Preference and Prey Switching in a Generalist Predator Attacking Local and Invasive Alien Pests

Abstract

Invasive pest species may strongly affect biotic interactions in agro-ecosystems. The ability of generalist predators to prey on new invasive pests may result in drastic changes in the population dynamics of local pest species owing to predator-mediated indirect interactions among prey. On a short time scale, the nature and strength of such indirect interactions depend largely on preferences between prey and on predator behavior patterns. Under laboratory conditions we evaluated the prey preference of the generalist predator Macrolophus pygmaeus Rambur (Heteroptera: Miridae) when it encounters simultaneously the local tomato pest Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) and the invasive alien pest Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae). We tested various ratios of local vs. alien prey numbers, measuring switching by the predator from one prey to the other, and assessing what conditions (e.g. prey species abundance and prey development stage) may favor such prey switching. The total predation activity of M. pygmaeus was affected by the presence of T. absoluta in the prey complex with an opposite effect when comparing adult and juvenile predators. The predator showed similar preference toward T. absoluta eggs and B. tabaci nymphs, but T. absoluta larvae were clearly less attacked. However, prey preference strongly depended on prey relative abundance with a disproportionately high predation on the most abundant prey and disproportionately low predation on the rarest prey. Together with the findings of a recent companion study (Bompard et al. 2013, Population Ecology), the insight obtained on M. pygmaeus prey switching may be useful for Integrated Pest Management in tomato crops, notably for optimal simultaneous management of B. tabaci and T. absoluta, which very frequently co-occur on tomato.

New parasitoid-predator associations: female parasitoids do not avoid competition with generalist predators when sharing invasive prey

“…It parasitizes the four T. absoluta larvae instars, with a preference for the second and third instars (Chailleux et al 2014). The predator Macrolophus pygmaeus Rambur (Hemiptera: Miridae) is a native generalist omnivorous predator that feeds on eggs and occasionally on T. absoluta young larvae by extracting hemolymph through the larva cuticle (through a stylet mouthpart) (Urbaneja et al 2009;Jaworski et al 2013). The objectives of this study were (i) to characterize interference competition between the larval parasitoid and the generalist omnivorous predator and (ii) to assess any predator avoidance behavior by naive parasitoid females which had never previously encountered the generalist omnivorous predator.…”

Developmental biology and prey preference of Diomus notescens Blackburn (Coleoptera: Coccinellidae): A predator of Aphis gossypii Glover (Hemiptera: Aphididae)

“…Predator preference was calculated by applying the following formula to the data, which is a specific case of Manly's preference index (Manly, 1974 (Jaworski et al, 2013). Differences in development time of each immature stage at each temperature were tested for significance by ANOVA using a general linear model.…”

“…Switching in response to changing prey densities does occur in some species, for example the adults of the generalist predator Macrolophus pygmaeus Rambur will switch to the most abundant prey when offered both B. tabaci and the alternative prey Tuta absoluta (Meyrick) (Jaworski et al, 2013). In another predatory mirid, Macrolophus caliginosus Wagner prey preference for Trialeurodes vaporariorum Westwood eggs increases with increasing proportions of this prey type, when present with Tetranychus urticae Koch eggs (Enkegaard et al, 2001).…”

“…Prey preference is largely due to trade-offs between various mechanisms, including the ease of attacking the prey and their nutritional value (Eubanks and Denno, 2000;Jaworski et al, 2013). The ease at which prey are attacked is due to various factors, including capacity to detect prey, access to the prey, defence responses of the prey against predation, and the capacity of the predator to effectively feed on the prey (Jaworski et al, 2013). Both B. tabaci eggs and A. gossypii nymphs appeared to be easy for D. notescens to find and prey on.…”

Foraging behaviour of the parasitoid Eretmocerus eremicus under intraguild predation risk by Macrolophus pygmaeus

“…33,34 It is a generalist predator, and, among other exploitable prey, it feeds on all stages of whiteflies, from eggs through adults. 31,35 Depending on the feeding and thermal regimes, M. pygmaeus females can oviposit up to 150 eggs and live for 40 days. 36 In addition, this predator species can exert IGP over parasitoids (e.g.…”