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 believe 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 South 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 and Thyas miniaca. However, the proboscis of these moths is not capable of piercing the intact, firm, fruit. They are often blamed for causing damage 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 following 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, 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 Inospora smilacina is particularly important. Larvae of E salaminia have 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 fruit-piercing 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 host plants, with Erythrina variegata the most preferred. During times of outbreak, e.g., 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 a previous regional fruit piercing 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.