Beyond Venom and Constriction: Bite Performance and Trophic Ecology in the Genus Drymarchon

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  Beyond Venom and Constriction: Bite Performance and Trophic Ecology in the Genus Drymarchon Abstract Snakes exhibit extreme cranial kinesis that facilitates ingestion of prey with large cross-sectional area, but this ability is widely predicted to reduce bite performance due to decreased structural rigidity. Consequently, most large-bodied snakes rely on envenomation or constriction to subdue prey prior to ingestion. Species within the genus Drymarchon represent a notable exception: these large, non-venomous, non-constricting snakes routinely consume a wide range of prey, including large and potentially dangerous vertebrates, using only simple seizing and pinioning behaviors. Here, we quantify bite performance in three species of Drymarchon ( D. corais, D. couperi, and D. melanurus ), examine morphological predictors of biting performance, compare biting pressure to constriction pressure in similarly sized snakes, and synthesize dietary records across the genus. Our results sh...

Minimising insect mortality during grassland mowing: The potential of insect chasing devices

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Minimising insect mortality during grassland mowing: The potential of insect chasing devices

Abstract

  1. Early and frequent mowing is a threat to grassland arthropods. To date, measures to counteract these losses have largely been limited to extensification concepts, which are not always feasible on intensive grasslands.
  2. One option for insect-friendly mowing is the use of chasing devices, which are designed to chase away arthropods before mowing. Scientific research on their effectiveness is limited to one study on parasitic microhymenoptera. Studies on other groups are lacking.
  3. In a 3-year experiment, we have investigated the effectiveness of three devices, that is, two mechanical flushing bars (truck tarpaulin, hanging down metal brackets) and a blowing device. We tested different driving speeds and distances of the flushing bar from the mower on seven abundant arthropod groups that differ in their escape strategies.
  4. We found the blowing device to be the most effective. At the maximum driving speed of 12 km/h, it had an effect on almost all taxonomic groups studied except Araneae and Hymenoptera. At this speed, the metal bracket flushing bar was only effective on Diptera and Coleoptera. The truck tarpaulin flushing bar was only effective at a low driving speed of 5 km/h, albeit on four out of seven taxa.
  5. Chasing devices have a great potential to deter arthropods prior to mowing, thereby reducing mortality. Whilst a blowing device works at higher speed, mechanical flushing bars have a limited effectiveness (metal brackets) or only work at low speed (truck tarpaulin).
Frank, J., Erhardt, S., Betz, O., M. Steidle, J. L., Böttinger, S., & Sann, M. Minimising insect mortality during grassland mowing: The potential of insect chasing devices. Insect Conservation and Diversity. https://doi.org/10.1111/icad.12854