Influence of intraguild predation among generalist insect predators on the suppression of an herbivore population

Abstract

We evaluated the influence of intraguild predation among generalist insect predators on the suppression of an herbivore, the aphid Aphis gossypii, to test the appropriateness of the simple three trophic level model proposed by Hairston, Smith, and Slobodkin (1960). We manipulated components of the predator community, including three hemipteran predators and larvae of the predatory green lacewing Chrysoperla carnea, in field enclosure/exclosure experiments to address four questions: (1) Do generalist hemipteran predators feed on C. carnea? (2) Does intraguild predation (IGP) represent a substantial source of mortality for C. carnea? (3) Do predator species act in an independent, additive manner, or do significant interactions occur? (4) Can the experimental addition of some predators result in increased densities of aphids through a trophic cascade effect? Direct observations of predation in the field demonstrated that several generalist predators consume C. carnea and other carnivorous arthropods. Severely reduced survivorship of lacewing larvae in the presence of other predators showed that IGP was a major source of mortality. Decreased survival of lacewing larvae was primarily a result of predation rather than competition. IGP created significant interactions between the influences of lacewings and either Zelus renardii or Nabis predators on aphid population suppression. Despite the fact that the trophic web was too complex to delineate distinct trophic levels within the predatory arthropod community, some trophic links were sufficiently strong to produce cascades from higher-order carnivores to the level of herbivore population dynamics: experimental addition of either Z. renardii or Nabis predators generated sufficient lacewing larval mortality in one experiment to release aphid populations from regulation by lacewing predators. We conclude that intraguild predation in this system is wide-spread and has potentially important influences on the population dynamics of a key herbivore.

Functional diversity positively affects prey suppression by invertebrate predators: a meta‐analysis

“…Several studies suggest that intraguild predation by generalists on specialist predators can lead to herbivore communities being released from predation (e.g., Rosenheim et al. 1993, Hodge 1999, Snyder and Ives 2001). However, our analysis would suggest that the combination of both generalist and specialist predators in polyculture treatments can lead to greater prey suppression than the mean of the component species.…”

Effects of mass releases of Trichogramma brassicae on predatory insects in maize

“…As T. brassicae is searching efficiently in maize (Babendreier et al, 2003c), we hypothesised that the inundative releases of T. brassicae into maize fields may negatively affect populations of other beneficial insects present in maize, which could in turn lead to increasing pest populations and an increasing use of pesticides. Evidence for such adverse effects on pest control due to intraguild competitors is accumulating (e.g., Dinter, 1998;Yasuda & Kimura, 2001), and Rosenheim et al (1993) have also shown that the experimental addition of top predators such as Zelus renardii (Kolenati) (Hemiptera: Reduviidae) or Nabis spp. (Hemiptera: Nabidae) caused sufficient predation on C. carnea to release aphid populations from regulation.…”

Lutter contre les insectes nuisibles en agriculture biologique : intervenir en harmonie face à la complexité

“…En effet, l'efficacité des ennemis naturels peut être affectée par des interactions négatives de type « prédation intraguilde », lorsqu'un ennemi naturel dévore un compétiteur (Lucas et al 1998). À titre d'exemple, dans les champs de coton aux États-Unis, des lâchers de chrysopes effectués pour réduire les populations du puceron du coton ont échoué parce que les prédateurs indigènes ont éliminé les chrysopes (Rosenheim et al 1993). Toutefois, les effets de la prédation intraguilde sur la lutte aux ravageurs ne sont pas nécessairement négatifs, particulièrement dans le cas d'une lutte « inoculative » où la prédation intraguilde peut contribuer à stabiliser le système (Rosenheim et al 1995).…”