EUROPEAN AND MEDITERRANEAN PLANT PROTECTION ORGANIZATION
ORGANISATION EUROPEENNE ET MEDITERRANEENNE POUR LA PROTECTION DES PLANTES
09-14703 (maps incorporated)
P PM Point 7.3
Diaphania indica: notes on fitting CLIMEX maps
Document prepared by Alan MacLeod, CSL 25th October 2008
1. Overall distribution
The pest basically has a tropical and sub-tropical distribution from the Caribbean and northern South America,
across sub-Saharan Africa, Asia and the Pacific (Table 1).
Table 1: Geographic distribution of Diaphania indica
North America:
USA (Florida)
Central America & Cuba, French Guiana, Jamaica, Puerto Rico, Dominican Republic*
Caribbean:
South America:
Paraguay, Venezuela
Europe:
Absent (intercepted only)
Africa:
widespread in sub-Saharan Africa
Asia:
Saudi Arabia, Yemen, India, China (Hainan, Hong Kong, Hubei, Shandong, Taiwan, Zhejiang),
Japan, South Korea, SE Asia to Papua New Guinea, Bangladesh*
Oceania:
Australia (common in Northern Territory, present in Queensland, New South Wales, Western
Australia), wide spread through Pacific islands
(Source: EPPO, 2005; CABI CPC)
* based on detections in consignments from these countries.
There were particular challenges concerning Diaphania indica that made it especially difficult to model in
CLIMEX.
2. Non-climatic factors potentially limiting distribution and abundance
2.1 In the USA, D. indica is a quarantine pest (EPPO, 2005) and although it occurs in Florida, existing
phytosanitary measures may currently restrict its actual distribution in the USA, perhaps explaining why CLIMEX
predicts D. indica to be present in southern Texas (see Maps 1 and 2 below) whereas in reality D. indica is not
known to occur in Texas.
1. D. indica EI global distribution using parameters shown
1
2. D. indica EI global distribution with irrigation
2.2 In India, D. indica adults are present year round with the highest populations between April and September and
lowest between November and February. However, climate may not be the primary factor affecting abundance in
India. Peter & David (1991) examined D. indica population dynamics and noted peak populations occurred when
parasites were absent. At times of low adult abundance, between November and February, two parasites were
significant in keeping D. indica populations down. However, Peter & David (1991) did not report any climate data
and did not comment on whether climate had any effect on D. indica populations during winter months.
3. Contradictory factors
3.1 Whilst some variation in biological characteristics is to be expected within the scientific literature, such as
varying threshold temperatures for development (11.5 C from Shin et al., (2000); 13.8 C from Liu (2004)), there
is a surprisingly large difference in the number of generations reported in southern China with CABI CPC reporting
a maximum of four generations per year (CABI, CPC) and Liu (2004) predicting 12 generations per year in Hainan
Province. The full references were not available to look into this further.
4. Factors possibly explaining wider actual distribution than CLIMEX predicts
4.1 In Korea, D. indica is a pest of watermelons grown in rain-sheltered houses (Choi et al., 2003). Thus D. indica
is likely to be protected from cold and wet stresses that affect its distribution in Korea as predicted by CLIMEX.
4.2 Diaphania indica was first observed in Yemen in 1977 in fields of cucurbits (Ba-Angood, 1978, 1979). I expect
that irrigation is used to grow cucurbits in Yemen and elsewhere in the Middle East. By switching on a CLIMEX
irrigation scenario and using the default “top up to 3.6mm in summer months”, Yemen becomes favourable and
Iran, where D. indica also occurs (Namvar & Alipanah, 2002) becomes much more favourable (see map 2 see
above and 3 see below). Note that the North African coast along the Mediterranean appears at greater risk using the
irrigation scenario.
2
3. Where irrigation makes a difference
5. The EPPO regions where climatic factors favour establishment
5.1 The predicted phenology of D. indica at Haifa (Israel) (slide 6) closely matches that in southern China
(Xiamen, slide 7). Slide 8 shows D. indica eco-climatic indices (EI) at 8 locations in the southern EPPO region that
appear most suitable in a scenario of “top-up” summer irrigation.
6. Predicted growth/ phenology at met. station in Israel,
(with irrigation)
7. Growth in southern China
3
5.2 However, when the eco-climatic indices from point stations (Map 5) are interpolated across the land surface,
the area for suitable establishment is reduced (Map 9). The table in Slide 10 shows how EI changes when
interpolated. Only in the Canary Isles and south-western Morocco would climate appear suitable for establishment
of D. indica.
