Biology of a new species of socially parasitic thrips (Thysanoptera: Phlaeothripidae) inside Dunatothrips nests,with evolutionary implications for inquilinism in thrips

Akainothrips francisi sp. nov. is shown to be an inquiline (i.e. it invades, and breeds within, domiciles of another species). Currently, its only known host is Dunatothrips aneurae, a subsocial thrips that creates silken domiciles by securing together phyllodes of mulga (Acacia aneura) in the arid zone of Australia. We found Ak. francisi prolifically breeding inside live D. aneurae host domiciles, both immature and mature. Akainothrips francisi did not kill its host and we saw no evidence of antagonistic host‐inquiline interactions. This is thus the second demonstrably inquiline species of Acacia thrips, although other possible inquilines have been suggested including two Akainothrips. We found that Ak. francisi occurred with positive density dependence, and was associated with moderately reduced host reproduction. This latter association was especially evident in larger host domiciles, suggesting that Ak. francisi either inhibits further host reproduction after invasion or exploits poor quality hosts more successfully. Sex ratios were slightly female biased. Akainothrips francisi males were exceptionally variable in size, colour, and foreleg size compared to females, with morphs co‐occurring within domiciles, suggesting sexual selection and the possibility of different male reproductive strategies. The discovery of Ak. francisi highlights particular morphological affinities among known or suspected inquiline Acacia thrips within Akainothrips and other genera, allowing us to hypothesize a common origin of this lifestyle from within Akainothrips. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ?? , ??–??.     

Pleometrosis in phyllode-glueing thrips (Thysanoptera: Phlaeothripidae) on Australian Acacia

Pleometrosis, or colony founding by more than one female, is common in various social insects and it engenders opportunities for social cooperation as well as cheating. The life cycles of four species of thrips on Australian Acacia trees were examined to elucidate the extent and nature of colony founding by multiple individuals. Data from colonies of three species of thrips from the genus Dunatothrips Moulton and one species of Lichanothrips Mound were used to infer the prevalence of pleometrosis in each species. The results indicate that Dunatothrips species show high levels of cofounding, with up to 50% of colonies having more than one foundress. By contrast, colonies of Lichanothrips are predominantly established by a female and a male. As in some communal insects, pleometrosis is facultative in Dunatothrips , foundresses show more or less constant per capita reproduction with foundress number, and the selective pressures for pleometrosis may involve predation pressure during founding or survivorship insurance for the brood. In Lichanothrips , male founders are probably engaging in mate guarding, which also occurs in some species of gall-inducing thrips on Acacia . The differences in founding patterns between Dunatothrips and Lichanothrips may be due in part the nature of their domiciles: Dunatothrips engage in extensive construction of a domicile using anal secretions, whereas many Lichanothrips primarily improve a pre-existing partial enclosure. © 2002 The Linnean Society of London, Biological Journal of the Linnean Society , 2002, 75 , 467–474.     

Domicile constructing phlaeothripine Thysanoptera from Acacia phyllodes in Australia: Dunatothrips Moulton and Sartrithrips gen.n., with a key to associated genera

Abstract. Domiciles are constructed by adult females of species in several genera of Australian phlaeothripine Thysanoptera. This is done by glueing or sewing together two or more Acacia phyllodes, or by weaving a tentlike structure on a phyllode surface. These thrips then breed within the domiciles, sometimes for multiple generations. Mature females become dealate in seven of twelve species discussed, through fracture of the distal four-fifths of each wing, although young females and all males have complete wings. Of these twelve species, six are placed in Dunatothrips Moulton and six in a new genus, Sartrithrips . Adults of the latter genus have a spinelike structure dorsal to the anus, 'the supra-anal process', that is not found in any other member of Phlaeothripidae. Despite the many structural and biological character states shared by these twelve species, molecular methods using one nuclear gene ( wingless ) and one mitochondrial gene (cytochromome oxidase 1) demonstrated that the two genera are monophyletic but do not have a sister-group relationship. Identification keys are provided to nineteen described phlaeothripine genera that are known to be associated with Acacia phyllodes, and to the twelve species in Dunatothrips and Sartrithrips , of which ten are described as new.     

