The effects of plant essential oils on the functional response of Habrobracon hebetor Say (Hymenoptera: Braconidae) to its host.

Abstract

Habrobracon hebetor Say is an important ectoparasitoid wasp that can control Pyralidae and Noctuidae pests in agricultural crops. In this research, the effects of Allium sativum L., Rosmarinus officinalis L., Piper nigrum L., Salvia officinalis L. and Glycyrrhiza glabra L. essential oils were investigated on the functional response of H. hebetor to its host. The GC-MS analysis showed that tetracosamethyl cyclododeca siloxan, alpha-pinene, caryophyllene, beta-thujone and aristolene were major constituents of mentioned essential oils, respectively. In the experiments; the mated females of H. hebetor (under 24 h old) were exposed to sublethal concentrations (LC30) of isolated essential oils for 24 h with fumigant exposure method. In the control, the treatment was performed by using distilled water. Then, six treated wasps were selected randomly to densities of 2, 4, 8, 16, 32 and 64 Ephestia kuehniella Zeller 5 th instar larvae for 24 h under 25 ± 1 °C, 60 ± 5% RH and photoperiod of 16: 8 (L: D) h. Eight replicates were conducted for each host density in all treatments. The regression analysis based on Holling model (1959) indicated the functional response type II in the control, P. nigrum, S. officinalis and G. glabra and type III in A. sativum and R. officinalis essential oils. Also, R. officinalis essential oil and the control showed the longest (0.542 h) and shortest (0.411 h) handling times, respectively. The highest (0.047 h -1) and lowest (0.033 h -1) attack rates were also recorded in the control and R. officinalis essential oil, respectively. In addition, R. officinalis and G. glabra essentialoils showed the maximum and minimum negative effects on the functional response type and it’s parameters in H. hebetor, respectively. These results indicated that G. glabra essential oil can be recommended with H. hebetor in integrated pest management.