THE SURVIVAL IN SOIL OF APTERAE OF THE LETTUCE ROOT APHID, PEMPHIGUS BURSARIUS (L.)

Some aphids in a population of Pemphigus bursarius on the roots of a summer host do not form wings and fly back to poplar. The fate of these apterae has been investigated and it was found that they could successfully overwinter even though their original host plant had died. Having overwintered without their host, they were then able to colonize the roots of a spring-planted lettuce crop. Whether the soil was cultivated before or after winter seemed to have little effect on the numbers of apterae that survived. The influence of temperature on the survival of apterae was studied, and from the findings it appears to be well within the capacity of P. bursarius, in the Midlands, to hibernate in the soil without a host from October to April.