How to control the citrus black scale in orange orchards? The pure yellow aphelinid wasp comes to the rescue

[Morphological characteristics]

Female wasp body length 0.92-1.18 mm, yellow, without color spots. The posterior margin of the scutellum has dark brown stripes. The base of the forewing has short black stripes; the ventral side of the antennal scape is dark brown, and the remaining segments are deep fuscous. Legs yellow. Compound eyes with fine hairs. Thoracic hairs thick and black; the scutellum bears 4 hairs; the forewing is 2.25 times as long as wide; the ovipositor is 1.9-2.01 times the length of the middle tibia. Male wasp body length 0.71-0.92 mm; the forewing is wider than that of the female, 2.2-2.33 times as long as wide. Important differences from Aphytis chrysomphali: the pure yellow aphelinid wasp of the citrus black scale is a bisexual species, and the propodeum is shorter, 0.75-0.8 times the length of the scutellum. The fan-shaped projections are large and elongated. Strongly overlapping; the thorax and venter of the mature pupa are dark brown, with only the abdominal tip lighter in color. Aphytis chrysomphali is a unisexual species, with males rarely seen in nature; the propodeum is longer, equal to or slightly longer than the scutellum. The posterior margin is broadly arched; the fan-shaped projections are small, rounded, and not overlapping. The mature pupa is yellow, with only a single black longitudinal line on the mesothoracic ventrite.

[Occurrence pattern]

The pure yellow aphelinid wasp of the citrus black scale is a relatively specialized parasitoid wasp of the citrus black scale, and generally does not parasitize the California red scale.

[Protection and utilization]

(1) Use pumpkin and oleander leaves to rear the citrus black scale and propagate the aphelinid wasp. During the peak hatching period of the scale insect eggs, place the scale-infested branches and leaves on the above-mentioned plants; the hatched crawlers will climb up and settle to parasitize, and once the scale insects reach the second instar, the aphelinid wasps can be inoculated. The parasitized scale insects can be stored at low temperature and released into the orchard when needed.

(2) In early spring, cut branches and leaves bearing scale insects parasitized by the aphelinid wasp, move them into parasitoid wasp protection devices in the orchard to let the parasitoid wasps emerge, and then parasitize the scale insects.

(3) In winter, cut branches bearing scale insects parasitized by the aphelinid wasp, refrigerate them, and the following year, before the scale insects break out in large numbers, take out the branches and hang them separately in the orchard.

(4) Never apply broad-spectrum pesticides or those with a long residual period. Especially during the peak activity period of the adults, pesticide application should be stopped.