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June 2001. Fruit-piercing moths are a major problem for fruit growers in the South Pacific. More information on possible control methods (in addition to removal of host species such as Erythrina and Mikania and by physical means – going out at night with a torch and squashing them on the fruits) – was requested.
As an additional piece of information, it was said that Samoan foresters say that Terminalia species (T. superba and T. calamansanaii) are also hosts for the moth in Samoa.
In addition, to control measures, it was asked whether the indigenous and highly valued, but now uncommon, endemic Samoan Terminalia richii (malili) is also a host for the moth?
There were many lengthy
1. The food plants for Eudocima (Othreis) fullonia, the most serious pest species of fruit piercing moth, are various species of forest vines within the Menispermaceae, and in the Pacific, mostly species of Erythrina (often E. variegata, but also E. lithosperma, E. fisca, E. subumbrans, etc). E. fullonia will also develop on the vine Stephania japonica wherever it occurs (e.g., Vanuatu, Fiji, Samoa). It will lay on other plants such as pepper when moth densities are high, but the larvae fail to develop on them. A second species that often causes damage in Vanuatu, Australia and in Vietnam is Eudocima salaminia, but it is quite rare in Samoa and on the southern Pacific islands. Its larvae feed in the eastern part of its range (including Vanuatu) on Stephania japonica and its various forms.
Moths in the genus Eudocima all have a highly specialised proboscis with sclerotized spines capable of piercing hard, and sometimes unripe, fruit such as green citrus. Other piercing genera have been implicated in Guam and in Southeast Asia. There are many ‘fruit sucking’ moths (Catocalinae) – adult moths that visit fruit to feed when over-ripe, or when there is damage caused by piercing moths, and they may sometimes damage ripe or soft fruit. Species from various genera are commonly seen feeding in this way in the southwestern Pacific including Ophiusa, Achaea, Serrodes, Donuca, Erebus, Calyptra, Anomis, Phyllodes imperialis, Thyas miniaca. However, their proboscis is not capable of piercing the intact, firm, fruit. They are often blamed for causing damage actually caused by other species. One species in this category is Ophiusa coronata which has larvae that feed on various plants including Terminalia spp.
Biological control of E. fullonia, the most important species, has been quite successful in Fiji and Samoa folowing the introduction of two egg parasitoids (Telenomus lucullus Nixon, and an undescribed Ooencyrtus sp. (papilionis sp.- group) originally from Papua New Guinea. However, for soft fruit (e.g carambola) and after environmental disruption following cyclones and drought, outbreaks still occasionally occur on those islands.
There are several papers on biocontrol of the moths in the Pacific giving some background to the biocontrol work and food plants (e.g. Sands et al. 1993. Micronesica Suppl. 4: 99-105; Sands & Chan. 1996. Ent. Exp. & Applic. 80: 145-148).
2. The following was supplied from DPI&F, Queensland. E. fullonia only breeds on Erythrina and vines of the family Menispermaceae in the Pacific. In Australia, the seven species of Eudocima (or primary piercers) only breed on Menispermaceae, and the species inospora smilacina is particularly important. Larvae of E. salaminia has been seen on Stephania japonica var. timoriensis (fosteri) in Vanuatu, but it is thought that the pest status of E. fullonia is due to the proliferation of Erythrina in the Pacific. Grazing or hedging of Erythrina would promote considerable new growth for the 1st instars. This is critical to the development of pest populations.The fruit sucking (and sometimes fruit piercing) species Ophiusa coronata (which is a moth that looks vaguely like E. fullonia), is said to breed on Terminalia catappa in the southwest Pacific. DPI has been working on attractant baits for fruitpiercing moths over a number of years. These baits contain synthetic fruit odours which decoy moths away from fruit and onto the baits. They appear to work well in crops such as citrus as fruits mature and ripen over time. DPI hopes to conduct large-scale trials with these baits in commercial citrus crops next season.
3. A response from Samoa could not confirm that Terminalia (talie) was a host plant of fruit piercing moth (Othreis fullonia) in Samoa. All species of Erythrina there are the host plants, with Erythrina variegata the most preferred. During times of outbreak, eg after Cyclone Ofa (1990), eggs of the moth were found on Mikania and black pepper. Natural enemies of the moth are well established in Samoa.
4. And from a person on the regional fruit pierciing moth project …… In Samoa in 1988/1989 foliage of Terminalia catappa was heavily damaged by large grey caterpillars which were reared through to produce adults of Ophiusa coronata. Since their hindwings are orange-coloured and are active in the evening and at night they are easily confused with E fullonia by farmers. However, they can damage only soft-skinned fruit like carambola and ripe guavas.
5. Some other control methods mentioned were:
- jaggery (un-refined sugar cane) soaked in chlorpyriphos. The sugarcane juice is boiled to a solid state and then mixed with water, ferments, and then emits a foul odour that attracts the moths.
- baits: containing synthetic feeding attractants – sugar, preservative and a a toxicant in a gel, all loaded into a sausage skin at 50 g per bait, then completely waxed with cheese-wax to minimise loss of the volatile attractants. The baits were placed out in orchards (i.e., hung from fruit trees as bait stations) at different densities and distributions, and deployed at different stages of crop maturity, during an extensive series of trials. The majority of the trials were in citrus (navel, navelina, mandarin, pummelo and grapefruit).
The following extract from the Final Report summarises the trial results.
Moderate to high numbers of moths were recorded during three quarters of the trials, during which Eudocima fullonia made up around 80-90% of the moths observed. These trials produced three different scenarios. 1. The baits could not compete with large quantities of ripe to over-ripe fruit (mainly carambolas) near the end of trials. 2. Bait attractiveness declined from much higher levels (e.g. 75 to 30 %) if moth activity increased with crop maturity, or increased rapidly close to harvest. 3. With moth numbers declining from higher levels the baits attracted an increasingly greater proportion of the moths in an orchard. The trial data are largely based on the numbers of moths in an orchard and the numbers of feeding strikes on the baits after a two-week exposure period, and should be considered indicative rather than conclusive as the efficacy estimates are derived rather than actual. In citrus, the average proportion of moths attracted to the baits was 53.7%. In mangoes, this figure was half this at 26.7%. The proportion was even lower in carambolas at 14.5%, but this was influenced by the large numbers of ripe and over-ripe fruit. The baits were estimated to reduce damage to fruit from 23.6% to 4.8% and from 38.6% to 11.7% in citrus, and from 21.4% to 4% in mangoes. These are considered significant reductions, even if they over-estimate the ???kill rate??? of the baits. These data suggested that the baits need to be deployed throughout a crop at one bait per tree or two trees, while if moth numbers are high or increasing rapidly, there would need to be an increased concentration of baits in those particular areas of the crop where the moths were most active. This could result in the numbers of baits varying between 100 and 800 per hectare. Bait deployment in periods of increasing moth numbers would need to occur about 10 weeks before harvest, which would result in five baiting cycles through a crop.
The full report has been published by Horticulture Australia: Fruitpiercing moth bait evaluation in fruit
crops by Harry Fay, QDPI&F, Project No. HG01036, 2005. ISBN 0 7341 1029 4. It can be obtained from Horticulture Australia Ltd, Level 1, 50 Carrington Street, Sydney NSW 2000
Australia. Fax. (+2) 8295 2399 Email. [email protected].
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