Pest Risk Analysis for Diaphania Indica
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CSL Pest Risk Analysis for Diaphania indica CSL copyright, 2005 Pest Risk Analysis For Diaphania indica STAGE 1: PRA INITIATION 1. What is the name of the pest? Diaphania indica (Saunders, 1851) Lepidoptera Pyralidae cucumber moth* * not an official DEFRA common name Synonyms Botys hyalinalis Boisduval Palpita indica Saunders Eudioptis capensis Zeller Phacellura indica Saunders Glyphodes indica Saunders Phakellura curcubitalis Guenée Hedylepta indica Saunders Phakellura gazorialis Guenée Margaronia indica Saunders Phakellura zygaenalis Guenée Notes on the pest name: In two recent papers (Choi et al., 2003; Shin et al., 2002) this organism is cited as “Palpita indica (Diaphania indica)” suggesting that the name has been revised and should now be considered as Palpita indica. However, the most recent paper on this organism, Liu (2004) uses the name Diaphania indica. Diaphania indica is used in this PRA. 2. What is the reason for the PRA? After this organism was intercepted three times in 2001, a PRA was undertaken in 2002 (MacLeod, 2002). The current PRA was initiated after the Netherlands informed CSL that D. indica had been detected in consignments of Momordica from Kenya and Surinam in 2005. NL was aware of the previous UK PRA and informed CSL of new information concerning the thermal biology and overwintering strategy of the pest. 3. What is the PRA area? This PRA considers the whole EPPO region concentrating on the European and Mediterranean area, i.e. EPPO west of the Ural mountains. STAGE 2: PEST RISK ASSESSMENT 4. Does the pest occur in the UK, EPPO or EU region or does it arrive regularly as a natural migrant? This pest does not occur in the UK. There are three unconfirmed 18th Century records of this species in the UK (Maitland-Emmet & Health, 1991). The pest is occasionally found associated with imported produce, especially Momordica from Kenya imported during September, although the pest has been found year round, detected in consignments from other countries too (see 12. for more details). 5. Is there any other reason to suspect that the pest is already established in the UK, EPPO or EU region? No. 6. What is the pest’s EU Plant Health Directive status? Not listed. 7. What is the pest’s EPPO Status? Diaphnia indica is not listed by EPPO but is considered a quarantine pest by the USA, where D. indica is present in Florida (EPPO, 2005). 1 of 9 CSL Pest Risk Analysis for Diaphania indica CSL copyright, 2005 8. What are its host plants? D. indica primarily attacks Cucurbitaceae, although it has also been recorded from other plant families, notably Leguminosae and Malvaceae. Table 1 lists the most common hosts on which this pest is found. Table 1: Diaphania indica hosts Binomial name Common name Benincasa hispida wax gourd Brassica juncea var. juncea Indian mustard Cajanus cajan pigeon pea Citrullus lanatus watermelon Cucumis melo melon Cucumis melo var. dudaim Small melon Cucumis sativus cucumber Cucurbita moschata pumpkin Cucurbita pepo ornamental gourd Cucurbitaceae cucurbits Gossypium herbaceum short staple cotton Lagenaria siceraria bottle gourd Luffa acutangula angled luffa Luffa aegyptiaca luffa Momordica charantia bitter gourd Passiflora passion fruit Phaseolus beans Trichosanthes cucumerina var. anguinea Snake gourd Trichosanthes cucumerina Vigna unguiculata cowpea 9. What hosts are of economic and/or environmental importance in the PRA area? Beans (Phaseolus spp.), cowpea (Vigna unguiculata), cucumber (Cucumis sativus), melon (Cucumis melo), pumpkin (Cucurbita moschata) and watermelon (Citrullus lanatus) are all important within the EPPO region. 10. If the pest needs a vector, is it present in the PRA area? No vector is required. This is a free living organism. 11. What is the pest’s present geographical distribution? This is primarily a tropical and sub-tropical species from Africa, Asia and the Pacific. Table 2: Geographic distribution of Diaphania indica North America: USA (Florida) Central America: Absent (no records) South America: Paraguay, Venezuela Caribbean: Cuba, French Guiana, Jamaica, Puerto Rico, Dominican Republic* Europe: Absent (unconfirmed 18th Century UK record) Africa: widespread in sub-Saharan Africa Middle East: Saudi Arabia, Yemen Asia: India, China, Japan, South Korea, SE Asia to Papua New Guinea, Bangladesh* Oceania: Australia (common in Northern Territory), wide spread through Pacific islands (Source: EPPO, 2005) * based on detections in consignments from these countries. 