Seasonal Changes in the Synusia of Pine Sawflies (Hym., Diprionidae) during their Latency

1989

S. 217-226

5 Abb., 2 Tab., 28 Lit. Ang.

Unselbständiges Werk

200035951

Seasonal changes of the abundance and dominance in the synusia of pine sawfly larvae on Scots pine (Pinus sylvestris) during their low population density (latent phase) were examined in pure stands in southern Bohemia (Czechoslovakia). The synusia included altogether 8 species of sawflies in stands of different ages in 1984-1988. Within the long space of time two significant annual peaks of larval abundance were recorded: the first during the spring feeding period in June, when several species were usually present (5.8 on the average in 5 years); the second in late August/early October when the average was 4.8 species in 5 years. The second maximum was divided into two peaks corresponding to at least two waves of diprionids during the summer period. The proportion of "rare" and outbreak species was approximately balanced, the average proportion of solitary species making up 57.7% of the population of sawflies inthe 5 years. Solitary species, especially Gilpinia frutetorum, prevailed in older stands (38-88 years old), Neodiprion sertifer was the eudominant species in young stands. Larval feeding lasted from May to late Octobr, but significant are variations in the population density of individual species during the latent phase. The estimate of endemic sawfly populatins is given.