Intrinsic competition and its effects on the survival and development of three species of endoparasitoid wasps

In natural systems, pre‐adult stages of some insect herbivores are known to be attacked by several species of parasitoids. Under certain conditions, hosts may be simultaneously parasitized by more than one parasitoid species (= multiparasitism), even though only one parasitoid species can successfully develop in an individual host. Here, we compared development, survival, and intrinsic competitive interactions among three species of solitary larval endoparasitoids, Campoletis sonorensis (Cameron) (Hymenoptera: Ichneumonidae), Microplitis demolitor Wilkinson, and Microplitis croceipes (Cresson) (Hymenoptera: Braconidae), in singly parasitized and multiparasitized hosts. The three species differed in certain traits, such as in host usage strategies and adult body size. Campoletis sonorensis and M. demolitor survived equally well to eclosion in two host species that differed profoundly in size, Pseudoplusia includens (Walker) and the larger Heliothis virescens (Fabricius) (both Lepidoptera: Noctuidae). Egg‐to‐adult development time in C. sonorensis and M. demolitor also differed in the two hosts. Moreover, adult body mass in C. sonorensis (and not M. demolitor) was greater when developing in H. virescens larvae. We then monitored the outcome of competitive interactions in host larvae that were parasitized by one parasitoid species and subsequently multiparasitized by another species at various time intervals (0, 6, 24, and 48 h) after the initial parasitism. These experiments revealed that M. croceipes was generally a superior competitor to the other two species, whereas M. demolitor was the poorest competitor, with C. sonorensis being intermediate in this capacity. However, competition sometimes incurred fitness costs in M. croceipes and C. sonorensis, with longer development time and/or smaller adult mass observed in surviving wasps emerging from multiparasitized hosts. Our results suggest that rapid growth and large size relative to competitors of a similar age may be beneficial in aggressive intrinsic competition.     

Mitochondrial DNA phylogeography of the Cotesia flavipes complex of parasitic wasps (Hymenoptera: Braconidae)

The Cotesia flavipes species complex of parasitic wasps are economically important worldwide for the biological control of lepidopteran stem borers. The complex currently comprises three species: Cotesia flavipes Cameron, C. sesamiae (Cameron) and C. chilonis (Matsumura) (Hymenoptera: Braconidae), which appear morphologically similar. Despite their economic importance, little is known about the genetic diversity and phylogeography of these parasitoids. Differences in the biology of geographic populations have generally been interpreted as genetic divergence among strains, but direct genetic evidence is lacking. In Australia, several stem borer pests in neighbouring countries have been identified as significant threats to the sugar industry. However, the status of C. flavipes in Australia is unknown. To examine the genetic variation among worldwide populations of the C. flavipes complex and investigate the status of the Australian C. flavipes-like species, partial sequence data were generated for mitochondrial gene regions, 16S rRNA and COI. Parsimony, minimum evolution and Bayesian analyses based on 21 geographic populations of the complex and four outgroups supported the monophyly of the complex and the existence of genetically divergent populations of C. flavipes and C. sesamiae. The geographically isolated Australian haplotypes formed a distinct lineage within the complex and were ~3.0% divergent from the other species. The results indicated that historical biogeographic barriers and recent biological control introductions play an important role in structuring lineages within these species. This study provides a phylogeographical context for examining adaptive evolution and host range within biologically divergent strains of the C. flavipes complex.     

