The Effect of Physical Factors on the Emergence and Subsequent Behaviour of Adults of the European Pine Shoot Moth, Rhyacionia buoliana (Schiff.)

Abstract

Adults of the European pine shoot moth emerge for the most part between dawn and 0900 hr. E.S.T. within a temperature range of approximately 11 to 25 °C. Adult emergence follows a field rhythm, emergence behaviour being initiated in pupae that have completed their development by the daily dark:light transition. Pupae held at constant temperature and under continuous light or darkness in the laboratory produced adults at any time of the day or night, whereas adults emerging from pupae held in an altered light cycle showed peak emergence following the dark:light transition. Observations of adult emergence in the field indicate that an average of 71 minutes was taken from the first appearance of the pupa in the exit hole until the wings of the newly emerged moth were expanded, dried, and returned to the normal resting position. Duration of the various phases of emergence behaviour are given, and discussed in relation to physical factors and predators. Following emergence, adults moved about the trees to more secluded and cooler sites once temperatures in exposed sites exceeded about 30 °C. During the hotter parts of the day, these movements commonly took the insects deep within the multiple tops of infested trees. As conditions moderated in the evening, and light intensities became conducive to flight, mating, and oviposition, the moths appeared in more exposed sites on the host trees.