1984] 
Rut ow ski — Pieris protodice 
149 
Table 2. A comparison of the performance of males in matings separated by 24 
hours. See text for details. 
First copulation 
Second copulation 
Parameter (units) 
X±SD 
N 
Range 
X±SD 
N 
Range 
Copulation dura- 
tion (min) 
3 3 . 2± 1 1.8 
10 
22-60 
32. 6± 10.8 
7 
23-54 
Mass of material 
passed (mg) 
4.47±1.44 
10 
1.78-5.9 
2.37±0.504 
12 
1.45-3.12 
% of male body 
mass passed 
8.8± 1 .95 
10 
2.75-12.7 
5.88±0.898 
10 
4.7-6.95 
Volume of ma- 
terial corpus 
bursa 
3.63±0.997 
10 
1.56-4.6 
1.85±0.41 1 
12 
1.18-2.52 
GO 
stimulating female refractoriness to courtship immediately after 
mating (Sugawara 1979) selection must favor males that produce a 
quantity of material that will cause most females to be unreceptive 
after mating. Sperm precedence has been shown in another pierid 
(Boggs and Watt, 1981) so stimulating female refractoriness will 
help protect a male’s investment from exploitation by other males. 
The lack of a relationship between male size and the absolute 
quantity of material a male is likely to pass may help understand the 
observation that very few unsuccessful courtships were observed 
during this study or in another (Rutowski, 1979a) that were lengthy 
and thereby suggested termination by the female. This is in contrast 
to recent observations on Colias eurytheme Boisduval in which 
almost half of all observed unsuccessful courtships were apparently 
female-terminated (Rutowski, unpublished data). In P. protodice 
choice by females on the basis of size among males may not yield 
significant material benefits. In a pyralid moth ( Plodia interpunc- 
tella), Greenfield (1982) found that male size was proportional to 
mating success and that large males passed larger quantities of 
material. However, female egg output was not related to the size of 
her mate. 
In a previous study of P. protodice, males in copulations sepa- 
rated by an average of only 10 min produced one quarter of the 
material in the second copulation that they produced in the first 
(Rutowski, 1979b). In that study the quantity of material passed was 
assessed only by estimating the volume of secretions passed into the 
spermatophore. Similar assessments are given in this study for first 
