Imperfect diet choice reduces the performance of a predatory mite.

Two mutually unexclusive hypotheses prevail in the theory of nutritional ecology: the balanced diet hypothesis states that consumers feed on different food items because they have complementary nutrient and energy compositions. The toxin-dilution hypothesis poses that consumers feed on different food items to dilute the toxins present in each. Both predict that consumers should not feed on low-quality food when ample high-quality food forming a complete diet is present.

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

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.

Spatial patterns generated by simultaneous cooperation and exploitation favour the evolution of altruism.

In kin selection theory in the evolution of social behaviours, the relatedness between interacting individuals is influenced by the spatial structure of the population. It is generally considered that in the 'viscous' population competition among individuals tends to suppress the evolution of altruism. We consider that more complex interactions produce specific spatial patterns in the presence of competitive interaction, which could alter the process of kin selection in a given space.

Predatory interactions between prey affect patch selection by predators.

Abstract: When predators can use several prey species as food sources, they are known to select prey according to foraging efficiency and food quality. However, interactions between the prey species may also affect prey choice, and this has received limited attention. The effect of one such interaction, intraguild predation between prey, on patch selection by predators was studied here.

The role of web sharing, species recognition and host-plant defence in interspecific competition between two herbivorous mite species.

When competing with indigenous species, invasive species face a problem, because they typically start with a few colonizers. Evidently, some species succeeded, begging an answer to the question how they invade. Here, we investigate how the invasive spider mite Tetranychus evansi interacts with the indigenous species T.

No adaptation of a herbivore to a novel host but loss of adaptation to its native host.

Most herbivorous arthropods are host specialists and the question is which mechanisms drive the evolution of such specialization. The theory of antagonistic pleiotropy suggests that there is a trade-off between adaptation of herbivores to a novel host and their native host. The mutation accumulation hypothesis proposes that herbivores on a novel host lose their adaptation to the native host through the accumulation of mutations with negligible effects on performance on the novel host.

Cry-wolf signals emerging from coevolutionary feedbacks in a tritrophic system.

For a communication system to be stable, senders should convey honest information. Providing dishonest information, however, can be advantageous to senders, which imposes a constraint on the evolution of communication systems. Beyond single populations and bitrophic systems, one may ask whether stable communication systems can evolve in multitrophic systems.

Why do males choose heterospecific females in the red spider mite?

In some species, males readily show courtship behaviour towards heterospecific females and even prefer them to females of their own species. This behaviour is generally explained by indiscriminate mating to acquire more mates, but may partly be explained by male mate preference mechanisms that have developed to choose among conspecific females, as male preference for larger females causes mating with larger heterospecific females. Recently, we found that males of the red spider mite, Tetranychus evansi collected from Spain (invasive population), prefer to mate with females of the two-spotted spider mite, T.

Distribution and oviposition site selection by predatory mites in the presence of intraguild predators.

When intraguild prey and intraguild predators feed and reproduce in the same habitat and relatively immobile juveniles are the vulnerable stage, predation risk depends on oviposition site selection by the adult females. We studied how the availability of oviposition sites affected the distribution of two predatory mite species, Neoseiulus cucumeris (Oudemans) and Iphiseius degenerans (Berlese), over two patches that both contained food. The two plant-inhabiting species feed on pollen and thrips, prey on each other's juveniles, and prefer to oviposit on hairy parts of the leaf.

Plant Resources as a Factor Altering Emergent Multi-Predator Effects.

Multiple predator effects (MPEs) can modify the strength of pest regulation, causing positive or negative deviations from those that are predicted from independent effects of isolated predators. Despite increasing evidence that omnivory can shape predator-prey interactions, few studies have examined the impact of alternative plant food on interactions between multiple predators. In the present study, we examined the effects and interactions of two omnivorous mirids, Μacrolophus pygmaeus and Nesidiocoris tenuis, on different densities of their aphid prey, Myzus persicae.

Beyond Predation: The Zoophytophagous Predator Macrolophus pygmaeus Induces Tomato Resistance against Spider Mites.

Many predatory insects that prey on herbivores also feed on the plant, but it is unknown whether plants affect the performance of herbivores by responding to this phytophagy with defence induction. We investigate whether the prior presence of the omnivorous predator Macrolophus pygmaeus (Rambur) on tomato plants affects plant resistance against two different herbivore species. Besides plant-mediated effects of M.

Incomplete premating and postmating reproductive barriers between two parapatric populations of a social spider mite.

Closely related species with overlapping distributions often show premating reproductive barriers to avoid hybridization. Stigmaeopsis miscanthi (Saito) is a social spider mite infesting Chinese silver grass, and the species consists of two parapatric groups with frequent contacts within the contact zone. They differ in male-male aggressiveness, male morphology, female diapause traits, and life history parameters.

