Spatial distribution and activity of Microxeromagna armillatain an Australian citrus orchard – implications for pest management

Abstract: Microxeromagna armillata is a small, cryptic, introduced snail which inhabits bothterrestrial and arboreal environments in Australian citrus orchards. This species has causedsignificant problems for the citrus industry as a contaminant on exported produce to the UnitedStates of America. Snails have been found sheltering in the navel of export oranges, and costlyquarantine measures have been established when interceptions occur on produce. As the USA is akey export market for Australian Navel oranges, M. armillata poses a serious problem for theindustry. A key factor impeding development of a targeted control strategy is the lack ofunderstanding of M. armillata’s spatial distribution and activity in the tree canopy.In this paper, the activity patterns of M. armillata during fruit harvest and post harvest arereported. Microxeromagna armillata was active in all areas sampled within the orchard, althoughsnails were not equally active in all areas or on all sampling dates. Snail activity levels decreasedwith increasing height above ground during both the harvest and post harvest periods, withactivity on all surfaces higher during the latter.These findings suggest that late harvested citrus varieties may be more susceptible tocontamination by M. armillata, reinforce the recommendation to skirt trees, and highlight theneed to keep fruit-picking bins off the orchard floor.