Studies On Antimicrobial Molecules Of Egg Wax In Ixodid Ticks

As obligate blood-sucking ectoparasites, ticks are responsible to be vectors andreservoir hosts of many zoonotic natural foci diseases, which caused great damages tohuman health, wild animals and livestock production, and hence, researches focus onticks are of great importance in economic and public health. The life cycle of ticks iscomplex, and the four developmental stages include egg, larva, nymph and adult,among which egg is the most vulnerable stage and is easy to be affected byenvironment conditions or attacked by micro-organisms. Therefore, in the currentstudy, we investigated the antimicrobial activities of the eggs from Dermacentorsilvarum(collected from Zhangjiakou, Hebei), Hyalomma asiaticum(collected fromXinjiang), Haemaphysalis longicornis(bisexual population was collected fromZhangjiakou, Hebei; parthenogenesis population was collected from Cangxi, Sichuan)and Haemaphysalis doenitzi(collected from Cangxi, Sichuan), and extracted the eggwax using cholorform/methanol(v/v = 2:1) and distilled water, followed by Gaschromatography, high performance liquid chromatography and mass spectrometry tofurther analysis the antimicrobial molecules in the egg wax. Results indicated that:1. Eggs from D. silvarum and Hy. asiaticum can inhibit the growth ofgram-negative bacteria such as Escherichia coli and Pseudomonas aeruginosa, butshow no antimicrobial activity against the growth of gram-positive bacteria such asStaphylococcus aureus and Enterococcus faecalis. Eggs of H. longicornis(bothbisexual and parthenogenic population) can inhibit the growth of S. aureus and othergram-positive bacteria, but cannot inhibit the growth of gram-negative bacteria suchas E. coli. All the eggs denuded with egg wax lost activity against gram-positive orgram-negative bacteria.2. After extract of the egg wax using cholorform/methanol(v/v = 2:1) and water,the organic extract of the egg wax of the tick D. silvarum and Hy. asiaticum inhibitedthe growth of gram-positive bacteria but not gram-negative bacteria. The organicextract of the eggs from H. longicornis and H. doenitzi inhibited the growth ofgram-negative bacteria but not gram-positive bacteria.3. Lipid composition of the organic extract of the egg wax was analysed by lipidfractionation and results showed that neutral lipid was the most abundant followed byfatty acids/glycolipids, and phospholipid. Among than, fatty acids/glycolipids wasaccount for the antimicrobial activity, after analysed by GC/MS, the identifiedunsaturated fatty acids C18:2(C18H28O3)was found to show antimicrobial activity.4. After extract of the egg wax using cholorform/methanol(v/v = 2:1) and water,the aqueous extract of the egg wax from D. silvarum and Hy. asiaticum inhibited thegrowth of gram-positive bacteria but not gram-negative bacteria. The aqueous extractof the eggs from H. longicornis and H. doenitzi inhibited the growth of gram-negativebacteria, but not gram-positive bacteria.