Natural history and behaviour of Dunatothrips aneurae Mound (Thysanoptera: Phlaeothripidae), a phyllode‐gluing thrips with facultative pleometrosis

Thrips of the genus Dunatothrips (Thysanoptera: Phlaeothripidae) construct domiciles by tying phyllodes of Australian Acacia trees together with silk‐like glue. Females often co‐found domiciles (pleometrosis), an apparently cooperative behaviour that potentially provides insights into social evolution. However, little is known about their basic natural history, limiting the scope for testable predictions. Here, we address this crucial prerequisite step by investigating some key outstanding questions in the most common species, D. aneurae, on its host, Acacia aneura. We detail distribution in space and time, mating, dispersal, domicile building and defence. Dunatothrips aneurae was distributed in loosely reproductively synchronized patches, and tended to prefer east‐facing, terminal phyllodes on thin‐phyllode A. aneura varieties. Mature domiciles contained middens, concentrated areas of waste, suggesting active maintenance of domiciles and the potential for the division of labour. We observed inbreeding and outbreeding. Dunatothrips aneurae males engaged in short, truncated matings with sisters before dispersing locally, mating with females in nearby immature domiciles; longer distance dispersal, although it must happen, is still undocumented. Males and females mated multiply. Lone females required male presence to initiate domiciles, constructed them without male help and lost wings on nesting by abscission. Silk production occurred well before egg laying. Aggression or defence appeared to be entirely absent. Taken together, these observations suggest that research into co‐founding behaviour should focus on: (1) local crowding; (2) lack of aggression; and (3) potential division of labour with respect to egg production, silk production and domicile maintenance. These results should provide a springboard for questions on the potential evolution of cooperation in this species. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109 , 802‐816.     

Host-related fitness trade-offs in a presumed generalist parasitoid, Diaeretiella rapae (Hymenoptera: Aphidiidae)

Abstract.  1. Host ranges of parasitoid wasps are mediated by behavioural responses to hosts and their environment (infectivity), and development in hosts (virulence). Determinants of host range were measured in Diaeretiella rapae (Hymenoptera: Aphidiidae), which has been described as a generalist that attacks more than 60 species.
2. In northern Colorado, this wasp mainly attacks two hosts: cabbage aphid ( Brevicoryne brassicae ) and Russian wheat aphid ( Diuraphis noxia ). Here, laboratory experiments are described in which D. rapae originating from these two hosts were offered several hosts for oviposition. Both infectivity and virulence were measured.
3. Infectivity included host acceptance and handling time, while virulence was measured as productivity (number of progeny), survival of immatures within hosts, development time, and sex ratio.
4. Wasps had higher productivity and survival when attacking 'home' hosts than 'alternate' hosts, and trade-offs were found by quantitative genetic analyses to be genetically determined. Sex ratio and development times also showed trade-offs, but mainly related to the host environment in which females were reared.
5. In previous genetic studies in northern Colorado, populations were genetically subdivided on the scale of 1 km. The fitness differences described here could be strong enough to create populations adapted to different hosts, but it appears that gene flow is sufficient to prevent formation of separate lineages on the two hosts.
6. Rather than being a generalist with a broad host range, D. rapae is a serial specialist, attacking particular hosts according to availability in different seasons or in different geographical areas.     

Dispersal patterns of an Australian gall-forming thrips and its host tree (Oncothrips tepperi and Acacia oswaldii )

Abstract. 1. Clark and Evans' nearest-neighbour method was used to evaluate the distribution pattern of Acacia oswaldii and Oncothrips tepperi populations.
2. A random distribution pattern was supported statistically for both the host trees and trees that were parasitised by O. tepperi .
3. It is therefore likely that dispersal distances of colonising thrips are large enough to be able to traverse the 1 km² study site.     

Potential novel hosts for the lily leaf beetle Lilioceris lilii Scopoli (Coleoptera: Chrysomelidae) in eastern North America

Abstract.  1. Introduced insects often incorporate native plants into their diets and might be expected to show a predilection for novel hosts that are phylogenetically related to their normal hosts. The lily leaf beetle, Lilioceris lilii (Coleoptera: Chrysomelidae), is an introduced pest of cultivated lilies. Oviposition behaviour, larval behaviour, and development of L. lilii was examined on a range of potential host plants, as well as on the normal host, Asiatic hybrid lilies Lilium sp.
2. Neonate larval feeding behaviour was quantified on 15 food plant species: 10 from the Liliales, three from the Asparagales and two eudicots. Larvae fed plants closely related to the genus Lilium were more likely to initiate feeding, less likely to abandon their food leaf, and consumed more leaf area.
3. In no-choice tests, females oviposited on the novel hosts Lilium philadelphicum , Medeola virginiana , Clintonia borealis , Streptopus amplexifolius , and Polygonatum biflorum ; however, all but L. philadelphicum received very few eggs. Non- Lilium novel hosts were not used for oviposition when presented along with Asiatic lilies in choice tests.
4. A single individual was reared to the adult stage on the novel host S. amplexifolius . Several larvae survived to the pupal stage on M. virginiana , although no adults emerged from those pupae. Larvae reared on the native wood lily L. philadelphicum performed equally well or better than on the Asiatic cultivar.
5. Our results indicate that the lily leaf beetle poses a threat to native Liliaceae. Several native Lilium species, including L. philadelphicum , are threatened or endangered in certain jurisdictions throughout their range; these species should be monitored closely for colonisation by the beetle.     

