|Title||Morphologie en biologie van de schildluis Chionaspis salicis L.|
|Author(s)||Dinther, J.B.M. van|
|Source||University. Promotor(en): W.K.J. Roepke. - Wageningen : Veenman - 80|
|Publication type||Dissertation, internally prepared|
|Categories||Hemiptera / Animal Anatomy and Morphology|
|Abstract||To help fill the gap in information on scale insects in the Netherlands, a study was made on C. salicis, a species mainly infesting willows. It was considered useful to become familiar with scale insects because of the danger of the San Jos_- scale (a fruit-tree pest) spreading northwards from France and Germany.
All stages of C.salicis were described, distribution and recorded food plants were reviewed, literature on toxicity of insecticides against scale insects were summarized.
C. salicis overwintered as egg. Minimum hatching temperature was 17°-18°C. Experiments with temperatures from -1° to 13°C (90 % r.h.) showed temperature- sensitive egg stages; temperature below zero was not necessary for later development.
Young nymphs appeared in April, winged and wingless adult males in July; females oviposited in September, reproduction being mainly parthenogenetic. Sterility in the female was observed and an inverse relation between fertility and population density was found.
In experiments with other food plants, males developed on many, but females reached maturity and oviposited only on poplars.
C. salicis was parasitized, twice a year, by Aphytis fuscipennis to a total of 14%.