Leafroller larval and adult phenology at two Canterbury, New Zealand, organic apple orchards

Abstract

Leafroller larval and adult phenology were studied at two Canterbury, New Zealand, organic apple (Malus domestica Borkh.) orchards over three seasons. Larvae were sampled fortnightly from foliage and then reared to adult for unequivocal species-identification, or emergence of parasitoids. A total of 3304 larvae were found, comprising Planotortrix octo, Epiphyas postvittana, Ctenopseustis herana, and the most abundant larval parasitoid, Dolichogenidea tasmanica. There was an almost complete lack of C. herana larvae from 'Royal Gala' in 1993/94 and 1994/95, in contrast with its occurrence on nearby 'Red Delicious' in both seasons (9 and 11%, respectively of the total larvae at this site, cultivar, and year). Two larval generations per growing season were evident, with synchrony between the three leafrollers. The overwintering larval generation of late instar P. octo in October/November was followed by an absence of larvae in late November. Early instar larvae then peaked in late December, with a second generation of this stage evident in March and April. Eggs were evident in December and from late February-April. Peak catches of males in pheromone traps were generally well synchronised with troughs in larval abundance. H00022

Plant and host effects on the leafroller parasitoid Dolichogenidia tasmanica

“…The feral larvae population has previously been shown to be present on a range of host plants in the environs of Canterbury apple orchards (Suckling et al, 1998), with the life stages of early instar larvae that are susceptible to D. tasmanica present at this time (Burnip & Suckling, 2001). Potted plants of four species were grown in irrigated and fertilised potting mix (30 cm diam.…”

“…We chose the three leafrollers that are abundant in the Canterbury region (Suckling et al, 1998;Lo et al, 2000;Burnip & Suckling, 2001). We chose the three leafrollers that are abundant in the Canterbury region (Suckling et al, 1998;Lo et al, 2000;Burnip & Suckling, 2001).…”

The parasitoids of seed predators attacking snow tussocks,Chionochloaspp. (Poaceae)

“…comm.). Another species in the same genus, D. tasmanica, is a known parasitoid of several native and introduced leafroller moths (Lepidoptera: Tortricidae) which, in their larval stage, are horticultural pests in New Zealand (Charles et al 1996;Suckling et al 1998;Burnip & Suckling 2001). Per cent parasitism by D. tasmanica ranges between 7.3 and 20.8% and emergence peaks in December and March, the early days of development of the first two instars of its host (Burnip & Suckling 2001).…”

“…There is evidence that D. tasmanica also attacks native New Zealand leafrollers (Burnip & Suckling 2001). …”

Bibliography of research from the Winchmore Irrigation Research Station, Canterbury, New Zealand: 1951 to 2011

“…Mr Don Rickard offered his opinion by adding some additional history to that given by Rickard & Moss (2012). 1 To summarise, Don was of the opinion that the introduction of irrigation into Canterbury was not fully accepted by the farming community. Some of the concerns were that irrigation water would leach nutrients from the soil, irrigation water would lower the soil temperature, pasture persistence would be poor and the widespread use of irrigation in mid-Canterbury would give rise to water-logging near the coast.…”