Studies on the Biology of Apion arrogans Wenck. (Col. Curculionidae) in Israel 1

Summary Apion arrogans Wenck., causes damage in vetch fields in Israel. Its distribution outside of Israel is limited and it has been recorded, according to the W inkler catalogue (14), only from Asia Minor and from Syria. With the exception of this record, no other information is available. The insect was reared in all its stages in the laboratory. The female usually laid her eggs between the closed leaflets on the heads of vetch plants and in the buds of the side branches. The highest number of eggs (average −39.5, maximum −175) were laid by females which were fed vetch, and almost none were laid when fed on clover. A rise in the temperature raised the rate of oviposition, but that shortened the oviposition period. Humidity also exerts an influence upon the amount of eggs laid by A. arrogans . Females reared in vials with a humidity of 60–85% laid more eggs than those reared at 80–90 %. The longest life span was when the beetles were fed vetch, and when they were kept at 10–14° C. The development of the egg takes place in the head of the vetch plant where it is laid. In the laboratory, eggs were reared in petri dishes over moist blotting paper. The incubation period at temperatures from 7–34° C fluctuated between 1.7 and 20.5 days. The threshold of embryonic development was found to be 6.5° C. A high amount of hatching was recorded at a high relative humidity in all temperatures. The larvae remains throughout its development at the site where the egg was laid, and it feeds by gnowing the tissue surrounding it. At temperatures ranging between 15.5 and 24° C the larval period lasted 11–32 days. The cavity created by the feeding of the larva serves as the site in which it pupates after spining a cocon. The pupal development at 10–32° C lasted 18.5–30 days. A. arrogans raises but one generation in Israel. The main period of activity of the aestivating beetles is January‐February. Their offspring complete their development in March. This generation does not reproduce before passing through the period of aestivation, which begins with the rise in temperatures in May. Zusammenfassung Die Lebensweise und Entwicklung des an Leguminosen in Israel schädlichen Rüsselkafers Apion arrogans wurden im Freiland und Labor näher untersucht. Unter anderem wurden die Beziehungen zwischen der Eizahl und der Ernährung des Weibchens sowie der Luftfeuchtigkeit während der Eiablage, die Wirkung der Temperatur auf die Lebensdauer der Käfer sowie auf die Entwicklungszeit der Eier und die Abhängigkeit der Larvenentwicklung von der Temperatur betrachtet.