G. M. Burnip

Eradication of the Australian Painted Apple Moth Teia anartoides in New Zealand: Trapping, Inherited Sterility, and Male Competitiveness

The incursion of the native Australian painted apple moth Teia anartoides Walker into Glendene, West Auckland in May 1999, prompted an area-wide eradication programme by the New Zealand Ministry of Agriculture and Forestry Biosecurity Authority. The Australian painted apple moth is a polyphagous pest of horticulture and plantation forestry and threatened New Zealands native vegetation. The economic and ecological impact of the moths incursion was estimated at NZD 50-350 million (approximately USD 30.5-212.9 million) over 20 years if no action was taken to eradicate the insect. The eradication programme (1999-2006) used a combination of tactics, including the first use of the sterile insect technique (SIT) in New Zealand. The SIT component was added to the eradication programme in 2002 but releases started in 2003 as an end game tactic once the pest population was brought down to ca 1% of the population level in 2001-2002, as indicated by trap catches. The aerial spray programme using Bacillus thuringiensis (Berliner), subsp. kurstaki (Btk) accompanied by release of sterile males drove the wild population to extinction, with overflooding ratios up to 100:1 based on trapping data. Sterility was assessed from the egg hatch of the F1-F3 generations and competitiveness examined using emergence rates and wind tunnel flight performance. When males exposed to 100 or 160 Gy mated with non-irradiated females, there was no significant effect on female egg production, but a lower egg hatch was observed for both doses. When F1 and F2 offspring were outcrossed to fertile moths, 100 Gy irradiation gave relatively similar inherited sterility levels to 160 Gy, with full mortality achieved at the F3 generation. The lowest effective dose of radiation needed to induce inherited sterility is likely to offer the best competitiveness and mating success of the released males, representing a potential trade-off between sterility and competitiveness. Subsequently, the induced dominant lethal mutations carried by the released males (when mated to wild females), will be inherited through the surviving F1 proportion of the progeny. Moth emergence rate was not affected at 100 Gy, but the response to seek and mate with wild calling females in the wind tunnel was reduced by 33%. The use of wind tunnel for quality assurance in integrated pest management programmes is discussed.

Frass sampling and baiting indicate European earwig (Forficula auricularia) foraging in orchards

Abstract:u2002 Earwigs are significant generalist predators of a range of orchard pests, but quantitative assessment of earwig density and beneficial impact is difficult. A sampling system was designed and tested, based on field placement of polycarbonate tubes in apple trees as scotophase arboreal refugia. Tubes containing artificial diet and provided with a black plastic sleeve had the highest earwig counts. Tubes with diet or the black sleeve alone were less preferred. Presence of distinctive frass was also evident in polycarbonate tubes containing artificial diet, and earwig frass was recorded at a higher frequency than earwig presence, indicating foraging and detection of the tubes at a higher rate than their use as shelters. At the tree level, there was a weak correlation between frass abundance and predation rates on leafroller egg batches placed as baits in the canopy, but not with earwig density measured by corrugated cardboard rolls or diet tubes. Diet tubes have the potential to offer new insights into earwig foraging behaviour in orchards.

Dispersal of Epiphyas postvittana (Walker) and Planotortrix octo Dugdale (Lepidoptera: Tortricidae) at a Canterbury, New Zealand orchard.

Abstract Mated pairs of Epiphyas postvittana and Planotortrix octo were marked and released at a point source in a young, 40 ha orchard. Port wine bait traps and pheromone traps along eight radiating transects were checked daily. In 1988, recapture of E. postvittana was 0.24% of females in bait traps, 0.23% of males in bait traps, with 3.4% of males in pheromone traps. In 1990, recapture of both male and female E. postvittana was more successful (12.2% of females in bait traps, 4.4% of males in bait traps, and 12.4% of males in pheromone traps). No marked males and only one marked female P. octo were recaptured in bait traps, although 5.1% of males were recaptured in pheromone traps. The maximum dispersal distance recorded for E. postvittana males was 600 m, but 80% of released males were recaptured within 100 m. For female E. postvittana, the maximum distance recorded was 275 m, with 99% dispersing 100 m or less. Male P. octo exhibited similar dispersal capability to male E. postvittana, with a maximum o...

Orientation disruption of Planotortrix octo using pheromone or inhibitor blends

Orientation disruption (indicated by reduced trap catch) of adult male Planotortrix octo (Lepidoptera: Tortricidae) was examined in eight small plot trials at four apple orchards over three years, using either (i) Z5–14:OAc (inhibitor), (ii) a blend of 25:75 Z5–14:OAc and Z8–14:OAc (inhibitor plus partial pheromone), or (iii) 50:50 Z8–14:OAc and 14:OAc (pheromone) in polyethylene rope dispensers at 100 or 200 dispensers per 0.1 ha. Use of inhibitor plus partial pheromone gave significant reductions in trap catch in all eight trials. Inhibitor alone gave statistically significant reductions in catch in all three trials where it was tested, but was not as effective as the inhibitor plus partial pheromone in one of these trials. Three trials comparing efficacy between the pheromone and the inhibitor plus partial pheromone blend showed no difference between these blends. Analysis of covariance of trap catch after treatment, using the catch in the first generation in each trap as a covariate, was useful for detection of treatment effects. Traps containing the blend of Z5–14:OAc and Z8–14:OAc were not attractive, suggesting that false trails may not be important where this blend is used, since it is an incomplete pheromone and contains an inhibitor.

