Detailed Explanation of the Harm, Morphological Characteristics and Control Techniques of the Green Rice Bug
Insect green rice bug belongs to the order Hemiptera, family Pentatomidae. It occurs in all sweet orange producing areas of China. Besides harming citrus, it also damages rice, corn, peanuts, cotton, legumes, cruciferous vegetables, rapeseed, sesame, eggplant, chili pepper, potato, peach, plum, pear, apple, etc. Both adults and nymphs harm tobacco plants, piercing and sucking the sap of tender leaves and tender stems at the top, often causing water-soaked wilting at the pierced and sucked parts of the leaves first, followed by drying up. In severe cases, the upper leaves or the top shoots of the tobacco plant wilt.
I. Morphological characteristics of the green rice bug:
Adults have multiple forms, and the various biotypes often interbreed, so their morphology is variable.
1. Spot type
(spot green bug) Body length 13~4.5 mm, width 6.5~8.5 mm. The entire dorsal surface is orange-yellow to orange-green, with 1 small black spot in each ocellar region, generally not very distinct. The pronotum has 3 green spots, the central one largest, often prism-shaped. The basal margin of the scutellum has 3 green spots, the middle one largest, nearly round, and its end and the rear end of the coriaceous part of the wing each have a green patch.
2. Yellow-shouldered type
(yellow-shouldered green bug) Body length 12.5~15 mm, width 6.5~8 mm. Very similar to the typical form of the green rice bug, but the head and the front half of the pronotum are yellow; the yellow area of the pronotum is sometimes orange-red, tangerine-red or brown-red, with the posterior margin wavy. Eggs are ring-shaped, light brownish-yellow when first laid. The top of the egg has a ring of white denticles. Nymphs have 5 instars in total, resembling adults, green or yellow-green, with black spots scattered on the pronotum and wing pads, the outer margin tangerine-red, and the ventral margin with semicircular red or brown spots. Legs reddish-brown, tarsi and tips of antennae black.
3. All-green type
(typical form) Body length 12~16 mm, width 6~8 mm, oval, body and legs entirely fresh green, head nearly triangular, the end of the 3rd antennal segment and the apical half of the 4th and 5th segments black, the rest blue-green. Ocelli red, compound eyes black. The angles of the pronotum bluntly rounded, the anterior lateral margins mostly with narrow yellow edges. Scutellum long triangular, narrowly rounded at the end, with 3 small white spots on the basal margin and 1 small black spot outside each lateral angle. Ventral surface pale, abdominal terga entirely green.
II. Control techniques for the green rice bug
1. Reduce pest sources
During winter and spring, clear weeds near the field edges in conjunction with compost accumulation to reduce overwintering pest sources.
2. Manual capture and killing
Taking advantage of the adults' poor flying and activity ability in the morning and evening, carry out manual capture and killing.
3. Chemical control
Apply pesticides at the peak of nymph outbreak, when they cluster near the egg shells and have not yet dispersed. Options include 90% trichlorfon 700-fold solution, 80% dichlorvos 800-fold solution, 50% fenitrothion emulsifiable concentrate 1000~1500-fold solution, 40% dimethoate 800~1000-fold solution, 25% phosmet 700-fold solution, or pyrethroid pesticides 3000~4000-fold solution for spraying.