1. Five species of psyllid occurred on seven species of Salk at Meade River, Alaska. Studies were made on the two common species P s y h plJmeni Lb'w and P.phlebophyZ&e Hodkinson. The former feeds on the phanerophytes M i x pulchm. S.hnata, S.alaxenSis and S.glauca, the latter on the chamaephytes S.phlebophylla and S.teticuhta 2. Both P.palmeni and P.phlebophylhe had a 1-year life cycle and nymphal development took place on the female M k catkin. The life cycle was generally closely synchronized with the period of catkin development. However, only a few eggs were laid on S.g&uca. 3.Se.asonal perturbation of the host plant by flooding, ice movement and blown sand prevented psyllids breeding in certain areas colonized by the host 4. In P.palmeni densities and 'feeding pressure', measured as biomass of psyllids per gram of catkin, on the different host plants followed the sequence S.puZchm > S.laMta > S.alarensis > S.gfauca. In P.phlebophyllae densities and feeding intensities were similar on S.phlebophyZla and S.rericulara and grazing intensity was comparable with P.palmeni on S.pulchra. 5. A highly significant negative correlation was found between psyllid density and catkin dry weight in S.pulchm, S.phlebophylla and S.reticulata, suggesting that psyllid feeding is affecting catkin growth. 6. Predation of psyllid nymphs by syrphid larvae was heavy but there was no evidence of parasitism. 7. The life history strategies of the five psyllid species are discussed within the context of the constraints imposed by the arctic environment. plant.

No abstract

No abstract