Full-text - Norsk entomologisk forening

Reproductivity of Eupsilia transversa 403Fig. 5. Bursa copulatrix of E. transversa with one and seven spermatophores.only twice a day, and particularly for the samples kept at 30°,the cooling of the eggs during checking, when they were removedfrom the thermocabinet, may have been important. Also, theoutdoor temperatures were at times below the 6" threshold.Table I11 gives the results of incubation experiments during1963 at 20" and 30". Considering that the samples were checkedonly once a day for hatched eggs, the observed times of developmentare well in line with those calculated from the equationfitting the 1964 data.E. transversa has a flight period during September-November,and, after hibernation, a spring flight period during April-May. From spermatophore investigations it may be concludedthat generally no mating takes place during the autumn flightperiod.Of thirty or forty females trapped during the autumn of 1963and 1964, none contained any spermatophores, while 72 femalestrapped in the spring (most of them used in the ovipositionexperiments) contained as a mean 3.4 spermatophores.According to Williams (1938), Stern and Smith (1960), Dustan(1964) and Ouye et al. (1964), each spermatophore may beassumed to represent one successful mating. In the presentexperiments 80.6 per cent of the females contained more thanone spermatophore, and 9.8 per cent and 5.7 per cent containedseven and eight spermatophores respectively (Fig. 5).The number of matings seemed to increase as the flight periodprogressed. In the glass jars no matings were observed duringthe experiments. Fig. 6 demonstrates the significant positivecorrelation between number of spermatophores and date ofcapture of the females. No significant correlation was found betweenthe number of spermatophores and the number of eggsoviposited. The viability of eggs showed no correlation to thenumber of copulations, which is in agreement with the findingsof Shorey (1963) for the noctuid -I'richoplusia ni.