The fresh weight, dry weight, and C and N content of the eggs, egg shells and neonate larvae of several satyrines were measured. This was done in order to assess the specificity of the composition of the egg and larvae, the phylogenetic or ecological nature of the variation and the existence of structural constraints on the composition of the offspring. All the traits investigated were found to be highly species-specific. The nature of the variation was not primarily phylogenetic, suggesting that the composition of the offspring has an ecological meaning. However, only a slight association was detected between three life history traits or habitat features and the compositions of the eggs or larvae, namely: female egg dropping was associated with a high C content of the eggs, xerophily with a high C : N ratio, and a high content of N in the larvae with egg diapause. The evidence for intra-specific allometry between the traits investigated and egg weight varied among the species, suggesting that the slope of such relationship may be a specific feature. There was a close to isometric relationship between C and N contents in every species. Therefore simple C : N ratios are independent of egg size, hence they can be used directly in comparative studies. Across species analyses indicated that small offspring contained a proportionally low amount of carbon and had a high dry matter content, suggesting that selection for small eggs was accompanied by selection for an enhanced proportion of nitrogen per egg. Finally, the species with large adult females invested comparatively more nitrogen per egg, which indicates a potential, constraint-based advantage of large adult size.
Wolbachia is a maternally transmitted intracellular symbiont which causes reproductive distortions in the arthropods it infects. In recent years there has been an increasing interest in using Wolbachia as a potential tool for biological control by genetic manipulation of insect pests. In the present paper we report Wolbachia infection in several Trissolcus wasps (Hymenoptera: Scelionidae) which are important egg parasitoids of the sunn pest, Eurygaster integriceps Puton (Heteroptera: Scutellaridae). We used DNA sequence data for a gene encoding a surface protein of Wolbachia (wsp) not only to confirm Wolbachia infection but also to discriminate Wolbachia strains. Phylogenetic analyses indicated that Wolbachia strains in Trissolcus species were closely related to one another and belonged to supergroup B. Determination of the infection status of various populations, the possible role of Wolbachia in causing the incompatibility and knowledge of the reproductive compatibility of Trissolcus populations is important for the success of parasitoids in sunn pest management., Nurper Guz ... [et al.]., and Obsahuje seznam literatury
Wolbachia pipientis (Hertig) (Rickettsiaceae) is an endocellular bacterium infecting numerous species of arthropods. The bacterium is harboured by males and females but is only transmitted maternally because spermatocytes shed their Wolbachia during maturation. The presence of this endosymbiont can lead to feminisation of the host, parthenogenesis, male-killing or reproductive incompatibility called cytoplasmic incompatibility (CI). Although Wolbachia transmission is exclusively maternal, phylogenetic evidence indicates that very rare inter-species transmission events have taken place. Horizontal transmission is possible in the laboratory by transferring cytoplasm from infected to uninfected eggs. Using this technique, we have artificially infected lines of the fruit fly Drosophila simulans Sturtevant (Drosophilidae). Recipient lines came from two different D. simulans populations. One ("naive" host) is not infected in the wild. The other ("usual" host) is a population naturally carrying Wolbachia in the wild. In this second case, recipient flies used in the experiment came from a stock culture that had been cured off its infection beforehand by an antibiotic treatment. Infected D. simulans laboratory stocks were used as donors. We assessed the three following parameters: (i) trans-infection success rate (ratio of infected over total female zygote having survived the injection), (ii) level of cytoplasmic incompatibility expressed by trans-infected males three generations post-trans-infection, and (iii) infection loss rate over time in trans-infected lines (percentage of lines having lost the infection after 20 to 40 generations). We observed that parameter (i) did not differ significantly whether the recipient line came from a "naive" or a "usual" host population. However, both (ii) and (iii) were significantly higher in the "naive" trans-infected stock, which is in agreement with earlier theoretical considerations.
A detection dog and handler team were used to recover scats in areas newly colonized by wolves outside the Alpine mountains of France between October 2018 and May 2019. Survey areas were classified as occupied by a resident wolf pack (WP) or dispersers (no-WP). The efficiency of monitoring by a targeted dog-handler team was compared to opportunistic monitoring by trained observers. Use of the detection dog allowed up to 99.6% time savings relative to monitoring by trained observers. Wolf scats found by the dog represented 82.1% of genetically confirmed samples in the 12 sample units (each being 10 × 10 km) monitored by both trained observers and the dog-handler team. Occupancy modelling was used to estimate wolf detection probabilities. Ten kilometres of survey with the dog were required to reach a 98% detection probability in WP territories and 20 km to reach 96% in no-WP areas. By contrast, two years of opportunistic monitoring by trained observers were required to obtain a 90% and 76% probability of detecting wolves in WP and no-WP areas, respectively. The use of the detection dog via dog-team surveys greatly increased the collection of viable samples for genetic analysis and individual genotype identification. Our study offers further confirmation that dog-handler teams can be very effective at locating scats from target carnivores, to supplement or complement human search efforts.