Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

Endoparasitic Flies, Pollen-Collection by Bumblebees and a Potential Host-Parasite Conflict

Regula Schmid-Hempel and Paul Schmid-Hempel
Oecologia
Vol. 87, No. 2 (1991), pp. 227-232
Published by: Springer in cooperation with International Association for Ecology
Stable URL: http://www.jstor.org/stable/4219685
Page Count: 6
  • Download ($43.95)
  • Cite this Item
Endoparasitic Flies, Pollen-Collection by Bumblebees and a Potential Host-Parasite Conflict
Preview not available

Abstract

Conopid flies (Conopidae, Diptera) are common larval parasites of bumblebees. The larva develops inside the abdomen of workers, queens and males. Development is completed within 10-12 days after oviposition when the host is killed and the parasite pupates in situ. Development results in parasitised bees becoming unable to carry large loads of nectar, as the conopid larvae reside where the honey crop is normally located. Furthermore, an addition to the bee's unloaden body mass is likely (average larval weight reached at pupation by the common parasite species Sicus ferrugineus: ±SD 36.3±12.3 mg, n=59; by Physocephala rufipes: 55.8±16.9 mg, n=108). We here asked whether the propensity of workers of the bumblebee Bombus pascuorum to collect nectar rather than pollen is related to the presence of conopid larvae. For samples of bees (n=2254 workers) collected over 3 years of field studies in northwestern Switzerland, there was no difference in the frequency of bees caught as pollen collectors among parasitised (38.1% of cases, n=210) as compared to non-parasitised bees (43.9%, n=360) (χ 2 = 1.83, n.s.). However, compared to the non-parasitised bees (n=360), those hosts containing a third (last) instar larva (n=9) were less likely to collect pollen than expected by chance (χ 2 = 6.91, P=0.003). Similarly, hosts with short survival time between capture and being killed by the developing larva (which hence must have harboured a late instar parasite at time of capture) were less likely to collect pollen (8%, n=25) than those found not parasitised (37.6%, n=891) (χ 2 = 9.16, P<0.001). Late instar larvae grow so big that they fill the entire abdomen. Although there was also a tendency for presumably older bees to collect less pollen, this is unlikely to explain the observations. We also discuss whether these changes in foraging behaviour of bumblebees may reflect a host-parasite conflict over the type of resource to be collected.

Page Thumbnails

  • Thumbnail: Page 
[227]
    [227]
  • Thumbnail: Page 
228
    228
  • Thumbnail: Page 
229
    229
  • Thumbnail: Page 
230
    230
  • Thumbnail: Page 
231
    231
  • Thumbnail: Page 
232
    232