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Plantwise Technical Factsheet

tea looper (Biston suppressaria)

Host plants / species affected
Acacia (wattles)
Albizia
Camellia sinensis (tea)
Chrysanthemum indicum (chrysanthemum)
Dalbergia latifolia (blackwood)
Eucalyptus
Litchi chinensis (lichi)
Mangifera indica (mango)
Paulownia tomentosa (paulownia)
Phyllanthus emblica (Indian gooseberry)
Prunus domestica (plum)
Prunus salicina (Japanese plum)
Psidium guajava (guava)
Vernicia fordii (tung-oil tree)
List of symptoms/signs
Leaves  -  external feeding
Symptoms
The damage caused by looper caterpillars (B. suppressaria) to tea leaves is very similar to that caused by twig caterpillars (Ectropis bhurmitra). The young larvae nibble irregular holes along the margins of tender leaves causing the leaves to appear as though holes have been punched in them. As the larvae grow, small pieces of leaf are eaten initially along the margin but later the entire leaf is affected. Later larval instars prefer to eat the older maintenance leaves and in severe attacks, entire bushes can be completely stripped of foliage. As with E. bhurmitra, severe attack by B. suppressaria caterpillars in tea fields recovering from pruning can result in death of the bushes. Damage occurs mostly during the night and early mornings. During the day, the caterpillars rest on the twigs and branches of tea bushes, where they are camouflaged and not revealed by superficial examination.
Prevention and control
Physical Control

Adult moths, which congregate on tree trunks and rocks, can be collected by hand, as can the caterpillars and pupae. This serves as a useful tool to control B. suppressaria (Cranham, 1966).

In northern India, it was thought that constant use of UV-light traps for 3 years, in conjunction with pyrethroid insecticide, could eradicate the pest (Das and Gope, 1987).

Biological Control

In the tea areas of Sri Lanka and India, natural populations of parasites and diseases keep B. suppressaria under control for most of the time. However, localized spraying of persistent pesticides may be used when occasional pest outbreaks occur. The parasitoid Apanteles sp. is known to keep the pest under control (Danthanarayana and Kathiravetpillai, 1969; Chen Xuefen and Yin Kunshan, 1987).

In China, NPV is commonly used to suppress the population of B. suppressaria (Xie and Peng, 1979; Gan, 1981). NPV is host specific and pure genotypes of B. suppressaria NPV are used to control the pest (Liang et al., 1997). Recent studies have shown the NPV of B. suppressaria (BusuNPV) belongs to a distinct baculovirus species within the Baculoviridae (Hu et al., 1998a, b). Purified NPV, cultured on ovarian tissue cells of B. suppressaria, together with virus protecting material, UV absorbing agents, wetting agents, emulsifiers and antibodies, has been formulated and used commercially as a pesticide. Spraying cultured NPV suspensions gave excellent control of B. suppressaria in tea fields in China with no impact on the environment (Peng et al., 1991). Good control was also achieved in tung oil (Aleurites fordii) trees (Qi et al., 1985). In 1989, the application of the NPV of B. suppressaria (BusuNPV) to 100 ha of infested Metasequoia trees resulted in about 95% mortality of the pest.

Studies carried out in tea fields at Tocklai experiential Station in Assam, India, showed that a commercial preparation of Bacillus thuringiensis, B. thuringiensis var. kurstaki, was very effective in controlling B. suppressaria. About 90% mortality was obtained with a 1:100 dilution of the commercial preparation (Barbora, 1995). Bt Strain HB III provided about 96% mortality (Barbora, 1995). However, studies in India using B. thuringiensis strain HB III, indicated only about 50% mortality of third-, fourth- and fifth- instar larvae at spore concentrations of 62.4, 135.8 and 177.8 mg/l after 148, 120 and 96 h exposure, respectively (Borthakur and Raghunathan, 1987).

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:

Impact
B. suppressaria is a destructive pest of tea and several other tree crops but crop loss data is limited to only a few crops.

In China, it causes serious damage to tea and several other tree species. Of 3500 ha of tea bushes assessed during the 1970s, about 1300 ha were reported to have been damaged by B. suppressaria (Peng et al., 1991).

Severe damage has also been reported on Metasequoia trees in China. Control of the pest using the NPV of B. suppressaria resulted in a saving of 200,000 yuan (Peng et al., 1991).

The damage threshold level of B. suppressaria on tea bushes in China was determined to be about 5 larvae per plant (Chen Xuefen and Yin Kunshan, 1987).

A report by the Pakistan Agricultural Research Council (http://www.parc.gov.pk/honey.htm) indicated that the population of B. suppressaria can increase to alarming levels on Acacia modesta causing severe defoliation and thereby affecting honey production. A. modesta contributes to about 70% of the total honey production by Apis spp. During the late 1980s, about 109 commercial bee keepers in Punjab were deprived of 30-50% of their honey crop.

In north-east India, B. suppressaria has caused considerable losses to tea plantations since 1944. However, exact crop loss data are not available (Das, 1965). The use of cyclodiene compounds against the shot hole borer (Euwallacea fornicatus) in Sri Lanka resulted in severe outbreaks of B. suppressaria in the mid-1960s and far greater damage than that normally caused by the pest (Danthanaryana, 1967). The withdrawal of these pesticides and the adoption of integrated management techniques with minimal use of pesticides, have kept B. suppressaria under control with only sporadic outbreaks observed. B. suppressaria is considered a mild pest in southern India.
Related treatment support
 
External factsheets
TNAU Agritech Portal Crop Protection Factsheets, Tamil Nadu Agricultural University, English language
TNAU Agritech Portal Crop Protection Factsheets, Tamil Nadu Agricultural University, Tamil language
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