Defense suppression benefits herbivores that have a monopoly on their feeding site but can backfire within natural communities.

Background: Plants have inducible defenses to combat attacking organisms. Hence, some herbivores have adapted to suppress these defenses. Suppression of plant defenses has been shown to benefit herbivores by boosting their growth and reproductive performance.

Spider mites suppress tomato defenses downstream of jasmonate and salicylate independently of hormonal crosstalk.

Plants respond to herbivory by mounting a defense. Some plant-eating spider mites (Tetranychus spp.) have adapted to plant defenses to maintain a high reproductive performance.

Effects of kinship or familiarity? Small thrips larvae experience lower predation risk only in groups of mixed-size siblings.

In many species of insects, larvae are distributed in an aggregated fashion. As they may differ in size and size matters to predation risk, small larvae may be less likely to fall prey to predators when near large and therefore better-defended larvae. We hypothesize that the small larvae may profit even more when these large larvae are siblings.

The endosymbionts Wolbachia and Cardinium and their effects in three populations of the predatory mite Neoseiulus paspalivorus.

Whereas endosymbiont-induced incompatibility is known to occur in various arthropod taxa, such as spider mites, insects and isopods, it has been rarely reported in plant-inhabiting predatory mites (Acari: Phytoseiidae). Recent cross-breeding studies with the phytoseiid mite Neoseiulus paspalivorus De Leon revealed a complete post-mating reproductive isolation between specimens collected from three geographic origins-Northeast Brazil (South America), Benin and Ghana (West Africa)-even though they are morphologically similar. We carried out a study to assess to what extent these populations exhibit genetic differences and whether endosymbionts are involved in the incompatibility.

Male-male aggression peaks at intermediate relatedness in a social spider mite.

Theory predicts that when individuals live in groups or colonies, male-male aggression peaks at intermediate levels of local average relatedness. Assuming that aggression is costly and directed toward nonrelatives and that competition for reproduction acts within the colony, benefits of aggressive behavior are maximized in colonies with a mix of related and unrelated competitors because aggression hurts nonkin often, thereby favoring reproduction of kin. This leads to a dome-shaped relation between male-male aggression and average relatedness.

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

Apart from interacting, prey and predators may also avoid each other by moving into refuges where they lack food, yet survive by switching to an energy-saving physiological state. Lotka-Volterra models of predator-prey interactions ignore this option. Therefore, we have modelled this game of 'joining versus opting out' by extending Lotka-Volterra models to include portions of populations not in interaction and with different energy dynamics.

Neoseiulus paspalivorus, a predator from coconut, as a candidate for controlling dry bulb mites infesting stored tulip bulbs.

The dry bulb mite, Aceria tulipae, is the most important pest of stored tulip bulbs in The Netherlands. This tiny, eriophyoid mite hides in the narrow space between scales in the interior of the bulb. To achieve biological control of this hidden pest, candidate predators small enough to move in between the bulb scales are required.

Single versus multiple enemies and the impact on biological control of spider mites in cassava fields in West-Africa.

To determine whether to use single or multiple predator species for biological pest control requires manipulative field experiments. We performed such tests in Benin (West Africa) in cassava fields infested by the cassava green mite Mononychellus tanajoa, and the cotton red mite Oligonychus gossypii. These fields also harboured the cassava apex-inhabiting predator Typhlodromalus aripo and either the leaf-inhabiting predator Amblydromalus manihoti or Euseius fustis.

Generalist red velvet mite predator (Balaustium sp.) performs better on a mixed diet.

Generalist predators have the potential advantage to control more than one pest and to be more persistent than specialist predators because they can survive on different foods. Moreover, their population growth rate may be elevated when offered a mixture of prey species. We studied a generalist predatory mite Balaustium sp.

Females as intraguild predators of males in cross-pairing experiments with phytoseiid mites.

Studies on intraguild interactions between phytoseiid species have shown that intraguild predation occurs and is most commonly manifested as adult females of one species feeding on juveniles of another. Whether such intraguild interactions can also occur between adult females of one species and adult males of another, is not known. Herein, we report on intraguild interactions between adults of the two sexes in cross-pairing experiments involving three related phytoseiid species (Neoseiulus paspalivorus, N.

Human cooperation by lethal group competition.

Why humans are prone to cooperate puzzles biologists, psychologists and economists alike. Between-group conflict has been hypothesized to drive within-group cooperation. However, such conflicts did not have lasting effects in laboratory experiments, because they were about luxury goods, not needed for survival ("looting").