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Research article2015Peer reviewedOpen access

Niche separation of pollen beetle parasitoids

Berger, Josef; Jonsson, Martin; Hedlund, Katarina; Anderson, Peter


Species with similar resource requirements are commonly assumed to competitively exclude each other, unless they differentiate their ecological niches. Hence, parasitoid wasps that use the same host species need to find some way to avoid competition. The aim of this study was to identify the role of volatile cues from oilseed rape plants and the larval host in niche separation between three coexisting parasitoid species. We examined howPhradis interstitialis, Phradis morionellusandTersilochus heterocerus, sympatric parasitoids ofBrassicogethes aeneus, differ in their abundances, distribution on buds and flowers, and oviposition behavior in the field. Furthermore, we tested their preferences for odors from uninfested and infested oilseed rape plants in the bud and flowering stage, and their preferences for odors from three developmental stages of pollen beetle larvae in a two-choice olfactometer bioassay.P. interstitialiswas active in the field early in the season, preferred odors of infested buds vs. uninfested, and oviposited into buds which contained only pollen beetle eggs, whileP. morionelluswas active late in the season, preferred odors of infested buds as well as odors of infested flowers over uninfested, and oviposited into buds which contained only larvae.T. heteroceruswas active throughout the season, and preferred odors of infested flowers over uninfested. NeitherPhradisspecies were attracted to larval odors, whereasT. heteroceruswas attracted to odors from first-instar pollen beetle larvae both in the absence of plant odors, and when presented simultaneously with uninfested plant odor. This suggests that the twoPhradisspecies are separated on a temporal scale and that they parasitize different host stages, while the larval parasitoidsP. morionellusandT. heterocerusare separated by choice of microhabitat. The former oviposits into larvae in buds, and the latter in flowers.


niche separation; Tersilochus heterocerus; Phradis interstitialis; Phradis morionellus; pollen beetle

Published in

Frontiers in Ecology and Evolution
2015, Volume: 3, article number: 45