Comparing Deliveries of Sterile Codling Moth (Lepidoptera: Tortricidae) by Two Types of Unmanned Aerial Systems and from the Ground.

New Zealand apple exports must meet strict phytosanitary measures to eliminate codling moth (Cydia pomonella Linnaeus) (Lepidoptera: Tortricidae) larval infestation. This study was part of a program attempting the localized eradication of codling moth within an isolated cluster of seven orchards (391 ha). A conventional management program of insecticide sprays and pheromone mating disruption was supplemented with weekly releases of sterile moths for 1-6 yr. Our objective was to compare the recapture rate of sterile moths following their release by four methods, and the efficiency of each system. The methods were the following: a fixed-wing unmanned plane flying ~40-45 m high at 70 km/h, an unmanned hexacopter travelling 20 m high at 25 km/h, and manually from the ground via bicycles or motor vehicles. The different release methods were used in different years or weeks. Sterile male moths were recaptured in grids of pheromone traps positioned throughout each orchard. The highest recapture rate followed delivery by hexacopter, then bicycle, vehicle, and plane. There was a 17-fold difference in catches between releases by hexacopter and plane, and sixfold between vehicle and plane in the same season. Bicycle delivery had a 3.5-fold higher recapture rate than the plane in different years. The wind-borne horizontal drift of moths was investigated as a possible explanation for the disparity of recaptures between the two aircraft delivery systems. The methods in ascending order of time per hectare for delivery were the following: plane and vehicle, hexacopter, then bicycle. The advantages and disadvantages of each moth delivery method are discussed.

Combined Effects of Mating Disruption, Insecticides, and the Sterile Insect Technique on Cydia pomonella in New Zealand.

Codling moth was introduced into New Zealand, and remains a critical pest for the apple industry. Apples exported to some markets require strict phytosanitary measures to eliminate the risk of larval infestation. Mating disruption and insecticide applications are the principal means of suppression in New Zealand. We tested the potential for the sterile insect technique (SIT) to supplement these measures to achieve local eradication or suppression of this pest. SIT was trialed in an isolated group of six integrated fruit production (IFP) orchards and one organic orchard (total 391 ha), using sterilized insects imported from Canada, with release by unmanned aerial vehicle and from the ground. Eradication was not achieved across the region, but a very high level of codling moth suppression was achieved at individual orchards after the introduction of sterile moths in combination with mating disruption and larvicides. After six years of releases, catches of wild codling moths at three IFP orchards (224 ha) were 90-99% lower than in 2013-2014, the year before releases began. Catches at three other IFP orchards (129 ha) decreased by 67-97% from the year before releases began (2015-2016), from lower initial levels. At a certified organic orchard with a higher initial population under only organic larvicides and mating disruption, by 2019-2020, there was an 81% reduction in wild moths capture from 2016-2017, the year before releases began.

Will Peri-Urban Cydia pomonella (Lepidoptera: Tortricidae) Challenge Local Eradication?

Codling moth, Cydia pomonella (Lepidoptera: Tortricidae), is a phytosanitary pest of New Zealand's export apples. The sterile insect technique supplements other controls in an eradication attempt at an isolated group of orchards in Hawke's Bay, New Zealand. There has been no attempt in New Zealand to characterize potential sources of uncontrolled peri-urban populations, which we predicted to be larger than in managed orchards. We installed 200 pheromone traps across Hastings city, which averaged 0.32 moths/trap/week. We also mapped host trees around the pilot eradication orchards and installed 28 traps in rural Ongaonga, which averaged 0.59 moths/trap/week. In Hastings, traps in host trees caught significantly more males than traps in non-host trees, and spatial interpolation showed evidence of spatial clustering. Traps in orchards operating the most stringent codling moth management averaged half the catch rate of Hastings peri-urban traps. Orchards with less rigorous moth control had a 5-fold higher trap catch rate. We conclude that peri-urban populations are significant and ubiquitous, and that special measures to reduce pest prevalence are needed to achieve area-wide suppression and reduce the risk of immigration into export orchards. Because the location of all host trees in Hastings is not known, it could be more cost-effectively assumed that hosts are ubiquitous across the city and the area treated accordingly.

Peri-Urban Community Attitudes towards Codling Moth Trapping and Suppression Using the Sterile Insect Technique in New Zealand.

New, more socially-acceptable technologies are being developed to suppress horticultural pests, because suppression is technically difficult with current technologies, especially in urban areas. One technique involves the release of sterile insects to prevent offspring in the next generation. This technology involves aerial or ground release systems, but this could also create issues for the public. This study investigated community perceptions of a recently-introduced response to codling moth control in New Zealand-Sterile Insect Technique (SIT). Community attitudes to SIT were examined in Hastings, New Zealand, in April, 2018. Eighty-six detailed interviews were undertaken with a random sample of households. This community was very willing (98% agreement) to host a sex pheromone trap in their gardens, and condoned regular visits to monitor traps. Attitudes to SIT were very positive (98% in favor). Once explained, the concept of using unmanned aerial vehicles to deliver sterile insects was also acceptable (98%) to the community. Use of unmanned aerial vehicles to release sterile insects during a hypothetical incursion response of an exotic fruit fly was also supported at 98% by respondent householders. Investigation of community attitudes can be valuable to guide practitioners in determining suitable technologies before an area-wide programme is launched.

Factors Responsible for Changes in Leafroller (Lepidoptera: Tortricidae) Species Composition on Orchards and Vineyards 1974-2015, in Hawke's Bay, New Zealand.