Phenotypic plasticity in host-plant specialisation in Aphis fabae

Abstract.  1. The study of phenotypic plasticity in host utilisation is crucial for predicting evolutionary patterns of insect – plant interactions. The presence of sufficient variation in plasticity may facilitate host race formation and sympatric speciation.
2.  Aphis fabae genotypes showed high levels of phenotypic plasticity in the intrinsic rate of natural increase ( r _m), relative growth rate (RGR), birth weight (BW), adult weight (AW), fecundity ( F ), and development time (1/ d ).
3. Thirteen A. fabae genotypes reared both on broad bean and nasturtium exhibited statistically significant genotypic variability in phenotypic plasticity.
4. Some genotypes displayed fitness improvement on novel host plants.
5. Differences in genotypic correlation among fitness components between the two hosts and increased variance on nasturtium indicated different genomic expression on nasturtium.
6. The results indicated that phenotypic plasticity in a novel environment may be a major determinant of the evolutionary trajectory of a parasitic species and might support the idea that speciation starts with phenotypic plasticity.     

Host age and fitness-related traits in a koinobiont aphid parasitoid

Abstract.  1. Trade-offs play a key role in species evolution and should be found in host–parasitoid interactions where the host quality may differ between host age categories.
2. The braconid wasp, Aphidius ervi , is a solitary endoparasitoid that allows its aphid hosts to continue to feed and grow after parasitisation. The hypotheses that host age influences their quality and that female parasitoids exploit their hosts based on that quality were tested under laboratory conditions using no-choice tests.
3.  Aphidius ervi females accepted the aphid Myzus persicae for oviposition and their progeny developed successfully in all host ages. The fitness-related traits of parasitoids did not increase linearly with the host age in which they developed. Host quality was found to be optimal at intermediate host ages and the females preferred to parasitise these hosts. The shortest progeny development time and a more female-biased sex ratio were observed in hosts of intermediate age.
4. This study suggests the existence of multiple interactive trade-offs occurring during host–parasitoid interactions according to host age related quality.     

Morphological phylogenetics of Australian gall-inducing thrips and their allies: the evolution of host-plant affiliations, domicile use and social behaviour

A phylogeny for seventy-two species of Australian thrips in the subfamily Phlaeothripinae, based on cladistic analysis of forty morphological adult characters, is presented. We use this phylogeny to infer the evolutionary history of host-plant affiliations, gall induction and other types of domicile use, and different forms of social behaviour. Maximum parsimony analysis yielded forty-eight cladograms of length 316, and the strict consensus of these cladograms was well resolved. This phylogeny indicated that: (1) associations of thrips with their host plants tend to be evolutionarily conservative, with monophyletic groups of thrips on the host-plant genera Acacia, Casuarina and Geijera, (2) galling has evolved multiple times, on different host plants, (3) transitions in domicile use include changes between galling and living in holes or old galls, between living in glued phyllodes and living in old galls, and between leaf-feeding and galling, and (4) in three of five cases, inquiline lineages were not closely related to their host lineages and the evolution of inquilinism apparently involved a host-plant shift. However, in two cases, inquilines were very closely related to their gall-inducing hosts. Eusocial behaviour (involving soldier castes) has evolved in different lineages from those that exhibit communal behaviour (cooperation in building or defending domiciles), suggesting a lack of direct transition between the two social systems. This phylogeny serves as a framework for future molecular systematic studies, and future comparative analysis of ecology and behaviour in the Phlaeothripinae.     

