The 2019 Fiji Poinciana Looper Moth Invasion: A call for Action PaCE-SD Technical Report 1 (2019) Randy Thaman and Rahul Dutt Pacific Centre for Environment and Sustainable Development (PaCE-SD) The University of the South Pacific Suva, Fiji May 31, 2019 The 2019 Fiji Poinciana Looper Moth Invasion: A call for action Randy Thaman1 and Rahul Dutt2 Last week (May 23, 2019), we noticed increasingly serious defoliation and die-back of the royal poincianas or flamboyant trees (Delonix regia) along Moana Drive, the main entry road to The University of the South Pacific (USP) Suva Campus, FiJi. Upon closer examination, it became clear that the trees, known in FiJian as sekoula (“golden flower”), and which burst forth in a profusion of bright orange-red flowers over the Christmas holidays (Fig. 1), had been invaded by an army of yellow-green caterpillars of the poinciana looper moth (Pericyma cruegeri)(PLM), which had devoured the leaflets of the beautiful frond-like compound leaves, before pupating and weaving young terminal leaves of the outer branches into cottony white cocoons in which golden brown chrysalises formed, from which the adult looper moths emerge. Fig. 1. Mature healthy poinciana or flame tree, sekoula in Fijian (Delonix regia) tree in full bloom (left); and healthy flaming flower clusters (right), Cakobau Rd., Suva, Fiji, Sept. 2007 (Photos: R. Thaman). Although native to Southeast Asia (Hong Kong, China, Thailand, Vietnam, Malaysia, Indonesia and the Philippines) and possibly New Guinea and northern Australia, and accidentally introduced into Guam and Hawai’i in the early 1970s (as eggs or pupal stages on poinciana cuttings and seedlings or as egg-carrying females aboard military or civilian airplanes), into Okinawa, Japan by 1986, and to Tonga, the Northern Marianas and Federated States of Micronesia at an unknown date, until now, PLM has never been reported present in FiJi, thus indicating that this is a recent invasion. 1 Emeritus Professor of Pacific Islands Biogeography, The University of the South Pacific, Suva, Fiji. 2 Environmental Health and Safety Officer, Office of Occupational Health and Safety, The University of the South Pacific, Suva, FiJi. Based on Jackson’s 2017 fact sheet on PLM and our observations of the USP infestation, the PLM’s life cycle begins when adult moths lay small yellowish to bluish green eggs on the tree’s leaflets, which after hatching in 2-3 days, go through five stages, beginning with the small young caterpillars feeding together in small groups on the leaflets, and culminating when the fully grown, light-green caterpillars (up to 7 cm long), with wavy white bands running the length of the body and a large green to orangish head (Fig. 2), go through an intense period of feeding (Fig. 3), followed by pupation and the formation of cotton-like cocoons made by binding together the young terminal leaflets with silken threads (Fig. 4), in which form golden brown chrysalis (Fig. 5), from which, after about 10 days, emerge the adult PLM, which have mottled brown wings with a wingspan of about 4 cm, and variably decorated with black wavy lines (Fig. 6). Fig. 2. Adult poinciana looper moth (PLM) caterpillar feeding along poinciana (Delonix regia) leaf midribs, showing the distinct wavy white, black and olive-green longitudinal patterns and large olive- green head (left); and five (3 clearly visible) poinciana looper moth (PLM) caterpillars actively feeding on the leaflets in the canopy of the same poinciana tree near the Japan-ICT Centre, USP Laucala Campus, 25 May 2019 (Photos: R. Thaman). Fig. 3. Mature camouflaged PLM caterpillars feeding on foliated poinciana leaflet midribs (left) and a late-afternoon photo of PLM caterpillars on defoliated leaflet midribs (right); FBE Parking Lot near “ground zero of the 2019 USP PLM Invasion, USP Laucala Campus, 23 May 2019 (Photos: R. Thaman). Figure.4. Young leaves on the tips of the outer branches of a poinciana tree in the process of being woven into a cocoon by PLM caterpillars (left); and completed cocoons along poinciana branchlet ends (right), USP Laucala Campus, 23 May 2019 (Photos: R. Thaman). Fig. 5. Fully formed PLM chrysalises hanging from the ends of poinciana tree (Delonix regia) branchlets (left); and a close-up of a chrysalis (Fig. 11), from which the adult poinciana looper moths (PLM) emerge, USP Laucala Campus, 23 May 2019 (Photos: R. Thaman). Fig. 6. Topside and underside photos (left and right, respectively) of adult poinciana looper moths (Pericyma cruegeri)(PLM) from Okinawa, Japan (Source: I. Tanahara, Nov. 2000). Nature and Suspected Origin of the PLM Invasion The apparent “ground zero” of the PLM outbreak is centered on the inner roundabout of the new USP entry road that is nearing the end of construction. From here it extends outward affecting over 100 mature trees, including both recent 2010 plantings along the main road as well as trees over 50 years old. As of Friday 31 May, the area of continuous infestation, in some cases almost total defoliation, extended from this ground zero area to trees bordering the parking of the Faculty of Business and Economics (Fig. 7), over 50 trees bordering the main USP road and in the tree grove immediately west of the roundabout, and into trees around the USP Book Store, ending with the infestation of the large very old tree in the roundabout opposite the Oceania Centre for Arts and Culture and Pacific Studies (OCAP-PS) Building (Fig. 8). There is also a geographically separate infestation of a number of trees between the Japan Pacific ICT Centre and the USP Administration Block. Figure. 