Early Leaf Abscission Has Little Effect on Larval Mortality of Ectoedemia cerviparadisicola (Lepidoptera, Nepticulidae) Associated with Quercus gilva

Abstract

Abstract There has been an argument as to whether early leaf abscission substantially affects larval mortality of leafminers because of leaf senescence. Recently, a study reported that leaf abscission considerably increased the mortality of a leafminer (Ectoedemia cerviparadisicola Sato, sp. nov.) associated with Quercus gilva (Blume) in Nara Park, central Japan, where sika deer (Cervus nippon (Temminck)) have been protected for 1,200 yr, because deer consumed many abscised leaves containing living larvae. The study, however, did not investigate the life history of the leafminer or survey the leaf-fall pattern of Q. gilva through the season, so that it failed to quantify larval mortality because of deer predation. To test whether deer have a substantial effect on larval mortality of this leafminer, we regularly collected abscised and nonabscised leaves of Q. gilva through the season, examining mines and larvae in those leaves. Over 90% of mined leaves abscised in the period of peak leaf fall, when almost all larvae had already emerged from mines to pupate. Most dead larvae in abscised leaves were judged to have already died at the time of abscission from their instars and body features. The proportion of living larvae in abscised leaves was estimated to be <1.8%. Thus, even when deer preyed upon all living larvae in abscised leaves, they would hardly contribute to the increase in larval mortality. These results indicate that the effect of leaf abscission on leafminer mortality via deer predation and other causes is limited. The leafminer was described as new to science in the Appendix.