ON THE INFLUENCE OF PHOTOPERIOD AND TEMPERATURE 

 ON THE LIFE CYCLE OF SOME UNIVOLTINE INSECTS 



Влияние фотопериодизма и температуры на жизненный цикл некоторых 

 моновольтинных насекомых 



G. W. ANKERSMIT 



(Entomological Laboratory of the Agricultural University, Wageningen Netherlands) 



The photoperiod combined with temperature is one of the main ecological 

 factors which regulate the life cycle in insects. Many investigations have been 

 made in recent years concerning this subject. Especially with multivoltine 

 insects, many interesting results have been obtained. With univoltine insects 

 only a few investigations are known, and these only concern immature stages. 

 For these reasons it was thought interesting to test the influence of the photo- 

 period and temperature on some univoltine beetles with a diapause in the adult 

 stage. As such we have chosen the cabbage gall weevil Ceuthorrhynchus pleuro- 

 stigma Marsh.; the cabbage flea beetle PsylUodes chrysocephala L., and the 

 cabbage seed pod weevil Ceuthorrhynchus assimilis Payk. 



The types of life cycle occurring in these beetles may be summarized as 

 follows: 



1. Eggs are laid in the spring (case of C. assimilis). The adults emerge 

 in the summer and enter diapause after a feeding period of a few weeks. 

 These adults emerge from their winterquarters next spring. 



2. Eggs are laid in the autumn (case of C. pleur ostig ma). The larvae or 

 pupae hibernate, the adults emerge in the spring, they aestivate after a short 

 feeding period and become active again in the end of august or in September. 



In this paper experiments will be described with some insects which possess 

 these two different types of life cycle. 



Methods 



Full-groAvn larvae or pupae луеге collected in the field and kept in glass 

 dishes. The emerging beetles were reared in these dishes on daily renewed 

 food. The dishes were put in containers with fixed photoperiods and tempera- 

 tures. In some cases the insects were reared at room temperatures, only the 

 photoperiods being fixed. Fluorescent tubes were used as a light source. 



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