Abstract
Predatory behavior ofMedetera aldrichii Wheeler (Dolichopodidae) larvae was observed in bark-Lucite sandwiches infested with immature broods of the bark beetle preyDendroctonus pseudotsugae Hopkins (Scolytidae). Predator larvae could not penetrate unmined phloem or prey galleries tightly packed with frass, but moved through loose frass and bark-Lucite interspaces formed when the mined inner bark dried. At high prey densities interspace formation and gallerly contiguity enabled the predator to move freely and attack several prey in rapid succession. At low prey densities the predator was frequently isolated from prey by impenetrable strips of phloem.
Predator larvae maintained singly in small plastic arenas consumed an average of 14.7 immature prey, but required only 6.2 prey when reared exclusively on large prey.
Résumé
Le comportement de prédation des larves deMedetera aldrichii Wheeler a été étudié dans des sandwichs d'écorce et de lucite infestés par les stades juvéniles de leur proie, le scolyteDendroctonus pseudotsugae Hopkins. Les larves du prédateur ne peuvent pas pénétrer dans le phloème sans galeries ou dans les galeries hermétiquement remplies de déjections, mais elles se déplacent à travers des déjections lâches ainsi que dans les espaces entre l'écorce et la lucite qui se forment lorsque l'écorce minée à l'intérieur se dessèche. Pour des densités importantes en proies la formation de ces espaces et la contiguïté des galeries permettent au prédateur de se déplacer librement et d'attaquer plusieurs proies rapidement les unes après les autres. Pour des densités faibles en proies le prédateur se trouve fréquemment isolé de la proie par des bandes de phloème impénétrables. Les larves du prédateur placées isolément dans de petites boîtes en matières platique consomment une moyenne de 14,7 proies jeunes mais ont besoin seulement de 6,2 proies lorsqu'elles sont élevées exclusivement avec de grosses proies.
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Technical Paper No. 3889, Oregon Agricultural Experiment Station. Research supported in part by National Science Foundation, Grants GB-1420 and GB-5496.
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Nagel, W.P., Fitzgerald, T.D. Medetera aldrichii larval feeding behavior and prey consumption [Dipt.: Dolichopodidae]. Entomophaga 20, 121–127 (1975). https://doi.org/10.1007/BF02373458
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DOI: https://doi.org/10.1007/BF02373458