Conception and implementation of classical weed biological control programs using insects – the Queensland experience

Abstract

Classical weed biological control are long-term programs spanning over many decades. Target weeds are prioritised based on the current and potential impact, and biological control feasibility. The program essentially involves native range surveys, host specificity testing and agent release and monitoring. The methodology evolved over the years, incorporating genetic and climatic modelling tools to prioritise native range to source biological control agents, and plant response to herbivory, field host range and potential impact as filters to prioritise agents for host specificity testing. Modern host specificity testing based on centrifugal phylogenetic method involve no-choice tests, followed by choice and multi-generational demographic trials, if non-target attack occurs in no-choice tests. Approval to release the agent is based on the non-target risk assessment derived from host specificity tests. Agents released in climatically favourable areas, over a three-to-five-year period and the time taken for establishment range from a few months to more than a decade. To fast-track dispersal, agents are field collected and redistributed to wider geographic range. Evaluation of the impact and economic benefits is the least studied aspect of biological control programs. Successful agents in Queensland have been introduced into other countries around the world. © 2025, The Entomological Society of India. All rights reserved.