Brown Widow Fecundity
Authors:Amy Ansalmo, Daniel Clarke, Douglas Danielsen, Douglas Danielsen, Stephen Valle, Rick Vetter Vetter, Leonard Vincent
- Leonard Vincent, Professor Biology, Fullerton College
- Rick Vetter, Research Associate, University of California Riverside
We examined egg sac fecundity for the brown widow spider, Latrodectus geometricus C. L. Koch, 1841, in southern California. In order to determine whether seasonal variation would occur over a 5-month period, June through October, and also captivity vs. field-generated sacs for one month. Egg production was continuous rather than periodic through the 5-month time frame with the only significant difference being between the means for June in comparison to September. September had a higher mean than June. Because fecundity decreases with spider age, this probably indicates that early season females are part of the previous year’s cohort of spiders and that there is continual replenishment of older females with newly maturing females. Egg fecundity in between field and captivity-generated sacs did not differ in a statistically significant fashion, indicating that laboratory data should accurately reflect field fecundity. This information is useful for an applied study that developed a key to spider egg sacs for an agroecosystem.