Ovipositional host choice by an invader accelerates displacement of its indigenous competitor

While competition for resources leading to invasion success is well recognized, avoidance of competition is much less so. Changes in behaviour that lead to avoidance are usually displayed by the weaker competitor. In our case though it was the stronger competitor that changed its behaviour by choosing a host for oviposition that was unacceptable to its competitor and avoiding one that was mutually acceptable; this accelerated the displacement of the competitor. We showed this by enclosing both invader (Middle East Asia Minor 1, B biotype) and indigenous (Australia, AN biotype) members of Bemisia tabaci species complex (sap sucking insects known as whiteflies) into field cages with either two plants that were a mutually acceptable oviposition host or one host that was acceptable to both and the other acceptable to the invader only. When only the mutually acceptable host was available, invader and indigenous females oviposited equally across the two plants. However, when given the choice, adult invaders still distributed themselves evenly across both hosts, but shifted their oviposition away from the mutually acceptable host and instead laid mostly on the host poorly utilized by the indigenous competitor. This indicates that the invader can change ovipositional choice to escape into competition free space.