5. Focus on Euro-Mediterranean region (with irrigation)
9. EI Interpolated between meteorological stations (with
irrigation)
4
Table slide 10)
Location
Country
Las Palmas
Spain (Canaries)
EI
EI (point data)
(interpolated)
15
55
Haifa
Israel
0
51
Sidi Ifni
Morocco
51
38
Cape Juby
Morocco
48
35
Tangiers
Morocco
0
29
Naxos
Greece
0
27
Sicily
Italy
0
14
Crete
Greece
0
13
6. The Korean and Japanese “variant” of Diaphania indica
6.1 It was difficult to modify the parameters such that D. indica would fit into Korea and Japan without the
organism spreading very much in North America. However, from comparing the thermal biology of D. indica
populations from southern India and Japan, Kinjo & Arakaki (2002) suggest that because the climates are so
different between these locations, “it is likely that local populations or strains have adapted” [i.e. to Japanese
conditions]. The same may be true for Korean populations.
6.2 When I was using the diapause function and slightly different parameters, it was not possible to get good EI
values in Korea and Japan whilst maintaining the predicted distribution in India, Australia and North America.
Given that there has been some taxonomic confusion over D. indica in the past (see CABI CPC) I wonder if what is
called D. indica from Korea and Japan should indeed be considered as different to the more tropical D. indica in
Central America, the Caribbean, Africa and southern Asia, as per Kinjo & Arakaki (2002). As such I prepared
another set of CLIMEX parameters focussing on ensuring presence outdoors in Japan and with a period of
facultative diapause as occurs in Korea.
•D. indica “variant” in Korea & Japan
EI global distribution using parameters shown
5
3. Comparison of EIs for D. indica (blue) and “variant”
(red)
5. EI for D. indica “variant” in Euro-Med (without irrigation)
6
6. EI for D. indica “variant” in Euro-Med (with irrigation)
12. Interpolated eco-climatic indices for D. indica “variant”
across EPPOs Euro-Med region (with irrigation)
Note: In southern Japan EIs are around 20; in southern Korea EIs are around 10
12
31
11
20
20
23
34
26
39
32
33
39
46
44
7. Conclusion
If the hypothesis of there being different strains of D. indica is accepted, then because it is the less cold hardy strain
from Africa and Asia that arrives in Europe on produce (MacLeod, 2002; 2005), this CLIMEX study suggests that
the area suitable for Diaphania indica establishment in the EPPO region is very small (Map 5). When the Ecoclimatic Indices for point stations are interpolated across the land surface, the area for establishment is further
reduced (Map 9).
REFERENCES
Ba-Angood SAS. 1978. People's Democratic Republic of Yemen-outbreak of the melon worm, Diaphania indica
Saund. FAO Plant Protection Bulletin, 26 (1), 31-32
Ba-Angood SAS. 1979. Bionomics of the melon worm Palpita (Diaphania) indica (Saund) (Pyralidae:
Lepidoptera) in PDR of Yemen. Zeitschrift fur Angewandte Entomologie. 88 (3), 332-336.
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Choi DC, Noh JJ, Lee KK, Kim HS. 2003. Hibernation and seasonal occurrence of the cotton caterpillar, Palpita
indica (Lepidoptera: Pyralidae), in watermelon. Korean Journal of Applied Entomology 42 (2), 111-118.
EPPO, 2005. PQR database v 4.4. Paris, France: EPPO.
Kinjo K, Arakaki N. 2002. Effect of temperature on development and reproductive characteristics of Diaphania
indica (Saunders) (Lepidoptera: Pyralidae) Applied Entomology and Zoology 37 (1), 141-145,
Liu K. 2004. Threshold temperature and effective accumulated temperature of Diaphania indica Saunders. China
Vegetables. 1, 38-39.
Namvar P, Alipanah H. 2002. Diaphania indica (Saunders) (Pyralidae: Pyraustinae), as a first report for
Lepidoptera fauna of Iran. Applied Entomology and Phytopathology 70 (1), 22-23
MacLeod A. 2002. Pest risk analysis: Diaphania indica. Unpublished CSL report.
MacLeod A. 2005. Pest risk analysis: Diaphania indica. Unpublished CSL report.
Peter C, David BV, 1991. Population dynamics of the pumpkin caterpillar, Diaphania indica (Saunders)
(Lepidoptera: Pyralidae). Tropical Pest Management, 37(1):75-79.
Shin WK, Kim GH, Song C, Kim JW, Cho KY. 2000. Effect of temperature on development and reproduction of
the cotton caterpillar, Palpita indica (Lepidoptera: Pyralidae). Korean Journal of Applied Entomology. 39:
3, 135-140.
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