caa a22 4500 388036338 CHVBK 20180307125005.0 cr unu---uuuuu 161130e199810 xx s 000 0 eng 10.1017/S0007485300026043 doi S0007485300026043 pii (NATIONALLICENCE)cambridge-10.1017/S0007485300026043 Evidence of density-dependent oviposition behaviour by Listronotus bonariensis (Coleoptera: Curculionidae) in Canterbury pasture [Elektronische Daten] Argentine stem weevil (Listronotus bonariensis) (Kuschel) is a pasture pest of Lolium spp. in New Zealand and is the target of a classical biological control programme using the parasitoid Microctonus hyperodae Loan. However, laboratory experiments have indicated a strong density-dependent egg laying response which may have important implications for the biological control effort. Two field experiments were conducted using a manipulated range of weevil densities within 2.0-2.4 m-2 field enclosures and oviposition activity measured by weekly sampling of grass tillers within the enclosures. In both experiments, density had no effect on general oviposition behaviour although the percentage of tillers found to be infested with eggs increased significantly at higher densities. In experiment 1, L. bonariensis exhibited strong density-dependent oviposition with a significant decline in eggs/tiller/female with increasing adult density. An initial population of five L. bonariensis m−2 oviposited 32 times more eggs/tiller/female than 200 L. bonariensis m−2. By comparison, density-dependent oviposition was absent in experiment 2 with eggs/tiller/female comparable for all densities. The dramatic difference between the two experiments in the expression of density-dependent oviposition was attributed to prevailing spring temperatures during the sampling interval, which in the second experiment were much cooler and delayed the onset of egg laying. It is probable that in experiment 2, oviposition was not regulated by density-dependent cues but limited by temperature and age related mortality in the adult population. The mechanism for density-dependent oviposition, its occurrence in the field and impact on the effectiveness of the parasitoid M. hyperodae are discussed. Copyright © Cambridge University Press 1998 McNeill M.R. AgResearch, Canterbury Agriculture and Science Centre, PO Box 60, Lincoln, New Zealand Baird D.B. AgResearch, Canterbury Agriculture and Science Centre, PO Box 60, Lincoln, New Zealand Goldson S.L. AgResearch, Canterbury Agriculture and Science Centre, PO Box 60, Lincoln, New Zealand Bulletin of Entomological Research Cambridge University Press 88/5(1998-10), 527-536 0007-4853 88:5<527 1998 88 BER https://doi.org/10.1017/S0007485300026043 text/html Onlinezugriff via DOI 1 review-article jats NATIONALLICENCE 856 40 https://doi.org/10.1017/S0007485300026043 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- McNeill M.R. AgResearch, Canterbury Agriculture and Science Centre, PO Box 60, Lincoln, New Zealand NATIONALLICENCE 700 1- Baird D.B. AgResearch, Canterbury Agriculture and Science Centre, PO Box 60, Lincoln, New Zealand NATIONALLICENCE 700 1- Goldson S.L. AgResearch, Canterbury Agriculture and Science Centre, PO Box 60, Lincoln, New Zealand NATIONALLICENCE 773 0- Bulletin of Entomological Research Cambridge University Press 88/5(1998-10), 527-536 0007-4853 88:5<527 1998 88 BER CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge