The unrestricted risk for Planococcus kraunhiae, Planococcus lilacinus, Pseudococcus comstocki and Pseudococcus cryptus is: LOW.
Unrestricted risk is the result of combining the probability of entry, establishment and spread with the outcome of overall consequences. Probabilities and consequences are combined using the risk estimation matrix shown in Table 2.5.
The unrestricted risk estimate for the mealybugs of ‘low’ exceeds Australia's ALOP. Therefore, specific risk management measures are required for these pests.
There are over 5000 described species of Tortricidae (leafrollers) and the family is considered one of the largest of the so-called micro-Lepidoptera. A large number are still to be described, particularly in the tropics. The family is more strongly represented in temperate and tropical upland regions than in the lowland tropics, although it is worldwide in distribution (Meijerman and Ulenberg 2000).
The family is of great economic importance, as the larvae of many species cause major damage to horticultural crops, including pome and stone fruits, citrus fruits, grapes, ornamental crops, tea, coffee, cereals and cotton (Meijerman and Ulenberg 2000). Leafroller moth larvae damage fruit by chewing large holes that usually cause fruit rot on a wide range of economic species (CAB International 2007).
Adoxophyes spp. have previously been identified as of quarantine concern on Fuji apple from Aomori Prefecture in Japan (AQIS 1998), and on Korean pear from the Republic of Korea (AQIS 1999). In the import risk analysis for Fuji apples from Japan the leafroller species was specified as Adoxophyes orana fasciata (AQIS 1998). MAFF identified Adoxophyes orana fasciata and Adoxophyes sp. [Lepidoptera: Tortricidae] as pests associated with unshu mandarin (MAFF 1990). In Japan, “Adoxophyes sp.” is currently considered to comprise the two species A. dubia and A. honmai.
The leafroller moths considered in this import risk assessment are Adoxophyes dubia, A. honmai,A. orana fasciata and Homona magnanima. These species have been grouped together because of their related biology and taxonomy. In this assessment, the term ‘leafroller moths’ is used to refer to these species, unless otherwise specified.
Probability of entry
Probability of importation
The likelihood that leafroller moths will arrive in Australia with the importation of fresh unshu mandarin fruit from the production area in Japan is: LOW.
Adoxophyesspecies and H. magnanima are associated with unshu mandarin fruit throughout Japan (MAFF 2003; Sakamaki and Hayakawa 2004).
Adoxophyes species are present in the designated export areas in the Shizuoka Prefecture (Sakamaki and Hayakawa 2004). MAFF advised that a tortricid moth had been intercepted on unshu fruit for export to the USA and New Zealand on two occasions during the past ten years.
Up to 400 eggs can be laid by a single Adoxophyes female and up to 700 eggs of H. magnanima on fruit, leaves, and trunks of host plants in severe infestations (Carter 1984; CAB International 2004). Homona magnanima lays its eggs in masses on the upper side of leaves (CAB International 2007). The presence of silk webbing on leaves and fruit indicates the presence of Adoxophyes species and H. magnanima, allowing detection by fruit sorters and packers.
Adoxophyes species have 2–7 generations per year and H. magnanima has 4 generations per year. Adults reproduce rapidly, particularly in warm climates. Japan advised in 1999 that Adoxophyes sp. in Kyushu (southern Japan) has five generations, and in most other regions there are four generations per year. An Australian native species has seven generations per year (Smith et al. 1997). A temperature increase of only 2–3oC can induce earlier adult emergence and an extra one or two generations per year in Japanese species of Adoxophyes (Yamaguchi et al. 2001). The longevity of adults of Adoxophyes privatana, a Chinese species, varies from 2–22 days (Meijerman and Ulenberg 2000). The life span of adult H. magnanima is about 10 days (CAB International 2007). The occurrence of adult tortricid activity ceases by October prior to commencement of the proposed export season (early December).