Geographic variation in male courtship acoustics and genetic divergence of populations of the Cotesia flavipes species complex

Courtship behaviors of insect populations can vary across the range of a species. Populations exhibiting divergent courtship behavior may indicate genetic divergence or cryptic species. Courtship acoustic signals produced by male wing fanning and genetic structure (using amplified fragment length polymorphisms) were examined for seven allopatric populations of the Cotesia flavipes (Hymenoptera: Braconidae) species complex, using four C. sesamiae (Cameron) and three C. flavipes Cameron populations. Members of this species complex parasitize lepidopteran pests in gramineous crops including sugarcane, maize, and rice . Significant variation was detected in courtship acoustic signals and genetic structure among populations of both species. For C. sesamiae, courtship acoustic signals varied more between populations of two biotypes that were collected near an area of sympatry. The two biotypes of C. sesamiae were also genetically divergent. For C. flavipes, significant differences in acoustic signals and genetic structure occurred among allopatric populations; these differences support the recent designation of one population as a new species. Courtship acoustics play a role in reproductive isolation in this species complex, and are likely used in conjunction with chemical signals. Ecological factors such as host range and host plant use may also influence the divergence of both courtship acoustic signals and genetic structure among populations in the C. flavipes complex.     

Molecular phylogeny of Indo‐Pacific carpenter ants (Hymenoptera: Formicidae,Camponotus) reveals waves of dispersal and colonization from diverse source areas

Ants that resemble Camponotus maculatus (Fabricius, 1782) present an opportunity to test the hypothesis that the origin of the Pacific island fauna was primarily New Guinea, the Philippines, and the Indo‐Malay archipelago (collectively known as Malesia). We sequenced two mitochondrial and four nuclear markers from 146 specimens from Pacific islands, Australia, and Malesia. We also added 211 specimens representing a larger worldwide sample and performed a series of phylogenetic analyses and ancestral area reconstructions. Results indicate that the Pacific members of this group comprise several robust clades that have distinctly different biogeographical histories, and they suggest an important role for Australia as a source of Pacific colonizations. Malesian areas were recovered mostly in derived positions, and one lineage appears to be Neotropical. Phylogenetic hypotheses indicate that the orange, pan‐Pacific form commonly identified as C. chloroticus Emery 1897 actually consists of two distantly related lineages. Also, the lineage on Hawai?i, which has been called C. variegatus (Smith, 1858), appears to be closely related to C. tortuganus Emery, 1895 in Florida and other lineages in the New World. In Micronesia and Polynesia the C. chloroticus‐like species support predictions of the taxon‐cycle hypothesis and could be candidates for human‐mediated dispersal.     

Phylogeny of the Homalotina (Coleoptera: Staphylinidae: Aleocharinae) based on morphology

The aleocharine subtribe Homalotina Heer represents one of the most diverse lineages of Staphylinidae. Despite its wide distribution and diversity, the phylogenetic relationships of the subtribe remain poorly understood. Here, we present the first cladistic analysis of the Homalotina based on morphological data. The subtribe is hypothesized to be a monophyletic group consisting of seven genera (Anomognathus Solier, Cephaloxynum Bernhauer, Holisomimus Cameron, Homalota Mannerheim, Neomalota Cameron, Stenomastax Cameron, and Thecturota Casey). The dataset for phylogenetic analysis comprised 83 characters representing 245 character states derived from adult morphology. These data were analysed using equal weighting and implied weighting schemes (k = 1–6) and results support the monophyly of the subtribe based on two synapomorphic characters (complete postoccipital sutures on head, posterolateral margin of metacoxae with macrosetae) and three homoplastic characters (medial setae on prementum not extended to apex of ligula, medial setae on labium contiguous, posterolateral angle of elytron slightly sinuate). Generic relationships differ in each analysis within the Homalotina (EW, IW with k = 1, 2–4, 5–6) although there are some identical topologies among the IW trees. Clades A, B, C, D, H, J and G were resolved as monophyletic in all weighting regimes. The monophyly of the genera is relatively well supported except for the genera Homalota and Stenomastax. Homalota species were recovered in four independent clades (clade C, D, I, K) and the Stenomastax species were recovered in two independent lineages. Candidates for the possible new genera are discussed. We herein transfer Homalota flavomaculata Bernhauer to the genus Stenomastax, resulting in the new combination [Stenomastax flavomaculata (Bernhauer)]. Our preliminary character correlation tests using phylogenetic pairwise comparisons did not support the hypothesis of association between flattened body form, and subcortical habitat and anterior shift of antennal insertion in Homalotini.     

