revealed the imagoes fed on A. sambuci did not show a higher death-rate and 

 their Ovaria examined after 14 days through dissection were maturating. 

 However, лvhen these experiments were repeated, we discovered the copul- 

 ation and maturation of о varia failed to induce the oviposition (during 24 days). 

 Only after another- 9 days when a suitable food was introduced the first ovi- 

 positions appeared. Accordingly, the nutrition with A. sambuci even if not 

 completely hindering the maturation of ovaria inhibits in some way the ovi- 

 jjosition being thus an unsuitable food, too, for old hibernated imagoes. 



To exclude the possibility the unfavourable effects of A. sambuci might 

 be due to the reduced amount of food we introduced breeds with Ьлуег rates 

 of a suitable food than those of A. sambuci consumption. As a result, their 

 development was considerably retarded, but the death-rate remained normal 

 and the pupation and emergence appeared to be in no way affected. 



Consequently, the negative affect of A. sambuci as prey for С 7 -punctata 

 does not consist in the reduced amount of this unsuitable food. Although it is 

 not altogether impossible the disagreeing effects to be due to the unsufficient 

 nutricity or unfavourable chemical composition, it seems highly probable 

 the main harmful effect comes directly from the toxic substances contained. 

 One of the efficient chemical compounds contained in the elder (*S'. nigra) 

 is the glycoside sambunigrin splitting enzymatically or by means of diluted 

 acids into D-glucosis, benzaldehyde and cyanic acid. Sambunigrin may be 

 transferred with food from the elder into aphids und further into coccinellids 

 causing their death by poisoning them with the cyanic acid produced by the 

 action of glycoside-splitting ferments occuring precisely in the coccinellids 

 (Kuznecov, 1948). 



For the lady-bird Adalia bipiaictata L. A. sambuci seems to be a rather 

 less dangereous food than for C. 7 -punctata, even it not being exactly the most 

 satisfying. Compared to controls the experimented individuals had their 

 larval development retarded b}^ a fifth, their total death-rate being double; 

 nearly a half finished larval development and about one third gave origin 

 to new imagoes. 



The reason for this different reaction of both coccinellid species seems to be 

 their different way of life. The coccinellid A. bi punctata liable to biotojDs such 

 as orchards, groves, shrubery, hop-fields etc. all over, the middle and east 

 Europe is obviously adapted to feed on A. sambuci occurring in the same 

 biotop as a monophag of the elder. On the other hand, the coccinellid С 

 7-punctata as a typical inhabitant of cultivated open areas does not appear 

 to be pre-disposed to such an adaption. 



An analogic situation was found in the breeds of the ladj^-bird SemiadaUa 

 11-notata Schneid. It Avas impossible to achieve normal larval development 

 and ovarial maturation Avhen fed on the aphid P. medicaginis Koch 

 which had been previoush^ foimd a suitable prey for С 7-punctata. A. fabae, 



315 



