The bite of a widow spider ( Theridiidae) has long been considered to be the most painful and dangerous of all North American spiders.  One result of urban expansion into desert habitats is that humans are encountering widow spiders more and more frequently.  Indeed, in Western cities such as Tucson and Phoenix, the local widow species, is so common in and around homes that many residents, particularly those with small children, have begun contracting with pest control agencies to spray for widow spiders.  Despite the fact that many pesticides are currently labeled for use against spiders, pesticides are, in fact, largely ineffective at killing web-building spiders such as widows.  This is because widow spiders rarely leaves their web and thus does not come into contact with toxins sprayed indiscriminately. 

The combination of a rise in widow population numbers in and around human homes and the ineffectiveness and dangers of widespread pesticide use to combat widow spiders suggest that it is of paramount importance to develop an alternative approach to controlling the abundance of these spiders in urban habitats.  The above-stated problem can be addressed in a similar manner to that of biological invasions by non-native, introduced species.  can be thought of as a novel species introduced somewhat suddenly to urban habitat in the West.  Thus, we can attempt to control the proliferation of widows in urban habitats in many of the same ways that we attempt to control the spread and establishment of invasive species. 

The aim of this project is to develop a thorough understanding of the interaction between widow behavior and population ecology that results in colonization and population establishment/growth in urban habitats.    What behavioral differences have arisen between these relatively recently diverged populations?  For example, are spiders from urban environments, on average, bolder or shyer towards predators than spiders from desert habitats?  Is this boldness the result of different predation regimes experienced across the population types?  In other words, does the interaction between behavior (e.g. boldness towards predators) and ecology (e.g. degree of predation risk) explain the explosive success of urban widow spiders?  Similar questions will be asked regarding population differences in the behavioral ecology surrounding foraging, mating, agonism and parental care. 

Finally, what can genetic variation within and between these populations tell us about the success of urban populations?  The study of non-native species introductions has emphasized the importance of reduced genetic variation that typically accompanies the colonization of new habitats by only a few introduced individuals.  Do urban populations show evidence of low levels of genetic variation similar to that predicted for invasive species?  If so, this may explain local adaptation to urban environments.