Aberrant wing venation in twelve British species of Psocoptera

Abstract. In a sample of 1760 British specimens of Psocoptera 7.8% had aberrant wing venation. Twenty species were examined, twelve of which showed aberration. The aberrations were usually dyssymmetric, in the apical part of the forewing, and least common in brachypterous forms.     

The early stages of Ptenopsila Enderlein (Psocoptera,Caeciliidae)

All early stages of Ptenopsila, a characteristic psocid genus of southern South America, are described and features of taxonomic value are illustrated. Examination of early stages confirms the placement of this genus in the Caeciliidae.     

Effectiveness of sulfuryl fluoride for control of different life stages of stored-product psocids (Psocoptera)

With the phase-out and impending ban of methyl bromide, sulfuryl fluoride is among the most promising alternative fumigant insecticides for control of stored-product insect pests. It has been evaluated for control of several stored-product insect pests, but there are few data available on its efficacy for control of stored-product psocids (Psocoptera). We evaluated sulfuryl fluoride for control of different life stages of the psocids Liposcelis paeta Pearman, L. entomophila (Enderlein), L. bostrychophila Badonnel, L. decolor Pearman, and Lepinotus reticulatus Enderlein (Trogiidae) in 48-hr trials at 27.5 degrees C. Adults and nymphs were susceptible to sulfuryl fluoride. Complete (100%) adult and nymphal mortality was recorded at concentrations between 4 and 8 g/m3, except for L. decolor for which all adults were only killed at 24 g/m3. Eggs were tolerant to sulfuryl fluoride. Complete egg mortality was achieved at 24 and 72 g/m3 for L. reticulatus and L. decolor, respectively. Survival of L. paeta eggs was recorded even after exposure to 96 g/m3. Given that the highest United States label concentration for sulfuryl fluoride for a 48-h exposure interval is 31.25 g/m3, our study indicates that high doses and/or longer exposures are needed for complete mortality of eggs of L. decolor and L. paeta. Moreover, the present work suggests that there is considerable variation in efficacy of sulfuryl fluoride for control of different psocid species.     

Psocoptera of the Mascarene Islands

Analysis of the known and recently discovered differentiation patterns of 58 forest butterfly species (of the total 66) in the tribe Heliconiini, including over 300 races and forms, has led to the drawing of a map of core areas for evolution in the group. The majority of these are not isolated by any obvious modern physiogeographic barriers to dispersal of these butterflies, and probably correspond to forest refugia during the two or three most recent Quaternary dry periods. The map is in good accord with the results of similar studies in other groups of animals (forest vertebrates and invertebrates) and in forest trees, but indicates a larger number of significant operative refugia (38) than other analyses. Bases for the understanding of differentiation patterns in polytypic continental species are developed, in accord with the refuge theory and using intensive and extensive data on local monomorphic populations and secondary contact zones between differentiated forms. The known forms discussed include: Dione juno miraculosa Hering, Eueides libitina Staudinger, Heliconius xanthocles explicata Stichel, H. eleuchia (Hewitson) and H. leucadia Bates together with a supplementary revision of the tribe giving information published since 1972. The following new forms are described: Eueides emsleyi sp. n. and nine new subspecies of Heliconius: H. aoede philipi, H. wallacei araguaia, H. pardalinus orteguaza, H.p. butleri, H. hecale australis, H.h. barcanti, H. clysonymus tabaconas, H. congener aquilionaris, H. sapho candidus. Geographical details of the refugia are given in Appendix I, and in Appendix II the heliconians are assigned to the postulated refugia.     

Sperm Structure in the Psocoptera

An account is given of the ultrastructure of the sperm in Psocoptera. Three main types of sperm occur. Type one, in Suborder Trogiomorpha, is an uncoiled long sperm with a filamentous head and a flagellum containing two or three lateral ridges and two central tubules. Twenty three per cent of this type has two axonemes and four mitochondrial derivatives. The second type, in the Suborder Psocomorpha, lacks both central tubules and lateral ridges. Four per cent of this type contain biaxonemes and four mitochondrial derivatives. In the third type, in the Suborder Troctomorpha. 100% of the sperm have two axonemes and two mitochondrial derivatives. The possible function and the method of locomotion of these types are described. The similarity between sperm structure in the Psocoptera and in Anoplura and Mallophaga suggests a close phylogenetic relationship between the three orders.     