Conserved oviposition preferences in alpine leaf beetle populations despite host shifts and isolation

Abstract.  1. Choosing the plant on which to lay their eggs is the last act of care that most female herbivorous insects bestow upon their offspring. These decisions play a pivotal role in insect–plant interactions, placing host preference under strong selection and contributing to the diversity of phytophagous insects as one of the first traits to adapt to new hosts.
2. This study presents a test of whether extreme isolation and exposure to different host plants can produce intra-specific divergence in oviposition preference in alpine insects. Geographic variation should impose selection to fine-tune host plant ranking and specificity to the plants normally encountered, to avoid wasting time during the very limited reproductive season experienced at high altitudes.
3. Beetles from five populations of Oreina elongata differing in host availability were offered three natural hosts: Cirsium spinosissimum , Adenostyles alliariae , and Adenostyles glabra . A novel application of a continuation ratio model (logistic regression) was made to sequential no-choice experiments, combined with quasi-likelihood analysis of multiple-choice experiments.
4. The results show little geographic variation in host plant choice: all populations strongly preferred Cirsium in multiple-choice trials, and in no-choice experiments laid around 47% of their remaining eggs during each stage, almost regardless of the host present.
5. Enemy-free space seems to explain the preference for Cirsium , but isolation and exposure to different plants has clearly not caused local adaptation in host plant ranking or specificity. Reasons for this conservatism despite divergence in other characteristics are discussed.     

Density, dispersal, and feeding impact of western flower thrips (Thysanoptera: Thripidae) on flowering chrysanthemum at different spatial scales

Abstract.  1. This study evaluated the effect of dispersal on the density and feeding impact of a phytophagous insect in relation to the spatial distribution of its host plants.
2. The interaction between density, dispersal, and feeding impact of western flower thrips on flowering chrysanthemum was quantified at three spatial scales, with infested and uninfested plants either isolated in 0.25 m² individual cages, or enclosed together in 2.25 m² communal cages or 75 m² greenhouses.
3. In individual cages, the rate of dispersal from chrysanthemum plants to blue sticky traps increased with the density of thrips for females but not males. Uninfested plants consistently had fewer thrips when they were individually caged rather than enclosed with plants infested with adults, indicating that dispersal mediates inter-plant distribution of thrips.
4. The feeding impact of thrips on inflorescences was evaluated using the absorbance of ethanol extracts at wavelengths characteristic of yellow carotenoid pigments associated with chrysanthemum inflorescences (415, 445, and 472 nm). Increasing absorbance of extracts with increasing density of thrips per inflorescence suggests that feeding by thrips results in ruptured cells leaching carotenoid pigments.
5. In communal cages, the distribution of thrips was uniform for infested and uninfested plants, whereas the density and feeding impact of thrips in greenhouses were higher for infested than uninfested plants. These results suggest that short-range dispersal by adults homogenises the density and feeding impact of thrips among host plants only on a small spatial scale.     

Species diversity and structure of phytophagous beetle assemblages along a latitudinal gradient: predicting the potential impacts of climate change

Abstract.  1. Assemblages of phytophagous beetles on Acacia were examined along a 1150 km latitudinal gradient in eastern Australia to investigate the potential effects of climate change on insect communities. The latitudinal gradient was used as a surrogate for differences in temperature. Several possible confounding variables were held constant by selecting comparable sites and emphasising a single host-plant species.
2. Total species richness increased towards the tropics, but there were no significant differences among latitudes for average species density, species richness, Fisher's α , or average Chao-1 index.
3. Beetles sampled along the gradient were classified into four climate change response groups, depending on their latitudinal range and apparent host specificity: cosmopolitan species, generalist feeders , climate generalists , and specialists . These four groups might respond differently to shifting climate zones. Cosmopolitan species (22% of community, found at more than one latitude and on more than one host plant) may be resilient to climate change. Generalist feeders (16%, found only at one latitude but found on more than one Acacia species) may well feed on several species but will have to move with their climatic envelope. Climate generalists (6%, found only on Acacia falcata but found at more than one latitude) may be constrained by the host species' ability to either cope with the changing climate or move with it. Finally, specialists (55%, found only on A. falcata and at only one latitude) may be forced to move poleward concurrently with their host species, or go extinct.
4. The analyses indicate that community structure may be fairly resilient to temperature change. The displacement or local extinction of species, especially the species that are found at only one latitude and on only one host plant, however, may lead to significant changes in community composition.     

