| Box tree moth | |
|---|---|
 | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Lepidoptera |
| Family: | Crambidae |
| Genus: | Cydalima |
| Species: | C. perspectalis |
| Binomial name | |
| Cydalima perspectalis (Walker, 1859) | |
| Synonyms | |
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Cydalima perspectalis or thebox tree moth is a species ofmoth of the familyCrambidae, first described byFrancis Walker, the Englishentomologist, in 1859. Native to Japan, China, Taiwan, Korea, far-east Russia and India,[1] it hasinvaded Europe; first recorded in Germany in 2006, then Switzerland and the Netherlands in 2007, Great Britain in 2008, France and Austria in 2009,[2][3][4][5] Hungary in 2011,[6] then Romania,[7] and Spain.[8] It has been seen in Slovakia, Belgium[9] and Croatia.[10]
It was during preparations for the2014 Winter Olympics in 2012, that it was introduced from Italy toSochi,European Russia, with the planting stock ofBuxus sempervirens. The following year it defoliatedBuxus colchica in large quantities.[11]
It was recorded in Ontario, Canada in August 2018[12] and in the eastern United States in May 2021.[13]
Eggs are 1 mm in diameter, pale yellow, and placed under green leaves without herbivory present. First larvae just coming out from the egg are about 1–2 mm long. Larvae development brings them in four weeks to about 35–40 mm at maximum. There is some shrinkage at the beginning of the nymphosis, pupae are 25–30 mm long, first green with browning longitudinal lines, then more and more brownish. Thewingspan of the adult form is 40–45 mm. Two variants are observed, the most common one is mostly white while the other is most entirely light brown. With one of the variants, the light brown with the white streaked wings has not been reported in North America as of yet.[14]
There are two or three generations per year with adults on the wing from April/May to September.[citation needed]. In the warmest parts of the European importation area, with cold conditions coming late in the year, there might be sometimes four generations per year. The species overwinters as a juvenile cocooned larva (about 5–10 mm long), protected in an hibernarium made of two leavingBuxus leaves solidly joined by silk.[citation needed]
The larvae feed on the leaves and shoots ofBuxus species.[15] Young larvae often eat only the upper part of the leaf, leaving the tougher veins and the waxy lower epithelium as if the leaves had been peeled. These peeled leaves eventually die. The young, newly hatched feed on small portions of the leaves, but as they grow older and the bigger they grow, then the more the larvae eat, therefore doing more damage.
Old larvae are the most damaging: they massively and completely eat the leaves, sometimes leaving a thin part at the contour and center of the leaf. Green ball-shapedfrass can usually be seen on host plants.
In the area of origin (Asia) natural regulation occurs, as witnessed by the non-destructive behavior ofC. perspectalis. In the area of Europe where the moth has been introduced, the damage is very serious because natural regulation does not occur at a significant level. However, in European areas where the Asian hornet (Vespa velutina) is present prior to the introduction ofC. perspectalis, some degree of predation by the wasp is observed (not confirmed by scientific and clear results). This is namely in the south-west of France, the first place whereV. velutina was introduced to Europe in 2004 (C. perspectalis invaded this area in 2012).V. velutina is able to capture small larvae, and larvae preparing for the nymphosis in their cocoon. WhereV. velutina has been introduced this causes other problems as itpreys on honey bees andEuropean honey bees are more vulnerable than their Asian counterparts.Research is being conducted for the suitability of parasitoid species, such as the tachinidExorista larvarum as abiological control agent.[16]
Pheromone traps (attracting adult males) are able to prevent impregnation of adult females and therefore control the severity of the damage. A more important proportion of sterile eggs is deposited by adult females. The selectivity of the pheromone is very good and useful indigenous species are not attracted.Pheromone traps must be in place from March–April to October–November.[17]
Bacillus thuringiensis ssp. kurstaki is a bacterium which produces an insect-specific endotoxin which perforates the caterpillars' gut lining, leading to paralysis and death.
Nematodes also have an action on the digestive system of larvae (difficult to adopt on this moth).
Insecticides would not be very useful, as these could be a potential waste of resources if these are unwarranted, as there are also secondary harmful effects. Some may even kill beneficial mites on the plants that keep the plant feeding mites in check.[18]
Insecticide,Bacillus and nematode treatments must be repeated three times at an interval of about ten days, because they mostly affect young larvae. Syntheticinsecticides such ascypermethrin anddeltamethrin are efficient, but must be thoroughly applied inside the bush and under leaves. Natural pyrethrin insecticides, extracted fromChrysanthemum and mixed withcolza oil, can also be used.Spinosad, based on chemical compounds found in a bacterium, is also efficient.
The species has become widespread in London and surrounding areas and has been ranked as a top garden pest in Great Britain. TheRoyal Horticultural Society provides anon-line survey to keep track of the pest.[19]
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