Effects of the juvenoid fenoxycarb on the reproductive behavior and anatomy of the German cockroach, Blattella germanica (L.)

The purpose of the present study was to show that there is an obvious connection, suggested but not documented before, between treatment with fenoxycarb and Blattella germanica (L.) sterility. Sterility was defined as prevented mating, a result of an alteration in female feeding behavior on the male tergal gland or in anatomy of male reproductive external genitalia. Comparisons of age classes, sex and dose levels revealed that reproductive failure in fenoxycarb treated B. germanica pairings occurred at several levels: (1) during reproductive behavior at the tergal gland (between female feeding (FF) and short copulation (SC) events), (2) during copulation attempts (a consequence of the male\u27s malformed and prolapsed left phallomere), and (3) at the ootheca. Nymphally treated males were more sensitive than females to doses of juvenoid. Adult females were most sensitive to doses of juvenoid. Low dose pairings were capable of copulations and production of viable offspring. High dose pairings showed no successful copulation attempts and no resulting offspring. Videotape, scanning electron microscopy (SEM) and light microscopy (LM) evidence were used to document these findings. It has been demonstrated that sterility levels in juvenoid treated B. germanica populations have a correlation of twisted wing levels found in the adults of that population (Bennett & Reid 1995, Reid et al. 1990, Zeman et al. 1992, Brenner et al. 1988, Staal et al. 1985). Morphological evidence that strongly supports this proposed connection is reported here. High doses of fenoxycarb will give rise to high levels of the most severe twisted wing score of “5” in the population. Males exhibiting this twisted wing rating will also display a continuously everted, prolapsed left phallomere. Severely twisted wing level can thus be strongly associated with mechanically compromised left phallomeres. Therefore, morphological alterations in the left phallomere preclude matings and give rise to high levels of sterility in a B. germanica population. Twisted wing score of “5” is a strong indicator of sterility in a B. germanica male