Diapause incidence in the two-spotted spider mite increases due to predator presence, not due to selective predation

Abstract

Diapause incidence in the two-spotted spider mite increases due to predator presence, not due to selective predation. Kroon, A.; Veenendaal, R.L.; Egas, C.J.M.; Bruin, J.; Sabelis, M.W. (2005). Diapause incidence in the twospotted spider mite increases due to predator presence, not due to selective predation. Experimental and Applied Acarology, 35, 73-81. DOI: 10.1007/s10493-004-1980-x General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Abstract. We recently reported evidence for increased diapause incidence in the spider mite Tetranychus urticae in presence of the predatory mite Typhlodromus pyri. This effect may arise from (1) selective predation on non-diapause spider mites, (2) predator-induced diapause in spider mites, or (3) both. Using a different strain of T. urticae, we first recovered increased diapause incidence in association with predators. Then, we tested for selective feeding in two-choice experiments with equal numbers of non-diapause and diapause spider mites. We found that the predatory mite had a significant preference for the latter. This indicates that increased diapause incidence in association with predatory mites is not due to selective predation. Therefore, predator-mediated physiological induction of diapause seems a more likely explanation. The cues leading to induction appear to relate to the predators, not their effects, since predation simulated by spider-mite removal or puncturing did not significantly affect diapause incidence. Why spider mites benefit from this response, remains an open question. IntroductionIn a previous study we demonstrated that the physical presence of the predatory mite Typhlodromus pyri Scheuten significantly enhanced diapause induction in a Greek strain of the spider mite Tetranychus urticae Koch (Kroon et al. 2004). The proportion of diapause spider mites at long-night photoperiods and 18°C increased by more than 50% in the presence of predatory mites. This higher incidence of diapause could be explained in two ways: either the predators physiologically induce diapause among the surviving female spider mites, or the predators selectively feed on spider mites that do not enter diapause.Using a Dutch strain of spider mites, we test the effect of predators on diapause incidence again, and to what extent th...

Joining or opting out of a Lotka–Volterra game between predators and prey: does the best strategy depend on modelling energy lost and gained?

“…Diapause has always been thought to emerge solely to overcome the winter season and to emerge in response to abiotic factors signalling the onset of the winter season, but it may also emerge in response to food scarcity and/or the risk of being eaten, as recently shown for the case of predator mites and fruit-tree red spider mites (Acari: Phytoseiidae, Tetranychidae) [5][6][7][8][9][10][11][12]. Although empirical proof of these diapause-governing principles is limited, they may well hold generally in ecological interactions.…”

“…This leads us to conclude that the prey's decision to enter diapause is part of a game where the predator is the leader, and the prey needs to find an optimal response to the predator. Another complicating factor is that an early diapause raises the demands on the energy storage of the individual prey mite, which needs to cover a longer period before terminating diapause at the beginning of the next summer season-the energy level at diapause termination will determine the reproductive capacity of the prey mite [11]. Thus, the decision to enter diapause within a year will depend on the current internal energy store of the prey mite, as this will have farreaching consequences for winter survival and reproduction in the summer season of the next year.…”

“Sleeping with the enemy”—predator-induced diapause in a mite

“…Spider mites in refuges do not feed, thus precluding betrayal to their foes by feeding-induced plant signalling. Based on preliminary experiments (Kroon et al 2004(Kroon et al , 2005, we hypothesise that cues associated with predation enhance diapause induction in the two-spotted spider mite (Tetranychus urticae Koch). The ensuing change in metabolism would allow adult females to survive longer without food and to disperse into enemy-free space even if this harbours no food.…”

Spatial and nonspatial evolutionary games and their applications

“…They may then move into refuges that are free of their enemies, but may lack food, and where survival may demand a switch to an energy-saving physiological state, such as the so-called diapause (Danks, 1987;Veerman, 1992). Diapause has always been thought to emerge solely to overcome the winter season and to emerge in response to abiotic factors signaling the onset of the winter season, but it may also emerge in response to food scarcity and/or the risk of predation, as it is believed to happen in the system of the so-called predatory mites (Acari: Phytoseiidae) and the fruit-tree red spider mites (Acari: Tetranychidae; prey mites) (Tauber et al, 1986;Danks, 1987;Veerman, 1992Veerman, , 1994Veerman, , 1985Kroon et al, 2004Kroon et al, , 2005Kroon et al, , 2008. Although empirical proof of these diapause-governing principles is limited, they may well hold more generally for ecological interactions in many other systems.…”

“…As without natural enemies, this diapause emerges in response to abiotic factors signaling the onset of the winter season, such as sufficient night length or low temperatures, it can be relatively easily induced in a greenhouse (Veerman, 1992(Veerman, , 1994. However, using another but similar species of spider mites, the two-spotted spider mite (Acari: Tetranychidae), it was shown that the decision to enter diapause also depends on abundance of its predators during summer (Kroon et al, 2004(Kroon et al, , 2005(Kroon et al, , 2008. From the point of view of the prey mite, going into diapause in response to predation risks makes intuitive sense as it faces a grim future with increasing predator densities and thus an increased risk of death: it may then do better by giving up reproduction, moving away from leaves to twigs and branches, and entering diapause.…”