Optimization of pheromone lure and trap characteristics for currant clearwing, Synanthedon tipuliformis.

Currant clearwing Synanthedon tipuliformis (Sesiidae) has been a pioneering and successful target of mating disruption in New Zealand, with virtually universal black currant industry adoption since c. 1990. Recent unexplained control failures using mating disruption lead to questions about pheromone efficacy. In this study, we have investigated the possible reasons for reduced control from mating disruption, and report improvements in trap catch based on pheromone loading and trap color. No differences were found in electrophysiological responses to pheromone components from two New Zealand populations. Male moth catches in traps baited with synthetic lures were disrupted in the presence of mating disruption dispensers (> 99.99%) indicating no apparent barrier to efficacy from the pheromone formulation. Field behavioral observations confirmed this result. Male attraction to yellow delta traps was equivalent to green delta traps, but was greater than to red, black, blue, or white traps. Solid yellow delta traps were more attractive than black traps with yellow stripes, the latter designed to mimic the color pattern of the insect. Solid yellow funnel traps were less attractive than a composite of green, yellow, and white funnel traps. Trap catch increased as a function of pheromone loading and trap color. In another experiment conducted in Tasmania, there was no difference in catch with single component [(E,Z)-2,13-octadecadienyl acetate] or two component lures [97% (E,Z)-2,13-octadecadienyl acetate:3% (E,Z)-3,13-octadecadienyl acetate], refuting the suggestion of a different pheromone strain there.

Factors affecting feeding site preferences of lightbrown apple moth, Epiphyas postvittana (Lepidoptera: Tortricidae), on apple trees in New Zealand.

Abstract The infestation of apple (Malus domestica) trees by Epiphyas postvittana (Walker) larvae was studied over 3 years. Fresh damage to leaves increased progressively during the season, although in Nelson it declined in April. Fruit damage was first detected in December and increased throughout the season. The incidence of fruit damage was most strongly correlated with the surface area of fruit. Single leaves were the preferred feeding site for larvae on terminal shoots, although when whole branches were examined, most shelters occurred between two leaves. Feeding sites on fruit predominantly involved contact with a leaf or another apple. A field experiment examined the influence of physical contact and fruit maturation on leafroller damage. E. postvittana larvae were offered a choice of feeding sites involving leaves and three types of “apple” namely untreated apples, apples treated with chlorethephon to promote ripening, and plastic balls. There was 16% more damage on treated compared with untreated fruit, but similar levels of damage to leaves touching the three types of apple. Although riper fruit were more attractive to E. postvittana larvae, their preference for physical contact had a greater influence on the selection of feeding sites. The increase in fruit damage over time was mainly due to the increasing extent of contact between leaves and other fruit as the apples enlarged.

Can Parasitoid Sex Pheromones Help in Insect Biocontrol? A Case Study of Codling Moth (Lepidoptera: Tortricidae) and Its Parasitoid Ascogaster quadridentata (Hymenoptera: Braconidae)

Abstract Synthetic female sex pheromone was used to monitor the phenology of male Ascogaster quadridentata Wesmael, an egg-larval parasitoid of codling moth, Cydia pomonella (L.), in conjunction with pheromone trapping of the moth and the banding of trees to determine larval parasitism. Catch of this parasitoid was typically ≈10 times less than the moth catch, and larval parasitism varied from 7 to 12%. The emergence of the parasitoid occurred slightly later than the female moth emergence, by both outdoor emergence cages and pheromone trapping. The seasonal activity of male parasitoids was otherwise synchronous with male codling moth flight. A survey of orchards in four regions of New Zealand showed considerable regional variation in the capture of the parasitoid in pheromone traps. The potential value of the parasitoid may be limited by the nil tolerance of the pest in export fruit, but pheromone trapping of this parasitoid could improve the understanding of biological control in non-export situations, where the economic threshold is higher. Pheromone trapping for insect biological control agents is a valuable tool that can help to determine and improve parasitoid success.

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, Cteno‐pseustis 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.

Host range testing for risk assessment of a sexually dimorphic polyphagous invader, painted apple moth

A wide known host range in Australia and novel herbivory on native and naturalized species in New Zealand supported the decision to commence a NZ

Integrated fruit production for New Zealand pipfruit: evaluation of pest management in a pilot programme.

65u2009million eradication programme against painted apple moth [Teia anartoides (Walker) (Lepidoptera: Lymantriidae)] in Auckland (1999–2007). Laboratory no‐choice tests were designed to examine the ‘host’ status of the associations seen in the field. Laboratory tests investigated 79 native and introduced plant species with 122 provenances. Forty‐two percent of plants were capable of supporting larval development to adulthood, with male bias; 30% were defined as potential hosts with female larvae developed through to the pupal stage; >u200910% survival indicated probable physiological hosts. Sporadic or more frequent attack of New Zealand native broom, and introduced lemon, apple, sycamore, walnut, cherry and poplar, was likely, with a wider range of hosts supporting male emergence. A few negative laboratory results contradicted field observations of significant damage by large numbers of larvae. The present study highlights the challenge faced with respect to predicting the ecological host range of invasive polyphagous species, whose biology is little known, during the early stages of a first invasion. The implications of a wider host range found in males than females are discussed.