This paper studied the fumigating activity of Litsea cubeba oil and citral on Solenopsis invicta, identified and analyzed the chemical constituents and volatile components of L. cubeba oil via solid-phase microextraction which were then identified via gas chromatography-mass spectrometry. The results showed that citral and (z)-3,7-dimethylocta-2,6-diena were the main components of L. cubeba oil, as well as its volatile compounds. According to the experimental results, L. cubeba oil and citral had good fumigating activity on workers, and also had significant inhibition on the walking ability and climbing ability of workers. At the same time, the effects of the two agentia on the fumigating activity and behavioral inhibition of microergate were stronger than those of macroergate. After treating with L. cubeba oil and citral for 24 hours, the walking rate and grasping rate of microergate were both 0 %. The results showed that L. cubeba oil and citral had good control effect on S. invicta.

There is a certain temperature rise in the field running cable because of the load bearing. To study the influence of cable temperature rise on the polarization and depolarization current (PDC) method, 10kV XLPE short cables were accelerated aging three months by water needle electrode method, and the PDC method was used to test the new and aged cables under constant humidity. The polarization and depolarization current of the cable samples was analyzed, and the conductivity and low frequency dielectric loss spectra were obtained and inspected. The results show that: in the experiment selected test temperature, the change laws of conductivity of the new and aged cables are the same, and the conductivity gradually rose after a slight drop in 40 °C; in the dielectric loss spectrum, the polarization of the new sample is low and the polarization loss changes little with temperature, and the dielectric loss is mainly affected by the conductivity, so the test result is clearly divided into two regions. And water tree aged samples have strong polarization and are obviously affected by temperature, so their low frequency dielectric loss showed the trend of first rising and then decreasing and the maximum appeared at 60 °C.

In order to further study the effect of different degree of acidity and alkalinity on cable insulation aging, the aging condition of cable insulation was compared and analyzed under different pH values. The samples of cable insulation material slice and short cable were carried out the accelerated aging test, which were placed in the conditions of different pH values. And then the test results of micro morphology and electrical properties between the different samples were compared and analyzed after aging. According to the test results in this paper, the micro morphology of the cable insulation material slice would change differently under the aging conditions of different acidity and alkalinity, which indicated that the degree of oxidation degradation of insulation material aging was different from the different acidity and alkalinity conditions. In addition, both acid or alkaline environment would accelerate the aging of cable insulation and reduce the service life of cable, while strong acid and strong alkaline environment are more conducive to the formation of interpenetrating water tree in cable insulation material and cause the operation accident of power cable. Furthermore, the test results of electrical properties of short cable samples after aging showed that the aging degree of short cable samples was more serious in alkaline environment, and the decline of electrical properties was faster.