Author
Jackie Steel
jackie.steel@agriculture.vic.gov.au
Agriculture Victoria
Melbourne
Coauthors
Kym L. Butler, Animal Welfare Science Centre, University of Melbourne, Melbourne, Australia
J Paul Cunningham, Agriculture Victoria, Melbourne, Australia
Raelene M Kwong, Agriculture Victoria, Melbourne, Australia
Abstract
No-choice laboratory trials are widely used to assess the host range of candidate weed biocontrol agents but can overestimate risk. When insects are deprived of their preferred host, oviposition and development can occur on test plants that are not utilised as a host in the field. We investigated time-dependent oviposition behavior of the crown-boring weevil, Listronotus sordidus (Gyllenhal), a candidate agent for Sagittaria platyphylla (Engelm.) J.G.Sm., across a range of Alismataceae species. Oviposition was recorded at 6 hours, 24 hours, and 4 days to distinguish between acceptance periods similar to the host and oviposition latency on non-target species. While all test species received some eggs, all but one non-Sagittaria species had substantially lower total oviposition. Test species receiving an intermediate total number of eggs, such as Alisma plantago-aquatica L. and Hydrocleys nymphoides (Humb. And Bonpl. ex Willd.) Buchenau showed delayed as well as reduced oviposition, suggesting they may not be utilised in the field. Time-dependent measures revealed behavioral differences not apparent from total egg counts alone, highlighting the value of incorporating measures of oviposition latency into host-specificity testing. This approach can improve risk assessment by distinguishing likely host species from non-host species, reducing the likelihood of rejecting safe agents and enhancing the predictive power of laboratory trials for field host range.
keywords
Oviposition latency
Host-specificity testing
Risk assessment
Listronotus sordidus
Alismataceae
Highlights
Time-dependent oviposition latency reveals host discrimination not measured by total egg counts.
Incorporating behavioral plasticity into host testing improves biocontrol risk assessment.
Oviposition on non-targets may reflect insect behavior under experimental conditions, not field risk