Brownheaded leafrollers - Population dynamics

The population dynamics of brownheaded leafrollers have not been investigated. Those ecological studies which have been carried out suggest that some of the factors which are known to be important for lightbrown apple moth populations are also probably key factors affecting the populations of brownheaded leafrollers. These include high mortality of young caterpillars after hatching from the eggs and wide variation in fecundity (the total numbers of eggs laid) between females, generations, and host plants. Predation by a wide variety of predators plays the key role in the mortality of young caterpillars of lightbrown apple moth in Australia and it is likely that a similar complex of predators (e.g. spiders) occurs here and feeds on young brownheaded leafrollers. Many of the parasitoids which attack brownheaded leafroller eggs and caterpillars cause only minor mortalities but there is circumstantial evidence of leafroller population decline following the introduction of Trigonospila brevifacies and Xanthopimpla rhopaloceros from Australia, particularly in populations outside orchards. This requires investigation.