Geographic distribution and abundance of the Afrotropical subterranean scale insect Stictococcus vayssierei (Hemiptera: Stictococcidae), a pest of root and tuber crops in the Congo basin.

Stictococcus vayssierei is a major pest of root and tuber crops in central Africa. However, data on its ecology are lacking. Here we provide an updated estimate of its distribution with the aim of facilitating the sustainable control of its populations. Surveys conducted in nine countries encompassing 13 ecological regions around the Congo basin showed that African root and tuber scale was present in Cameroon, Central African Republic, Congo, Democratic Republic of Congo, Equatorial Guinea, Gabon and Uganda. It was not found on the sites surveyed in Chad and Nigeria. The pest occurred in the forest and the forest-savannah mosaic as well as in the savannah where it was never recorded before. However, prevalence was higher in the forest (43.1%) where cassava was the most infested crop, compared to the savannah (9.2%) where aroids (cocoyam and taro) were the most infested crops. In the forest habitat, the pest was prevalent in all but two ecological regions: the Congolian swamp forests and the Southern Congolian forest-savanna mosaic. In the savannah habitat, it was restricted to the moist savannah highlands and absent from dry savannahs. The scale was not observed below 277 m asl. Where present, the scale was frequently (87.1% of the sites) attended by the ant Anoplolepis tenella. High densities (>1000 scales per plant) were recorded along the Cameroon-Gabon border. Good regulatory measures within and between countries are required to control the exchange of plant materials and limit its spread. The study provides information for niche modeling and risk mapping.

Molecular phylogenetics of Aspidiotini armored scale insects (Hemiptera: Diaspididae) reveals rampant paraphyly, curious species radiations, and multiple origins of association with Melissotarsus ants (Hymenoptera: Formicidae).

The armored scale insect tribe Aspidiotini comprises many pest species that are globally invasive and economically damaging. The taxonomy of scale insects is based almost solely upon morphological characters of adult females, and little prior work has been done to test the classification of aspidiotines against molecular evidence. To address these concerns, we reconstruct a molecular phylogeny for aspidiotine armored scales that expands greatly upon taxonomic and character representations from previous studies. Our dataset includes 127 species (356 terminal taxa) and four gene regions: 28S, EF-1α, COI-COII, and CAD. Nearly 50% of the species treated are identified as pests and several more may represent emerging pests. Phylogenetic data were analyzed in a Bayesian framework using MC3 iterations. The majority of sampled aspidiotine genera are not monophyletic as currently defined. Monophyly constraints for 'worst offenders' were imposed on the phylogeny and stepping-stone MCMC was performed to calculate marginal likelihood scores. Comparisons of marginal likelihoods from runs with constrained vs. informative priors support the interpretation that pest-rich genera are not monophyletic. We use character mapping to illustrate signal and convergence for selected traits that have been used to define or recognize genera and evaluate consistency and retention indices for these traits. The phylogeny illustrates a pervasive pattern in which extremely polyphagous pests - typically having large populations and wide geographical distributions - are frequently intertwined with range-limited specialists on the phylogeny. Finally, the phylogeny recovers three origins of ant association among the Aspidiotini. The history of ant/diaspidid symbioses involves periods of sustained partner fidelity, spanning multiple speciation events, which have been punctuated by opportunistic switches to novel partners.

Micro- and Macroevolutionary Trade-Offs in Plant-Feeding Insects.

A long-standing hypothesis asserts that plant-feeding insects specialize on particular host plants because of negative interactions (trade-offs) between adaptations to alternative hosts, yet empirical evidence for such trade-offs is scarce. Most studies have looked for microevolutionary performance trade-offs within insect species, but host use could also be constrained by macroevolutionary trade-offs caused by epistasis and historical contingency. Here we used a phylogenetic approach to estimate the micro- and macroevolutionary correlations between use of alternative host-plant taxa within two major orders of plant-feeding insects: Lepidoptera (caterpillars) and Hemiptera (true bugs). Across 1,604 caterpillar species, we found both positive and negative pairwise correlations between use of 11 host-plant orders, with overall network patterns suggesting that different host-use constraints act over micro- and macroevolutionary timescales. In contrast, host-use patterns of 955 true bug species revealed uniformly positive correlations between use of the same 11 host plant orders over both timescales. The lack of consistent patterns across timescales and insect orders indicates that host-use trade-offs are historically contingent rather than universal constraints. Moreover, we observed few negative correlations overall despite the wide taxonomic and ecological diversity of the focal host-plant orders, suggesting that positive interactions between host-use adaptations, not trade-offs, dominate the long-term evolution of host use in plant-feeding insects.

