Pseudococcus cryptus Hempel

(Synonym: Pseudococcus citriclus Green)

Taxonomic placing: Insecta, Hemimetabola, Hemiptera, Sternorrhyncha, Coccomorpha, Coccoidea, Psedocooccidae.

Common name: Citriculus mealybug. In Israel it was initially misidentified as Comstock’s scale, Pseudococcus comstocki Kuwana (a valid species), and then as Pseudococcus citriculus Green (a synonym of Pseudococcus cryptus).

Geographical distribution: Cosmopolitan.

Host plants: In the Middle east, mostly on citrus, and on avocado roots. In other regions, a serious pest of coffee.

Morphology: The body of the grey to pink to yellow female is about 2.5 mm long and is covered by mealy wax. The antennae are 8-segmenetd and there are 17 pairs of cerarii with a corresponding number of marginal wax filaments that are increasingly larger towards the scale’s posterior end. The anal filaments are longest, about half the length of the body

Life history: Each female lays about 200 eggs (more in summer, less in winter) that are placed in ovisacs. They are dispersed by the ambulatory females all over the host plants, including the roots. A life cycle is completed at 27ºC in about four weeks, whereas 8-9 weeks may be needed at 20ºC; the threshold of development was calculated to be 11.6ºC and 490 day-degrees are needed to complete a generation. On citrus trees in the Middle East the pest completes 6-7 annual generations.

Economic importance: The pest forms large and very noticeable clusters on leaves and twigs. Damage is due to secreting vast amounts of honeydew that is colonized by sootymold fungi, covering fruits and leaves by thick black mats. Photosynthesis is disrupted, resulting in reduced citrus crop quantity and quality. Fruit may drop and tree growth is adversely affected. Most damage is to young orcahrds of the more susceptible grapefruit and peeling varieties, as well as to lemons. Pest outbreaks may occur if the pest’s natural enemies were killed by indiscriminate pesticide usage.

Management

Monitoring: The beginning of a new generation can be determined by using traps baited with the pest’s sex pheromone. The crawlers then begin to emerge when about 300 day-degrees above 10ºC had accumulated after the initial male occurrence in the trap.

Chemical control: Organophosphates may be used in very severe outbreaks.

Biological Control: In the past the pest was apparently controlled by the introduced encyrtid endoparasitoid Clausenia pupurea Ishii, and more recently by the introduced Anagyrus sawadai Ishii. Several Coccinellidae prey on the pest, provided they are not disrupted by pesiticides.

References

Arai, T. 2002. Attractiveness of sex pheromone of Pseudococcus cryptus Hempel (Homoptera: Pseudococcidae) to adult males in a citrus orchard. Applied Entomology and Zoology 37: 69-72.

Blumberg, D., Ben-Dov, Y. and Mendel, Z. 1999. The citriculus mealybug, Pseudococcus cryptus Hempel, and its natural enemies in Israel: history and present situation. Entomologica 33: 233-242.

Holat, D., Kaydan, M.B. and Muştu, M. 2014. Investigations on some biological characters of Pseudococcus cryptus (Hempel) (Hemiptera: Pseudococcidae) on four citrus species. Acta Zoologica Bulgarica, Supplement 6: 35-40.

Swirski, E., Wysoki, M. and Izhar, Y. 2002. Subtropical Fruits Pests in Israel. Fruit Board of Israel (in Hebrew with English Summary).

Websites: http://www.idtools.org/id/scales/gallery_index.php?page=5#prettyPhoto[media]/9/