Establishment of pine woolly aphid, Pineus pini (Gmelin) (Adelgidae) on some host trees in Kenya

Abstract

The establishment of Pineus pini (Gmelin) on six common Pinus species is examined with references to possible causes for observed differences in the rates of infestations, on the different host species. Pine woolly aphid crawlers are positively Apoptotic, but do not settle onto surface exposed to strong light. They appear negatively photostatic to strong light and consequently tend to settle in hidden and tight crevices. The undersides of lateral branches which receive only moderate light tend to harbor a higher concentration of aphids than the upper surfaces. Possibly, positive thigmotaxis and' negative phototaxis operate together, tending to bring crawlers into situations satisfying feeding and thigmotactic instincts.