In memoriam: Richard G. Harrison - his life and legacy.

Richard G. Harrison passed away unexpectedly on April 12th, 2016. In this memoriam we pay tribute to the life and legacy of an extraordinary scientist, mentor, friend, husband, and father.

Scale insect host ranges are broader in the tropics.

The specificity of the interactions between plants and their consumers varies considerably. The evolutionary and ecological factors underlying this variation are unclear. Several potential explanatory factors vary with latitude, for example plant species richness and the intensity of herbivory. Here, we use comparative phylogenetic methods to test the effect of latitude on host range in scale insects. We find that, on average, scale insects that occur in lower latitudes are more polyphagous. This result is at odds with the general pattern of greater host-plant specificity of insects in the tropics. We propose that this disparity reflects a high cost for host specificity in scale insects, stemming from unusual aspects of scale insect life history, for example, passive wind-driven dispersal. More broadly, the strong evidence for pervasive effects of geography on host range across insect groups stands in stark contrast to the weak evidence for constraints on host range due to genetic trade-offs.

The nutrient supplying capabilities of Uzinura, an endosymbiont of armoured scale insects.

An emerging common physiological feature of plant sap-feeding insects is the presence of bacterial endosymbionts capable of providing essential nutrients to their host. These microbial partners are inviable outside of specialized host tissues, and therefore a cultivation-independent approach, namely high-throughput next-generation genome sequencing, can be used to characterize their gene content and metabolic potential. To this end, we sequenced the first complete genome of the obligate endosymbiont, Candidatus 'Uzinura diaspidicola', of armoured scale insects. At 263 431 bp, Uzinura has an extremely reduced genome that is composed largely of genes encoding enzymes involved in translation and amino acid biosynthesis. The tiny size of the Uzinura genome parallels that observed in some other insect endosymbionts. Despite this extreme genome reduction, the absence of a known obligate partner bacterial symbiont suggests that Uzinura alone can supply sufficient nutrients to its host.

The clones are all right.

Parthenogenetic grasshoppers confound predictions by showing no signs of decline.

Niche explosion.

The following syndrome of features occurs in several groups of phytophagous insects: (1) wingless females, (2) dispersal by larvae, (3) woody hosts, (4) extreme polyphagy, (5) high abundance, resulting in status as economic pests, (6) invasiveness, and (7) obligate parthenogenesis in some populations. If extreme polyphagy is defined as feeding on 20 or more families of hostplants, this syndrome is found convergently in several species of bagworm moths, tussock moths, root weevils, and 5 families of scale insects. We hypothesize that extreme polyphagy in these taxa results from "niche explosion", a positive feedback loop connecting large population size to broad host range. The niche explosion has a demographic component (sometimes called the "amplification effect" in studies of pathogens) as well as a population-genetic component, due mainly to the increased effectiveness of natural selection in larger populations. The frequent origins of parthenogenesis in extreme polyphages are, in our interpretation, a consequence of this increased effectiveness of natural selection and consequent reduced importance of sexuality. The niche explosion hypothesis makes detailed predictions about the comparative genomics and population genetics of extreme polyphages and related specialists. It has a number of potentially important implications, including an explanation for the lack of observed trade-offs between generalists and specialists, a re-interpretation of the ecological correlates of parthenogenesis, and a general expectation that Malthusian population explosions may be amplified by Darwinian effects.

Four new species of Aspidiotini (Hemiptera, Diaspididae, Aspidiotinae) from Panama, with a key to Panamanian species.

