DNA barcoding of pear psyllids (Hemiptera: Psylloidea: Psyllidae), a tale of continued misidentifications

Pear psyllids (Hemiptera: Psylloidea: Psyllidae: Cacopsylla spp.) belong to the most serious pests of pear (Pyrus spp.). They damage pear trees by excessive removal of phloem sap, by soiling the fruits with honeydew which, in turn, provides a substrate for sooty mould, and by transmission of Candidatus Phytoplasma spp., the causal agents of the pear decline disease. The morphological similarity, the presence of seasonal dimorphism that affects adult colour, size and wing morphology and uncritical use of species names, led to much confusion in the taxonomy of pear psyllids. As a result, pear psyllids have been frequently misidentified. Many of the entries attributed to Cacopsylla pyricola and other species in the GenBank are misidentifications which led to additional, unnecessary confusion. Here we analysed DNA barcodes of 11 pear psyllid species from eastern Asia, Europe and Iran using four mitochondrial gene fragments (COI 658 bp, COI 403 bp, COI-tRNAleu-COII 580 bp and 16S rDNA 452 bp). The efficiency of identification was notably high and considerable barcoding gaps were observed in all markers. Our results confirm the synonymies of the seasonal forms of Cacopsylla jukyungi ( = C. cinereosignata, winter form) and C. maculatili ( = C. qiuzili, summer form) previously suggested based on morphology. Some previous misidentifications (C. chinensis from China, Japan and Korea = misidentification of C. jukyungi; C. pyricola and C. pyrisuga from East Asia = misidentification of C. jukyungi and C. burckhardti, respectively; C. pyricola from Iran = misidentification of C. bidens, C. pyri and Cacopsylla sp.) are also corrected. There is no evidence for the presence of European pear psyllid species in East Asia.

The life-history of Aprosthema tardum (Klug, 1814) (Hymenoptera, Tenthredinoidea, Argidae)

Aprosthema species are usually rarely found. In recent years, in southern France, relatively strong populations of A. tardum were detected, which allowed observations on the behaviour and development of the species to be made. The host plant in the study area is Lathyrus latifolius (Leguminosae). As in a few other Aprosthema species, whose development has been previously investigated in northern Europe, A. tardum is bivoltine, although a partial third generation may occur in southern Europe under favourable weather conditions. Adults display seasonal dimorphism, similar to that already described for A. melanurum. Individuals which overwinter make stronger cocoons in the soil (winter cocoons), whereas the more loosely spun cocoons (summer cocoons) of individuals which complete their whole development in a single season are usually found on aerial parts of the host, or plants of other species growing near to the host. The head behind the eyes is more strongly developed in adults which emerge from winter cocoons. A few individuals of A. tardum in the first generation, which normally form summer cocoons, make winter cocoons and enter prolonged diapause, like almost all larvae of the second generation. During oviposition the valvulae 3 are deployed so that their inner surfaces are in very close contact with the leaf epidermis. We suggest that this behaviour is connected to the presence of spines on the valvula inner surface. The latter are found in many argid sawflies, but not in other families of Palaearctic Tenthredinoidea, in which the valvulae have not been observed to be used in a similar way.

Seasonal leaf dimorphism in Potentilla argentea L. var. tenuiloba (Jord.) Sw. (Rosaceae)

A pattern of seasonal changes in the morphological and anatomical leaf traits is reported for Potentilla argentea L. var. tenuiloba (Jord.) Sw. of temperate-climate areas in central Poland. Leaf area, perimeter, dry mass and lamina thickness were measured in summer and autumn leaves of the same individuals. Dissection index, density and specific leaf area were calculated. Significant differences were obtained between summer and autumn leaves obtained from the same individuals. The shapes of leaves of the P. argentea plants varied in the extent of incisions between teeth and the number of teeth on the margins. Fully expanded autumn leaves were larger in weight and area than summer leaves. The autumn leaves had lower leaf mass area and density than the summer leaves. Leaves were covered by considerably more trichomes in summer than in autumn. Anatomical leaf structure also changed with the season. The summer leaves were thick, with a lower number of chloroplasts in the cells of the compact mesophyll. Autumn leaves are thinner, with loose mesophyll. Chloroplasts from the two seasonal types of leaves differ on account of starch grain and plastoglobule content. The large variations in leaf density and thickness recorded here confirm great differences in cell size and amounts of structural tissue within species. Seasonal dimorphism of leaves may result from seasonal drought or from seasonality in leaf production, leaf fall or incoming solar radiation. Within this new context of seasonal leaf dimorphism, P. argentea can still be distinguished by the absence of deeply divided leaflets on late-formed leaves. The results confirmed the presence of several morpho- anatomical leaf traits of P. argentea that allow the species to adapt to environmental seasonal conditions.

Sexual and seasonal dimorphism in adult adfluvial bull trout (Salvelinus confluentus)

Sexual dimorphism in fishes may be obvious during the reproductive period and less clear during the nonreproductive periods. Despite being difficult to discern during the nonreproductive period, sex-related differences in body condition and shape can yield important insights into a species’ behaviour and ecology. The purpose of this study was to test hypotheses about body condition and shape variation related to sex and season (nonreproductive and reproductive periods) in a population of adult adfluvial bull trout (Salvelinus confluentus (Suckley, 1859)), which is a poorly understood and imperiled species across much of its range. Geometric morphometric samples were collected by angling in the spring and late summer in a reservoir in British Columbia. Principal components analysis identified two principal components (PC) that were related to body condition and that varied according to season and sex. Spring-caught females were in better body condition than spring-caught males. There was a significant sex × season interaction on body condition such that late-summer males were not different from late-summer females. Spawning bull trout exhibited a decline in body condition during the summer season. An additional PC that described head size was found to vary significantly between sexes; however, an assignment test showed that it failed to reliably distinguish between the sexes. We hypothesized that the ecology of these animals, including sex-specific behaviour, is responsible for sexual and seasonal differences in bull trout body condition and morphology. This study offers new insight into the ecology of bull trout and shows that shape data for fishes can be obtained nonlethally, which is particularly important for species that are imperiled.