Life cycle & seasonal dynamics
Experience from Japan has shown that this particular species of fruit fly can have up to 13 generations per year. Populations build and build until late summer when crops are most at risk.
Depending on the temperature it can take between 12 and 79 days to develop from egg to adult. The warmer it is, the quicker the development and reproduction will be.
Females can lay 7-16 eggs per day, over 300 eggs in a lifetime and are active from around 10oC. Development and activity peaks at 27oC. Pupae can be found inside or outside the fruit.
Overwintering adults are the parents of the summer generation so there is a need to take early action. The pest overwinters as adult females and males, although the exact place of overwintering is currently unknown. Overall populations are reduced to a very low level during the winter.
Female SWD can lay eggs between spring and autumn. In protected crops, where temperatures remain higher, this period of egg laying may be elongated. Research has shown that first detection in the spring is dependent upon on the coldness and longevity of the winter. Mild winters will result in earlier occurrence of SWD in crops, highlighting the importance of monitoring.
Growers need to be prepared to monitor early