SAMPLING METHODS AND MORTALITY ESTIMATES OF THE EGG AND FIRST INSTAR OF THE SYCAMORE LACE BUG, CORYTHUCHA CILIATA (SAY).

摘要

Sycamore trees, Platanus occidentalis L., were sampled during 3 summers in order to develop a method for estimating the egg and first-instar densities of the sycamore lace bug, Corythucha ciliata (Say), for a given tree. The eggs were generally more abudant on the south and west sides of the tree, but the density of the first instar was the same in each direction. Neither stage was more abundant in either the upper ((GREATERTHEQ) 5m) or lower ((LESSTHEQ) 3.5m) part of the tree.; Using Taylor's power law, the number of leaves needed to estimate the mean population of eggs or first-stage nymphs per leaf, with a fixed level of accuracy, was determined. The required sample size was inversely related to the egg and first-instar densities.; The method recommended for estimating the density of either stage of C. ciliata, per leaf, was: (1) take an equal number of leaves from each cardinal direction, (2) sample the lower ((LESSTHEQ) 3.5 m) part of the sycamore, (3) allow 2 weeks to elapse between sampling days, and (4) avoid sampling very small and very large leaves. In addition, the relationship between the egg density and the amount of leaf chlorosis of a tree defined the relative degrees of infestation of C. ciliata.; Egg and first-instar mortalities were estimated through 2 summers. Egg mortality gradually increased during the summer, with ca. 50% of the eggs deposited on the sampled trees not hatching. Mortality of the first instar averaged ca. 55% for the 2 years.; The effects of leaf desiccation, moderate temperatures, parasitoids, predators, and inviability on the hatching of C. ciliata eggs were investigated. Leaf desiccation and temperature did not affect the hatching of the eggs. A mymarid parasitoid (Erythmelus sp.) was found emerging from C. ciliata eggs in September. Under laboratory conditions, the predators Diaphnocoris provancheri (Burque), Haplothrips subtilissimus (Haliday), and Leptothrips mali (Fitch) did not feed on C. ciliata eggs, while Chrysopa rufilabris Brumeister, Deraeocoris nebulosus (Uhler), and Orius insidiosus (Say) did. Inviability accounted for 8 to 25% of the lace bug's eggs not hatching.