Maternal Care and Infanticide by Males in Helvibis longicauda (Araneae: Theridiidae)



Marcelo O. Gonzaga, Instituto de Biologia, Universidade Federal de Uberlândia, Campus Umuarama, Bloco 2D, Uberlândia, Minas Gerais, CEP 38400-902, Brazil.



Maternal care in spiders varies from just the construction of a protective silken structure for the eggs and the selection of a safe site to place them, to a long period of association between the mother and spiderlings. Such extended care may involve the active protection from predators and parasitoids, food regurgitation, the production of trophic eggs and even matriphagy. In this study, we describe extended maternal care in Helvibis longicauda (Theridiidae) and evaluate the effectiveness of maternal protection against predators of eggs and spiderlings. We conducted experiments comparing the frequency of egg sac destruction and mortality of spiderlings in the presence and absence of mothers. We also observed the behaviour of the mother and spiderlings during prey capture events and interactions with possible predators. Helvibis longicauda females guard their egg sacs until the emergence of the young and guard the spiderlings for several instar stages, fighting possible predators, including conspecifics. We found that aggressive behaviour by females increased the survival of both eggs and spiderlings in our experiments. Intruder males were the main source of mortality in the absence of females. The benefits of maternal care for the young also include the acquisition of prey items that are captured, immobilized and pre-digested by the mother. Effective maternal protection and the extended period of supplying food to juveniles probably contribute to the late dispersal of offspring in H. longicauda.