Analysis of the effects of the spotted tentiform leafminer (Phyllonorycter blancardella) on the photosynthetic characteristics of apple leaves

Publisher Website
Google Scholar
Abstract
Infestation of apple leaves with the spotted tentiform leafminer (STLM) reduced their net photosynthetic rate (Pn) over a range of light intensities. At a saturating irradiance level of 1240 μE∙m−2∙s−1 and 20 mines per leaf, 32.9% of the leaf area was injured but Pn was decreased by only 23.2%. Examination of parameters in a model for leaf photosynthesis showed a reduction in maximum photosynthetic rate (asymptotic value of the light-response curve) and mesophyll conductance but not in photochemical efficiency or dark respiration. The STLM injury had no effect on transpiration, stomatal conductance, and a slight effect on internal CO2 concentration and water-use efficiency. Mining reduced chlorophyll content of the leaves and this reduced the chlorophyll fluorescence of the mined areas. Tissue around the mines had a relatively high fluorescence reading confirming the Pn measurements and suggesting that this technique was suitable for these and similar studies. Mining by the STLM disrupts the photosynthetic apparatus of the leaf and affects a number of mechanisms in the photosynthetic process. Correlating these effects with field observations will help in determining economic thresholds for this insect.