What are the control methods for pineapple mealybug

The scientific name of the pineapple mealybug is Dysmicoccus brevipes (Cockerell), belonging to the order Homoptera, family Pseudococcidae. Dysmicoccus neobrevipes is the most commonly seen.

Damage symptoms: adults and nymphs damage the rhizomes, leaves, fruits and seedlings of pineapple by sucking their sap. Affected leaves first show symptoms starting from the lower part, gradually fading upward to yellow and finally turning red-purple; in severe cases all leaves soften, droop and wither, ultimately causing the entire plant to die. Affected roots first turn dark brown, then gradually rot, causing the plant to grow weak. After fruits are affected, the rind loses its luster, and the secreted “honeydew” can lead to sooty mold, with severe cases showing shriveling. Affected seedlings develop poorly and may even wither.

Morphological characteristics

Adult: the female adult is about 2.5-3 mm long, flat oval-shaped, covered with white wax powder, with waxy protrusions along the margin, 7-8 antennal segments, 17 pairs of cerarii, secreting waxy filamentous setae, and the anal lobes bearing 2 medium-sized conical spines. Tubular ducts are distributed on abdominal segments 6-8, grouped along the margin; the hind tibia is about twice as long as the tarsus. The female body color is mostly pink. When sexually mature, the posterior end of the abdomen bears a white waxy cotton-like ovisac. The male adult is very small, yellowish-brown, with transparent wings held flat on its back, and a pair of slender waxy structures at the end of the abdomen. It has one pair of transparent forewings.

Egg: about 0.35-0.38 mm long, oval, initially yellow, later gradually turning yellowish-brown, in irregular cotton-like masses attached to the host plant.

Nymph: 3 instars in total. It resembles the female adult but is smaller, with antennae and legs. Female nymphs become adults after 3 molts; male nymphs become pupae after 2 molts.

Pupa: located in a cocoon sac formed by filamentous waxy material; the cocoon is irregular in shape, mostly elongated, attached to the plant.

Occurrence pattern: one generation takes 45-59 days. The female adult can only mature its ovaries and reproduce after sucking the sap of the host plant; it reproduces by parthenogenesis, mainly viviparously. In winter, especially in January-February, oviparity often occurs, or oviparity and viviparity alternate. Viviparous nymphs tend to gather under the mother's body, and after finding a suitable site they begin to feed and cause damage; some remain motionless near the mother or crawl repeatedly on the mother's body. The nymph stage generally lasts 30 days in summer and up to 2 months in winter. The female adult lays eggs in a cotton-like ovisac. After emergence, the male adult generally remains motionless in crevices of plants, does not feed, and has a short lifespan of only a few days. The male nymph stage lasts about 14 days in summer, and the pupal stage generally 12-15 days. Heavy rain or continuous rainfall has a washing-off effect on mealybugs. Ants carry mealybug bodies, which helps the mealybugs spread and disperse. Ants like to feed on the excretions of mealybugs; when these excretions are consumed, it is favorable for mealybug growth and reproduction.

Control methods

1) Strengthen orchard management to enhance tree vigor, apply fertilizer and irrigate reasonably, and improve the tree's resistance. Prune scientifically, cut off diseased and weakened branches, and regulate ventilation and light penetration. Combined with pruning, clean up the orchard to reduce sources of the pest.

2) When planting, select pest-free seedlings; if necessary, treat the crowns by soaking in a 500-800 times dilution of 40% dimethoate.

3) Fumigation for insect control: for seedlings carrying the pest, fumigation can be carried out. In an enclosed space, use a mixture of 10-16 g sodium cyanide, 15-24 mL sulfuric acid, and 40 mL water to generate hydrocyanic acid gas and fumigate for 1-2 hours to eliminate the pest, after which the seedlings can be planted.

4) Chemical control: in severe outbreaks, spray rosin mixture.

Commonly used agent: rosin.