Non-persistent TBV transmissions in correlation to aphid population dynamics in tulip flower bulbs

Virus transmission by aphids causes millions of Euro’s damage in the flower bulb sector annually. Mineral oils and pyrethroids are applied weekly during the growth season to decrease the virus transmission by aphids in flower bulbs. Currently, little is known about the dynamics of aphid populations during the growth season of tulips and the accompanying risk of the non-persistent virus transmission of for example Tulip breaking virus (TBV). Therefore, population dynamics of aphids in tulip fields was monitored during three growing seasons. Simultaneously, the period of TBV transmission by aphids was investigated experimentally by exposing small tulip plots during specified intervals to naturally occurring aphids. Finally, timing of virus spread was correlated with aphid population dynamics and weather conditions. In 2007, TBV transmission started in April while the first aphids were found in May. Apparently, the first aphids of the season already contributed in great extend to the virus transmission and virus transmission was observed very locally in the tulip plots. A second, distinct TBV isolate was identified which resulted in the design of an improved TBV detection assay. The main objective of this research project is to enhance the knowledge about the risk of non-persistent virus transmission in relation to aphid population dynamics. This knowledge should enable us to formulate crop protection guidelines that are better fine-tuned with the risk of virus transmission and thereby decreasing the environmental damage caused by chemical crop protection.