Identification and control methods for Apophylia thalassina

Scientific name Apophylia thalassina (Faldermann), order Coleoptera, family Chrysomelidae. Also known as wheat stem leaf beetle, @#@245@#@ golden flower beetle. Its distribution runs from Heilongjiang and Inner Mongolia in the north, its southern limit does not cross the Huai River, and it reaches Gansu and Qinghai in the west. It is becoming increasingly serious in Shanxi, Gansu and Hebei.

Hosts include wheat crops, corn, goji berry, thistle, willow, etc.

Damage characteristics: the larvae bore into the wheat stem from 1.5cm below the soil surface to cause damage, resulting in dead hearts, dead seedlings, white heads and ineffective tillers, causing large areas of wheat fields to have missing plants and broken rows. It is a devastating pest of wheat.

Morphological characteristics: female adult body length 7-9mm, elytra bronze-colored, after laying eggs the abdomen elongates and enlarges beyond the elytra covering; male adult body length 6-7mm, front of head yellowish brown, rear part dark brown, antennae with 11 segments, whip-like, pronotum yellowish brown with 3 black markings, the middle one larger, elytra emerald green with fluorescence, densely covered with fine yellow hairs. Egg length 0.8-1.5mm, oval, initially light yellow, blue-gray when overwintering. Mature larva body length 9-12mm, yellowish brown, pronotal shield and anal plate dark brown, with dark black spots of varying sizes arranged neatly on each segment of the dorsal surface of the body. Naked pupa length 6-9mm, cream-colored, cylindrical, with 2 anal spines at the end.

Life habits: one generation per year in North China, overwintering as eggs 1 m below the soil surface; in late March of the following year, when wheat joints, the eggs begin to hatch, and in early April, during the peak jointing stage of wheat, the egg hatching peak occurs. The period from wheat jointing to booting is the peak damage period of wheat stem leaf beetle larvae; in the early booting stage of wheat the larvae begin to pupate, and during wheat flowering and grain filling the peak pupal eclosion occurs. The larvae have the habit of moving between plants to cause damage, and each larva can damage 7-16.9 plants. Adults often gather on small thistles in the morning and evening, eating the leaves into numerous holes, sometimes leaving only a small part of the main vein. Eggs are laid singly in soil cracks and loose soil. The occurrence of this insect is closely related to topography, cultivation and meteorological conditions; it generally occurs easily in shallow hilly areas, continuous wheat fields and fields with extensive cultivation, and outbreaks are severe in years with excessive rainfall during the peak egg hatching period.

Control methods: (1) Remove small thistles from wheat fields in mid-to-late May, which can reduce opportunities for adult egg laying. (2) During the peak adult occurrence period, spray 90% crystalline trichlorfon 1000-fold solution or 50% dichlorvos emulsifiable concentrate 1000-fold solution, 50% 1605 emulsifiable concentrate 1500-fold solution, 10% deltamethrin emulsifiable concentrate 1500-fold solution, 2.5% Baode emulsifiable concentrate 2000-fold solution, 2.5% deltamethrin emulsifiable concentrate 2000-fold solution, 50% malathion emulsifiable concentrate 1000-fold solution. (3) Egg control. Deep autumn plowing 25-30cm can destroy eggs. (4) Larva control. Use 1.5% methyl 1605 powder or 2.5% trichlorfon powder or 2% fenitrothion powder, about 2kg per 667 sq m, combined with intertillage and watering, carrying the pesticide into the soil, which can prevent larvae from moving between plants to cause damage. It is also possible to use 40% dimethoate emulsifiable concentrate 2000-fold solution or 50% 1605 emulsifiable concentrate or 90% crystalline trichlorfon 1000-2000-fold solution for root irrigation.