Phylogeny affects host's weight, immune response and parasitism in damselflies and dragonflies

Abstract

Host–parasite interactions are an intriguing part of ecology, and understanding how hosts are able to withstand parasitic attacks, e.g. by allocating resources to immune defence, is important. Damselflies and dragonflies show a variety of parasitism patterns, but large-scale comparative immune defence studies are rare, and it is difficult to say what the interplay is between their immune defence and parasitism. The aim of this study was to find whether there are differences in immune response between different damselfly and dragonfly species and whether these could explain their levels of gregarine and water mite parasitism. Using an artificial pathogen, a piece of nylon filament, we measured the encapsulation response of 22 different damselfly and dragonfly species and found that (i) there are significant encapsulation differences between species, (ii) body mass has a strong association with encapsulation and parasite prevalences, (iii) body mass shows a strong phylogenetic signal, whereas encapsulation response and gregarine and water mite prevalences show weak signals, and (iv) associations between the traits are affected by phylogeny. We do not know what the relationship is between these four traits, but it seems clear that phylogeny plays a role in determining parasitism levels of damselflies and dragonflies.

Chronic Exposure to High Concentrations of Road Salt Decreases the Immune Response of Dragonfly Larvae

“…To test how different levels of salinization from road salt affected the level of melanization of a simulated parasite, A. junius larvae were injected with 1 mm sanded monofilaments (diameter 0.20 mm) using a single-shot tag injector (Northwest Marine Technology, Inc.). This approach provides a standard measure of this aspect of immune function (Köning and Schmid-Hempel, 1995;Rantala and Roff, 2007), and has been used successfully in odonate larvae (e.g., Nagel et al, 2011;Duong and McCauley, 2016;Ilvonen and Suhonen, 2016).…”

Threats from the air: Damselfly predation on diverse prey taxa

“…Damselflies tend to discard less nutritious parts of their prey before ingestion (reviewed in Corbet, ), thus reducing their representation in the faecal DNA contents. Furthermore, our focal damselfly species are among the smallest odonates, whereas, for example, another rather common dragonfly of our study area, the Brown Hawker Aeshna grandis (Linnaeus, 1758), has a body mass of nearly a gram (mean 873.1 mg, SE = 29.5, n = 25; Ilvonen & Suhonen, ). As a consequence of their heavier bodies, larger dragonflies will most likely consume prey in considerably higher numbers and/or mass than their smaller relatives.…”

“…To derive estimates of W i , we used estimates published by Ilvonen and Suhonen (), according to whom the weights of our focal damselflies C. hastulatum , C. pulchellum and E. cyathigerum , are 33.9 mg ( SE = 1.3, n = 22), 36.1 mg ( SE = 1.3, n = 22) and 35.4 mg ( SE = 1.3, n = 22), respectively. The fourth focal damselfly species, C. lunulatum, was not directly weighed, but since its average length exactly matches that of C. hastulatum (Karjalainen, ), we used the weight (and SE ) of that species as accurate proxies.…”

Population‐level variation of digestive physiology costs of mounting an immune response in damselflies

“…For both the puncture and implant treatments, we used a 0.5‐μl syringe (7000; Hamilton Company, Reno, Nevada) to penetrate the second abdominal pleura on the dorsal side of the sternal–tergal margin, which has been shown to generate a melanisation response in damselfly larvae (Iloven & Suhonen, ; Fig. ).…”