Four new species of armored scale insect, Clavaspis selvatica sp. nov., Clavaspis virolae sp. nov., Davidsonaspis tovomitae sp. nov., and Rungaspis neotropicalis sp. nov., are described and illustrated from Panama. We also transfer two previously described species of Panamanian Aspidiotini to new genera, Hemiberlesia crescentiae (Ferris) comb. nov. and Rungaspis rigida (Ferris) comb. nov., and report the first record of Selenaspidopsis browni Nakahara in Panama. A key to the species of Aspidiotini occurring in Panama is provided.

Taxonomic and identification review of adventive Fiorinia Targioni Tozzetti (Hemiptera, Coccomorpha, Diaspididae) of the United States.

This work provides general descriptions, illustrations, molecular diagnostic data, taxonomic keys, slide mounting recommendations, and Florida distribution records for Fiorinia Targioni Tozzetti species occurring in the USA. Species treated are F.externa Ferris, F.fioriniae (Targioni Tozzetti), F.japonica Kuwana, F.pinicola Maskell, F.phantasma Cockerell & Robinson, F.proboscidaria Green, and F.theae Green. New descriptions of second-instar males and females of all seven species in addition to first-instar nymphs and adult females of F.phantasma and F.proboscidaria are presented. Taxonomic keys to second-instar males and females are developed for the first time and previously available taxonomic keys to first-instar nymphs and adult females are improved. DNA sequences were used to further evaluate the monophyly of Fiorinia and provide additional diagnostic tools for Fiorinia species. Multigene phylogenetic analyses, COI barcoding methods, and examination of type material indicate that F.yongxingensis Liu, Cai & Feng, 2020, syn. nov. is a junior synonym of F.phantasma. A morphological survey of the genus demonstrates, for the first time, the utility of second-instar males for diagnostics. This study will help inform regulatory and pest management decisions by facilitating morphological and molecular identification of adventive Fiorinia species occurring in the USA.

Sex, males, and hermaphrodites in the scale insect Icerya purchasi.

Androdioecy (the coexistence of males and hermaphrodites) is a rare mating system for which the evolutionary dynamics are poorly understood. Here, we investigate the cottony cushion scale, Icerya purchasi, one of only three reported cases of androdioecy in insects. In this species, female-like hermaphrodites have been shown to produce sperm and self-fertilize. However, males are ocassionally observed as well. In a large genetic analysis, we show for the first time that, although self-fertilization appears to be the primary mode of reproduction, rare outbreeding events do occur in natural populations, supporting the hypothesis that hermaphrodites mate with males and hence androdioecy is the mating system of I. purchasi. Thus, this globally invasive pest insect appears to enjoy the colonization advantages of a selfing organism while also benefitting from periodic reintroduction of genetic variation through outbreeding with males.

A phylogenetic analysis of armored scale insects (Hemiptera: Diaspididae), based upon nuclear, mitochondrial, and endosymbiont gene sequences.

Armored scale insects (Hemiptera: Diaspididae) are among the most invasive insects in the world. They have unusual genetic systems, including diverse types of paternal genome elimination (PGE) and parthenogenesis. Intimate relationships with their host plants and bacterial endosymbionts make them potentially important subjects for the study of co-evolution. Here, we expand upon recent phylogenetic work (Morse and Normark, 2006) by analyzing armored scale and endosymbiont DNA sequences from 125 species of armored scale insect, represented by 253 samples and eight outgroup species. We used fragments of four different gene regions: the nuclear protein-coding gene Elongation Factor 1α (EF1α), the large ribosomal subunit (28S) rDNA, a mitochondrial region spanning parts of cytochrome oxidase I (COI) and cytochrome oxidase II (COII), and the small ribosomal subunit (16S) rDNA from the primary bacterial endosymbiont Uzinura diaspidicola. Maximum likelihood, and Bayesian analyses were performed producing highly congruent topological results. A comparison of two datasets, one with and one without missing data, found that missing data had little effect on topology. Our results broadly corroborate several major features of the existing classification, although we do not find any of the subfamilies, tribes or subtribes to be monophyletic as currently constituted. Using ancestral state reconstruction we estimate that the ancestral armored scale had the late PGE sex system, and it may as well have been pupillarial, though results differed between reconstruction methods. These results highlight the need for a complete revision of this family, and provide the groundwork for future taxonomic work in armored scale insects.

