Brownheaded leafroller - biological control

Brownheaded leafrollers are attacked by a wide range of predators, and parasitoids. However, these benefical species have never been the primary method of control in commercial orchards. This is because brownheaded leafrollers are quarantine pests and must be controlled to extremely low levels. Natural enemies are rarely effective in controlling pest populations at these low densities. However, with the introduction of more selective insecticides, such as insect growth regulators, and the increase in organic production, the natural enemies of brownheaded and other leafrollers have become more important. Classical biological control of brownheaded leafrollers, which are native insects, has never been attempted. However, parasitoids introduced for control of lightbrown apple moth (an Australian species) have been found parasitising brownheaded leafrollers. This includes the 1920s introduction, Goniozus jacintae from Australia and three species introduced against lightbrown apple moth in the 1960s and 70s, Glabridorsum stokesii, Trigonospila brevifacies, and Xanthopimpla rhopaloceros. These are contributing to reducing pest populations of brownheaded leafrollers not only in orchards but also on their many host plants in the surrounding environment. This could minimise immigration of moths into orchards and reduce the need for chemical control.

Insect pathogens, such as bacteria and viruses, offer an alternative method of biological control. They can be formulated as sprays and applied to apple trees using conventional spray machinery. The bacterium Bacillus thuringiensis is widely used for control of leafrollers.

Another biological method of controlling brownheaded leafrollers is mating disruption, which uses high concentrations of the insect pheromone to prevent mating.