Studies on the ecology of Oncopera intricata Walker (Lepidoptera: Hepialidae). 1.Fecundity of the female moths.

Abstract

The fecundity of field-collected moths of Oncopera intricata Walker was determined in the period 1958-63. Individual regression lines for the effect of moth size (expressed as wing length, x) on fecundity (Y) were calculated for all years and the regression relationships were found to be very highly significant (P<0.001) in all cases. An analysis of the combined data showed that the slope or position or both of these regression lines may differ between populations and between generations of the one population. A regression analysis using the mean wing lengths (x) and mean fecundities (Y) from all sets of data indicated a significantly greater fecundity in those populations where the mean moth size was larger. This relationship was expressed as: Y = -1069.3+78.13x S.E. (b) = 12.10. The variations in the mean size and fecundity of the moths are discussed in relation to the prior abundance and distribution of the larvae in the field populations from which the moths were obtained. It is concluded that moths arising from dense larval populations are smaller and less fecund than those from sparse populations.