SEXUALLY-TRANSMITTED DISEASE IN A PROMISCUOUS INSECT, ADALIA-BIPUNCTATA

1. Sexually transmitted diseases (STDs) have rarely been reported in i nsects and other invertebrates. The majority of those reported involve organisms where sexual transmission is augmented by either vertical ( i.e. inherited) transmission, or horizontal transmission, independent of host sexual activity. 2. We here demonstrate the existence of an ST D in the coccinellid beetle Adalia bipunctata. This species bears a pa rasitic mite of the genus Coccipolipus. We show that, like many other podapolipid mites, this mite is transmitted between host individuals a t a high rate during copulation, It also appears to be transmitted at a low rate between non-copulating individuals. 3. We show that infecte d female A.bipunctata produced eggs at a reduced rate, and that the eg gs produced by infected females have highly decreased viability. Howev er, no effect of infection upon host longevity was observed. 4. The re sults are discussed in relation to the incidences of sexually transmit ted disease in invertebrates in general, the causes of disease symptom s, and the importance of this disease in the evolution of A.bipunctata .