Retinia perangustana Snellen belongs to the order Lepidoptera Tortricidae. It is distributed in Inner Mongolia, Heilongjiang, Jilin, Liaoning and other places. It is mainly responsible for Larix gmelinii, Larix olgensis, and Japanese larch.
The larvae harmed the cones and seeds, and the affected scales were dry and discolored, while the cones were bent and deformed. The unvictimized seeds were also stunted.
Morphological characteristics
Adult body brown, body length 3.2-5.2mm, wingspan 10-15mm. The forewings are dark brown, with two stripes that are mostly composed of silver-gray scales. The outer treaty is located in one-third of the wings and the inner treaty is located one-half of the wing length. There are several silver-gray short lines on the leading edge, with gray-brown taupe. The hind wings are pale gray and black, with no markings.
Egg white or reddish, oval, about 0.6-0.7mm long;
Larval mature larvae are 8-10mm long and yellow-white. The head is brown-yellow, the back of the pronotum is dark brown, and the rest is pale yellow-brown.
Yellowish-brown, about 5mm long, 10 hips, white, long oval, 6-8mm long.
The law of occurrence occurred in the Daxinganling region of Inner Mongolia for 1 year and 1 year. There were also some partridges diapause until the third year before emergence. Wander under the bark scales or within the cones for wintering. Adults began eclosion in mid-May and began spawning in late May. The larvae hatched in mid-June. In mid-July, some of the larvae began to leave the cones and were randomized. The larvae penetrate into the cones after hatching, and no harm is seen from outside after the damage. After 2 years of age, it was transferred to the base of the Fruit scale and damaged along the fruit axis, feeding immature seeds and nearby scales. The affected scales are dry and discolored, and the cones are deformed. Usually there is only one larva in one cone and two or more in the year of major occurrence. The larval period was about 36 days, and peeling occurred 3 times. Except for a few in the cone, most of the larvae left the cones for wintering in the bark seams. The worms were distributed on the sunny slopes, followed by the tops of the mountains, and the shades were the least. Natural enemies include the moth velvet bees, long-bodied bees, pine borer bees, larvae, and roaring bees, and the parasitism rate is 20-45%; the fungal parasitic rate in the flood season reaches 40%.
Control methods
(1) Agricultural control.
In the afforestation period, coniferous and broad-leaved mixed forests will be implemented to strengthen tending management, increase tree vigor, and reduce damage; when seed orchards and mother trees collect seeds, insect conidium will be blown out and burned.
(2) Physical control.
According to adult habits of phototaxis, light trapping can be performed during adulthood of adult feathers.
(3) Protect and use natural enemies.
(4) Chemical control.
In the middle of July, when the larvae left the cones, they were sprayed and controlled. The agent used avermectin.
Avermectin
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Fruit
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