Induction of Antibacterial Substances in the Orb-weaving Spider Larinioides cournutus (Aaraneae, Araneidae) and Their Antibacterial Activity

Induction of Antibacterial Substances in the Orb-weaving Spider Larinioides cournutus (Aaraneae, Araneidae) and Their Antibacterial Activity

  There are many studies on the induction, isolation and molecular cloning of antibacterial agents of insects and other arthropods, but there is only rudimentary information in relation to antibacterial agents in spiders (Araneae).,. The purpose of this study was firstly to explore whether antibacterial agents could be induced from the haemolymph of Larinioides cornutus (Araneae, Araneidae) and then to determine the characteristics of immune lymph (cell-free haemolymph), including the induction kinetics of antibacterial activity, heat stability and the antibacterial spectrum. After spiders were challenged by either UV irradiation, bacterial injection or hungry, haemolymph was collected and immune lymph was used to measure antibacterial activity by agar-well diffusion method. The immune lymph at 60h after inducted by UV irradiation was used to assay antibacterial spectrum against 11 species of bacteria. The results showed that the haemolymph of L. cornutus could be induced to produce antibacterial effects when the spiders were vaccinated by three inducing methods. UV irradiation was the most efficient and convenient inducing method. Antibacterial activity of the immune lymph collected at different time intervals changed with time. There was a rapid response after induction with a peak of activity at 60h; then the antibacterial activity weakened and kept at a low level for a period of time. Incubated at 40℃ and 60℃, the antibacterial activity of immune lymph stayed stable, while it decreased when being incubated at 80℃ for 15min or 100℃ for 5min. It disappeared when being incubated at 100℃ for 15min. The immune lymph from L. cornutus displayed a broad antibacterial spectrum of having antibacterial effect against ten out of eleven species of tested bacteria.