Diazepam inhibits reproduction and reproductive behavior of oriental hornet. A possible role for the peripheral-type benzodiazepine receptor.

Feeding of diazepam to young hornets completely inhibits or delays development of their ovaries for a relatively long period. In control hornets, the ovaries usually develop within a day or two post eclosion and comb building commences on the second day of life. The hornets then oviposit into the comb cells and the deposited ova give rise to larvae. Trials were performed on parallel groups of hornets of various ages. When the sedative diazepam was administered to hornets aged 0-24 hours the ovaries of these young hornets failed to show any development, so that no oocytes ripened and consequently there was no oviposition whatsoever. Neither were any comb cells built or, at best, only a few were built. When the diazepam was administered to hornet's being the age of 48 hours, it exerted no change, that is, the eggs developed normally and comb building was the same as in the control group. Longevity of hornets was uniform in all the test groups and similar to that in the control.