Insect clip cages rapidly alter photosynthetic traits of leaves

In plant-insect interaction experiments, a clip cage is frequently used to isolate insects or other small pests on a leaf. Clip rage effects on the ph ysiology of the leaf could possibly confound experimental results, Our obje ctive was to quantitate the effects of an insect clip rage of the type typi cally used for small pests such as whiteflies (Bemisia sp,), aphids (Aphis sp,) and mites (Urticae sp.) on the photosynthetic traits of cotton (Gossyp ium hirsutum L. cv. Coker 100A-glandless) and muskmelon (Cucumis melo L, cv , imperial 45) lea, es. Clip cages that enclosed 11.3 cm(2) of both the aba xial and adaxial sides of a leaf were attached to young fully expanded leav es. For the leaf tissue within the clip rage, incident radiation was decrea sed and leaf temperature was increased. After 24 h, chlorophyll content of tissue within the clip cage was significantly increased compared with nonca ged-control samples taken from the opposite half of the same leaf. Three da ys after clip cages were attached to leaves, compared with controls, the ti ssue within the cage had a lower light-saturated, steady-state CO2 exchange rate (CER) and leaf soluble protein content. The cage effect on CER and so luble protein could be explained, at least in part, by decreased light-satu rated initial Rubisco activity for leaf tissue within the clip cage. We con clude that the clip rages caused physiological and biochemical alterations of leaves that could alter insect nutrition. Thus, it is suggested that cli p cage effects on leaf physiology and microenvironment must be considered w hen interpreting results of plant-insect interaction experiments.