Eurydema spp.
Crops: Cole crops, beans, spinach
Why is it a problem? Harlequin bugs can be damaging during the seedling stage and early stage of the crops in Bhutan. The concentrated attack causes widespread withering of young leaves. However, it rarely causes economic losses.
Where and when is it a problem? This pest is probably present and common in all Cole crop-growing areas. Major, widespread outbreaks have not been reported.
IDENTIFICATION
The Harlequin bug is a striking insect with a distinctive black and orange or red pattern on its body. Two very similar species of harlequin bug are commonly encountered in Cole crops in Bhutan (E. dominulus and E. liturifera). Adults are about 10 mm long and give an unpleasant odor when disturbed. They are either orange or reddish with black spots. Nymphs (immature bugs) also display bright coloration but are smaller and rounder compared to adults. The coloration and pattern make them easily recognizable. Eggs are barrel-shaped greyish-white, and about 0.5 mm in diameter. They are laid in batches of two overlapping rows.
SYMPTOMS
Harlequin bugs feed by piercing plant tissues with their mouthparts and sucking out the sap. This feeding behavior causes the formation of small white or yellow spots at feeding sites, leaf wilting and yellowing, stunted plant growth, and death of young plants if the infestation is severe.
Confusion with other pests: Their distinctive coloration means that adults are not easily confused with other pests.
BIOLOGY
Lifecycle: Harlequin bugs may likely produce two to three generations in a year in Bhutan.
Dispersal: Adults fly.
When can damage be expected? Damage has never been quantified in Bhutan and significant outbreaks have never been recorded.
Hosts: Both species are commonly found on Cole crops
MANAGEMENT PRACTICES
This pest is rarely a problem, and then only for young Cole crop stages. Chemical control is only needed in the most severe cases.
Monitoring
Constant monitoring is required for this and other pests on Cole crops. The presence of bugs needs to be determined particularly during the early stages of the crop.
Effect of variety
Not Known.
Non-chemical management
- Removing plant debris and weeds that can serve as alternate hosts helps reduce overwintering sites.
- In smaller gardens, manually removing and destroying bugs and egg clusters can help manage populations.
Chemical management
- Chemical spray will rarely be justified, and should only be directed to where the pest is dense.
- Chlorantraniprole 18.5 % SC (0.3 ml per 1 liter of water) can be used. A waiting period of at least two weeks after spraying is needed before harvesting.
Version: NPPC 2017. Harlequin bug V1.0. Bhutan Pest Factsheet. www.PestsofBhutan.nppc.gov.bt. Date produced: 14 April 2017. Last date modified: 18 June 2024. Contact: nppcsemtokha@gmail.com
Image acknowledgements: NPPC.
