Population density dynamics of leaf rollers (Tortricidae) and loopers (Geometridae) in apple plantations during the spring-summer period.
A considerable increase in the population densities of species of the families Tortricidae and Geometridae was observed in apple plantations in several regions of Bulgaria during the spring-summer period of the years 1975-77. In this period the larvae of these pests damage both the vegetative and reproductive organs of apple trees. In 1977, on average, 2.93% of the flower buds, 13.78% of the leaves and 1.69% of the fruits were damaged. On some varieties, up to 15% of the fruit was recorded as damaged. The highest population densities were recorded for the tortricid species Archips podanus (Scop.), Pandemis dumetana (Treitschke) and Adoxophyes orana (Fisch. v. Roesl.) (reticulana (Hb.)), and the geometrid species Lycia hirtaria (Cl.) (Biston hirtaria), B. strataria (Hfn.), Apocheima hispidaria (Schiff.) (B. hispidaria) and Operophtera brumata (L.).