitalia with phallus and females with ovipositor invaginated. Morphometric data indicated that D. agilis is 3–5 mm in length with evident sexual dimorphism, with females being larger than males in all structures except the antennae. The morphological features of D. agilis are necessary to differentiate this species from other Mirid species with phytophagous habits in agricultural crops and to establish biological control programs in Colombia.
The taxonomy and phylogeny of Cuerna, a widespread North American leafhopper genus, were examined. Eight species (C. cuesta, C. inflata, C. lugens, C. nielsoni, C. pseudoalba, C. reducta, C. septentrionalis, and C. xyla) are synonymized and three new species (C. emeljanovi, C. lyrifora, and C. oaxacensis) are described, making a total of 26 species in the genus. An annotated checklist with distribution records, brief descriptions, and details on intraspecific morphological variation and separate dichotomous keys to males and females of Cuerna are provided. In addition, a web-based interactive key to species is made available online using 3I software. Four species groups are recognized based on morphology, but only three of them are recovered as monophyletic, with minimal or no node support, in phylogenetic analysis of the morphological data set of 21 characters. Phylogenetic analyses using DNA sequences from mitochondrial Cytochrome oxidase I and II genes yielded nearly identical, well-resolved topologies with most nodes well supported. The resulting tree is only partly consistent with the species groups defined based on morphological characters. Moreover, at least seven species have not been recovered as monophyletic. In at least one case this may be due to interspecific mitochondrial introgression.
Flohria subcoerulea (LeConte), a relictual genus and species of the subtribe Philonthina (tribe Staphylinini) from the Americas, is redescribed and illustrated, its distribution documented, and lectotypes designated. The phylogenetic position of the genus within Philonthina, as well as its potential age and origin, is discussed.
The southeast Asian spittlebug tribe Capnodistini (Hemiptera: Cercopoidea: Aphrophoridae) is defined to include two genera Capnodistes Breddin and Dinda Distant. Three new species are described and illustrated: Dinda flavimacula sp. nov. (southwest China: Yunnan, Guangxi, Guizhou), Capnodistes latipenis sp. nov. (Indonesia: Sumatra) and Capnodistes sandakanensis sp. nov. (Malaysia: Borneo). Daha Distant is proposed as a new junior synonym of Capnodistes Breddin. Three new combinations, Capnodistes arietarius (Distant, 1908), comb. nov. (from Daha), C. kuchingensis (Distant, 1908), comb. nov. (from Daha) and Dinda carpio (Breddin, 1903), comb. nov. (from Capnodistes) are established. Lectotypes are newly designated for D. maura, C. arietarius, and C. kuchingensis. Dinda carpio, C. arietarius, and C. esox are reported from Singapore, Laos and Malaysia (Malay Peninsula, Sarawak), and Singapore, respectively, for the first time. Keys for the separation of Capnodistes and Dinda and their included species are respectively provided. New ultrsastructural characters of antennal and rostral sensilla are presented with scanning electron micrographs. Cladistic analysis of the phylogenetic relationships among species in Capnodistini shows that Capnodistini, Capnodistes and Dinda are all monophyletic. The biogeographic implications of the tribal distribution are discussed on the basis of the phylogenetic hypothesis. A distinct distributional track running from southwest China (including south Yunna, south Guizhou, and south Guangxi) via Indochina and Malay Peninsula to Lesser Sunda (including Borneo and Sumatra) is revealed. Three areas of endemism, e.g., southwest China (including south Yunnan, south Guizhou, and south Guangxi) north Burma north Indochina, Malay Peninsula, and north Boreno are recognized, and the area relationships revealed by the area cladograms are southwest China north Burma north Indochina (Malay Peninsula north Borneo).
