Invasive species are a problem worldwide, both in natural and agricultural systems.  Bemisia tabaci biotype B is considered one of the world’s top 100 invaders, and its ability to inflict damage to many types of crops and ease of developing resistance to insecticides make it a challenge to manage. Anecdotal information suggests that it disperses widely, but this has not been tested in Australian agricultural systems.  Over the course of a summer growing season, I sampled a range of crops for B. tabaci populations across a sub-tropical agricultural landscape with considerable topographic relief.  Using microsatellite data I tested the relatedness of populations over time, as well as relatedness due to landscape structure and geography.

Results/Conclusions

Results show that landscape structure and geography do not exert significant effects on population structure.  Rather, there are two genetically distinct pulses early in the season followed by dispersal and panmixia across the system occurring within the single growing season of 4 months.  Population structure and movement is attributed to time, suggesting early immigration events into the crops from distinct populations at the start of the season.  These immigrants could be from far away or locally from isolated weeds where B. tabaci is known to overwinter.  These results also suggest that B. tabaci is extremely vagile and disperses widely across a landscape during the summer from small discrete overwintering refugia.  This type of information may provide insight on how:  1) highly invasive species disperse across a landscape and 2) to plan resistance and pest management strategies.