Distribution of domestic Psocoptera in Madrid apartments

Domestic Psocoptera were sampled in Madrid throughout a complete year (1991-92) by means of sticky traps in bathrooms, kitchens and inside windows. A total of 409 individuals comprising ten species of psocids was caught from 4056 traps inspected fortnightly. The predominant species were Liposcelis decolor, Li. brunnea, Psyllipsocus ramburi, Li. bostrychophila, Li. pearmani, Dorypteryx domestica and Lachesilla pedicularia, in descending order of abundance. Apartments were classified according to eight quantitative variables: age and area of building, level of apartment (i.e. storey), numbers of windows, inhabitants, their pets (birds and mammals), ornamental plants indoors; and two qualitative factors: floor material and presence or absence of trees adjacent to the house. Psocid communities in human habitations were assessed by the island biogeography theory: diversity increased with apartment size and the number of species decreased with building date. Psocid populations were most abundant in bathrooms, which presumably act as sources for dispersal to other parts of the premises. No other significant correlations were found with the other housing factors investigated. Whereas psocids were active indoors during all months of the year, the peak prevalence was in summer, July and August, one or two months ahead of the local seasonal pattern for non-domestic psocids. Although psocids are usually not seriously unhygienic, causing only minor problems of contamination and allergies, this information should help towards their environmental control.     

Molecular systematics of Psocomorpha (Psocoptera)

Abstract.  Previous classification of the insect order Psocoptera has relied on morphological characters. Psocoptera are generally divided into three suborders: Trogiomorpha, Troctomorpha, and Psocomorpha. Traditional classification divides the Psocomorpha into four infraorders (Homilopsocidea, Caeciliusetae, Psocetae and Epipsocetae), but a recent morphological cladistic study removed Archipsocidae from Homilopsocidea and Hemipsocidae from Psocetae. We investigated the phylogenetic relationships within the suborder Psocomorpha using DNA sequences from the nuclear 18S and mitochondrial 16S, 12S and cytochrome oxidase I genes. Phylogenetic analyses of these gene sequences supported monophyly for Psocomorpha. In addition, monophyly of the traditional subgroups Caeciliusetae and Psocetae was generally supported. Monophyly of Homilopsocidea was not supported, and Archipsocus is removed from this group. Although the molecular phylogeny is generally consistent with recent cladistic studies of morphological characters, we found no evidence that Hemipsocidae should be removed from Psocetae.     

Parthenogenesis in Psocids (Insecta: Psocoptera)

SYNOPSIS. Obligate thelytokous parthenogenesis and, more rarely,facultative thelytoky are known to occur in psocids. The formerphenomenon is known in 28 species. The latter is known onlyin two species, both of which have obligatorily thelytokousforms as well as bisexual ones. Attempts to force thelytokousfemales to mate have been carried out for four nominal species.All have failed. Differences in color or color pattern betweenthe bisexual and thelytokous forms of a nominal species havebeen observed in two instances. In Echmepteryx hageni this seemsto involve divergence where the two forms occur sympatricallybut on different habitats. Investigations of geographic distributionof bisexual and thelytokous forms of a nominal species showin several cases that the thelytokous forms are much more widespreadthan the bisexual ones. In eastern United States, bisexual formstend to occur peripherally and in ecologically unusual areas.The areas of occurrence of bisexual populations may be relictual,and some of them may have been Pleistocene refugia. Most ofthese areas correspond to areas where coniferous trees now forman important part of the forest.     

