Control of citrus fruit fly

[Morphological characteristics]

Adult body length 6-8 mm, wing span 16 mm, all dark black and yellow alternate. There are 11 pairs of bristles on the chest, most of which are yellow brown, including 2 pairs of shoulder bristles, 2 pairs of dorsal bristles, 1 pair of anterior wing bristles, 2 pairs of posterior wing bristles, 1 pair of medial lateral bristles, 1 pair of lateral wing bristles, 1 pair of anterior bristles of small shield and 1 pair of terminal bristles of small shield. The abdomen is oval, male has 4 nodes and female has 5 nodes. The oviduct is well developed, but less than half the length of the abdomen, and the narrow part of the posterior end is shorter than the fifth abdominal segment. Egg fusiform, one end slightly pointed, slightly curved, about 1 mm long, about 0.1 mm wide, milky white. Larvae The first instar larvae are 1.2- 1.3mm long, the second instar 2.5- 5.8mm long, and the third instar 7.0- 11mm long. The first instar larvae are translucent, the second and third instars are milky white, and the mature larvae after the third instar are orange. The body is conical, the front end is small and pointed, the mouth hook is black, and the button structure inside the valve plate is larger and obvious. Pupa elliptic, ca. 5 mm long, ca. 2.5 mm wide, pale yellow.

[Rules of occurrence]

The fruit fly has 3-5 generations every year. It overwinters as pupae in areas with obvious winter, but there is no strict overwintering process in areas with warm winter. Life history is irregular, and all insect states often exist at the same time. Adults appear in Guangdong all year round, with a large number occurring from May to October. Citrus orchards, such as summer flowers and orange ripeness, are not nearby. Fruit, peach, pear, papaya, guava and other fruit trees, fruit fly adults will not be too much in citrus orchards before the fruit coloring, but orange fruit coloring will come to citrus orchards a large number of eggs. In the early stage of oviposition, it is necessary to feed on the excrement of insects such as scales, aphids and whiteflies to supplement protein in order to make the ovary mature. Adults can mate many times and lay eggs many times. The eggs are laid between the flesh and pericarp of the fruit and like to lay eggs on mature fruits. Fruit on the spawning needle size, often gelatinous liquid discharge, condensed into a milky process. Oviposition marks can be stained with 1% red pigment, eosin and methyl green. On orange fruits picked before eggs are hatched, the oviposition holes are often small brown spots, which then turn into taupe and tan circles. After hatching, the eggs are gray or reddish brown spots, and the internal flesh is rotten. Larvae cluster in the fruit to suck the juice in the flesh petal, although the appearance of the victim fruit is still fresh, but the flesh petal shriveled and contracted, into grayish brown, often premature first drop. Larvae mature when the hole out, after the fruit jump side transfer, and then into the loose topsoil pupation.

The decomposed products of yeast and soybean with water have strong attraction to female and male adults, and methyl eugenol has strong attraction to male insects. The long-distance transmission mainly follows the movement of the injured fruit. Its natural enemies are fruit fly cocoon wasps, jumping wasps, golden wasps and ants.

[Control methods]

① Trapping and killing the male of fruit fly. 2 g of 90% crystalline trichlorfon or 2 ml of 20% fenpropathrin emulsifiable solution are added into 2 ml of methyl eugenol stock solution, 1.5 ml of mixed solution is taken and dropped on a lure core rolled with polyurethane foam with a diameter of 1.5 cm and a length of 5 cm, the lure core is placed in a trap made of cola bottle, the trap is hung in an orchard at a height of about 1.5 meters and an interval of 60-80 meters, and a sexual attractant is dropped once every 1-2 months.

(2) Spray for control. 50% phoxim 800-1000 times solution was sprayed on the ground during the peak period of larva shedding and adult emergence, and 80% dichlorvos EC or 90% crystalline trichlorfon or 50% malathion EC 800-1000 times solution was sprayed on the tree crown during the main damage period.