Volume 19(3), 26- 31, 2015 JOURNAL of Horticulture, Forestry and Biotechnology www.journal-hfb.usab-tm.ro

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Cydalima perspectalis Walk. (Lepidoptera: Crambidae), a dangerous pest of Buxus sempervirens in Timis County, Romania

Fora C.G.1, Poşta D.S.1

1Faculty of Horticulture and Forestry Timişoara

*Corresponding author. Email: foraciprian@yahoo.com Abstract Cydalima perspectalis Walk. (Lepidoptera: Crambidae) is, in present, a dangerous pest on species of Buxus sempervirens in Europe to. The importance of this pest result from his spread on almost entire continent, spread realized in less than one decade, and from damages which can produce it on host plants, damages which can contributes to drying of defoliated individuals. In Romania this pest is present to, in special in Timis County, where has been observed in 90% of localities targeted by our research, and where seems to found good climatic condition to multiplying. In all 10 localities, both in urban and rural area of county, defoliation oscillated from 0 to 100%, damage levels being very different even in the same locality. Thus, it was determined that 19.35% from analyzed box tree individuals were not damaged, 50.00% from individuals had a weak damage level, 8.06% had middle damage level, 6.45% had strong damage level and 16.14% very strong damage level. In general has been observed that the damage level of box tree individuals was weak to middle. If on effects of defoliation produced by C. perspectalis overlap the effect of dry summers, with very high temperatures, lake that from summer of 2015, the risk that individuals of box tree to dry is more accentuated.

Key words Cydalima perspectalis, damage level, Buxus sempervirens, Timis County, Romania

In Romania the most prevalent species of

Genus Buxus is Buxus sempervirens. To us, Buxus

sempervirens is one of the most cultivated wood

species in parks and gardens (Şofletea and Curtu,

2007). In Europe, as in our country, the species of

Buxus are threatened in last years by a dangerous pest

Cydalima perspectalis Walk., found for the first time in

Germany in 2007 (Krüger, 2008). In Romania has been

found for the first time in 2010, in 3 different locations

from Bucharest (Iamandei, 2010), respectively in 2011,

in North-West part of the city and in a yard of a

kindergarten (Szekely et al., 20011). In Timişoara we

found him for the first time in larva stage in summer of

2013 on few individuals of Buxus from Young

Naturalists Park. From first report to present, the

species widespread continuously and very much, which

suggest the high mobility of it. Therefore, it can be

observed in Switzerland (Billen, 2007), Holland (Muus

et al., 2009), England (Mitchell, 2009), France

(Feldtrauer et al., 2009), Austria (Rodeland, 2009),

Liechtenstein (Slamka, 2010), Belgium (Casteels et al.,

2011), Italy (Biondi, 2010), Hungary (Sáfián and

Horváth, 2011), Czech Republic (Šumpich, 2011),

Turkey (Hizal et al., 2012), Slovenia (Seljak, 2012),

Croatia (Matošević, 2013), Slovakia (Pastorális et al.,

2013), Denmark (Hobern, 2013). The box tree moth, C.

perspectalis, is a crambid moth native to eastern Asia

(Leraut, 2012). It was most probably introduced to

Europe with containered Buxus seedlings (Mally and

Nuss, 2010). The importance to studying of this species

derive from the very large area of spreading, from

injuries which can cause it, sometimes the injuries can

be a total defoliation, from the fact that in Europe is a

pest mainly on Buxus sempervirens, recently

introduced in our region and therefore with predators

and parasitoids almost unknown.

Our paper follow on the one side to establish

the spreading of this pest in Timis County, the

westernmost county of Romania, and on the other side

to appreciate the damage level produced on analyzed

box trees, fact with a high significance for practice. All

of these elements are a first step in order to studying

the biology of the pest in conditions of our country,

which is almost unknown in present.

Material and Method

The spread study of defoliator C. perspectalis,

on individuals of B. sempervirens, was conducted in

summertime of 2015, in parks and gardens from urban

and rural places of Timis County, 10 localities being

covered: Buzias, Carpinis, Cenad, Comlosu Mic, Deta,

Jimbolia, Lovrin, Lugoj, Sannicolau-Mare and

Timisoara. It has been done visual assessments on a

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number of 62 individuals of B. sempervirens, box trees

(25 individuals) and hedges (37 pieces). It was

followed, in principal, the appreciation of defoliation

percentage done by pest caterpillars on host plants.