Intraguild predation of immature stages of British and Japanese coccinellids by the invasive ladybird Harmonia axyridis

Declines in native aphidophages in North America have been linked to intraguild predation (IGP) by the invasive coccinellid Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae). It is feared that many British species will face a similar fate following the recent establishment of H. axyridis in the UK. Meanwhile, H. axyridis exists in apparent ecological equilibrium with other members of its guild in Japan. The impact of H. axyridis on British coccinellids is uncertain but intraguild predatory interactions do occur, particularly amongst immature stages. This study investigates IGP between immature stages of H. axyridis and various British and Japanese coccinellids. The only asymmetric IG predator of H. axyridis at first instar was Anatis ocellata (Linnaeus). Harmonia axyridis engaged in symmetric IGP with Coccinella septempunctata Linnaeus, Calvia quatuordecimguttata (Linnaeus), Harmonia quadripunctata (Pontoppidan) and Eocaria muiri Timberlake, but was the asymmetric IG predator of all other species studied. The level of IGP was high between fourth instar larvae, and frequently biased towards H. axyridis, except in the case of A. ocellata, which again was the only IG predator of H. axyridis. In interactions between fourth instar larvae and pre-pupae, IGP was unidirectional towards H. axyridis for all species except A. ocellata, which acted as both IG predator and IG prey. Pupae were better protected against IGP than pre-pupae but most species were still susceptible to attack by H. axyridis, although IGP was symmetric with A. ocellata, and H. quadripunctata pupae were never attacked. The differences in susceptibility of the various species and developmental stages to IGP by H. axyridis are discussed in relation to physical defence structures. We find no evidence that Japanese species have superior defences to British ones and suggest that behavioural strategies may enable co-existence in the native range. We discuss the relevance of IGP by H. axyridis to the species it is likely to encounter in Britain.     

The karyotypes of two bark-lice species (Psocoptera, Psocomorpha, Amphipsocidae): the first description of the neo-XY sex chromosome system in Psocoptera

Karyotypes of two bark-lice species Amphipsocus japonicus End. and Dasypsocus japonicus End. (Amphipsocidae, Psocomorpha, Psocoptera) were studied for the first time. D. japonicus displayed 2n = 16 (14 + XX/X0). The XX/X0 sex chromosome system observed in this species is characteristic of the order Psocoptera. A. japonicus showed 2n = 16 (14 + neo-XY). This is the first observation of the neo-XY sex determination system in Psocoptera. In this species a large amount of constitutive heterochromatin was found in the original X-part of the neo-X chromosome.     

Levels of genetic diversity at different stages of the domestication cycle of interior spruce in British Columbia

Concerns over the reductionist nature of the domestication of forest-tree species focus on the possibility of potential genetic erosion during this process. To address these concerns, genetic diversity assessments in a breeding zone the Province of British Columbia “interior” spruce (Picea glauca×engelmanni) program was conducted using allozyme markers. Genetic-variation comparisons were made between natural and production (seed orchard) populations as well as seed and seedling crops produced from the same breeding zone’s seed orchard. The natural population sample consisted of a total of 360 trees representing three stands within each of three watersheds present in the Shuswap-Adams low-elevation zone of interior British Columbia. Small amounts of genetic differentiation were observed among the nine natural populations (4%) and this was attributable to extensive gene flow Consequently, the sum of these nine populations was considered as a baseline for the genetic variation present in the breeding zone. The comparisons between the seed orchard and the breeding zone produced a similar percentage of polymorphic loci while the expected hetrozygosity (0.207 vs 0.210) and the average number of alleles per locus (2.7 vs 2.4) were slightly lower in the seed orchard. A total of seven natural populations’ rare alleles were not present in the orchard population, while one allele was unique to the orchard. The %P increased to 70.6% in the seedlot, but dropped to the natural populations level (64.7%) in the plantation. The observed increase in %P was a result of pollen contamination in the orchard. It is suspected that the reduction in the plantation was caused by an unintentional selection in the nursery. Simulated roguing in the orchard did not drastically reduce even if up to 50% of the orchard’s clones were rogued. However, roguing was associated with a reduction in the average number of alleles per locus (i.e., sampling effect). Received: 2 January 1996 / Accepted: 24 May 1996