Five new species of Aspidiotini (Hemiptera, Diaspididae, Aspidiotinae) from Argentina, with a key to Argentine species.

Five new species of armored scale insect from Argentina are described and illustrated based upon morphological and molecular evidence from adult females: Chortinaspis jujuyensis sp. nov., Clavaspis patagonensis sp. nov., Hemiberlesia ozolita sp. nov., Melanaspis lilloi sp. nov., and Melanaspis targionoides sp. nov. The genera Chortinaspis and Melanaspis are recorded for the first time from this country. An identification key to all recorded species from tribe Aspidiotini occurring in Argentina is provided.

Nonadaptive host-use specificity in tropical armored scale insects.

Most herbivorous insects are diet specialists in spite of the apparent advantages of being a generalist. This conundrum might be explained by fitness trade-offs on alternative host plants, yet the evidence of such trade-offs has been elusive. Another hypothesis is that specialization is nonadaptive, evolving through neutral population-genetic processes and within the bounds of historical constraints. Here, we report on a striking lack of evidence for the adaptiveness of specificity in tropical canopy communities of armored scale insects. We find evidence of pervasive diet specialization, and find that host use is phylogenetically conservative, but also find that more-specialized species occur on fewer of their potential hosts than do less-specialized species, and are no more abundant where they do occur. Of course local communities might not reflect regional diversity patterns. But based on our samples, comprising hundreds of species of hosts and armored scale insects at two widely separated sites, more-specialized species do not appear to outperform more generalist species.

Evolution and diversity of facultative symbionts from the aphid subfamily Lachninae.

Many aphids harbor a variety of endosymbiotic bacteria. The functions of these symbionts can range from an obligate nutritional role to a facultative role in protecting their hosts against environmental stresses. One such symbiont is "Candidatus Serratia symbiotica," which is involved in defense against heat and potentially also in aphid nutrition. Lachnid aphids have been the focus of several recent studies investigating the transition of this symbiont from a facultative symbiont to an obligate symbiont. In a phylogenetic analysis of Serratia symbionts from 51 lachnid hosts, we found that diversity in symbiont morphology, distribution, and function is due to multiple independent origins of symbiosis from ancestors belonging to Serratia and possibly also to evolution within distinct symbiont clades. Our results do not support cocladogenesis of "Ca. Serratia symbiotica" with Cinara subgenus Cinara species and weigh against an obligate nutritional role. Finally, we show that species belonging to the subfamily Lachninae have a high incidence of facultative symbiont infection.

An online interactive identification key to common pest species of Aspidiotini (Hemiptera, Coccomorpha, Diaspididae), version 1.0.

Aspidiotini is a species-rich tribe of armored scale insects that includes several polyphagous and specialist pests that are commonly encountered at ports-of-entry to the United States and many other countries. This article describes a newly available online interactive tool that can be used to identify 155 species of Aspidiotini that are recognized as minor to major pests or that are potentially emergent pests. This article lists the species and features included with a description of the development and structure of the key. The interactive key is free to access at https://idtools.org/id/scales/aspidiotini/about_index.php.

Phylogeny and classification of armored scale insects (Hemiptera: Coccomorpha: Diaspididae).

