Studies on Sex Pheromone Communication System in Orthaga Achatina Butler
|School||Nanjing Agricultural College|
|Course||Agricultural Entomology and Pest Control|
|Keywords||Orthaga achatina sex pheromone GC-MS EAG scanning electromicroscope(SEM)|
Orthaga achatina Butler is an important pest of camphor tree, a common tree planted in gardens and along city roads, especially in South China. Because of its special biological characteristics and control requests, methods other than traditional chemical control are exigently required. Insect sex pheromone, as an alternative method to chemical insecticides, has many advantages such as high sensitivity, species-specificity and safety to environment, and therefore has been considered to be one of the prosperous green methods in pest control. For the purpose to develop the method with sex pheromone in control of O. achatina, some aspects of O. achatina sex pheromone communication system were studied, which included the emergence, calling and mating behavior of adult moths, identification of female sex pheromone, and morphology and distribution of different sensillae in female and male antenna. The main results are as follows:1 The calling and mating behavior of adult Orthaga achatinaOrthaga achatina Butler is a serious pest of camphor trees, especially in South China. The emergence, calling and mating behavior of adult O. achatina were investigated under laboratory conditions at 27±1℃,60±10%RH and 14L:10D photoperiod. The results showed that male and female of O. achatina could emergence at photophase and scotophase of the whole day, but the emergence amount in photophase is slightly higher than those in scotophase. There is no difference in emergence rhythm between males and females. The observation of female calling behavior showed that females did not call until start of the scotophase. Calling percentage of females increased sharply at 5th hour and reached a peak at 6th-7th hour of the scotophase. The calling percentage varied with moth age, with the highest of>70% at 2-4d old. The mating behavior indicated that the mating behavior of both males and females could be divided into two successive periods:calling period and mating period. The copulation between females and males occurred during 5th-9th hour with the peak time point of 6th-7th hour into the scotophase, which were in agreement with the female calling behavior. Females mated at most one time during their whole life under the laboratory conditions. However, compared to 1(?):1(?) treatment,1(?):2(?) treatment showed a significantly higher female mating percent, but a significantly longer mating duration time. These results provided the basis for the further elucidation of the sex communication system in O. achatina.2 Primary identification of O. achatina female sex pheromoneThe female sex pheromone gland extracts of Orthaga achatina Bulter were examined by GC and GC-MS analysis. Two compounds were identified:(Z)-11-hexadecen-l-ol acetate (Z11-16:Ac) and 1-hexadecanol acetate (16:Ac), the average ratio of these two components was about 60:40. The results of EAG response of Z11-16:Ac and 16:Ac showed that Z11-16:Ac can induce the remarkable EAG responses, but 16:Ac can’t. So we thought Z11-16:Ac was one component of sex pheromone.3 Observations on antennal sensilla of Orthaga achatina with scanning electromicroscopeThe external morphological structures of the antennae of Orthaga achatina were observed with a scanning electromicroscope. The antennae of the male and female moths consist of scape, pedicel and 75-85 flagellar segments, dorsal side is covered by scales, most antennal sensilla are located at ventral side and lateral side of the antennae. The flagellar segments covered of reticular cuticle, but the cuticle of the scape and pedicel lacks the reticular characteristic. The sensilla found on the antennae of male and female moths include sensilla trichodea, sensilla chaetica, sensilla coeloclnica, sensilla auricillica, sensilla squamiformia, sensilla styloconica, Bohm bristles and sensilla cavitata-peg. The sensilla trichodea are the most abundant and can be subdivided into two distinct types(typeⅠand typeⅡ) according to form and surface substructure. All sensilla, except Bohm bristles, occur on the reticular area of the antennae.