Green mirid, Creontiades dilutus is an important pest of cotton. There is an ongoing

debate as to whether mirids that occur in cotton are derived from locally occurring

populations or whether they arrive in cotton after a long distance migration. Nancy

Schellhorn has data which shows that mirid juveniles occur on a range of native

Chenopods that occur in a continuous north-south distribution extending from coastal

regions to the interior. The question is therefore whether mirids form a contiguous

panmictic population across this resource or whether populations follow a

metapopulation structure. Microsatellites are the tool of choice for teasing apart this

structure and to determine effective population size. De Barro (Molecular Ecology, in

press) has used microsatellites to unravel the geographic structure of Bemisia tabaci in

Asia and Australia and Schellhorn, De Barro, Buckley (CSE/UQ), Riginos (UQ) are about

to undertake a joint PhD project aimed at using microsatellites to investigate questions of

scale and landscape structure in regards to the silverleaf whitefly. By collecting mirids at

different geographic locations; from a range of different plant host species and at

different times in the year it will be possible to tease apart the structure of mirid

populations. The patterns uncovered will enable the relative contributions of distance

and host to population structure and the source of mirids infesting cotton to be

determined.