7. Severely defoliated poinciana trees along Faculty of Business and Economics (FBE) Parking lot near ground zero of the 2019 FiJi PLM Invasion (left); and totally defoliated trees with caterpillar cocoons near the ends of leaf midribs, along the tree grove inland from ground zero of the 2019 Fiji PLM Invasion, 24 May 2019 (Photos: R. Thaman). Fig. 8. Old heavily PLM caterpillar-infested poinciana tree (Delonix regia) (left); and heavily defoliated branches and leaves of the same tree (right), Oceania Centre for Arts and Culture and Pacific Studies (OCAC-PS) roundabout, USP Laucala Campus, 25 May 2019 (Photos: R. Thaman). Interestingly, extensive surveys by the authors of over 1000 trees and/or plantings throughout USP Suva campuses and the Greater Suva Urban Area showed that trees on the rest of the Upper Laucala Campus and the Lower and Statham Campuses, and all maJor poinciana plantings in Suva, along roadsides (e.g., Queen Elizabeth Dr., Grantham and Vuya Rds.); in parklands, school compounds, Thurston Botanical Garden, FiJi Golf Club and other ornamental plantings throughout the Suva area showed absolutely no signs of infestation, thus indicating that the 2019 FiJi PLM Invasion is currently restricted to the above-described areas of assumed introduction and current spread. This currently very localized nature of the PLM infestation leads us to speculate that, much like the introductions of PLM into Hawai’i, Guam and elsewhere, the eggs or pupal stages or egg- carrying females have been inadvertently brought to FiJi. This may have been unintentionally brought in either by ship or by plane along with equipment, clothing or other personal effects by the two Mainland Chinese contractors currently involved with the New USP entrance road and the new Confucius institute. The two contractors have been responsible for maJor roadwork, construction and provision of machinery, vehicles and other equipment, at both of the geographically separate sites of the USP PLM invasion: the new USP entry road and the entry road from the old USP main gate and the Japan-Pacific ICT Centre. Impact and Management In severe attacks, such as along Catalina Drive adjacent to Maile Rugby grounds, where entire trees have been defoliated but, if healthy, they will reportedly recover, although in Guam re- infestation occurred when the trees produced new foliage after the initial attack, and continued defoliation has resulted in trees with smaller leaves, dieback, lack of or erratic flowering, attacks by bark borers and general loss of vigor, with some of the USP trees currently appearing almost dead. Although its main host plant is poinciana, PLM is also known to feed on yellow poinciana or copper pod (Peltophorum pterocarpum), acacias (Acacia spp.), Caesalpinia and other legumes, including the golden shower tree (Cassia fistula) and leucaena (Leucaena leucocephala), all of which are present on the USP Campus, but as of now unaffected (Jackson 2017). According to Jackson (2017), at present, there seems to be no practical control for the PLM, apart from: 1) use of dangerous and costly insecticides or the naturally occurring bacterial insecticide Bt, (Bacillus thuringiensis), which has shown to be effective at parasitizing PLM, but in most situations is too expensive or difficult to obtain in sufficient quantities to combat large incursions; 2) the introduction of parasitic organisms, such as unsuccessful efforts to control PLM in Guam, without effect, by the introduction of a parasitic chalcid wasp (Brachymeria lasus) from Papua New Guinea; or 3) natural controls, such as the serendipitous presence of natural predators and seasonal climatic controls unfavorable to PLM. In terms of natural controls, surveys in Guam reported low levels of parasitism, with the only predators being preying mantis, pentatomid bugs and chickens, which attacked caterpillars that fell to the ground after trees had been defoliated. In terms of possible control in FiJi, our surveys at USP have found the very limited presence of green praying mantises (possibly Orthodera sp.) and localized, sporadic mass feeding on the caterpillars by red vented bulbuls (Pycnonotus cafer), Vanikoro broadbill (Mylagra vanikorensis) and the FiJi white eye (Zosterops explorator) (Fig. 9). All three birds are known to glean insects from tree canopies; and Pacific bird and environmental expert Dick Watling, also suggests that there are parasitic wasps that target looper caterpillars, that may contribute to keeping PLM populations under control.