Bacillus thuringiensis var. israelensis (Bti) has become the most commonly used larvicide to control mosquitoes worldwide. Bti is considered non‐toxic to most organisms, except some Diptera such as chironomids, which are a major prey in wetland food webs. Although Odonata are important predators of mosquitoes and chironomids at the larval and adult stages, no study has ever considered the potential indirect effects of Bti on Odonata abundance through trophic interactions. We addressed this topic in the Camargue where 2500 of the 25 000 ha of mosquito larval biotopes are Bti‐sprayed (aqueous solution of VectoBac 12AS at 2.5 L ha−1) whenever mosquito larvae appear in water bodies (i.e. 30–50 aerial treatments overall annually). Adult Odonata were surveyed along a 100‐m line transect in spring, summer and autumn at three control and three treated sites over a 5‐year period. Mean number of species (9.9 vs. 5.2) and of individuals (100 vs. 50) detected per year were significantly higher in control areas compared to Bti‐sprayed areas. Bti treatment contributed to 87.3% of the explained variance in Odonata richness, compared to 2.9% for site, 6.8% for year and 3.0% for salinity effects. These results are coherent with other studies carried out in the same area and time period highlighting a lower abundance of chironomids, and a lower intake of odonates by breeding birds in treated areas. We conclude that mosquito control using Bti should be acknowledged as a potential threat to Odonata.

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International audienceWe studied growth patterns within a marbled newt population (Triturus marmoratus, Urodela) at the southeastern limit of its geographical range by skeletochronology of the phalanges and humeri. Seasonal and annual changes in growth rates were assessed through the analyses of 56 females, 66 males and 34 juveniles sampled in different seasons and years. Age and growth cycles were estimated by cross sections of the diaphyseal region of the bone. These analyses revealed a clear line of metamorphosis caused by the metamorphic process itself and the transition to the terrestrial environment. A line of arrested growth (LAG) was observed in winter in both juveniles and adults. Another LAG was recorded in summer among adults. These growth patterns corroborated field observations on life-history traits of the population under study, but differ from those reported for the marbled newt in other environments

Mortality during emergence in two species of dragonfly, Onychogomphus uncatus and Orthetrum coerulescens, was studied at a Mediterranean irrigation canal in France. Overall mortality was 5.2% (n=1901) and 5.7% (n=611), respectively. Predation was low in both species. The prime cause of mortality was incomplete ecdysis resulting from different factors among which heavy wind was the most important in O. coerulescens and lack of suitable emergence supports in O. uncatus. Besides data on mortality the emergence curves of both species are provided.

Successful management practices for declining bird species depend often on long-term surveys acquired by point counts. Despite high standardization of field protocols, uncertain detection probability remains an important source of variability and bias in point-count data. This effect is of main importance in low-responsive species as the Red-legged partridge (Alectoris rufa), but it can be counterbalanced, increasing detection probability. In this 2-year study, we sampled using traditional point-count methods, followed by playback sessions for each repetition. We measured detection probability and the efficiency of playback for detectability in the context of a feasibility study on long-term point-count surveys for a harvested game bird, the Red-legged partridge. The results for both study years show a distinct increase in detection probability (23% and 45%, respectively) when using playback vs. the traditional point-count method. We also tested our results for heterogeneity, trap dependence, and time dependence, and no effect was detected. Thus, we suggest that the future design of long-term surveys on Red-legged partridges should consider abundance indices using playback sessions.