VARIATIONS IN CLEANING BETWEEN THE SEXES OF 8 INELLA COECA ( COLLEMBOLA : ENTOMOBRYIDAE ) * BY

With the widespread and frequent occurrence of pheromones among insects, it is easy to appreciate the significance of cleaning and grooming behaviors. However these behaviors are as yet poorly known. Among springtails two papers by Simon (96, 963) present the most thorough reports. These describe the types of cleaning in representatives of several families, noting the widespread, though infrequent, use of cleaning droplets released trom the mouth. My work examines Sinella coeca (Schott) (Family Entomobryidae) t:or behavioral differences between the sexes. In particular, I have determined the frequency of cleaning and the duration of bouts of cleaning behavior. The initial expectation is that the sexes will spend about equal time cleaning. However, since males are more active, moving about most of the time, their bouts of cleaning are probably shorter. To compensate, I expected males to have more frequent cleaning sessions. An experiment was carried out to test these expectations.


RESULTS
The data in Table present the overall characteristics o males and females.Comparison of the lengths o bouts using a t-test shows that these are not significantly different (t 1.o49).However the number o bouts is significantly larger in males than in females (t 1.949; .05>P>.oI ).Rather than the expected differences, it appears that male sessions of cleaning are of equal length and more frequent than those o 'emales.
At times of observations some individuals were pharate, some vials contained exuviae and others eggs.These allowed the animals to be subdivided into groups corresponding approximately to position in instar.Among the males only two ecdysed within the 24 hour isola- tion period, a sample too small to be meaningful.However among the emales, the categories were sufficiently large to permit evaluation.
Table 2 gives the data for females o different types.Of the our pharate females, none exhibited any cleaning behavior.Com- parison of recently ecdysed emales and females with eggs to remain- ing emales revealed no significant differences in bout length.In contrast, comparisons of cleaning requency among these females showed that females with eggs clean significantly more often (t 2.488; 25dr; P .oI) than other emales.

DISCUSSION
As Simon (1961) has noted, the antennae, the location of im- portant sensory receptors, are cleaned most often.There is possibly a positive correlation between frequency of cleaning and the required sensitivity of receptors.In pharate females the old receptors have presumably lost their nervous connections, so that there is no adaptive advantage in cleaning them.In contrast, females that have recently deposited eggs are sensitive to the required stalked spermatophores on the substrate.If this species has alternate reproductive and non-  reproductive instars with oviposition confined to early in the repro- ductive instar as Sinella curviseta (Waldorf, I97), newly ecdysed females are possibly a mixture of two types: sensitive ones early in the reproductive interval and indifferent, or less sensitive ones, early in the nonreproductive instar.Although the distribution of numbers ot: cleaning bouts per female is not bimodal, the mean of this category is 1.63, approximately the average (.57) of the sensitive group with eggs and the remaining females.Note also that the variance of the number of bouts of recently ecdysed females is 1.796 and that of females with eggs and remaining females are .o2and .998respectively.
Considering males, Mayer (957) has reported that males of Sminthurides aquaticus Bourlet clean more (requently when clasping the antennae of females than when alone.This is consistent with the hypothesis that these males are highly sensitive to olfactory stimuli. The data indicate that males engage in more total cleaning than females.My recent studies o Sinella curviseta (Waldorf, in manu-  script) demonstrate that females of this species produce ,a sex pheromone.This stimulates spermatophore deposition by males in the reproductive instar.Of the males in the present study 48 of 5o were in the reproductive instar at observation time.By frequent cleaning, these maintain their sensitivity to olfactory stimuli including possible pheromones.

Table 1 .
Characteristics of male and female bouts of cleaning behavior.

Table 2 .
Characteristics of cleaning bouts by females of various types.