Host-plant use in the range expansion of the pine processionary moth, Thaumetopoea pityocampa

Abstract.  1. During range expansions of phytophagous insects, secondary or novel hosts may allow colonisation of areas without primary hosts. Because plant species often differ in their relative attractiveness and suitability for insects, insect preference for, and performance on, these hosts can determine recruitment potential in the current and future expansion areas.
2. This study explores the relative roles of female preference and larval performance in an important pine defoliator, Thaumetopoea pityocampa (Denis & Schiffermüller) (Lepidoptera, Notodontidae), which colonises three Pinus species at its current range margin in the Italian Alps: P. nigra (primary host), P. sylvestris (secondary host), and P. mugo (novel host).
3. Host use patterns in multiple insect populations were studied through choice and no-choice oviposition experiments in cages, field surveys of mixed stands, and laboratory and field monitoring of larval growth and mortality. It was predicted that a specific life-history trait – time limitation of short-lived females to lay a single batch of eggs – would act as a component of female performance, and lead to similar rates of host acceptance in no-choice settings.
4. In the choice experiment, P. nigra was accepted the most frequently while P. sylvestris was accepted the least frequently, confirming nest density patterns in the field. Contrary to prediction, females remained discriminating in no-choice settings in spite of time limitation. In contrast, relative growth rate (RGR) and mortality of larvae did not differ significantly among the three hosts, highlighting a discrepancy between female preference and larval performance.
5. Recruitment potential of T. pityocampa in future expansion into stands of P. sylvestris and P. mugo is evaluated by combining host quality, conservatism in oviposition behaviour, habitat suitability, and the opportunity for local adaptation.     

Effects of tomato spotted wilt virus (TSWV) isolates, host plants, and temperature on survival, size, and development time of Frankliniella fusca

The effects of different isolates of the tomato spotted wilt tospovirus (TSWV), host plants, and temperatures on Frankliniella fusca (Hinds) (Thysanoptera: Thripidae), the most important vector of TSWV in North Carolina, were measured in the laboratory. Thrips were reared at either 18.3, 23.9, or 29.4 °C until adult eclosion on excised leaves of Datura stramonium L. or Emilia sonchifolia (L.). Plants were either infected with the TSWV isolates CFL or RG2, or left uninfected (control). The results revealed a positive relationship between larval survival and temperature, regardless of host plant or TSWV isolate. Both survival to adult and percentage transmission of TSWV by F. fusca were significantly affected by the interaction between host plant and TSWV isolate. The consequence of this interaction was that the cohort‐based percentage transmission from infected E. sonchifolia plants for CFL was 1.3‐fold greater than that of RG2, whereas the percentage transmission from infected D. stramonium plants for RG2 was twice that of CFL. Both host plant and TSWV isolates showed significant effects on thrips development time to adult and head capsule width of adult thrips, as well as on the incidence of thrips infection with TSWV. The infection status of these thrips was determined by ELISA for the NSs viral protein. Infected thrips reared on infected host foliage took longer to develop to adult and were smaller than non‐infected thrips which had also been reared on infected host foliage, demonstrating a direct effect of the TSWV on thrips. However, non‐infected thrips reared on non‐infected leaves took longer to develop than non‐infected thrips reared on infected leaves, suggesting an effect of the plant tissue on thrips. In addition, adult thrips reared on TSWV‐infected D. stramonium at 29.4 °C developed smaller head capsules than thrips developing on infected foliage at lower temperatures and on non‐infected leaves of D. stramonium or E. sonchifolia. Both TSWV isolates and host plants differentially affected females more than males. In conclusion, both the infection of thrips by TSWV and TSWV‐mediated changes in host plant quality were found to have significant biological effects on F. fusca.     

On understanding seasonal increases in damselfly defence and resistance against ectoparasitic mites

Abstract.  1. Defence against parasites and pathogens can be essential, yet not all hosts respond similarly to parasitic challenge. Environmental conditions are thought to explain variation in host responses to parasites.
2.  Lestes forcipatus damselflies emerging later in the season have shown higher resistance to the mite, Arrenurus planus , than hosts emerging earlier. This study was undertaken to determine whether variation in environmental temperatures characteristic of early vs. late emergence times, degree or costs of mite parasitism, and/or size of newly emerged adults could explain seasonal variation in defence and resistance to ectoparasitic mites.
3. In this study damselflies from early vs. late emergence groups differed in size at emergence and mite intensity. In general, early hosts were larger and had more mites than later hosts. However only experimental temperatures experienced by damselflies at emergence influenced defence and resistance against mites and not host size or degree of parasitism.
4. More specifically, hosts from early and late emergence groups did not differ in defence and resistance when held at the same temperatures in incubators. Housing at a high temperature, indicative of later in the season, was associated with higher defence and resistance for damselflies from both early and late emergence groups.
5. These results indicate that daily temperatures in relation to emergence timing can account for seasonal increases in resistance for this temperate insect. Seasonal increases in resistance may be expected for other temperate insect–parasite associations and should have important implications for the phenology of parasites and for seasonal variation in parasite-mediated selection.     