After establishing of the defoliation percentage, it was

appreciated the damage level using our own scale of

interpretation (table 1), scale established taking into

account the injuries that caterpillars can do on host

plants and the effects that the defoliation had on host

plants, knowing that the species of Buxus have a very

slow growing, the recovery of foliage is in many times

difficult and can cause, in some cases, the drying of

defoliated individuals.

Table 1

Injury scale of defoliation percentage at Cydalima perspectalis Walk.

Crt. no. Defoliation (%) Damage level Damage significance

1. 0 0 undamaged

2. 1-20 1 weak

3. 21-40 2 middle

4. 41-60 3 strong

5. >60 4 very strong

Results and Discussions

The obtained results show that the defoliator

C. perspectalis was present in the majority of studied

localities, with exception of village Comlosu Mic

where has been identify, in garden from a front of one

house, just 2 box trees of B. sempervirens, these being

unattacked. The percentages of defoliation oscillated

from 0 to 100%, more than 80% from analyzed

individuals of B. sempervirens presenting different

percentages of defoliation.

Using our injury scale of interpretation of

defoliation percentage at C. perspectalis it can be

observed that 19.35% of individuals were not

defoliated, 50.00% from all individuals had a low level

damage, 8.06% middle damage, 6.45% strong damage

and 16.14% very strong damage (figure 1). In general

it can be observed that the damage level was low to

middle that underline the necessity of detailed studies

of biology and dynamic of species in conditions of our

country in order to apply of control measures correct

and in time.

Fig. 1. C. perspectalis damage level in Timis County, Romania (2015)

Adults of C. perspectalis have a wingspan of

around 4 cm (Leuthardt and Baur, 2013), white color

slightly iridescent wings with a large dark brown band

at the outer margin and a characteristic white spot on

the forewing, in the discoidal cell (figure 2). Hind

wings are white with the same band at the outer margin

as in the forewings (Mally and Nuss, 2010). In a less

common color variant, the adults are completely

brown, but still show a white forewing spot. The moths

are good flyers and can reach a lifespan of up to two

weeks. After mating the females laid eggs on the leaves

of the host plant in groups of 5-20, coated with a

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translucent jelly (Leuthardt and Baur, 2013). At

beginning the eggs are pale yellow, but close to

hatching, the black heads of the larvae are visible. The

light green larvae are characterized by black stripes

with white dots and hairs and a shiny black head and in

the last larval stage they can reach a length of up to 4

cm (figure 2). The pupae are between 1.5 and 2.0 cm

long (figure 2), initially are green with dark stripes on

the dorsal surface, towards the end of pupation they

turn brown with a dark pattern corresponding to the

brown wing borders of the adult. They are concealed in

a cocoon of white silk spun among the leaves and twigs

(Korycinska and Eyre, 2009).

The caterpillars of C. perspectalis feed on

leaves of Buxus spp. (B. sempervirens, B. microphylla,

B. sinica and B. colchica), Ilex purpurea, Euonymus

alata and Euonymus japonicus and are considered to be

serious defoliators (Korycinska and Eyre, 2009).

Recent study investigated the oviposition choice and

larval food preference and performance on five

commonly used European box-tree varieties: B.

sempervirens ‘Sempervirens’, B. s. ‘Rotundifolia’, B. s.

‘Argenteo - variegata’, B. s. ‘Aureovariegata’ and B.

microphylla ‘Faulkner’. The study showed that females

prefer the variety ‘Rotundifolia’ for oviposition, but

revealed no differences in larval growth rate and

survival on the five varieties. However, a strong

seasonal variation in larval performance was found, the

spring generation growing faster than the autumn

generation (Leuthardt and Baur, 2013).

Larvae feed mainly on leaves but may also

attack the bark. Young larvae prefer leaves containing

a high concentration of alkaloids (older leaves).

Indeed, under natural conditions, young larvae tend to

feed on old leaves at the bottom of box tree plants

(Leuthardt and Baur, 2013). This behavior permits a

fast uptake of large amounts of alkaloids within a short

time to increase protection against predators, before

maximizing the larval growth rate. Young larvae feed

at beginning with superior part of leaves and after that

with entire leaf. Total defoliation is common (figure 2)

and usually results in the death of the trees. One

possibility to stimulate the recovery of box tree leaves

is irrigation in summertime, in period when usually the

dryness is present.