Larvae of Adoxophyes species and H. magnanima damage the fruit by eating holes into the rind and flesh. The damage to fruit is conspicuous, allowing a significant degree of detection during pre-export inspections. The second generation of larvae of Adoxophyes orana penetrate shallowly into the fruit flesh to form large irregular depressions before entering diapause. Point-like holes are left in the fruit tissue from larval feeding, which consists of sting-feeding. Larvae of Adoxophyes species and H. magnanima are external feeders and do not enter fruit. Surface grazing causes injury to extensive areas of the fruit skin. These activities result in a down-grading of the economic value of the fruit (Meijerman and Ulenberg 2000).
Adoxophyes species mainly inhabit the temperate regions of Japan (Yasuda 1998a; Sakamaki and Hayakawa 2004). Similar climatic conditions occur in the southern parts of Australia. Adoxophyes species may survive commercial cold storage and transportation, because diapausing larvae tolerate freezing temperatures on apple (Jo and Kim 2001). The study by Jo and Kim (2001) indicates that Adoxophyes orana is a freeze-susceptible species and that diapause significantly enhanced cold hardiness.
Japanese plant quarantine records from 1989–1998 indicate that there were no records of any development stage of tortricids during pre-export inspections of fresh unshu mandarins transported to overseas markets. The number of shipments inspected was 3073, totalling 14 507 tonnes of fruit.
The association of egg and larval stages with citrus fruit and the ability of larvae to survive cold temperatures by entering diapause support a risk rating for importation of ‘Moderate’.
Probability of distribution
The likelihood that leafroller moths will be distributed within Australia in a viable state, as a result of the processing, sale or disposal of fresh unshu mandarin fruit from the production area in Japan is: MODERATE.
Although adults will most likely move off the fruit when disturbed, immature forms, i.e. the larval and pupal life stages, may remain within fruit during distribution via wholesale or retail trade. In trade Adoxophyes species and H. magnanima may be carried on vegetative, above-ground plant parts of cutflowers or other host plants.
Pupation may occur during transport and live adult leafrollers could emerge soon after consignments arrive in Australia.
Uneaten fruit that is not discarded is likely to be a suitable site for larvae to complete their development, but discarded fruit in compost bins or pits is likely to degrade quickly. Discarded fruit is unlikely to be suitable for larvae to complete development. This would impede on the successful distribution of these pests.
Sexual reproduction is essential for leafrollers (Weires and Riedl 1991). After successful pupation, adults would need to locate a mate, which will constrain their capacity to distribute in a reproductively viable state to a host.
The ability for flight increases the dispersal of leafrollers and the likely chances to locate a host. Adults are winged, and highly mobile. Adults of A. honmai and H. magnanima can fly about 5 km per night (Shirai and Kosugi 1997, 2000). At the age of two days both sexes of Adoxophyes honmai displayed maximum flight duration. Females could travel 9.6 km and males 8.5 km. These distances were obtained from continuous measurements over a 24 hour period (Shirai and Kosugi 2000).
The ability of immature life stages to remain with fruit moderated by the need to complete development and find a mate for sexual reproduction support a risk rating for distribution of ‘Moderate’.
Probability of entry (importation distribution)
The likelihood that leafroller moths will enter Australia and be transferred in a viable state to a susceptible host, as a result of trade in fresh unshu mandarin fruit from the production area in Japan, is: LOW.
Probability of establishment
The likelihood that leafroller moths will establish within Australia, based on a comparison of factors in the source and destination areas considered pertinent to their survival and reproduction, is: HIGH.
Adoxophyes species and H. magnanima are pests of a very wide range of fruit crop plants and ornamental species such as pome and stone fruits, citrus fruits, grapes, ornamentals, tea, coffee, cereals and cotton (Carter 1984; Meijerman and Ulenberg 2000; CAB International 2004). Adoxophyes honmai is a pest of Eucalyptus spp. (Nasu et al. 2004), which is endemic to Australia. A food source distributed across the country is more likely to support the establishment of moth populations.