Host selection by virgin and inseminated females of the parasitic wasp, Dinarmus basalis (Pteromalidae, Hymenoptera)

1. Fitness is related to reproduction and survival. There apparently exists a negative correlation between the numbers of male and female offspring. There also exists a trade-off between survival and reproduction. This paper investigates optimal decisions with the reproduction and survival trade-off in host selection by wasps.
2. Whereas inseminated female wasps could manipulate the sex of their offspring, virgin females produced only male offspring. I surveyed behavioural differences and the consequences of oviposition by inseminated and virgin females of a solitary parasitic wasp in host choice situations.
3. Two host types were available at the same time to both inseminated and virgin female wasps: one (a 17-day-old host in one bean) presenting difficulties for the laying of eggs, but more benefits for the offspring and the other (five 12- or 13-day-old hosts in one bean) easier for the female wasp for laying of eggs but less beneficial for the offspring.
4. Inseminated female wasps chose more 17-day-old hosts than 12-day-old hosts, but more 13-day-old hosts than 17-day-old hosts in each pair-wise choice. Virgin females chose the smaller hosts in both situations.
5. Virgin females, having greater longevity than inseminated females, laid larger numbers of eggs than the inseminated females during their lifetime by adopting an energy-saving host choice that had little effect on male offspring fitness.     

Costs and consequences of superparasitism in the polyembryonic parasitoid Copidosoma koehleri (Hymenoptera: Encyrtidae)

Abstract.  1. Polyembryonic wasps provide dramatic examples of intra-specific developmental conflict. In these parasitoids, each egg proliferates into a clonal lineage of genetically identical larvae. If more than one egg is laid in a host (superparasitism), individuals of different clones may compete for food resources.
2. In the polyembryonic encyrtid Copidosoma koehleri , one larva per clone can differentiate into a sterile soldier. It is shown that soldiers are always females, and that they attack intra-specific competitors.
3. Research hypotheses were that (a) clones that develop in superparasitised hosts suffer heavier mortality than clones that develop in singly parasitised hosts, and (b) female clones cause higher mortality to their competitors than male clones, hence larval survival is lower in superparasitised hosts that contain females than in male-only broods.
4. The potential frequency of superparasitism in C. koehleri was manipulated by varying parasitoid–host ratios and exposure durations.
5. As parasitoid densities and exposure durations increased, the frequency of superparasitism rose, brood sizes increased, but the number of hosts that completed development was reduced. The number of offspring per parasitoid female decreased with increasing parasitoid–host ratios. Offspring size and longevity were inversely correlated with brood size. As superparasitism rates increased, fewer all-male broods were produced. Male–female broods were female-biased, suggesting selective killing of males by female soldiers. All-female broods were significantly smaller than all-male broods at high parasitoid densities only, possibly reflecting aggression among soldiers of competing clones.
6. The results support the working hypotheses, and suggest that female larvae outcompete males in superparasitised hosts.     

Gall morpho-type corresponds to separate species of gall-inducing thrips (Thysanoptera: Phlaeothripidae)

Kladothrips rugosus Froggatt has previously been considered a single polyphagous species that, in Australia, induces galls on several species of Acacia , with the gall structure varying both within and between hosts. On Acacia papyrocarpa , two types of gall are induced by this species, one with the surface ridged but the other with the surface smooth. Using sequence data from cytochrome oxidase subunit I (CO I ) and elongation factor-1 alpha gene fragments, we show that the thrips inducing these two gall-types are genetically distinct and comprise separate lineages. Uncorrected ' p ' distances calculated from CO I gene fragments were 0.000 and 0.006 within lineages and 0.074 and 0.078 between lineages. The between-lineage distances are comparable with distances between morphologically distinct species of other Acacia gall-thrips. Re-examination of adult thrips from the two gall types revealed consistent differences in body colour, as well as in body sculpture. Together with observations on gall founding behaviour, these data indicate that the thrips populations in the two gall types on A. papyrocarpa are reproductively isolated and should be considered as separate species. The form from smooth galls on A. papyrocarpa is therefore described as Kladothrips nicolsoni sp. nov. , although the form from ridged galls can be considered only as ' K. rugosus agg.'. These inconsistencies in the taxonomic status of the various units within the K. rugosus species complex are discussed, although most of them cannot be distinguished morphologically at present.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 88 , 555–563.