Distribution of Spotted Wing Drosophila Life Stages
The chronological development of internally feeding insects on fresh fruit is rarely consistent and depends, to a large extent, on the quality of the host fruit. Poorer quality fruit hosts tend to exaggerate developmental differences within a cohort with the effect being a broadening of the developmental stage(s) vs. chronological age(s). Developing postharvest control treatments against insect pests typically requires the most treatment-tolerant life stage to be identified and used as the target to establish protocols. Targeting and treating a specific life stage for externally feeding pests is relatively uncomplicated since they can be readily identified and isolated. For internally developing pests, however, diagnosing the life stage present during treatment has been difficult and often assumed.
Here, a tool to calculate the probability distribution of life stages present at any given point in time from post hoc adult emergence is presented and applied to spotted wing drosophila (SWD), Drosophila suzukii (Diptera: Drosophilidae), developing on several types of commercially ready postharvest fruit (blackberries, blueberries, sweet cherries, raspberries, and strawberries). The Developmental Timespan (DTS) calculator may be downloaded as an Excel 2010 (xlsm) spreadsheet.
Three key variables are used in the DTS calculator:
1. The duration of exposure to ovipositing SWD females (in days).
2. The duration of incubation (in days). This is the time the commodity is held without the presence of ovipositing SWD.
3. The age (in days) of an emerging adult SWD taken from the onset of the infestation.
The DTS calculator is based on:
1) Bellamy DE & Walse SS (2013) Quantifying host-specific time spans of development for internally feeding insects: life stage distributions versus age. Journal of Economic Entomology (Submitted).
2) Bellamy DE & Walse SS (2013) The application of the Developmental Time Span Model to spotted wing drosophila, Drosophila suzukii, on fresh fruit and its application in postharvest treatment scenarios. Journal of Economic Entomology (Submitted).
In an effort to make the DTS calculator as useful as possible, please send any feedback or comments relating to the DTS calculator to Dr. Dave Bellamy.
