Willow-carrot aphid (Cavariella aegopodii) infests carrot and other Apiaceous crops. The aphid can cause direct damage and may also transmit several types of virus. This species overwinters primarily as eggs on Salix species which generally hatch around February and March (Dunn, 1965) and initial colonies pass through either one or two generations of apterous females there (Dunn, 1965; Kundu & Dixon, 1995). Winged forms are produced later and these migrate to secondary host crops over a 5 to 6 week period. Cavariella aegopodii may also be present as adult or immature stages upon apiaceous crops throughout the winter (Dunn, 1965; Dunn & Kirkley, 1966). These mobile stages are capable of rapidly producing spring colonies, with winged forms potentially arising earlier than those developing on willows (Gratwick, 1992).
Our emphasis has been on identifying treatment timings and active ingredients that control willow-carrot aphid and minimise the risk of transmission of virus.
To aid treatment timing we have developed a simple day-degree forecast based on information provided by the Rothamsted Insect Survey on captures of winged aphids in the network of suction traps in the UK. Information from the suction traps at Wellesbourne and Kirton were used to estimate the mean number of D° from 1 February until the first aphid of the year is caught in a suction trap (the start of the migration to carrot). This is after approximately 360D° above a base temperature of 4.4°C.
We have also identified active ingredients that control willow-carrot aphid on carrot crops in HDC Project FV 375, the SCEPTRE project and the SCEPTREplus project.
Bulletins using the day-degree forecast are available on the AHDB Pest Bulletin website hosted by Syngenta.
HDC Project FV 375 - Novel strategies for pest control in field vegetable crops.
SCEPTRE project (HortLINK project HL01109)
AHDB Project FV 445
AHDB Project FV 460
Dunn, J. A. 1965. Studies on the aphid, Cavariella aegopodii Scop. Ann. Appl. Biol. 56: 429-438.
Dunn, J. A., & Kirkley, J. (1966). Studies on the aphid, Cavariella aegopodii Scop: On secondary hosts other than carrot. Ann. Appl. Biol. 58: 213-217.
Gratwick, M. (1992). Crop pests in the UK: collected edition of MAFF leaflets. Chapman & Hall.
Kundu, R., & Dixon, A. F. G. (1995). Evolution of complex life cycles in aphids. J. Anim. Ecol. 64: 245-255.