Spotlight on the invasion of a carabid beetle on an oceanic island over a 105-year period island

The flightless beetle Merizodus soledadinus, native to the Falkland Islands and southern South America, was introduced to the sub-Antarctic Kerguelen Islands in the early Twentieth Century. Using available literature data, in addition to collecting more than 2000 new survey (presence/absence) records of M. soledadinus over the 1991–2018 period, we confirmed the best estimate of the introduction date of M. soledadinus to the archipelago, and tracked subsequent changes in its abundance and geographical distribution. The range expansion of this flightless insect was initially slow, but has accelerated over the past 2 decades, in parallel with increased local abundance. Human activities may have facilitated further local colonization by M. soledadinus, which is now widespread in the eastern part of the archipelago. This predatory insect is a major threat to the native invertebrate fauna, in particular to the endemic wingless flies Anatalanta aptera and Calycopteryx moseleyi which can be locally eliminated by the beetle. Our distribution data also suggest an accelerating role of climate change in the range expansion of M. soledadinus, with populations now thriving in low altitude habitats. Considering that no control measures, let alone eradication, are practicable, it is essential to limit any further local range expansion of this aggressively invasive insect through human assistance. This study confirms the crucial importance of long term biosurveillance for the detection and monitoring of non-native species and the timely implementation of control measures

The alien beetle Oopterus soledadinus (Coleoptera: Carabidae) in the Kerguelen islands: a major threat to native arthropod communities.

12-14/07/200

The alien beetle Oopterus soledadinus (Coleoptera: Carabidae) in the Kerguelen islands: a major threat to native arthropod communities.

12-14/07/200

The alien beetle Oopterus soledadinus (Coleoptera: Carabidae) in the Kerguelen Islands: a major threat to native invertebrate communities?

Poste

Impact of the insecticide Alphacypermetrine and herbicide Oxadiazon, used singly or in combination, on the most abundant frog in French rice fields, Pelophylax perezi

International audienceThe potential impact of agricultural pesticides is a major concern with regard to biodiversity conservation. Pesticides are considered as one of the main causes of the worldwide decline of Amphibians. They are rarely used singly, but their cumulative impact and interaction are often neglected, as is the importance of the age or stage of the animal on which the impact of the molecules is assessed. We therefore tested the potential cumulative impact of the only authorized insecticide (Alphacypermetrine) and the main herbicide (Oxadiazon) used in French rice fields on four replicates of 25 eggs, young larvae and prometamorphosis tadpoles of the most abundant frog in paddies (Pelophylax perezi). We found no significant effect of the insecticide and herbicide, used singly or in combination, on hatching and young tadpoles. However, we found a strong impact of insecticide and herbicide used singly and a highly deleterious impact of their combined use on prometamorphosis tadpoles. Among the four replicates, only one of the prometamorphosis tadpoles did not reach this adult stage in the control against 9, 9, 6, 4 and 13, 9, 8, 7 with the herbicide and insecticide, respectively. But when the two pesticides were used in combination, only two prometamorphosis tapdoles reached the adult stage. Our results emphasize the potential impact on amphibians of pesticides used in agriculture and highlight the necessity of testing their role as cocktails. They also stress the importance of the age and/or stage of the target organism, the choice of which can lead to contrasting conclusions. Finally, our results suggest a possible underestimation of the impact of pesticides on non-targeted fauna in the rice fields in particular, and on living organisms in general. (C) 2016 Elsevier B.V. All rights reserved

Oviposition plant choice maximizes offspring fitness in an aquatic predatory insect

© 2018, Springer International Publishing AG, part of Springer Nature. Evidence for the adaptive value of oviposition site selection in terms of increased offspring fitness is rare in predatory insects. We tested this in the damselfly Lestes macrostigma that prefers the plant Bolboschoenus maritimus. We carried out two experiments with shoots containing eggs: we flooded (1) some shoots of the same type (i.e. combination of species and desiccation state) at different dates and (2) different shoot types at the same date. Earlier flooding increased hatching success. Because B. maritimus grows in deeper parts of temporary ponds, it is flooded before other plants after the drought season, suggesting that adult oviposition site selection is driven by lower egg desiccation risk. Independently of flooding date, hatching success was higher and larvae hatched earlier when eggs were laid in B. maritimus. Faster embryonic development enhances chances to complete larval development before pond desiccation and reduces costs associated with time stress. Offspring higher fitness was more constant between shoots of B. maritimus compared to the other types of shoot, suggesting that laying eggs in one shoot of this plant leads offspring to high fitness more surely. Our results indicate that adults choose oviposition plants maximizing offspring fitness (higher hatching success and faster embryonic development).status: publishe

Monitoring amphibian species with complex chromatophore patterns: a non- invasive approach with an evaluation of software effectiveness and reliability

International audienceThe estimation of demographic parameters in wild populations is strengthened by individual identification. For amphibians, various techniques are used to either temporarily or permanently mark individuals for identification. Photo-identification of body patterns offers a non-invasive technique. However, the reliability of photo-recognition software is key to the reliable estimation of the true demographic parameters. In the current study, we assessed the effectiveness of fully-automated and semi-automated software: Wild-ID and APHIS. We used the cryptic salamander Hydromantes strinatii as our study species. We used the False Rejection Rate (FRR) of Top 1, Top 5 and Top 10 matches of chest and cloaca pictures. Finally, we assessed the bias induced by our FRR for the estimation of population size through simulation. Wild-ID FRRs ranged from 0.042 to 0.093 while APHIS' ranged from 0.227 to 0.547. Wild-ID was equally efficient with pictures from the chest and from the cloaca, while APHIS was significantly more efficient with chest pictures than cloaca pictures. Cropping pictures did not significantly improve Wild-ID effectiveness. Our Wild-ID FRRs are among the lowest ever obtained from pictures of an amphibian with a complex chromatophore pattern. Simulation showed that the Top 10 FRR from selected software Wild-ID induced a low bias 2.7% on the estimation of population size. The effectiveness and plasticity of Wild-ID provides opportunities for reliably monitoring amphibian species with complex colour pattern

Susceptibility to a metal under global warming is shaped by thermal adaptation along a latitudinal gradient

Global warming and contamination represent two major threats to biodiversity that have the potential to interact synergistically. There is the potential for gradual local thermal adaptation and dispersal to higher latitudes to mitigate the susceptibility of organisms to contaminants and global warming at high latitudes. Here, we applied a space-for-time substitution approach to study the thermal dependence of the susceptibility of Ischnura elegans damselfly larvae to zinc in a common garden warming experiment (20 and 24 °C) with replicated populations from three latitudes spanning >1500 km in Europe. We observed a striking latitude-specific effect of temperature on the zinc-induced mortality pattern; local thermal adaptation along the latitudinal gradient made Swedish, but not French, damselfly larvae more susceptible to zinc at 24 °C. Latitude- and temperature-specific differences in zinc susceptibility may be related to the amount of energy available to defend against and repair damage since Swedish larvae showed a much stronger zinc-induced reduction of food intake at 24 °C. The pattern of local thermal adaptation indicates that the predicted temperature increase of 4 °C by 2100 will strongly magnify the impact of a contaminant such as zinc at higher latitudes unless there is thermal evolution and/or migration of lower latitude genotypes. Our results underscore the critical importance of studying the susceptibility to contaminants under realistic warming scenarios taking into account local thermal adaptation across natural temperature gradients.status: publishe