Birds and bats as biological control agents in macadamia: How distant we are? Implications of the shift in arthropod communities across a spatial gradient

Agriculture affects and depends on all other life support systems. It is becoming essential to achieve the global food demand without compromising ecological integrity. However, little is known about important ecological interactions in agroecosystems. Such systems represent particular reserves for biodiversity with associated ecosystem services. One of the key ecosystem services in agriculture is the top-down control of crop pests exerted by predators. A large number of insectivorous bird and bat species have been found to efficiently decrease pest pressure in several crops worldwide. Scarce information is found on how the distance from forested areas impacts such ecosystem services. To our knowledge, no information is available for macadamia crops. Our study is the first of a series that attempt to explore the potential of regional bird and bat species as biological control agents in macadamia. The results describe the arthropod communities in these systems across a spatial gradient between the forest and the orchard. The study was conducted in 31 sites around Bundaberg (Australia). Arthropods were collected in macadamia orchards using sweep-net and light-traps at fixed distances from forest patches at each site. Results showed that the abundance and richness of arthropods decreased in points further away from forests. Points closer to forested areas had more balanced communities with higher percentages of predators and parasitoids and lower percentages of herbivores than points further away. Further research is being conducted to understand whether differences in spatial composition of arthropod communities are associated with the foraging activity of birds and microbats. An opportunity exists to integrate wildlife in macadamia production, and to benefit both the farmers and the environment.