Armored scale insects (Hemiptera: Coccomorpha: Diaspididae) are major economic pests and are among the world's most invasive species. Here we describe a system of specimen and identification management that establishes a basis for well-vouchered molecular identification. We also present an expanded Bayesian phylogenetic analysis based on concatenated fragments of 4 genetic loci: the large ribosomal subunit (28S), elongation factor-1 alpha (EF-1α), cytochrome oxidase I and II (COI‒II), and the small ribosomal subunit (16S) of the primary endosymbiont, Uzinura diaspidicola (Bacteroidetes: Flavobacteriales). Our sample includes 1,389 individuals, representing 11 outgroup species and at least 311 described and 61 undescribed diaspidid species. The results broadly support Takagi's 2002 classification but indicate that some revisions are needed. We propose a revised classification recognizing 4 subfamilies: Ancepaspidinae Borchsenius, new rank, Furcaspidinae Balachowsky, new rank, Diaspidinae Targioni Tozzetti, and Aspidiotinae Westwood. Within Aspidiotinae, in addition to the existing tribes Aspidiotini Westwood, Parlatoriini Leonardi, Odonaspidini Ferris, Leucaspidini Atkinson, and Smilacicolini Takagi, we recognize as tribes Gymnaspidini Balachowsky, new rank, and Aonidiini Balachowsky, new rank. Within Diaspidinae we recognize the 2 tribes Lepidosaphidini Shimer and Diaspidini Targioni Tozzetti, and within Diaspidini we recognize three subtribes: Diaspidina Targioni Tozzetti, Fioriniina Leonardi, and Chionaspidina Brues Melander. We regard Kuwanaspidina Borchsenius as a junior synonym of Fioriniina, Thysanaspidini Takagi as a junior synonym of Leucaspidini, and Protodiaspidina Takagi and Ulucoccinae Takagi as junior synonyms of Chionaspidina. To clarify the composition of the higher taxa we describe 2 new genera for Australian species heretofore misplaced in the genus Ancepaspis Ferris: Brimblecombia Normark (Aonidiini) and Hendersonaspis Normark (Leucaspidini). We also propose many additional minor modifications to the taxonomy of Diaspididae, including the following new combinations, revived combinations, and replacement names: Aonidia edgerleyi (Mamet), new combination (from Bigymnaspis Balachowsky); Aonidomytilus espinosai Porter, revived combination (from Porterinaspis González); Aspidiotus badius (Brain), new combination (this and the next 5 Aspidiotus species all from Aonidia Targioni Tozzetti); Aspidiotus biafrae (Lindinger), new combination; Aspidiotus chaetachmeae (Brain), new combination; Aspidiotus laticornis (Balachowsky), new combination; Aspidiotus rhusae (Brain), new combination; Aspidiotus sclerosus (Munting), new combination; Brimblecombia asperata (Brimblecombe), new combination (this and the next 5 Brimblecombia species all from Ancepaspis); Brimblecombia longicauda (Brimblecombe), new combination; Brimblecombia magnicauda (Brimblecombe), new combination; Brimblecombia reticulata (Brimblecombe), new combination; Brimblecombia rotundicauda (Brimblecombe), new combination; Brimblecombia striata (Brimblecombe), new combination; Cooleyaspis pseudomorpha (Leonardi), new combination (from Dinaspis Leonardi); Cupidaspis wilkeyi (Howell Tippins), new combination (from Paracupidaspis Howell Tippins); Cupressaspis isfarensis Borchsenius, revived combination (this species, the next 2 species in Cupressaspis Borchsenius, revived genus, and the next 9 species in Diaspidiotus Cockerell all from Aonidia); Cupressaspis mediterranea (Lindinger), revived combination; Cupressaspis relicta (Balachowsky), new combination; Diaspidiotus atlanticus (Ferris), new combination; Diaspidiotus marginalis (Brain), new combination; Diaspidiotus maroccanus (Balachowsky), new combination; Diaspidiotus mesembryanthemae (Brain), new combination; Diaspidiotus opertus (De Lotto), new combination; Diaspidiotus shastae (Coleman), new combination; Diaspidiotus simplex (Leonardi), new combination; Diaspidiotus visci (Hall), new combination; Diaspidiotus yomae (Munting), new combination; Diaspis arundinariae (Tippins Howell), new combination (from Geodiaspis Tippins Howell); Duplachionaspis arecibo (Howell), new combination (this and the next 10 Duplachionaspis MacGillivray species all from Haliaspis Takagi); Duplachionaspis asymmetrica Ferris, revived combination; Duplachionaspis distichlii (Ferris), revived combination; Duplachionaspis litoralis Ferris, revived combination; Duplachionaspis mackenziei McDaniel, revived combination; Duplachionaspis milleri (Howell), new combination; Duplachionaspis nakaharai (Howell), new combination; Duplachionaspis peninsularis (Howell), new combination; Duplachionaspis spartinae (Comstock), revived combination; Duplachionaspis texana (Liu Howell) new combination; Duplachionaspis uniolae (Takagi), new combination; Duplachionaspis mutica (Williams) (from