I have been raising "winter morphs" of Drosophila suzukii by exposing larvae at 5 deg. C for 2 - 4 weeks under totally dark conditions. The adults are very dark in pigmentation; however, none of the winter morph males have their usual wing spots. One specimen had just one wing spot on one wing. All other winter morph males were "spotless". The summer morph flies that emerged from the same cultures all had the usual apical wing spots. Is this normal? or does it take longer for "winter morph' flies to develop their wing spots? I included a picture. The winter morph males are in the upper left, summer morph males are in the upper right group. Corresponding females are below Hope you can help. Thanks in advance. Blair
Hi Blair,
I've been rearing D. suzukii at 16°C for full cycle, and all the individuals showed signs of winter morph (i.e. thoracic pigmentation, longer wings etc.) but all the males had spots. Even some females showed slight shades of pigmentation around the apical part of the wings when looked under a binocular.
At what age were the male when you took this picture? Sometimes the spot takes a few days to appear, might be the reason...if not, very interesting!
Best
Antoine
Hi Blair, just wanted to corroborate Antoine's observation - I also often observed lack of wing spots on very young males' wings. Made a big mess of one of my experiments where I should have had two groups of 5 males and 5 females... Good luck!
Hi Blair, I have also seen newly emerged males with absent or extremely faint wing spots. I have only captured two males from the field in the past four years that did not have spots. One of them was captured in blueberries on April 22, 2013, well into the spring season. I'm interested to hear what other information you find on this. Lindsy
Thanks everyone. You help is much appreciated. I believe my male winter morphs were the last to emerge, since they would have received the most chilling, and as such had to develop their spots once released from the cold room. I photographed them only hours after removal from the cold. I suppose they needed more time to develop their spots. Thanks again Blair
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