Leafrollers are polyphagous pests whose larvae damage fruit and cause market access problems for fruit crops exported from New Zealand. Leafroller larvae and pupae were collected mainly from four fruit crops, but also from hedges, ornamental trees, and understory weeds in orchards and vineyards of Hawke's Bay, a major fruit production region. Samples were collected from 1974 to 1977 and 1993 to 2015. This timespan was divided into periods that broadly coincided with broad-spectrum insecticide management, the transition to selective insecticides, and the full implementation of integrated fruit production (IFP) programs in apples, grapes, and stone fruit. Eight tortricid species were identified, but the accidentally introduced Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae) and two native species, Ctenopseustis obliquana (Walker) and Planotortrix octo Dugdale, comprised 95% of the samples. The proportions of these three species varied according to interactions between four factors: pest management regime, collection period, property location, and host plant. In the 1970s under broad-spectrum insecticide programs, the native species dominated on all hosts. By the mid-late 1990s when IFP was introduced, all the main leafroller species were in decline. However, E. postvittana declined to a lesser extent than the two native species, and consequently, it became relatively more prominent. This change in species composition was delayed in two districts where localized cases of organophosphate insecticide resistance occurred in C. obliquana and P. octo. From 2000 onwards, E. postvittana was the dominant species in all districts and on all hosts, albeit with a much-reduced pest status, except on hedges and ornamental trees where C. obliquana prevailed.

Past, Present, and Future of Integrated Control of Apple Pests: The New Zealand Experience.

This review describes the New Zealand apple industry's progression from 1960s integrated pest control research to today's comprehensive integrated pest management system. With the exception of integrated mite control implemented during the 1980s, pest control on apple crops was dominated by intensive organophosphate insecticide regimes to control tortricid leafrollers. Multiple pest resistances to these insecticides by the 1990s, and increasing consumer demand for lower pesticide residues on fruit, led to the implementation of integrated fruit production. This substantially eliminated organophosphate insecticide use by 2001, replacing it with pest monitoring systems, threshold-based selective insecticides, and biological control. More recently, new demands for ultralow-residue fruit have increased the adoption of mating disruption and use of biological insecticides. Widespread adoption of selective pest management has substantially reduced the status of previously important pests, including leafrollers, mealybugs, leafhoppers, and mites for improved phytosanitary performance, and contributed to major reductions in total insecticide use.

Regulatory Innovation, Mating Disruption and 4-Play(TM) in New Zealand.

Straight-chained lepidopteran pheromones are now regulated under a group standard in New Zealand, which is generic for moth pheromone products of similar low risk, under the Hazardous Substances and New Organisms Act (1996). This means that compliant new pheromone products can be developed and commercialized with low regulatory requirements. This encourages innovation and supports fruit industries interested in meeting export phytosanitary standards, while targeting low or nil residues of pesticides. Changes to pheromone blends for reasons such as technical improvements or variations in pest species composition in different crops can be made with minimal regulatory involvement. We illustrate how this system now operates with a four species mating disruption product commercialized in 2012. The odors involved in "4-Play™" consist of a range of components used by codling moth (Cydia pomonella), lightbrown apple moth (Epiphyas postvittana), green-headed leafroller (Planotortrix octo), and brown-headed leafroller (Ctenopseustis obliquana). The development of 4-Play™ illustrates how mating disruption of insects can support industry goals.

Prospects for the control of apple leaf midge Dasineura mali (Diptera: Cecidomyiidae) by mass trapping with pheromone lures.

BACKGROUND: Apple leaf midge, Dasineura mali (Kieffer), poses quarantine issues for some apple export markets because larvae occasionally pupate in the stem end and calyx of fruit. Pheromone-baited oil-filled containers were used in 1 ha orchard plots to trap adult male D. mali in order to test the potential for mass trapping to reduce populations. RESULTS: Mass-trapped plots had 97% fewer adult males in pheromone traps and 48% fewer larvae per shoot in the second D. mali generation compared with untreated areas. Oil traps caught on average 900 000 D. mali per plot over 11 weeks during the second and third generations. Catches averaged 9200 per trap at plot corners. By comparison, catches were 51% lower 10-25 m away along borders, 80% lower at the midpoint of borders and 95% lower >7 m from plot edges. Fruit infestation was low (four out of 8000 apples). CONCLUSION: The attractiveness of the pheromone, monophagous habit and low mobility of D. mali enhance the prospects for successful mass trapping. Countering this are high populations, multivoltinism and aspects of mating behaviour. Mass trapping would probably have been more effective had it been in place season long and conducted over successive years. It needs refinements and more study before becoming a feasible control option for D. mali.

Trapping Dasinuera mali (Diptera: Cecidomyiidae) in apples.

The midge Dasineura mali (Kieffer) (Diptera: Cecidomyiidae) is a significant pest of apples (Malus spp.), and the recent identification of the female sex pheromone is enabling new direct control tactics to be considered. Direct control using male suppression will require knowledge of the frequency of multiple mating, dispersal and colonization rates, and the efficiency of male removal. Males were able to mate up to five times, with a mean of 2.7 times when presented in a 10 female-to-1 male group, designed to simulate male suppression. Male catch in response to the pheromone loading was curvilinear over 4 orders of magnitude from 3 microg to 30 mg on rubber septa. Trapping using a high-dose pheromone lure was combined with oil-based traps similar to the inexpensive New Zealand "Lynfield trap" used for tephritid surveillance, to test male suppression in young orchard blocks at 500 traps per ha. Monitoring traps indicated 96% lower catch in the treated plots compared with control plots, over 137 d. However, a lack of shoot tip infestation in both treated and untreated plots indicated limited colonization and prevented an assessment of potential population suppression. Furthermore, a contribution to these results from communication disruption cannot be ruled out. Replicated transects of frequency of infested shoots from a mature orchard across the adjacent young block confirmed that colonization by ovipositing females was essentially limited to the first 30 m.