Aloaspis Williams), new combination; Epidiaspis doumtsopi (Schneider), new combination (from Diaspis Costa); Fiorinia ficicola (Takahashi), new combination (from Ichthyaspis Takagi); Fiorinia macroprocta (Leonardi), revived combination (this and the next 2 species of Fiorinia Targioni Tozzetti all from Trullifiorinia Leonardi); Fiorinia rubrolineata Leonardi, revived combination; Fiorinia scrobicularum Green, revived combination; Genaparlatoria pseudaspidiotus (Lindinger), revived combination (from Parlatoria); Greeniella acaciae (Froggatt), new combination (this and the next 4 Greeniella Cockerell species all from Gymnaspis Newstead); Greeniella cassida (Hall Williams), new combination; Greeniella grandis (Green), new combination; Greeniella perpusilla (Maskell), new combination; Greeniella serrata (Froggatt), new combination; Hendersonaspis anomala (Green), new combination (from Ancepaspis); Hulaspis bulba (Munting), new combination (this and the next Hulaspis Hall species both from Andaspis MacGillivray); Hulaspis formicarum (Ben-Dov), new combination; Lepidosaphes antidesmae (Rao in Rao Ferris), new combination (this and the next 19 species all from Andaspis); Lepidosaphes arcana (Matile-Ferrero), new combination; Lepidosaphes betulae (Borchsenius), new combination; Lepidosaphes citricola (Young Hu), new combination; Lepidosaphes conocarpi (Takagi), new combination; Lepidosaphes crawi (Cockerell), revived combination; Lepidosaphes erythrinae Rutherford, revived combination; Lepidosaphes incisor Green, revived combination; Lepidosaphes indica (Borchsenius), new combination; Lepidosaphes kashicola Takahashi, revived combination; Lepidosaphes kazimiae (Williams), new combination; Lepidosaphes laurentina (Almeida), new combination; Lepidosaphes maai (Williams Watson), new combination; Lepidosaphes mackieana McKenzie, revived combination; Lepidosaphes micropori (Borchsenius), new combination; Lepidosaphes punicae Laing, revived combination; Lepidosaphes quercicola (Borchsenius), new combination; Lepidosaphes recurrens (Takagi Kawai), new combination; Lepidosaphes viticis (Takagi), new combination; Lepidosaphes xishuanbannae (Young Hu), new combination; Lepidosaphes giffardi (Adachi Fullaway), new combination (from Carulaspis MacGillivray); Lepidosaphes garciniae (Young Hu), new combination (this and the next 2 species all from Ductofrontaspis Young Hu); Lepidosaphes huangyangensis (Young Hu), new combination; Lepidosaphes jingdongensis (Young Hu), new combination; Lepidosaphes recurvata (Froggatt), revived combination (from Metandaspis Williams); Lepidosaphes ficicola Takahashi, revived combination (this and the next 2 species all from Ungulaspis MacGillivray); Lepidosaphes pinicolous Chen, revived combination; Lepidosaphes ungulata Green, revived combination; Lepidosaphes serrulata (Ganguli), new combination (from Velataspis Ferris); Lepidosaphes huyoung Normark, replacement name for Andaspis ficicola Young Hu; Lepidosaphes tangi Normark, replacement name for Andaspis schimae Tang; Lepidosaphes yuanfeng Normark, replacement name for Andaspis keteleeriae Yuan Feng; Leucaspis ilicitana (Gómez-Menor), new combination (from Aonidia); Lopholeucaspis spinomarginata (Green), new combination (from Gymnaspis); Melanaspis campylanthi (Lindinger), new combination (from Aonidia); Mohelnaspis bidens (Green), new combination (from Fiorinia); Parlatoria affinis (Ramakrishna Ayyar), new combination (this and the next 4 Parlatoria species all from Gymnaspis); Parlatoria ficus (Ramakrishna Ayyar), new combination; Parlatoria mangiferae (Ramakrishna Ayyar), new combination; Parlatoria ramakrishnai (Green), new combination; Parlatoria sclerosa (Munting), new combination; Parlatoria bullata (Green), new combination (from Bigymnaspis); Parlatoria leucaspis (Lindinger), new combination (this and the next species both from Cryptoparlatorea Lindinger); Parlatoria pini (Takahashi), new combination; Parlatoria tangi Normark, replacement name for Parlatoria pini Tang; Pseudoparlatoria bennetti (Williams), new combination (from Parlagena McKenzie); Pseudoparlatoria chinchonae (McKenzie), new combination (from Protodiaspis Cockerell); Pseudoparlatoria larreae (Leonardi), revived combination (from Protargionia Leonardi); Quernaspis lepineyi (Balachowsky), new combination (from Chionaspis); Rhizaspidiotus nullispinus (Munting), new combination (from Aonidia); Rolaspis marginalis (Leonardi), new combination (from Lepidosaphes); Salicicola lepelleyi (De Lotto), new combination (from Anotaspis Ferris); Tecaspis giffardi (Leonardi), new combination (from Dinaspis); Trullifiorinia geijeriae (Froggatt), new combination (from Fiorinia); Trullifiorinia nigra (Lindinger), new combination (from Crypthemichionaspis Lindinger); and Voraspis olivina (Leonardi), new combination (from Lepidosaphes).

