Prey exploitation and dispersal strategies vary among natural populations of a predatory mite

Abstract

When predators commonly overexploit local prey populations, dispersal drives the dynamics in local patches, which together form a metapopulation. Two extremes in a continuum of dispersal strategies are distinguished: the “Killer” strategy, where predators only start dispersing when all prey are eliminated, and the “Milker” strategy, in which predator dispersal occurs irrespective of prey availability. Theory shows that the Milker strategy is not evolutionarily stable if local populations are well connected by dispersal. Using strains of the predatory mite Phytoseiulus persimilis, collected from 11 native populations from coastal areas in Turkey and Sicily, we investigated whether these two strategies occur in nature. In small wind tunnels, we measured dispersal rates and population dynamics of all populations in a system consisting of detached rose leaves, spider mites (Tetranychus urticae) as prey, and P. persimilis. We found significant variation in the exploitation and dispersal strategies among predator populations, but none of the collected strains showed the extreme Killer or Milker strategy. The results suggest that there is genetic variation for prey exploitation and dispersal strategies. Thus, different dispersal strategies in the Milker–Killer continuum may be selected for under natural conditions. This may affect the predator–prey dynamics in local populations and is likely to determine persistence of predator–prey systems at the metapopulation level.

Males cannibalise and females disperse in the predatory mite Phytoseiulus persimilis

“…The spider mite culture was kept on Lima bean plants (Phaseolus lunatus) in a climate room (26 °C, 60% RH and 16L:8D) and was used to maintain the predator cultures described below. We used two lines of P. persimilis that were selected for early and late dispersal (Revynthi 2017). Six rounds of selection were performed to create these lines.…”

“…Here we aim to investigate whether late dispersers indeed cannibalise more than early dispersers, making use of selection lines of P. persimilis that show different dispersal and exploitation strategies (Revynthi 2017), i.e., predators that depart early and late from a patch with spider mite prey. Even though we have information about the dispersal and exploitation strategies of these two selected lines, little is known about their cannibalistic tendencies.…”

Behavioural movement strategies in cyclic models

“…It has been suggested that some individuals do not perform behavioural strategies. This happens because they have not yet learned or, somehow, they cannot put the tactic into practice 34 , 39 , 40 . Therefore, to make the model more realistic, we describe the individual’s ability to execute the tactic by defining a conditioning factor.…”

Founder effects on trans-generational dynamics of closed inbreeding lineages of the predatory mite Phytoseiulus persimilis

“…Obviously, within population lineages exceeded a critical inbreeding coefficient in the F 2 generation (Fig 2), beyond which inbreeding depression effects became similar to those of lineages founded by sib-mated females. At the individual phenotypic level, genetic deficiencies associated with increasing inbreeding levels, may have adversely affected diverse inter-related physiological, life history and/or behavioral traits, such as decreasing general stress resilience, decreasing tolerance of energetic constraints, increasing mortality, prolonging development, decreasing fecundity, decreasing competitive abilities, and promoting the occurrence of cannibalism and dispersal tendencies [27,55,56,57]. Pinpointing the phenotypic mechanisms underlying the differences in performance of isolated lineages emerging from in- and out-bred founders requires additional experimental work.…”