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Contrasting host: parasitoid synchrony drives differing levels of biocontrol by two introduced Microctonus spp. in northern New Zealand pastures

journal contribution
posted on 2023-05-03, 17:28 authored by Pip GerardPip Gerard, Derrick WilsonDerrick Wilson, Martin UpsdellMartin Upsdell
Two species from the genus Microctonus Wesmael (Hymenoptera: Braconidae) have been introduced into New Zealand as biocontrol agents of pest weevils in pasture. Both parasitoids have similar life cycles and co-exist in pasture along with their respective weevil hosts. However, winter parasitism rates by M. hyperodae Loan are low in comparison to the Irish biotype of M. aethiopoides’ Loan. Population studies at two Waikato sites over three consecutive seasons of parasitoid activity showed that M. aethiopoides recovered from near extinction each spring and built up to effective levels by winter because hosts were available continuously throughout summer and autumn. In contrast, M. hyperodae began each season at higher larval populations and parasitism levels than M. aethiopoides, but populations and parasitism levels declined during late summer and early autumn due to low host availability. The contrast between species is consistent with the high levels of endophyte-conferred pest-resistant grass in the pastures, which impacts strongly on M. hyperodae’s host weevil abundance during summer but has no effect on M. aethiopoides’ host weevils which feed only on clovers. It was accentuated by a warming climate with the now regular occurrence of a third host generation after most M. hyperodae adult activity had ceased.

History

Rights statement

© International Organization for Biological Control (IOBC) 2021

Language

  • English

Does this contain Māori information or data?

  • No

Publisher

Springer Nature

Journal title

BioControl

ISSN

1573-8248

Citation

Gerard, P., Wilson, D., & Upsdell, M. (2021). Contrasting host: parasitoid synchrony drives differing levels of biocontrol by two introduced Microctonus spp. in northern New Zealand pastures. BioControl, 66, 727–73. https://doi.org/10.1007/s10526-021-10104-8

Funder

DairyNZ Ltd

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