Investigating hybridization in the parthenogenetic New Zealand stick insect Acanthoxyla (Phasmatodea) using single-copy nuclear loci.

The New Zealand stick insect genus Acanthoxyla Uvarov is extremely unusual among higher taxa of animals in that all known species are obligate parthenogens. We have used a combination of the mitochondrial DNA genes cytochrome oxidase subunits I and II, 28S nuclear ribosomal RNA, and the two single-copy nuclear genes elongation factor 1alpha and phosphoglucose isomerase to test hypotheses on the role of hybridization in the evolution of this genus. Alleles at the single-copy nuclear loci in three sampled species of Acanthoxyla were resolved by cloning the PCR products. Analysis of multilocus genotypes shows that most sampled individuals of Acanthoxyla possess three alleles at the single-copy nuclear loci, which we have interpreted to indicate triploidy. Because most of the alleles from Acanthoxyla form a monophyletic group, including sets of alleles possessed by the putative triploids, we have inferred that the extant parthenogenetic lineages formed via hybridization between species of Acanthoxyla, at least one of which must have been sexual. More recently, there have been multiple introgression events from the related species Clitarchus hookeri White, although C. hookeri does not appear to be involved with the origin of parthenogenesis in Acanthoxyla. Our study demonstrates the utility of cloning alleles from multiple single-copy nuclear genes for resolving the origins of parthenogenetic lineages.

Gene expression plasticity across hosts of an invasive scale insect species.

For plant-eating insects, we still have only a nascent understanding of the genetic basis of host-use promiscuity. Here, to improve that situation, we investigated host-induced gene expression plasticity in the invasive lobate lac scale insect, Paratachardina pseudolobata (Hemiptera: Keriidae). We were particularly interested in the differential expression of detoxification and effector genes, which are thought to be critical for overcoming a plant's chemical defenses. We collected RNA samples from P. pseudolobata on three different host plant species, assembled transcriptomes de novo, and identified transcripts with significant host-induced gene expression changes. Gene expression plasticity was pervasive, but the expression of most detoxification and effector genes was insensitive to the host environment. Nevertheless, some types of detoxification genes were more differentially expressed than expected by chance. Moreover, we found evidence of a trade-off between expression of genes involved in primary and secondary metabolism; hosts that induced lower expression of genes for detoxification induced higher expression of genes for growth. Our findings are largely consonant with those of several recently published studies of other plant-eating insect species. Thus, across plant-eating insect species, there may be a common set of gene expression changes that enable host-use promiscuity.