Identification and control of eggplant 28 ladybug

Coccinella octacospunctata belongs to Coleoptera family, alias acid syrup ladybug, commonly known as "flower sister", host crops include eggplant, tomato, green pepper, potato and other Solanaceae vegetables and cucumber and other cucurbitaceae vegetables, in addition to beans, acid syrup, cabbage and other crops, among which eggplant suffered more seriously. It is distributed in all parts of the country, but it occurs more in the south of the Yangtze River Basin and is seriously harmful.

1 Field identification

1.1 damage characteristics

Damage crops with adults and larvae. Hatching larvae live on the back of leaves and nibble on mesophyll, leaving only epidermis, forming many parallel translucent fine concave lines, and gradually disperse after slightly larger larvae. Adults and larvae can eat leaves into perforations, serious leaves only thick veins, damaged leaves dry, brown, the whole plant died. In addition, it can also harm tender stems, petals, sepals, fruits, etc. Not only the yield of the injured plants decreased, but also the quality of the fruits was poor. The nibbled parts of the eggplant and melon strips were often broken, the tissues became stiff, rough, bitter and inedible.

1.2 morphological characteristics

Adult hemisphere was ladle-shaped, yellow-brown or reddish-brown. There are six black spots on the proterplate, and the two in the middle are often connected into a horizontal spot. Coleoptera yellow-brown, 2 coleoptera each have 14 black spots, base 3, its rear 4 black spots almost in a straight line. 2. The black spots at the commissure of wings are not connected. The back of the wing is covered with fine short hairs, and the gloss is weak. The eggs are cannonball shaped, pale yellow at the beginning and yellow brown at the end. The egg positions in the egg mass are arranged densely. The first instar larvae are pale yellow, then white, spindle shaped, raised on the back, with neat branches and thorns on the back of the body, white branches and black brown ring patterns at the base. Pupa pale yellow, oval, the tail wrapped in the last instar larvae molt, the back has pale black stripes.

The morphological characteristics of potato ladybug are very similar to those of host crops. There are 14 black spots on each of the 2 elywings, but the 4 spots behind the 3 black spots at the base of elywing are not in a straight line. This is a significant difference between them. The adult potato ladybug is slightly larger, with a larger sword-like pattern in the center of the pronotum, two black spots on both sides (sometimes combined into one), and 1~2 pairs of black spots connected at the symphysis of 2 coleoptera. The egg grains are loosely arranged in the egg mass.

1.3 living habits

It occurs 3~5 generations a year in the Yangtze River basin and overwinters as adults under soil, bark cracks or weeds. It is mainly scattered and occasionally clustered. After the adults emerged in the second year, they first fed on the weeds of Solanaceae, and then moved to the vegetables of Solanaceae to damage them, especially eggplant. Overwintering adults lay eggs for a long time, so the generation overlap phenomenon is obvious. Adults with pseudo-death, there is a certain phototaxis, fear of strong light. The eggs are mostly laid on the back of leaves, often 15~40 upright into blocks, and a few are laid on stems and tender shoots. Larvae have weak dispersal ability. Larvae hatched from the same egg mass generally damage the plant and its surrounding plants. Larvae are more afraid of strong light than adults. Both adults and larvae have the habit of killing each other and feeding on eggs. Larvae have 4 instars. Most mature larvae pupate in the middle and lower parts of plants and on the back of leaves. The 2nd, 3rd and 4th generation of this insect are the main harmful generation, which is the peak growth period of Solanaceae vegetables in summer. At the end of August and the beginning of September, Solanaceae crops are harvested and ploughed successively, and the mortality of larvae and pupae is relatively high. The young and adults migrate to wild hosts, beans and autumn cucumbers. From the first and middle of October, the adults fly to the winter site again. The optimum temperature is 22~28℃ and the relative humidity is 76%~84%.

2 Methods of Prevention

2.1 physical control

Using adults with pseudo-death, using utensils to receive and beat plants to fall to collect and eliminate, noon time better effect; according to the characteristics of egg concentration, bright color, easy to find, combined with agricultural activities, artificial egg removal.

2.2 agricultural control

After harvest, clean the fields in time, bury or burn the residual plants deeply, and cultivate the fields to eliminate eggs, larvae and adults hidden in the cracks.

2.3 chemical control

The key is to control larvae before they disperse, that is, to apply drugs at the peak of larvae hatching or at the damage stage of young larvae. 4.5% methrin EC 2000 times, 10% bifenthrin EC 1500 times, 2.5% methrin EC 1500 times, 2.5% cyhalothrin EC 3000 times, 20% fenvalerate EC 2000 times, 50% phoxim EC 1000 times, 52.25% Nongdile EC 2000 times, 48% chlorpyrifos EC 1000 times can be sprayed comprehensively and thoroughly. Pay special attention to spraying on the back of the leaf.