Studies On The Semiochemicals Of Pissodes Yunnanensis And P.punctatus

Pissodes yunnanensis and P. punctatus are stem borers of pines and thay are specific species in China. P. yunnanensis mainly infests young Pinus yunnanensis while P. punctatus infests many kinds of pines such as P. tabulaeformis Carr. and P. armandii Franch. The two species of weevils are mainly distributed in Yunnan, Guizhou, Sichuan, Gansu Province, etc. They outbreaked and caused great losses to local forestry production and ecological environmental construction. The aim of researches was studing on the semiochemicals of P. yunnanensis and P. punctatus looking for effective attractants to the two weevils. Aggregation pheromones were also analyzed and tested for providing scientific basis for their later control, monitoring and prediction.The external morphology of both sexes of P. punctatus and P. Yunnanensis adults are highly similar and it is difficult to distinguish them. Two methods for sexing live adults were described. One was identifying terminal tergite of the abdomen with a dissecting microscope. The other one was identifying middle shape in the first segment of abdomen with naked eyes, which was a convenient sexing method in the field.The type, quantity and distribution of a??nal sensilla of P. yunnanensis and P. punctatus are almost the same and those of both sexes are also similar. Antennal sensilla of the two weevils were mainly divided into six types: sensilla trichodea, hand-shaped sensilla, sensilla basiconca, sensilla chaetica, sensilla chaetica variant and sensilla sporangium. The hand-shaped sensilla, sensilla chaetica variant and sensilla sporangiumⅡof P. punctatus were new discovery in this research.Host plant volatiles were collected with dynamic headspace sampling (aeration) techniques and live adults volatiles were collected with SPME techniques. These volatile components were isolated and identificated with GC-MS and GC techniques. The weevils'responses to the volatiles were tested with EAG and field traps. Results showed that myrcene andα-pinene were the most abundant monoterpenes in volatiles of its host Pinus yunnanensis Franch. var. pygmaea. Volatile components of healthy pine and infested pines were different, but they were basically the same in different parts of trees in the same heath condition. Myrcene and (1S)-(-)-α-pinene had significant EAG response to P. yunnanensis. In field assays, any monoterpene alone had no attraction to the weevils but the formulas made of several monoterpenes had significant attraction.3-carene is the most abundant monoterpene of P. punctatus's host, Pinus tabulaeformis Carr., in Jingyuan Gansu. There were almost no volatile changes between healthy and infested pines. Volatiles in different parts of healthy P. tabulaeformis were different. P. punctatus had significant EAG response to several monoterpenes and (1R)-(+)-α-pinene induced the biggest response. Activity and concentration of monoterpenes were linear positive correlated in certain extent. Field tests showed that monoterpene 1 and 4 and four formulas made of monoterpines had significant attraction to P. punctatus.Grandisol and grandisal, as synthetic compounds, with host shoots were significantly attractive to P. punctatus. The highest trap catch in the tests was on the treatment with grandisol and shoots. The second one was grandisal with shoots. Grandisol, grandisal with host shoots had no attraction to P. yunnanensis. Male adults or female with host shoots also were not attractive to both sex. Maybe grandisol and grandisal were components of P. punctatus's pheromone, but P. yunnanensis's. Grandisol and grandisal had not been found in the two species of weevils using SPME and GC-MS techniques.Flight is the main way of P. yunnanensis to spread and migrate. This weevil has a strong phototaxis. ??t is the main factor affecting its creep and flight and temperature also can affects its flight. P. yunnanensis prefers white color. Monoterpenes combined with white color were more attractive than using any of them alone. It showed that the combination of vision and olfaction acted synergistically to attract P. yunnanensis.