Evaluating targeted aerial spraying for insect control

Abstract

The main target zones in early plans for eradicating painted apple moth (PAM) (Teia anartoides) in Auckland New Zealand were narrow riparian strips of vegetation and steep gullies However there were concerns that achieving high levels of Bacillus thuringiensis var kurstaki (Btk) deposition in these riparian areas with minimal drift onto residential areas would be difficult This is because with a combination of small droplets and high release heights there would be considerable downwind movement of the spray cloud The concept of targeting riparian strips was evaluated using an aerial spray application simulation model Results indicated that targeted spraying is not a practical proposition at least where small droplets are used and high release heights are required The only solution would be to build larger target areas around the riparian strips For targeted spraying to become a practical proposition techniques must be developed for achieving efficacy using much larger spray droplets