effects of floral understoreys on parasitism of leafrollers (Lepidoptera: Tortricidae) on apples in New Zealand

• Published in: Agricultural and forest entomology 2006-01, Vol.8 (1), p.25-34
• Main Authors: Irvin, N.A, Scarratt, S.L, Wratten, S.D, Frampton, C.M, Chapman, R.B, Tylianakis, J.M
• Format: Article
• Language: English
• Subjects: Agricultural practices; Agronomy; Alyssum; Anacharis; Apples; Biological control; biological control agents; buckwheat; conservation biocontrol; conservation biological control; crop damage; Dolichogenidea; Dolichogenidea tasmanica; Epiphyas postvittana; Fagopyrum esculentum; Fecundity; Fruits; Insects; Larvae; leafroller; Lobularia maritima; Longevity; Malus; Malus domestica; Parasites; Parasitism; parasitoids; Pest control; Pests; Phacelia; Phacelia tanacetifolia; population density; Tortricidae; understorey management; understory; understory management
• ISSN: 1461-9555; 1461-9563
• DOI: 10.1111/j.1461-9555.2006.00285.x

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.