2 of 9 CSL Pest Risk Analysis for Diaphania indica CSL copyright, 2005 12. Could the pest enter the PRA area? Yes. Certain. D. indica has been intercepted as larvae on several occasions in the past on produce from Africa, Asia and the West Indies. Table 3 summarises the 24 PHSI interceptions since 1997. Table 3: PHSI interceptions of Diaphania indica 1997- 2005 Country of origin Dominican Host Kenya Republic Nigeria India Bangladesh Total Momordica 13 3 1 17 other 3 3 1 7 Total 16 3 3 1 1 24 The Netherlands has also intercepted this organism on Momordica (bitter gourd) from Kenya and Surinam. The month when most interceptions have occurred is shown in Figure 1. Clearly most interceptions occur in September. This coincides with the period of peak abundance as reported in the literature. Figure 1: Interceptions of Diaphania indica (1997-2005) by month of detection 9 8 7 6 5 4 3 Interceptions 2 1 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month D. indica could be carried in trade as eggs on the leaves of hosts or larvae on host fruit. Females are highly fecund and lay between 340 and 1,050 eggs each, depending upon the time of year adults emerge (Ke et al., 1986). Eggs are laid singly or in groups on the underside of leaves. The number of eggs laid on leaves varies between hosts but can range from 0.2 to 5.0 per leaf (Ke et al., 1988) 13. Could the pest establish outdoors in the PRA area? Perhaps yes (2, on a scale of 1-5), but only in the most southern warmer MS of the EU and EPPO that have sub-tropical climates, particularly where cucumbers, melons and gourds are grown (see Annex 1). In China there are a maximum of four generations per year. No adults are found earlier than July or later than November (Ke et al., 1986). The peak abundance of adults is from August to early September (Ke et al., 1988). D. indica has a similar phenology in South Korea with adults first emerging in mid to late July and peaking in late September (Choi et al., 2003). In India D. indica is present year round with the 3 of 9 CSL Pest Risk Analysis for Diaphania indica CSL copyright, 2005 highest populations between April and September and lowest between November and February (Peter & David, 1991). Based on the evidence above it appears that D. indica is suited to warm/hot environments and judging by its existing geographic distribution (mainly tropical) and its limited distribution in Australia (Northern Territory) and the USA (Florida) it would appear that it has a limited ability to overwinter in regions with cold or even cool winters such as the UK and northern Europe. The overwintering capability of this pest would appear to provide the key to its survival in the PRA area. In South Korea, which has cold winters, e.g. mean monthly mimima in January are between –2°C and –9°C, and maxima are between 0°C and 6°C, depending upon location, D. indica is reported to overwinter as pupae underground. Larvae descend from hosts and enter the soil during October and burrow to between 5 and 10cm below the soil surface where they form pupae and overwinter (Choi et al., 2003). Figure 2 shows monthly maximum and minimum temperature and rainfall profiles for locations in South Korea. Figure 2: The climate of South Korea (data from CRU UEA and Pearce & Smith, 2000.) 35.0 400 30.0 350 25.0 300 20.0 15.0 250 10.0 200 5.0 150 0.0 Temperature (C) 100 -5.0 -10.0 50 Monthly rainfall (mm) -15.0 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month Considering a scenario of mature larvae entering the UK on produce in the summer (June 1st), larvae could continue to develop and pupate, growing into adults by mid July. The subsequent generation could develop to form pupae by early September. Assuming this life stages overwinters in the soil (as it does in Korea, from October) the pupae would have to survive until the following May before development continued with adults emerging in late May or early July. In Korea the first peak of adult activity occurs in mid to late July (Choi et al., 2003) suggesting that these are the adults emerging from the overwintered pupal stage (see Annex 2). Based on the thermal biology of the pest alone (Annex 1 and text above) it would appear that D. indica could possibly survive outdoors in northern Europe, including UK. However, the known distribution of the pest and its limited occurrence in the USA and Australia would suggest otherwise. It is possible that other factors, in addition to temperature, play a major role in determining the distribution of this pest. Based on the known distribution of this organism, it is unlikely to be able to establish outdoors in the UK or northern Europe. 4 of 9 CSL Pest Risk Analysis for Diaphania indica CSL copyright, 2005 14. Could the pest establish in protected environments in the PRA area? Yes, probably.. Although not currently noted as a pest of glasshouse crops, this is a pest of melons grown in rain sheltered houses in Korea. In the PRA area the climate in glasshouses would be suitable for the development of this pest.