The effects of floral understoreys on parasitism of leafrollers (Lepidoptera: Tortricidae) on apples in New Zealand |
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Authors: | N. A. Irvin&Dagger ,S. L. Scarratt&Dagger ,S. D. Wratten&Dagger ,C. M. Frampton,R. B. Chapman&Dagger , J. M. Tylianakis&dagger |
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Affiliation: | Bio-Protection and Ecology Division, PO Box 84, Lincoln University, Canterbury, New Zealand,; University of Otago, Christchurch School of Medicine &Health Sciences, PO Box 4345, Christchurch, New Zealand and; Fachgebiet Agrarökologie, Georg August Universität, Waldweg 26, Göttingen, D-37073, Germany |
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Abstract: | Abstract - 1 Field and laboratory experiments on the conservation biocontrol of lepidopteran leafroller pests were carried out in apples at Lincoln, New Zealand.
- 2 Apple understoreys were planted with replicated treatments of alyssum (Lobularia maritima), phacelia (Phacelia tanacetifolia) and buckwheat (Fagopyrum esculentum).
- 3 Rates of parasitism of experimentally released larvae of the light‐brown apple moth, Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae), by Dolichogenidea tasmanica (Cameron) (Hymenoptera: Braconidae) were significantly lower in phacelia and control treatments, and leafroller pupae were significantly more abundant in controls than in buckwheat and alyssum treatments.
- 4 Naturally occurring leafroller damage was up to 29% lower above all the floral understorey treatments compared with controls and there were more than twice as many D. tasmanica cocoons in the alyssum and buckwheat treatments than in controls.
- 5 Suction sampling of the understoreys gave D. tasmanica adult densities that were significantly more abundant in alyssum compared with other treatments. Numbers of Anacharis zealandica (Hymenoptera: Figitidae) (a parasitoid of larvae of the predatory brown lacewing) did not differ between treatments.
- 6 In the laboratory, flowering buckwheat and alyssum enhanced D. tasmanica longevity by up to 78% compared with the control, and buckwheat also enhanced potential fecundity by 62%.
- 7 In choice experiments, leafroller larvae in the laboratory consumed more than three‐fold more apple leaf material than they did of the three understorey species, although alyssum increased leafroller fecundity and longevity.
- 8 The use of floral understoreys for conservation biocontrol of apple pests is discussed, along with the potential negative effects of some flowering species on pest populations and orchard agronomic practices.
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Keywords: | Alyssum buckwheat conservation biocontrol Dolichogenidea fecundity leafroller longevity phacelia Tortricidae understorey management |
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