Mate preference and disease risk in Zootermopsis angusticollis (Isoptera:Termopsidae

Authors: ROSENGAUS, REBECA - Northeastern University; JAMES, LADY-THELMA - Northeastern University; HARTKE, TAMARA - Northeastern University; Brent, Colin

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/30/2011
Publication Date: 12/1/2011
Citation: Rosengaus, R.B., James, L., Hartke, T.R., Brent, C.S. 2011. Mate preference and disease risk in Zootermopsis angusticollis (Isoptera:Termopsidae. Environmental Entomology. 40(6):1554-1565.

Interpretive Summary: Termites face significant threats from parasites and pathogens, particularly when winged reproductives disperse outside their nest to establish new colonies. In addition to normal environmental microbes, termites are exposed to infectious agents carried by a mating partner which may favor prescreening prospective mates for signs of illness. To determine the role of disease on mate preference in termites, female reproductives of the termite Zootermopsis angusticollis were simultaneously presented with reproductive males that were either healthy or exhibiting a progression of symptoms associated with infection by the fungus Metarhizium anisopliae. We compared duration and frequency of female visits to healthy and infected males. Additionally, we determined the physiological consequences for females exposed to fungus, either directly or indirectly through their mate. Females exposed directly to fungus had a reduced chance of survival, weight gain and ovarian activity compared to control females, however, females showed no preference for healthy over infected males. While there are important costs of pathogen exposure, the lack of mate selection based on disease risk suggests that more imminent ecological pressures (e.g. predators, desiccation) override the need for a careful and time-consuming assessment of a potential mate’s health.

Technical Abstract: Termites face significant and chronic intranidal selection pressures from parasites and pathogens that colonize their nests. They also encounter microbes outside their nest while foraging and during dispersal of winged primary reproductives to establish new colonies. The latter run the additional risk of becoming infected by a mating partner. Indeed, death of reproductives due to disease is a major cause of incipient colony failure and may favor prescreening prospective mates for signs of illness. To determine the role of disease on mate preference in termites, female primary reproductives of the dampwood termite Zootermopsis angusticollis (Hagen) were simultaneously presented with reproductive males that were either healthy or exhibiting a progression of symptoms associated with infection by the entomopathogenic fungus Metarhizium anisopliae (Metchnikoff Sorokin). We compared duration and frequency of female visits to healthy and infected males. Additionally, we determined the physiological consequences for females exposed to fungal conidia, either directly or indirectly through their mate. Females showed no preference for healthy over infected males. Moreover, only directly-exposed females experienced negative physiological effects, having a reduced chance of survival, gaining less weight, developing fewer functional ovarioles and producing significantly fewer vitellogenic oocytes than controls. While there are important fitness-related costs of direct exposure, the lack of mate selection based on disease risk suggests that more imminent ecological pressures (e.g. predators, desiccation) override the need for a careful and time-consuming assessment of a potential mate’s health.