DNA barcoding of six Ceroplastes species (Hemiptera: Coccoidea: Coccidae) from China

Ceroplastes Gray (wax scales) is one of the genera of Coccidae, most species of which are considered to be serious economic pests. However, identification of Ceroplastes species is always difficult owing to the shortage of easily distinguishable morphological characters. Mitochondrial cytochrome c oxidase I (COI) sequences (or DNA barcodes) and the D2 expansion segments of the large subunit ribosomal RNA gene 28S were used for accurate identification of six Ceroplastes species (C. floridensis Comstock, C. japonicus Green, C. ceriferus (Fabricius), C. pseudoceriferus Green, C. rubens Maskell and C. kunmingensis Tang et Xie) from 20 different locations in China. For COI data, low G·C content was found in all species, averaging about 20.4%. Sequence divergences (K2P) between congeneric species averaged 12.19%, while intra‐specific divergences averaged 0.42%. All 112 samples fell into six reciprocally monophyletic clades in the COI neighbour‐joining (NJ) tree. The NJ tree inferred from 28S showed almost same results, but samples of two closely related species, C. ceriferus and C. pseudoceriferus, were clustered together. This research indicates that the standard barcode region of COI can efficiently identify similar Ceroplastes species. This study provides an example of the usefulness of barcoding for Ceroplastes identification.     

Critical studies on the genus Callitetrarhynchus (Cestoda: Trypanorhyncha) with recognition of Rhynchobothrium speciosum Linton, 1897 as a valid species of the genus Callitetrarhynchus

Summary Callitetrarhynchus speciosus (Linton, 1897) n. comb. for Rhynchobothrium speciosum is redescribed from Pomatomus saltatrix and is compared with the only other species of the genus. C. gracilis (Rudolphi, 1819), also found in the same fish. The arrangement of hooks on the tentacle of both species is illustrated. The two species, which have been included under the name C. gracilis in the past, differ mainly in the oncotaxy, different shape of the hooks of the chainette, distinct distribution of frontal glands and in the different depth of the marginal bothidial groove. ac]19840904     

Single-step PCR differentiation of Cotesia sesamiae (Cameron) and Cotesia flavipes Cameron (Hymenoptera: Braconidae) using polydnavirus markers

Cotesia sesamiae (Cameron) and Cotesia flavipes Cameron (Hymenoptera: Braconidae) are the main larval parasitoids of cereal stemborers in sub-Saharan Africa. Cotesia sesamiae is endemic to eastern and southern Africa, while C. flavipes was introduced into the region for biological control against the exotic lepidopteran Chilo partellus (Swinhoe) (Lepidoptera: Crambidae). The two are sibling parasitoids, difficult to distinguish morphologically. The introduced insect could potentially lead its African biotype to extinction because of their similar ecological niche. In order to distinguish the two species, multiplex primer-specific and PCR-RFLP tests were developed. Rapid identification of the two species was possible using primer-specific tests on DNA extracts as well as on pieces of tissue in a single PCR step followed by gel electrophoresis. The CRV1 gene of the polydnavirus, a symbiont to the wasps, was used as the marker. The results show that the morphological identifications, validated by molecular tests, are accurate in 93% of cases.     

Scanning electron microscopy and intraspecific variation of Chordodes festae Camerano, 1897 and C. peraccae (Camerano, 1894) (Nematomorpha: Gordioidea)

The nematomorph species Chordodes festae Camerano, 1897 and C. peraccae (Camerano, 1894) are redescribed by using scanning electron microscopy (SEM). C. festae has a cuticle with four different areolar types, the crown areoles being the most noticeable with long spiniform processes. The terminal end in the male specimen has two short lobe-like structures and a ventral groove. C. peraccae has three areolar types in which, as in C. festae, some areoles form groups surrounding the crown areoles. Intraspecific variations were found in body length and body colour in both species and, in C. peraccae, also in the cuticle.