Antimicrobial activity in the egg wax of the African Bont Tick Amblyomma hebraeum

The female of the tick Amblyomma hebraeum coats her eggs with a waxy secretion that prevents desiccation and microbial attack. When incubated with bacteria, the eggs inhibited the growth of Gram-negative bacteria. The extract of the egg wax preserved antibacterial activity. The antibacterial activity of the extract disrupted the membranes of bacterial cells within 30 min. However, lysis was detected only after 1.5 h. The most evident cytological change observed by TEM was the formation of a precipitate within the cytoplasm. The egg wax is secreted by Gene's organ, a reproductive accessory gland active only during oviposition. Gene's organ grows during the first 7-10 days post-engorgement, although it lacks antimicrobial activity until about day 10, when oviposition starts. This suggests that growth and/or secretion of Gene's organ may be under hormonal control. However, injections of 20-hydroxyecdysone 20E did not stimulate growth of Gene's organ or secretion of antimicrobial activity.