For my undergraduate thesis, I identified and described the morphology of synanthropic Drosophila found in in Ontario fruit crops and compost. This project originated due to the arrival of Drosophila suzukii (Diptera: Drosophilidae), or the spotted winged drosophila in fruit crops of Ontario. This pest posed a huge threat to Ontario crops due to its serrated ovipositor that could damage unripe marketable fruit unlike other fruit flies that only target decomposing unmarketable fruit. Early identification was critical to the management and crontol of the pest.
Although there is a large body of taxonomic work availabel for Drosophila species, there was no key that was directly applicable to Ontario and our needs. The goal of my thesis was to provide the groundwork needed to produce a digital key by documenting the number of synanthropic Drosophila species present in Ontario fruit crops and compost. By using illustration was a medium to aid in the description of morphology, fourteen synanthropic drosophila were commonly found in Ontario crops and compost.
General public, entomologist, pest management, Ontario farmers
Pen and ink
Digital interactive identification key available on the web
Descriptions and identification of morphological characteristics were based on an examination of specimen housed within the University of Guelph Insect Collection (UGIC) in addition to specimen collected in vinegar traps by OMAFRA during the summer of 2011 and compost samples.
Identification of specimens
Examination of genitalia and illustrations were utilized to differentiate between species. To clear the tissue, abdomen of specimens clipped and boiled in boiling 10% potassium hydroxide. Clipped abdomens were rinsed in distilled water and placed on a depression slide with glycerine for dissection. Prepared genitalia were observed under an OPTI-TECH scientific Nikon microscope (SIN: 0T5739) allowing proportional and detailed pen and ink illustrations to be completed. Both lateral and posterior views of male genitalia were drawn while only the lateral view of the female oviscapt was illustrated.
Identification of species was achieved through matching illustrations of male genitalia from samples to illustrations in literature. In addition, dichotomous keys in Bächli et al. (2004), Markow & O’Grady, (2006) were utilized in the identification of specimen.
Critical point drying (CPD)
Specimens stored in alcohol were dehydrated via critical point drying (CPD) prior to photographing and examination. Drosophila were placed in porous containers constructed from plastic tubing with brass screening. Specimens were dehydrated in 100% ethanol.
To allow liquid CO2 to vaporize at its critical point, the pressure was maintained below 1350 PSI and above 1000 PSI and the temperature remained between 18-20 ͦ C by running cold water.
High resolution character photos of pinned specimen were taken using the Microptics Digital Lab XLT imaging system utilizing a Canon EOS 1 Ds camera and the Microptics ML 1000 flash fibre optic system. Images were further clarified using Adobe Photoshop CS3 (AP CS3) for windows allowing important morphological features to be emphasized.
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