How Female Diet Impacts Life History Traits in the Triangulate Cobweb Spider: Effects of Nutrition on Females and Their Offspring

Abstract

In spiders, nutrients in a mother's diet are provided to her offspring through the eggs she produces, and consequently food quality may impact offspring life history traits. In this study, I tested the effect of maternal diet quality on egg sac production and offspring survival in Steatoda triangulosa, the triangulate cobweb spider. The nutritional quality of a female's diet was experimentally manipulated by feeding her fruit flies with a gradient of lipid and protein. I measured several life history traits both for the female and her offspring, including female body size at maturation, number of egg sacs produced, whether or not those egg sacs were viable, and offspring quality. I evaluated two main predictions. First, that females fed the high protein diet would produce more egg sacs than females fed the low protein (high lipid) diet. Second, that offspring whose mothers were reared on the high protein diet would have higher survival rates and would develop faster than those offspring whose mothers were reared on the low protein diet treatment. Results showed that the female spider�s diet had a large impact on her reproductive success. Of the 94 females in the study, 22 produced egg sacs, with 11 of these producing multiple egg sacs. Females in the protein treatments were more likely to produce an egg sac (viable or not) and a higher average number of egg sacs per female, than in other treatments. Only females fed a protein-enriched diet made viable egg sacs that ultimately produced surviving spiderlings. The high protein mother�s spiderlings had a higher survival rate through the first and final molt and also developed at a faster pace than the intermediate protein mother�s spiderlings.