Ecology of the fruit spotting bug, Amblypelta lutescens lutescens Distant (Hemiptera: Coreidae) in cashew plantations, with particular reference to the potential for its biological control

The fruit spotting bug, Amblypelta lutescens lutescens, is one of the principal insect pests of cashews in Australia. Its population dynamics were studied using field observations and long-term monitoring to find suitable management methods. Observations of bugs reared in netting bags showed a sequence of change in bug-damage symptoms after 12 h and up to 3 d. Field observations revealed that adults preferred to feed and rest on the shady side of the tree. The number of bugs observed accounted for only 17-35% of the total variability in the number of damaged shoots, suggesting that the number of flushing shoots (leaf, flower or young nuts) with fresh damage symptoms was a more reliable parameter for determining the presence and level of activity of bugs than was a direct estimate of the number of bugs. The green tree ant, Oecophylla smaragdina (F), was the most important factor regulating bug populations. When predation was excluded as a factor, the number of flushing shoots and maximum temperature accounted for 80% of the total variability in the bug damage. Green tree ants should be considered as an important biological control agent for fruit spotting bug, and monitoring should be commenced when cashew trees start to flush (using damaged shoots as indicator).