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Plantwise Technical Factsheet

oriental tea tortrix (Homona magnanima)

Host plants / species affected
Arachis
Camellia sinensis (tea)
Chrysanthemum indicum (chrysanthemum)
Citrus
Diospyros kaki (persimmon)
Eurya
Glycine
Lithocarpus edulis
Malus domestica (apple)
Nandina domestica (Nandina)
Paeonia (peonies)
Paulownia tomentosa (paulownia)
Podocarpus
Prunus (stone fruit)
Prunus avium (sweet cherry)
Pyrus (pears)
Rhododendron (Azalea)
Rosa (roses)
Solanum melongena (aubergine)
List of symptoms/signs
Leaves  -  external feeding
Leaves  -  leaves rolled or folded
Leaves  -  webbing
Symptoms
The young larvae tie the margins of young leaves together, often enclosing the bud, and feed from within these leaf nests. When mature, they bind several (sometimes more than 10 leaves) leaves together to make a nest. The mature larvae are voracious feeders on the leaves, often leaving partly fed or dead leaves on trees. This feeding activity causes distortion of the leaves and young shoots and also defoliation, which can be seen from a distance.
Prevention and control
Chemical Control

Due to the variable regulations around (de-)registration of pesticides, we are for the moment not including any specific chemical control recommendations. For further information, we recommend you visit the following resources:

Pheromones

Noguchi (1979) developed a convenient and reliable method for determining the female sex pheromone of H. magnanima in Japan using a combination of low ambient temperature and continuous illumination (Noguchi, 1979). Three compounds ((z)-11-tetradecenyl acetate, (z)-9-dodecenyl acetate and 11-dodecenyl acetate) in the ratio of 30:3:1 were identified as the sex pheromones of H. magnanima. Field tests indicated that all three compounds were indispensable for attracting the males (Noguchi et al., 1979).

H. magnanima often occurs together with the smaller tea tortrix Adoxophyes sp. in the tea areas of Japan. Various combinations of the pheromone components related to H. magnanima and Adoxophyes sp. were therefore evaluated in the field as possible disruptants for both species. Three components, (z)-11-Tetradecenyl acetate, (z)-9- tetradecenyl acetate and (z)-9-dodecenyl acetate were identified as potential disruptants on the basis of disorientation experiments. In further studies, (z)-11-tetradecenyl acetate alone or a combination of the three acetates (1:1:1) were selected as disruptants for both species. The effect was more disruptive to H. magnanima than to Adoxophyes sp. (Tamaki et al., 1983). Kobayashi et al. (1988) conducted similar studies to control H. maganinma and Adoxophyes sp. in other crops such as roses.

H. magnanima was reported to develop resistance to the communication disruptant, Hamaki-con (composed of (z)-11-tetradecenyl) in tea orchards at Shizuoka prefecture, Japan, after about 12 years of use in the field thus causing low shut-down effects (Mochizuki et al., 2001).

The synthetic pheromone of H. magnanima retains its attractiveness to males for 2 days when supplied on a cotton rope wick, for 2 weeks when applied on plastic capsules, and for more than 1 month on a rubber septum (Noguchi et al., 1981). Pheromone trappings of this species revealed that catches were higher when population density was low (Shimada, 1980).

Synthetic pheromones are useful in pest surveillance and monitoring in the field. These pheromones have also been used to disrupt mating in the field thereby preventing the build-up of H. magnanima. Pheromone treatments have been reported to reduce populations and crop damage (Tamaki et al., 1983; Kobayashi et al., 1988). Mating disruption techniques have also been used to control multiple species of insects in the field (Izawa et al., 2000).
Impact
H. magnanima is an economically important pest. Although a seasonal pest, the manner of leaf folding and the voracious feeding activity can cause severe damage to the leaves and young shoots of the crop host during the larval period resulting in the death of leaves, defoliation and crop loss. The economic injury level for H. magnanima in tea fields was determined to be 4 larvae/m² (Takaji, 1976).

The fruits of trees are not affected by H. magnanima.
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