AUTOMATICALLY OPERATING RADARS FOR MONITORING INSECT PEST MIGRATIONS

Abstract  Over the last three decades, special-purpose "entomological" radars have contributed much to the development of our understanding of insect migration, especially of the nocturnal migrations at altitudes of up to ˜ 1 km that are regularly undertaken by many important pest species. One of the limitations of early radar studies, the difficulty of maintaining observations over long periods, has recently been overcome by the development of automated units that operate autonomously and transmit summaries of their observations to a base laboratory over the public telephone network. These relatively low-cost Insect Monitoring Radars (IMRs) employ a novel "ZLC" configuration that allows high quality data on the migrants' flight parameters and identity to be acquired. Two IMRs are currently operating in the semi-arid inland of eastern Australia, in a region where populations of migrant moths (Lepidoptera) and Australian plague locusts Chortoicetes terminifera (Orthoptera) commonly originate, and some examples of outputs from one of these units are presented. IMRs are able to provide the data needed to characterize a migration system, i.e. to estimate the probabilities of migration events occurring in particular directions at particular seasons and in response to particular environmental conditions and cues. They also appear capable of fulfilling a "sentinel" role for pest-management organisations, alerting forecasters to major migration events and thus to the likely new locations of potential target populations. Finally, they may be suitable for a more general ecological monitoring role, perhaps especially for quantifying year-to-year variations in biological productivity.