ABSTRACT

The Pacific damsel bug, Nabis kinbergii, is a potentially important predator of key cotton pests. Aspects of Pacific damsel bug behavioural ecology, particularly feeding behaviour, were investigated to develop a better measure of rates of predation on cotton pests. Direct observation studies in the glasshouse showed that the frequency of observer presence had no influence on Pacific damsel bug distribution and activity or prey (heliothis) mortality and distribution, during diurnal and nocturnal observation sessions. This represented the first documented test of observer presence in an insect species, and provided justification for future observational studies of Pacific damsel bug behaviour (Chapter 3). Pacific damsel bug behaviour did not vary significantly during diurnal periods in the field, but in the glasshouse feeding behaviour was greatest at dawn and during the morning. Further observations revealed that bugs fed at the same frequency during diurnal and nocturnal periods in the glasshouse. Knowledge of diel variation in Pacific damsel bug behaviour would be useful for predicting optimal times to Observation and inclusion cage studies in the glasshouse and field determined that Pacific damsel bugs fed on prey and cotton extrafloral nectar, but not on intact plant tissue. Pacific damsel bugs should be treated as an omnivore and beneficial, but not a pest species of cotton, and may respond positively to application of artificial food supplements to crops , count, collect and manage these arthropods.