BEHAVIORAL ASYMMETRY IN RELATION TO BODY WEIGHT AND HUNGER IN THE TROPICAL SOCIAL SPIDER ANELOSIMUS EXIMIUS (ARANEAE, THERIDIIDAE)

It has been hypothesized that larger females of the social neotropical spider Anelosimus eximius(Keyserling 1884) (family Theridiidae) take advantage of the food captured by smaller females, and thus maintain a higher social rank within a colony . To test this hypothesis, the behavior of adult females in three colonies of A. eximiuswas observed in the Panama rain forest . Adult spiders with low body weights did most of the building, cleaning and repairing of the communal web, while heavier spiders more often took care of egg sacs . The latter stayed mostly inside safe retreats while low-weight spiders were mostly outside the retreats, where mortality was high . Reproducing spiders were of high body weight . To test whether this behavioral asymmetry is related to the nutritional condition of a female a manip- ulation experiment was conducted . A comparison of adult females, which were either well fed or starved, showed that starved females do more web maintenance, spend more time outside the retreats and more often take part in attacking prey . I conclude that both hunger (recent feeding success) and general nutri- tional condition (body weight) are the cues for the observed behavioral asymmetry in colonies of Ane- losimus eximius .It is currently unknown whether the observed asymmetry is stable over time or whether it is age-related .

[1]  S. Riechert,et al.  DISPERSAL AND POPULATION‐GENETIC STRUCTURE OF THE COOPERATIVE SPIDER, AGELENA CONSOCIATA, IN WEST AFRICAN RAINFOREST , 1988, Evolution; international journal of organic evolution.

[2]  J. Jarvis.  Eusociality in a mammal: cooperative breeding in naked mole-rat colonies. , 1981, Science.

[3]  H. Wolda.  SEASONAL FLUCTUATIONS IN RAINFALL, FOOD AND ABUNDANCE OF TROPICAL INSECTS , 1978 .

[4]  R. Foelix,et al.  The biology of spiders. , 1987 .

[5]  Ann L. Rypstra,et al.  Prey Size, Social Competition, and the Development of Reproductive Division of Labor in Social Spider Groups , 1993, The American Naturalist.

[6]  W. Nentwig.  Social spiders catch larger prey: a study of Anelosimus eximius (Araneae: Theridiidae) , 1985, Behavioral Ecology and Sociobiology.

[7]  D. Smith.  Population genetics of Anelosimus eximius (Araneae: Theridiidae) , 1986 .

[8]  P. Ward.  Prey Availability Increases Less Quickly Than Nest Size in the Social Spider Stegodyphus Mimosarum , 1986 .

[9]  Leticia Avilés,et al.  Sex-Ratio Bias and Possible Group Selection in the Social Spider Anelosimus eximius , 1986, The American Naturalist.

[10]  S. Riechert,et al.  The Ecology of the Cooperative Spider Agelena consociata in Equatorial Africa (Araneae, Agelenidae) , 1986 .

[11]  Y. Lubin,et al.  Is there division of labour in the social spider Achaearanea wau (Theridiidae)? , 1995, Animal Behaviour.

[12]  E. Wilson.  The Insect Societies , 1974 .

[13]  P. Ward,et al.  Conflict and Cooperation in the Group Feeding of the Social Spider Stegodyphus Mimosarum , 1985 .

[14]  H. W. Levi.  The Spider Genera Neottiura and Anelosimus in America (Araneae: Theridiidae) , 1956 .

[15]  H. W. Levi.  The American Spiders of the Genus anelosimus (Araneae, Theridiidae) , 1963 .

[16]  F. Vollrath.  Colony Foundation in a Social Spider , 1982 .

[17]  John F Anderson.  Responses to Starvation in the Spiders Lycosa Lenta Hentz and Filistata Hibernalis (Hentz) , 1974 .

[18]  T. Christenson.  Behaviour of colonial and solitary spiders of the theridiid species Anelosimus eximius , 1984, Animal Behaviour.

[19]  Vincent Brach,et al.  ANELOSIMUS STUDIOSUS (ARANEAE: THERIDIIDAE) AND THE EVOLUTION OF QUASISOCIALITY IN THERIDIID SPIDERS , 1977, Evolution; international journal of organic evolution.

[20]  F. Vollrath.  ENVIRONMENT, REPRODUCTION AND THE SEX RATIO O F THE SOCIAL SPIDER ANELOSIMUS EXIMIU S (ARANEAE, THERIDIIDAE) 1 , 1986 .