Myllocerus sp. nr chloris
Crops: Apple, peach
Why is it a problem? Adults feed in groups on small apples, causing rot and making them unmarketable. They can arrive in large numbers. However, as they normally feed in groups total fruit loss is generally quite low and they can be relatively easily managed.
Where and when is it a problem? It has been reported as a problem around Thimphu and Paro from early April to early July.
IDENTIFICATION
Adult weevils are greenish with a characteristic “snout”. They are very small, about 3 mm long.
SYMPTOMS
Adults can be observed feeding on the small (marble-sized) fruits and less often on tender young leaves of apple trees and on young peaches. They cause surface damage on apples, but adults also burrow into fruit, which then rot.
Confusion with other pests: Cleorina leaf beetles and the flat spiny caterpillar also feed on marble-sized apples. However, the green apple weevil adults are distinctive.
BIOLOGY
Lifecycle: Very little is known about the lifecycle of this pest. Adults probably fly in from adjacent forests into orchards where they feed in groups on small fruits and on tender young leaves. They have also been observed on young peaches. They first appear in late April and can be found through to early July.
Dispersal: Adults are winged, and probably fly into orchards from adjacent forests.
When can damage be expected? Damage only occurs on marble-sized fruit which are present between late April and early July.
Hosts: The breeding hosts are unknown. Adults have been observed as a pest of apples and peaches.
MANAGEMENT PRACTICES
The green apple weevil is an occasional pest that should be easily detected through regular orchard monitoring. Chemical control is only needed in exceptional circumstances.
Monitoring
Weekly monitoring is important when apples are marble-sized (late April through to early July), especially in farms where there has been a history of this pest. Look for surface damage on young (marble-sized) apples, and then for tiny adults. Estimate the percentage of apples affected. If it is low then treat by hand as they are found.
Effect of variety
Not known.
Non-chemical management
- Beetles are gregarious so affected apples can normally be easily handpicked and immersed in a bucket of water with a few drops of kerosene added. Pick fruit gently to avoid adults dropping to the ground and escaping.
Chemical management
- The use of insecticides in orchards should be minimised at all times to prevent outbreaks of new pests such as red spider mite.
- Insecticide use is normally only needed if more than about 5-10% of small apples are damaged.
- As this pest is transitory only a single spray is normally needed. Use either Chlorpyrifos (4 ml in 1 litre of water) or Cypermethrin (1 ml in 1 litre of water).
Version: NPPC 2017. Green apple weevil V1.0. Bhutan Pest Factsheet. www.PestsofBhutan.nppc.gov.bt. Date produced: 14 April 2017. Contact: nppcsemtokha@gmail.com
Image acknowledgements: NPPC.
