Early season aphid activity 2009
The temperature during January and February is critical to M. persicae activity in the forthcoming growing season. The mean temperatures during this period at both SASA Gogarbank and SCRI Dundee were close to average (or very slightly warmer) than the mean for the same period since the late 1960s. January and February temperatures in 2009 rank 20th warmest over the past 41 years.
Table 1
|
Edinburgh |
2009 Prediction |
75% Confidence Limits |
2009 Observation |
2008 Observation |
|
Myzus persicae |
11 June |
18 May to 4 July |
N/A |
3 July |
|
Macrosiphum euphorbiae |
20 May |
1 May to 8 June |
N/A |
16 May |
|
Dundee |
2009 Prediction |
75% Confidence Limits |
2009 Observation |
2008 Observation |
|
Myzus persicae |
16 June |
22 May to 11 July |
N/A |
4 June |
|
Macrosiphum euphorbiae |
1 June |
7 May to 27 June |
N/A |
24 May |
The 75% confidence limits quoted in Table 1 provide an estimate of the expected accuracy of the 2009 prediction, i.e. 3 times out of 4 the prediction should fall within these limits. The average date of first capture for the Peach-Potato aphid (Myzus persicae) over the last 40 years is 13 June at Edinburgh (15 June at Dundee). The mean date for catching the first Potato aphid (Macrosiphum euphorbiae) at Edinburgh is 21 May (31 May at Dundee).
Total catches of potato aphids are likely to be very average. The model prediction is that 14 M. persicae will be caught at Edinburgh before 1 August (75% confidence interval of 3 to 55 aphids). At Dundee, the predicted catch over the same period is 16 M. persicae (75% confidence interval of 4 to 60). If these predictions are borne out then 2009 will rank 22nd out of the last 41 years in terms of the abundance of M. persicae.