Adults can reproduce rapidly, and several generations occur every year. The climate of Japan is very similar to that in many parts of Australia. Temperature is the main limiting factor to development of the immature stages and activity of adults. Temperatures most favourable to development (>10oC) and adult activity (>18oC) of A. honmai (Yamaguchi et al. 2001) occur over much of Australia.
Existing control programs (e.g. Cross 1997) would probably be effective for some but not all hosts. For example, Eucalyptus occurs across Australia, and control of Adoxophyes on this genus is not practical, considering the large pool of native hosts. Resistance to pesticides has also been recorded in Adoxophyes species (e.g. Funayama and Takahashi 1995).
Polyphagy, high fecundity and preadaptation to temperatures found in Australia and limited success of control measures for leafroller moths all support a risk rating for establishment of ‘High’.
Probability of spread
The likelihood that leafroller moths will spread within Australia, based on a comparison of those factors in source and destination areas considered pertinent to the expansion of the geographic distribution of these pests, is: HIGH.
The very large number and geographic ranges of host species in Australia such as Eucalyptus, pome and stone fruits, citrus fruits, grapes, ornamentals, tea, coffee, cereals and cotton (Carter 1984; Meijerman and Ulenberg 2000; CAB International 2004) would facilitate rapid spread of Adoxophyes species and H. magnanima. The extent and direction of spread will most likely vary depending on the moth species.
Adults of A. honmai and H. magnanima can fly about 5 km per night (Shirai and Kosugi 1997, 2000).
Adults and immature forms may also spread undetected via the movement of fruit or infested vegetative host material.
The presence or absence of natural enemies in Australia is not known.
As temperature increases, the reproductive rate and the number of generations also increases. Adoxophyes species and H. magnanima are likely to spread into the warmer, northern areas of Australia.
Similar environmental conditions (especially temperature) occur in Japan and Australia.
Readily available hosts, including eucalypts, and strong, directional flight ability support a risk rating for spread of ‘High’.
The likelihood that leafroller moths will be imported as a result of trade in fresh unshu mandarin fruit from the production area in Japan, be distributed in a viable state to a susceptible host, establish and spread within Australia, is: LOW.
Assessment of the potential consequences (direct and indirect) of leafroller moths for Australia is: MODERATE.
Estimate and rationale
Plant life or health
Impact score: E – minor significance at the national level
Adoxophyes species and H. magnanima are not native to Australia and can cause direct harm to a very wide range of plant hosts. These include Eucalyptus species, which occur all over Australia, and other commercial crops such as pome and stone fruits, citrus fruits, grapes, tea, coffee, cereals and cotton (Carter 1984; Meijerman and Ulenberg 2000; CAB International 2004). Larvae feed on fruit, which would retard the ability of plants to reproduce. Light infestations are usually not harmful to plants, but more severe infestations will most likely result in leaf curl, holes in fruit, fruit drop, stunting of shoot growth, and delay in production of flowers and fruit, as well as a general decline in plant vigour.
Adoxophyes species and H. magnanima introduced into a new environment may compete for resources with the native species. Their wide host range, including Eucalyptus species for A. honmai that occur throughout Australia, suggests that impacts on ecological communities and amenity plants are likely to occur.
Eradication, control etc.
Impact score: E – significant at the regional level
Programs to minimise the impact of these moths on host plants are likely to be costly and include pesticide and pheromone applications, crop monitoring, and the possible introduction of biological control agents. Existing control programs may be effective for some but not all hosts (e.g. Eucalyptus, Acacia species).
Impact score: D – significant at the district level
The presence of these pests in commercial production areas may have a significant effect at the district and local level due to resulting interstate trade restrictions on a wide range of commodities. These restrictions may lead to a loss of markets.
Impact score: D – significant at the district level
The presence of these pests in commercial production areas, such as citrus growing areas, may have a significant effect at the district level due to limitations to access to overseas markets where these pests are absent.
Environmental and non-commercial
Impact score: B – minor at the local level
Although additional pesticides may be required to control moths on susceptible crops, this is not considered to have significant consequences for the environment.