Rice whitefly
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Aleurocybotus indicus, a species of whitefly in the family Aleyrodidae (Homoptera), was previously known as Bemisia sp. This pest was first identified in 1991 in central and eastern Fujian Province. In recent years, it has become widespread in rice fields across Hunan Province, where it has emerged as a new and significant threat to rice production.
The host plant for this pest is rice. The nymphs feed by inserting their mouthparts into the leaves, sucking out the sap, which leads to blackening of the foliage, sooty mold development, and overall weakening of the plants. This damage can significantly reduce rice yields and affect grain quality.
Morphologically, adult females are approximately 0.71 mm long, while males are slightly smaller at about 0.64 mm. Newly emerged adults are covered with a white waxy coating on their bodies and wings, which disappears after 5–6 days. First-instar nymphs measure around 0.29 mm in length, have three pairs of thoracic segments, and develop antennae. They are pale yellow-green in color, flat and oval in shape, with 18 pairs of bristles along the edges. The front and rear bristles are longer and thicker than those on the sides. As they mature, their antennae and legs gradually degenerate. Second- and third-instar nymphs grow to 0.34 mm and 0.57 mm, respectively. The oyster-shaped pupae are approximately 0.92 mm long and 0.38 mm wide, elliptical in shape, with 4–6 bristles at the front and back. Most commonly, there are four bristles at the front, with an "upper" splitting line, and four at the back.
In terms of life habits, Aleurocybotus indicus completes 6 generations per year in Hunan and 7 in Fujian. The seventh generation includes both quail and adult stages. During winter, the pests overwinter on the undersides of grassy weeds and seedlings such as crabgrass, barnyard grass, Bermuda grass, and goosegrass. When temperatures rise above 16°C in mid to late April, adults emerge in early rice fields, with the first to fourth generations being most active during the double-crop early rice season. The main damaging generation is the third, with average temperatures of 26.8°C and humidity around 72%. The egg stage lasts 9–12 days, first instar 2–3 days, second instar 3–5 days, third instar 4–6 days, and the pre-pupal stage 6–8 days. The adult pre-oviposition period is 1–2 days, and adults live for 9–21 days.
In single-season rice, 3–6 generations may occur, with the 3rd to 5th generations being the main ones responsible for damage. For double-season late rice, the fifth and sixth generations are the primary threats, with the fifth being the most severe. Generations often overlap between the 3rd and 5th. The booting to filling stages of the rice plant are particularly vulnerable. Paddy fields with deep water, excessive weeds, overuse of nitrogen fertilizer, poor ventilation, and weak plant growth tend to suffer more damage. High temperatures and drought conditions during July and August also increase the risk of infestation. Natural enemies include spiders, ants, lacewings, and parasitic wasps.
For prevention and control, agricultural practices such as removing weeds along field edges and ditches, plowing fallow seedlings, and eliminating overwintering populations are recommended. Proper planting density, avoiding excessive nitrogen fertilizer, and improving field management—such as reducing deep irrigation and performing timely field drying—can help prevent overgrowth and poor air circulation.
In terms of chemical control, a strategy of "early detection and strict management" is advised for controlling the 3rd to 5th generations. Spraying should be done during the early nymph stage using products such as 25% Buprofezin WP (1000x dilution), 40% Omethoate EC (1000x), 8% Dextromethorphan (1500x), or 20% Schneiders Emulsion (1000x). Other options include 44% Speed Kai EC (1500x) and 20% Imidacloprid (Confodol) diluted 3000–4000 times. These measures can effectively reduce population levels and minimize crop damage.