Cockroach Reproductive Physiology
PI(s): Mullins, Donald E
Investigators:
Abstract: Traditionally, cockroaches have been considered pests on the basis of their presence in human dwellings, odors, their ability to acquire, harbor and transmit human pathogenic organisms. More recently, it has been shown that the presence of cockroaches in urban habitations can promote serious asthma reactions in humans, particularly in children. A variety of methods have been developed for cockroach control, but many have become less effective due to the development of pesticide resistance. As a result, there is a need for continued basic studies on cockroach biology to develop new pest control strategies for controlling these insects. Research in our laboratory is focused on cockroach reproduction physiology designed to examine the relationship of developing German cockroach embryos enclosed in an egg case that remains attached to the female until hatch.
Description:
The relationship between the German cockroach and her ootheca is complex since she carries it to the time of hatch or until just before hatch. We have found that females can provide significant amounts of water to their oothecae during the incubation period. There is also evidence that water flow may be bi-directional, since radiolabeled water from an ootheca may be found in the female to which it was attached. Further, we have discovered that small water-soluble molecules can pass from the female into the ootheca. It is quite likely that bi-directional water flow could provide a means for humoral communication between the female and her ootheca. We have found evidence that females may be able to recognize the age (level of maturity) of developing embryos within an ootheca residing in their vestibulum. The possibility of embryonic age recognition might explain how females determine the appropriate time to release their oothecae at or near the time of hatch. It is known that premature oothecal release from the vestibulum of females can result in oothecal hatch failure, particularly if the embryos are young at the time of removal or if they are exposed to low relative humidity. There is evidence that mature embryos (first instar nymphs) must coordinate their physical movements in order to escape from their ootheca . Failure of oothecal escape (hatch) may occur if insufficient numbers of embryos mature or if they do not synchronize their escape activities. Experiments using radiolabeled water have shown that over time, water is distributed throughout the ootheca. There is also structural evidence that the embryonic egg covering (chorion) placed between embryos and the interior of the ootheca might be capable of transporting fluids throughout the interior of the ootheca. If such a system does indeed exist, then it might provide for circulation of humoral factors that could serve to synchronize embryonic development and mediate in the timing of oothecal escape. We are conducting a series of studies comparing the dynamics of oothecal water balance and water distribution patterns in this insect species.
Commodities:
Resources:
Disciplines: Integrated Pest Management
Audiences: Graduate Students, Homeowners, Researchers, Teachers, Undergraduates
