Pseudococcus longispinus (Targioni Tozzetti)
{Synonym: Pseudococcus adonidum (L.)}
Taxonomic placing: Insecta, Hemimetabola, Hemiptera, Sternorrhyncha, Coccomorpha, Coccoidea, Pseudococcidae.
Common name: Long-tailed mealybug.
Geographical distribution: Occurring outdoors in most subtropical and tropical regions, indoors in temperate zone. CIE Map # 93, 1984 (revised).
Host plants: Polyphagous, infesting over 100 host plants.
Morphology: The elongate body of the female is 2.5-4.0 long, yellow, with a brownish dorsal stripe and covered by white waxy dust. It has 17 pairs of marginal wax filaments. The anal pair, which is longest, may exceed the pest’s entire length (hence its vernacular name). The antennae are 8-segmented.
Life history: The female lays 75-200 eggs (dependent on the host plant) and a generation is completed in about six weeks at 26ºC. Third-stage nymphs may also be inseminated, but oviposit only after having molted to females. Pest numbers peak in early summer, declining in autumn and winter. First instar nymphs may disperse by becoming wind-borne. Large populations are often attended by ants, which do not seem to affect the numbers of P. longispinus but hinder its natural enemies.
Economic importance: This pest damages avocado by sucking out nutrients and especially by producing much honeydew on which sootymold fungi settle. This retards fruit development and affects the yield. The effect on citrus fruit is similar. Damage is compounded by the honeydew moth, Cryptoblabes gnidiella Millère, which is attracted to the honeydew. This moth oviposits there and its larvae gnaw into the fruit. Although unable to complete their development there, they incur fruit blemishes, at times even fruit drop. In addition, P. longispinus may transmit grapevine leafroll virus 3.
Management
Plant resistance: Avocado varieties differ in their susceptibility to the pest.
Chemical control: The pest can be controlled with organophosphates, but that is usually unnecessary due to its natural enemies. A preparation of Neem was effective in greenhouses without affecting the natural enemies.
Biological control: The pest is usually kept below its economic injury level by natural enemies, especially the introduced encyrtid endoparasitoids Arhopoideus peregrina (Compere) and Anagyrus fusciventris Girault. Common predators include Chrysoperla carnea (Chrysopidae) and Coccinellidae. Such non-chemical control suffices unless disrupted by drifting pesticides.
References
Barras, I.C., Jerie, P. and Ward, S.A. 1994. Aerial dispersal of first- and second-instar longtailed mealybug, Pseudococcus longispinus (Targioni-Tozzetti) (Pseudococcidae: Hemiptera). Australian Journal of Experimental Agriculture 34: 1205–1208.
El-Minshawy, A.H., Karam, H.H. and El-Sawaf, S.K. 1974. Biological studies on the long tailed mealy bug, Pseudococcus longispinus (Targ. and Tozzeti) (Homoptera: Pseudococcidae). Bulletin de la Societe Entomologique d’Egypte 58: 385-391.
Lindemann, S. and Richte, E. 2007. Erfahrungen bei der biologischen Bekämpfung von Pseudococcus longispinus (Targioni Tozzetti) an Phalaenopsis Hybriden. Nachrichtenblatt Deutscher Pflanzenschutzdienst 59: 77–86.
Sandanayaka, W.R.M., Blouin A.G., Prado, E. and Cohen, D. 2013. Stylet penetration behaviour of Pseudococcus longispinus in relation to acquisition of grapevine leafroll virus 3. Arthropod-Plant Interactions 7: 137–146.
Serçe, C.U., Kaydan, M.B., Kilinçer A.N.and Ertunç, F. 2007. Investigation of mealybug (Hemiptera: Coccoidea: Pseudococcidae) species from Turkey by RAPD. Phytoparasitica 35: 232-238.
Swirski, E., Izhar, Y., Wysoki, M., Gurevitz, E. and Greenberg, S. 1980. Biological control of the longtailed mealybug Pseudococcus longispinus (Coccoidea, Pseudococcidae) in the avocado plantations of Israel. Entomophaga 25: 415-426.
Wysoki, M., Izhar, Y., Swirski, E., Gurevitz, E. and Greenberg, S. 1977. Susceptibility of avocado varieties to long-tailed mealybug, Pseudococcus longispinus (Targioni-Tozzetti) (Homoptera-Pseudococcidae) and a survey of its host plants in Israel. Phytoparasitica 5: 140-148.