A plant root warmer for studying phytophagous insect development and fecundity at temperatures below host plant tolerance

A simple root-warming device maintains the plants' roots at a higher temperature than that at which the rest of the plant is held. This permits the host plant to retain turgor, not wilt, and therefore remain suitable for and attractive to phytophagous insects. The technique was demonstrated in a development and fecundity test using the cotton aphid, Aphis gossypii Glover, reared on cotton seedlings, Gossypium hirsutum L., at foliar temperatures of 10.0 and 12.5 degree C. Root temperatures were held at 20 degree C. The device was also tested at a foliar temperature of 7.5 degree C in an additional fecundity test. In a control test, no differences were found in development rate, fecundity, or survivorship for aphids reared on plants with foliage at 15 degree C and roots at 15 or 20 degree C.