PINE NEEDLE SCALE
Chionaspis pinifoliae (Fitch) -- Diaspididae
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Pine needle scale is a native North American insect with many coniferous hosts. An outbreak occurred in South Lake Tahoe, California in 1968, which offered an opportunity to record a case of naturally occurring biological control in a town environment (Dahlsten & Hall 1999). South Lake Tahoe has encroached into the natural westside forests of the Sierra Nevada Mountains, where both lodgepole pine, Pinus contorta Dougl. and Jeffrey pine, Pinus jeffreyi Grev. & Balf., grow along the streets and in the town yards. Normally this scale occurs at low densities on both pine species; however in 1968 populations soared in areas that had been fogged with malathion for control of a mosquito, Culex tarsalis Coquillett. The insecticide treatments were stopped and the scale population declined within three years (Luck & Dahlsten 1975).
A uniparental population of scale was identified on lodgepole pine while a biparental population occurred on Jeffrey pine (Luck & Dahlsten 1974). Different species of parasitoids were also found on the different host tree species of the scale. The two scale parasitoids on lodgepole pine were Physcus howardi Compere and Prospaltella bella Gahan. The parasitoid attacking scale on Jeffrey pine was Acheysocharis phenacapsia Yoshimoto (Luck & Dahlsten 1974). The coccinellid predators Chilocorus orbus Casey var. monticolus Drea and Cryptoweisia atronitens (Casey) attacked the scale on both pine species. Dominant natural mortality factors were the coccinellids on both pine species and parasitization by P. bella on lodgepole pine (Luck & Dahlsten 1975). Other homopterans, such as Nuculaspis californica (Coleman), Pineus sp., Physokermes sp. and Matsucoccus sp., two mite species, Oligonychus sp. and Brevipalpus sp., and an aphid, Schizolachnus sp. were very abundant in the insecticide treated areas (Dahlsten et al. 1969, Dahlsten & Hall 1999).
REFERENCES: [Additional references may be found at: MELVYL Library ]
Dahlsten, D. L. & R. W. Hall. 1999. Biological control of insects in outdoor urban environments. In: Bellows, T. S. & T. W. Fisher (eds.), Handbook of Biological Control: Principles and Applications. Academic Press, San Diego, New York. 1046 p.
Dahlsten, D. L., R. Garcia, J. E. Prine & R. Hunt. 1969. Insect problems in forest recreation areas. Calif. agric. 23(7): 4-6.
Luck, R. F. & D. L. Dahlsten. 1974. Bionomics of the pine needle scale, Chionaspis pinifoliae (Fitch), and its natural enemies at South Lake Tahoe, California. Ann. Ent. Soc. Amer. 66: 309-16.
Luck, R. F. & D. L. Dahlsten. 1975. Natural decline of a pine needle scale (Chionaspis pinifoliae (Fitch)) outbreak at South Lake Tahoe, California, following cessation of adult mosquito control with malathion. Ecology 56: 893-904.