Orchid pest: tobacco thrips

Tobacco thrips Thrips tabaci L., also known as onion thrips, belongs to Thysanoptera, thrips, which is distributed all over the country except Xizang. With old insects, adults harm orchids, chrysanthemums, Fulang flowers, carnation, hyacinth, cyclamen and so on. The direct harm of tobacco thrips causes chlorosis or yellowish-brown markings on both sides of orchid leaves, thickening and brittleness of the leaf tissues of other flowers with more moisture, rolling or breaking to the front, resulting in fallen leaves and affecting growth. Petals will also appear chlorotic markings and affect the quality.

Morphological features:

Female adults: 1.1~1.3mm in length, brown to light brown in color, purplish red in compound eyes, slightly prominent in coarse-grained shape, 3 in one eye, arranged in triangles, one bristle between one eye and 7 antennae on each side, U-shaped sensory cone at the end of section 3.4, a short sensory cone on each side of the end of segment 5, and a slender sensory cone on section 6. There are 4-6 bristles on the upper vein of the forewing, such as 4 bristles, such as 5-6 bristles, mostly 2-3 bristles forming a group, and 14-17 inferior vein bristles, uniform and continuous.

Egg: long 0.2mm or so, kidney-shaped.

Nymphs: the first instar is about 0.37mm and the body length is about 0.9mm at the 2nd instar, and the color is light yellow to dark yellow.

Pre-pupa and pupa: pre-pupa phylum nymph) and pupa (4th instar nymph) are similar to the second instar nymph, but have wing buds and antennae are placed in front of the head.

Occurrence regularity: the algebra that occurs every year varies from place to place, and there are generally 6-10 generations, with adults, nymphs or pupae overwintering in basin soil, litter, bulb or some plant leaf sheaths, mainly adults overwintering. The activity began from March to April of the following year. Eggs are scattered on the surface of tender leaves, and adults and nymphs are often harmful near petioles and veins. Because of their fear of light, they often climb to the leaf surface in the morning and evening or cloudy days, and mostly in front of leaves or veins in sunny days. Adults are very lively, can fly and jump well, and spread quickly. Drought without rain is beneficial to it, and the activity is restrained in case of high temperature and humidity or rainstorm.

The average temperature of the generation in the greenhouse is 19C, the relative humidity is about 85%, the egg stage is 8 days, the 2-year-old nymph is 10-14 days, and the pre-pupa stage is 4-7 days. It takes more than 20 days to complete a generation, and only about 15 days in summer. Males are female in summer and male in autumn. Parthenogenesis is generally carried out, with each female laying 20 eggs and 200 eggs.

Prevention and control methods:

1. Take effective horticultural measures, such as removing weeds around flower beds, turning pots and changing soil after autumn.

2. See flower thrips for chemical control.

Liu Zhongjian