The Research On The Reaction Of Oryctes Rhinoceros Linnaeus Towards Volatiles Of Cocos Nucifera And The Ultrastructure Of Its Olfactory Sensilla

Oryctes rhinoceros (Linnaeus) is a serious pest of coconut and oil palms in Asia and South Pacific. We studied the electroantennogram (EAG) and olfactometer behavioral responses of adult O. rhinoceros to volatile of host plants. The ultrastructures of sensilla on the head of adults were observed by scanning electron microscope (SEM). The main results were showed as follows:1.Collection and identification of the volatiles from Cocos nucifera L.The volatiles from C. nucifera leaves were collected by adsorption-thermodesorption and identified by GC/MS. There were23compounds including alcohols, aldehydes, acids, ester, ketones and terpenes. The relatively high contents were3-ethoxy-1,1,1,7,7,7-hexamethyl-3,5,5-tris (trimethylsiloxy) tetrasiloxane, azulene, pentadecane, benzoic acid,2-methylpropyl ester propanoic acid,2-methyl,1-aminocyclopentanehydroxamic acid, the relatively contents were15.45%,8.31%,7.75%,6.63%,5.31%which accounted for50%of the total contents.2.EAG and behavioral responses of O. rhinoceros to the volatiles of C. nuciferaThe results showed that nine volatiles tested induced female and male beetles EAG responses compared with control. The EAG responses of adults to octanal, benzene1-propeny, acetophenone,1,2-benzenedicarboxylic acid bisester (10-2μl/ml) were significant (p<0.05). The results of behavioral responses showed that octanal and acetophenone attracted the females and males. The responses of males to β-methyl styrene and1,2-benzenedicarboxylic acid bisester were obvious (p<0.05) except females. However, heptanoic acid exhibited repellent to males.3.The study on monitoring O. rhinoceros using aggregation pheromone in the fieldThe results suggested that O. rhinoceros were active all the year and the peaks were twice a year (from March to June, form August to October). The number of adults traped was greatest from August to October. Activity monitoring in different host fields showed that the order was C. Nucifera>Elaeis guineensis Jacg>Areca catechu. according to the number of adults traped.4.The Ultrastructure of Sensilla on the Head of Adult O. rhinocerosThe ultrastructure and distribution of sensilla on the head of adults was observed by scanning electron microscope. The results showed that five types of sensilla on the head of adults and there types of olfactory sensilla on its antenna. Sensilla placodea (S.pl) in lamellae of O. rhinoceros were situated in cuticle or in the sunken cavity formed by antennal cuticle depressions. In addition to S.pl, there were sensilla trichodea (S.tr) and sensilla coeloconica (S.co). There were no difference in the types, numbers and locations of antenna senilla between males and females. Both maxillary palp and labial palp contained four types of sensilla, including sensilla trichodea (S.tr), sensilla coeloconica (S.co), sensilla twig basiconca (S.tb) and sensilla campullacea (S.ca). Sensilla twig basiconca of males and females were different on maxillary palp, the other three sensillas were not significantly different in types, numbers on maxillary palp and labial palp.