Tactile stimulation accelerates reproduction in German cockroach (Blattella germanica) females

The onset and pace of reproduction in most animals are dependent upon specific internal and external stimuli. Internal stimuli include the animal’s nutritional state, blood composition and osmolarity, and whether it has been inseminated. External stimuli include environmental conditions (e.g., temperature, humidity, photoperiod, host plants) and social interactions. Behavioral modulation of reproduction might be expected in social animals. For example, in some social insects, the queen pheromonally inhibits reproductive maturation in sterile workers and she maintains a certain division of labor within the colony. Social facilitation or suppression of reproduction are less common in non-social animals. Yet, examples have been documented of reproductive effects due to presence of conspecifics. In some insects, reproduction can be accelerated in females by individuals of various developmental stages, both sexes, and even different species. Social interactions have been found to have such an influence on the physiology and behavior of individuals in the German cockroach, Blattella germanica, where not only nymphs develop faster when grouped but females in groups reach sexual maturity earlier as well compared to isolated females. While testing sensory pathways, we have found that mainly the tactile channel is responsible for accelerated reproduction in B. germanica females. We hypothesize that the transduction of social signals occurs through a sensory pathway involving tactile stimulation by the antennae. I am currently delineating key characteristics of contact cues using artificial stimuli driven by motors.