How to control the mango tree borer (Chlorophorus annularis)
Distribution and damage: it occurs both at home and abroad, and in China it occurs to varying degrees in Yunnan, Guangdong, Guangxi, Fujian and other places. The larvae bore into and feed on the branches of fruit trees such as mango and cashew, usually entering from young branches and gradually boring downward to large branches and the trunk, seriously affecting the growth vigor of the plant and eventually causing the death of the whole tree.
Morphological characteristics: the adult is about 33 mm long and about 8 mm wide, chestnut or chestnut-black, with a slender body and parallel sides; between the antennae, around the compound eyes and on the top of the head there is dense golden-yellow pubescence; the antennae are relatively long, about 1/2 to 3/4 of the body length; the pronotum has 19 raised longitudinal ridges, and the deep grooves between the ridges are densely covered with pale yellow pubescence. The surface of the elytra is densely covered with punctures, the punctures at the base being coarser and densely wrinkled; besides grayish-white short hairs, there are also long markings formed by golden-yellow hairs arranged in five longitudinal rows; the underside of the body and the legs are densely covered with gray or grayish-brown pubescence.
Life habits: one generation occurs per year; adults appear from April to July, and emerge in large numbers in May and June. Adults often lay eggs at the broken parts or cracks near the tips of young branches, one egg per site; the hatched larvae then bore into the pith of the branch to feed, the tunnel being simple, cylindrical above and below, and at the end of the tunnel there is often an accumulation of white gelatinous material. When the branch is shaken, the larvae can move rapidly upward or downward; on the outside of the damaged branch, at certain intervals, there are frass holes. The frass is a viscous black liquid discharged from the frass holes, which is a prominent sign of damage by this insect.
After the larvae mature, they pupate inside the tunnel; after the pupae emerge, they remain in the pupal chamber for a period before gnawing the frass hole wider and going out to be active, feeding on young tender branches, tender buds and the bark of tender shoots as supplementary nutrition, then mating and laying eggs.
Control measures
1. Clean the orchard: in winter and spring, in conjunction with orchard pruning, cut off the damaged branches and burn them in a centralized manner.
2. Manual capture of adults: newly emerged adults are easy to capture manually during the supplementary feeding stage.
3. Spraying the canopy: use spraying to kill adults during their supplementary feeding stage. Some low-toxicity pesticides can be selected for spraying. For example: 25% or 30% julume mixture emulsifiable concentrate at 1500-2000 times dilution, or 20% guofengling wettable powder at 800-1000 times dilution, or 30% shachongling emulsifiable concentrate at 1000-1500 times dilution. Use any one of the above pesticides, alternating them, and spray once every 7-10 days during the adult occurrence period, for 2-3 consecutive sprays.
4. Injecting pesticide into insect holes: use 40% dimethoate emulsifiable concentrate at 50 times dilution, or 2.5% deltamethrin emulsifiable concentrate at 200 times dilution, or 80% dichlorvos emulsifiable concentrate at 100 times dilution, use any one, and use a syringe to inject the liquid directly into the insect hole, or dip absorbent cotton in the liquid and plug it into the insect hole, then seal the hole with wet mud. Note: before applying the pesticide, choose holes from which fresh frass is being discharged for injection or for plugging with medicated cotton. Then seal all frass holes on the whole tree with wet mud, so as to facilitate the pesticide fumigating and killing the larvae in the tunnels.