Drosophila melanogaster wounding in the wild

Wounding occurs across multicellular organisms. Wounds can affect host mobility and reproduction, with ecological consequences for competitive interactions and predator-prey dynamics. Wounds are also entry points for pathogens. An immune response is activated upon injury, resulting in the deposition of the brown-black pigment melanin in insects. Despite the abundance of immunity studies in the lab and the potential ecological and evolutionary implications of wounding, the prevalence of wounding in wild-collected insects is rarely systematically explored. We investigated the prevalence and potential causes of wounds in wild-collected Drosophilidae flies. We found that 31% of Drosophila melanogaster were wounded or damaged. The abdomen was the most frequently wounded body part, and females were more likely to have melanised patches on the ventral abdomen, compared to males. Encapsulated parasitoid egg frequency was approximately ten percent, and just under one percent of Drosophilidae species had attached mites, which also caused wounds. Wounding is prevalent in D. melanogaster, likely exerting selection pressure on host immunity for two reasons: on a rapid and efficient wound repair, and on responding efficiently to opportunistic infections. Wounding is thus expected to be an important driver of immune system evolution and to affect individual fitness and population dynamics.

Methods
The data were obtained from wild-collected flies. Collections were made in three collection periods, from three sites in Berlin and Brandenburg, Germany. For full details see the methods described in Subasi, Grabe, Kaltenpoth, Rolff & Armitage. How frequently are insects wounded in the wild? A case study using Drosophila melanogaster.