The bark beetle Dendroctonus mesoamericanus sp. nov. is described from a population in Parque Nacional Lagunas de Montebello, La Trinitaria, Chiapas, Mexico. This species belongs to the D. frontalis complex, which includes D. adjunctus Blandford 1897, D. approximatus Dietz 1890, D. brevicomis LeConte 1876, D. frontalis Zimmermann 1868, D. mexicanus Hopkins 1905, and D. vitei Wood 1975. The new species can be distinguished from closely related species D. frontalis, D. mexicanus, and D. vitei by four diagnostic morphological characters: the presence of striations on the preepisternal area of the prothorax (anterolateral pronotum) in both sexes, seminal rod with an approximately linear posterior margin of the dorsal process (in lateral view), irregularly sized ornamentations on the distal edge of squamiform plates present on the eighth abdominal tergite in females, and an inconspicuous pronotal callus in females. Furthermore, the karyotype of D. mesoamericanus sp. nov. (5AA Xyp / XX) differs from that of its sister species D. frontalis (7AA Xyp/XX). Dendroctonus mesoamericanus sp. nov. is distributed in Belize, Guatemala, El Salvador, Honduras, Nicaragua, and in the Michoacán, Oaxaca, and Chiapas states in Mexico. In these countries, this species has been collected at elevations above from 311 to 2600 m on six pine species, and it commonly occurs in syntopy with D. frontalis.
The first phylogenetic analysis of the genera Passipassalus and Paxillus is presented. We studied all species of these two genera, including Passipassalus nukak sp. nov., Paxillus amati sp. nov., Paxillus inca sp. nov., Paxillus martinezi sp. nov., and Paxillus akatanga sp. nov. A morphological matrix with 40 characters was analyzed employing maximum parsimony. Nine species from other genera of Passalini (Ameripassalus, Passalus, Spasalus, and Ptichopus) were included. A single most-parsimonious tree was found with three polytomies caused by collapsing zero-length branches. Two species of Paxillus were grouped with Passipassalus buhrnheimi Fonseca and Reyes-Castillo (Passipassalus macrocerus (Reyes-Castillo and Fonseca) n. comb. and Passipassalus corniculatus (Fonseca, Gouveia and Fernandez) n. comb.). The remaining species of Paxillus constitute a monophyletic group divided in two clades that we called the Leachi and Forsteri species groups. The transfer of two species from Paxillus to Passipassalus makes mandatory the redescription and redelimitation of these two genera. Likewise, reviewing the morphological characters, we found that the lacinia, a traditional character employed to delimit Paxillus, is bidentate in all species of Forsteri group. Our results suggest an early separation of the ancestors of Paxillus and Passipassalus within Passalini, and agree with observations by other authors about the paleoendemism of Paxillus in the Greater Antilles.
The morphological and genetic diversity of three parasitic wasps—Euaphidius cingulatus (Ruthe), Euaphidius setiger Mackauer, and Remaudierea plocamaphidis Starý—and their relationships with some species from the genus Aphidius Nees are examined in this article. Partial sequences of the mitochondrial cytochrome oxidase subunit I and nuclear 28SD2 genes revealed weak genetic differences between Euaphidius, Remaudierea, and the selected Aphidius species. Analysis of fore wing size and shape using geometric morphometrics showed that species from the genus Euaphidius have a shorter R1 vein and medially wider wings part than in Aphidius. On the basis of molecular analysis and shape of the wing, we redescribe E. cingulatus and E. setiger, including them in the genus Aphidius. Similar results were obtained for the species R. plocamaphidis, which is also included in the genus Aphidius. In addition to this, we propose to group both E. cingulatus and R. plocamaphidis in the subgenus Euaphidius within the genus Aphidius.
In a low-temperature scanning electron microscopy study aimed at determining whether the coffee berry borer [Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae)] possesses mycangia, we fortuitously detected the mesothoracic spiracles, which are usually concealed. The mesothoracic spiracles are ventrolaterally located in the intersegmental membranes between the prothorax and mesothorax, and contain a large number of setae. This is the first study that includes photographs of the mesothoracic spiracles in a bark beetle.
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