The influence of infection status and parasitism risk on host dispersal and susceptibility to infection inDrosophila nigrospiracula

Abstract

For many organisms, habitat avoidance provides the first line of defence against parasitic infection. Changes in infection status can shift the cost-benefit ratio of remaining in a given habitat vs dispersing. The aim of this study was to test the hypothesis that the propensity to disperse in Drosophila nigrospiracula is mediated by current parasite load and the risk of further infection by an ectoparasitic mite (Macrocheles subbadius). An activity monitor was used to assess dispersal propensity among infected and uninfected flies. The activity level of uninfected females increased threefold upon exposure to a mite, whereas the activity among uninfected males increased by 17-fold in the presence of a questing mite. Among infected flies, the risk of further infection also generated a change in activity, but the magnitude of the response was dependent on host sex. Current infection status influenced the probability of acquiring more parasites due to increased susceptibility to infection with mite load. The probability of acquiring additional mites among males increased more rapidly compared to female flies. Current infection status can potentially determine the risk of further infection, the host propensity and ability to disperse, with consequence for hosts and parasites at the individual, population and species level.

Fight not flight: parasites drive the bacterial evolution of resistance, not escape

“…To our knowledge, this field has nearly-exclusively focused on multicellular host species (Gibson and Amoroso 2022), where avoidance is fairly evolvable (Gibson and Amoroso 2022), and can be a low-cost and effective strategy (Kiesecker et al 1999; Taylor et al 2004; Daly and Johnson 2011). Multicellular hosts have been found to avoid parasites by limiting behavior that could expose them to parasites (Stephenson et al 2018; Paciência et al 2019), or by dispersing to escape local threats of parasitism (Sloggett and Weisser 2002; Fill et al 2012; Baines et al 2020; Brophy and Luong 2021; Zilio et al 2021). In contrast, microbes have only previously been found to avoid parasites by limiting swarming that could expose them to parasites (Bru et al 2019), and our work suggests that the evolution of escape may be rare or non-existent in microbes.…”

“…In fact, examples of parasite avoidance are common. For instance, the presence of parasitoid wasps causes aphids to produce more highly-dispersing offspring (Sloggett and Weisser 2002), and the presence of parasites induces greater dispersal in back-swimmers (Baines et al 2020), Drosophila (Brophy and Luong 2021), and freshwater protists (Zilio et al 2021).…”

“…In fact, examples of parasite avoidance are common. For instance, many organisms will avoid behavior that could expose them to parasites (Stephenson et al 2018; Paciência et al 2019), while others will use dispersal as a mechanism to escape the local threat of parasitism (Sloggett and Weisser 2002; Fill et al 2012; Baines et al 2020; Brophy and Luong 2021; Zilio et al 2021).…”

CO2 scrubbing, zero gases, Keeling plots, and a mathematical approach to ameliorate the deleterious effects of ambient CO2 during 13C breath testing in humans and animals

“…Chemical scrubbing of CO 2 from a stream of incurrent air (e.g., using Ascarite™, soda lime, or 13A molecular sieve beads) is common in VCO 2 studies especially when animal metabolic rates are low or when flow rates through a metabolic chamber are relatively high 110–114 . Unfortunately, this approach requires periodic replacement of exhausted chemicals (Figure 2B).…”

“…Ascarite™, soda lime, or 13A molecular sieve beads) is common in VCO 2 studies especially when animal metabolic rates are low or when flow rates through a metabolic chamber are relatively high. [110][111][112][113][114] Unfortunately, this approach requires periodic replacement of exhausted chemicals (Figure 2B). Moreover, the volumes of air that can be pushed (or pulled) through scrubber columns is generally limited to less than $5-10 LPM.…”