Fig. 2. Larva (up left); Pupa (up right); Pupa and Adult (down left);

Defoliation (down right); of C. perspectalis.

(Photo: Fora Ciprian George)

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The effect of the moth is often aggravated by

the occurrence of the box blight, caused by the fungal

pathogen Cylindrocladium buxicola Henricot, another

invasive species that arrived in Europe a few years

before C. perspectalis. In infested areas, it has become

impossible to maintain healthy box trees without

chemical treatment or laborious mechanical removal of

larvae (Kenis et al., 2013). Infestation symptoms

include feeding damage on the leaves of the shoot

edges by the larvae, which can leave only leaf

skeletons and the epidermis behind them (Leuthardt

and Baur, 2013).

Other associated symptoms are webbing of

the branches, frass and residues of molting such as

black capsules of different sizes. Heavy infestation

leads to dry plants and their defoliation, which

combined with the subsequent attack of the bark results

in the death of the plant. Box trees with a low level of

damage are often able to recover if they do not suffer

from renewed attacks (Strachinis et al., 2015). If heavy

defoliation overlaps on dry condition with lake of

precipitation in summertime increase the risk that

individuals of box tree to die. This species has up to three generations per

year in Asia, as well as in Europe (Korycinska and

Eyre, 2009), and overwinters in the caterpillar stage

(Zhou et al., 2005). The first flight occurred from late

May to mid June; the second one from mid July to mid

August and the third from early September to early

October. Males may be attracted by long distance

(Santi et al., 2015).

Young larvae overwinter in diapause in a

cocoon built between leaves. Diapause is induced by

day length and temperature experienced by young

larvae (Maruyama and Shinkaji 1993). Larval feeding

continues in spring and pupation also occurs in the

foliage (Kenis et al., 2013).

No natural enemies have been recorded in

Europe so far (Nacambo et al., 2013) while it is neither

attacked by predators (birds) because of the toxicity of

the host plant (Leuthardt et al., 2010). Given all these

circumstances this invasive pest has very favorable

conditions (no natural enemies, favorable climate,

widely available host plant) for spreading and

establishing in new areas. In Europe larval parasitism

was less than 1% and represented by a single tachinid

parasitoid, Pseudoperichaeta nigrolineata Walk. while

no egg or pupal parasitoids were found (Nacambo,

2012). Predators were not commonly observed either,

possibly due to the sequestration of toxic alkaloids

from their host-plant (Leuthardt et al. 2013).

Today, there are several possibilities to

control C. perspectalis. Besides the periodic

mechanical removal of larvae at low infestations levels,

chemical insecticides like deltamethrin or

diflubenzuron as well as Bacillus thuringiensis

preparations should be effective against the box tree

moth (Korycinska and Eyre, 2011; ). Furthermore,

there are promising investigations with application of

Trichogramma (Zimmermann et al., 2009) and

entomopathogenic nematodes (Choo et al., 1991).

Natural enemies of the pest include polyphagous

parasitoids (Nacambo et al., 2014) and birds exhibiting

low predation, probably due to the high levels of toxic

alkaloids sequestered by its larvae (Leuthardt and Baur,

2013). Recently, laboratory experiments have indicated

the susceptibility of C. perspectalis larvae to

baculovirus Anagrapha falcifera nucleopolyhedrovirus

(AnfaNPV) as a new opportunity to control this pest

(ROSE et al., 2013). Caterpillars of C. perspectalis are

more sensitive at chemical insecticides is young stages

(L1-L3). Because of that the control measures had to

be applied in spring as soon as possible, in our

conditions early in March. The treatments must be

repeated after that moment every 7 to 10 days until the

caterpillars disappears because the pest has two-three

generation per year and in some moments it can be

found in the same time eggs, larva and pupa on box

trees. A mechanical control measure can be applied in

autumn, before winter, when the caterpillars stay

together in overwinter places through cutting of

infested steams. Particular attention should be taken

regarding monitoring and control of this dangerous

pest because can contribute at destroying of important

ornamental species from parks and gardens.

Conclusions

Analyzing of our results obtained from

researches performed on spread of species C.

perspectalis and assessment of damage level on host

plant B. sempervirens, can be formulated next

conclusions:

- In Timis County the pest is present in majority of

localities targeted by our research;

- Damage levels has been from undamaged to very

strong damaged and can be observed a general

tendency of damage from weak to middle;

- It is required to continue to study biology and pest

dynamics in order to correct application and in

time of control measures.

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