The Effect Of Litsea Cubeba Oil And Azadirachtin For Guava And Bactrocera Dorsalis(Hendel)

In China,Bactrocera dorsalis has the characteristics of wide range of host,rapid reproduction and easy migration,and difficult control.In this paper,we studied the effects of azadirachtin and Litsea cubeba essential oil on B.dorsalis and its main host guava in South China.Gas chromatography-mass spectrometry(GC-MS)and high performance liquid chromatography(HPLC)were used to determine the attraction mechanism of guava volatiles to B.dorsalis.The penetration and degradation of L.cubeba and azadirachtin essential oil on host and environment were determined.The biological activity assay determined the effects of azadirachtin and L.cubeba oil on the reduction of egg production,hatching rate and phlegm rate of B.dorsalis.And the effect of delaying the growth and development of B.dorsalis was tested.Scanning electron microscopy was used to determine the excessive behavior of the adults exposed to L.cubeba oil and azadirachtin.Also,the activity of larvae in the two maturity guava was tested.Finally,the expressions of azadirachtin and L.cubeba essential oil on the head memory gene and c AMP-response element binding protein(CREB)of B.dorsalis were determined by PCR and Western-blot.The results of GC-MS showed that the main peak area of the main components of the mature guava wax layer accounted for 33.92%,alkane 49.35%,olefin 12.21%,naphthalene2.69%,lipid 3.39% and steroid 1.13%.A large amount of phenols 31.91%,lipids 5.43%and olefins 21.88% were found in the intact mature guava volatiles.Phenols and lipids in the guava volatiles are the key to the changes in the electroantennography(EAG)of B.dorsalis.The results of HPLC showed that the main component of 1000 mg/kg of L.cubeba oil citrate reached the 2 cm of the flesh through the guava epidermis within 4-8 h and all degraded within 32 h.The results of EAG showed that the L.cubeba can increase the relative EAG of the mango volatiles from 0.56 ± 0.01 m V to 1.78 ± 0.14 m V,and the relative EAG of guava volatiles increased from 1.46 ± 0.26 m V to 2.45 ± 0.14 m V,it can interfere with the sensory organ antennae and affect its EAG response.The indoor bioactivity assay determined the difference in the effect of 800mg/kg L.cubeba oil and 20mg/kg azadirachtin,and the synergistic effect of the two agents.It can prolong larval stage 3-4 days,pupal stage 4-5 days and sexual maturity 4-5 days.It reduces the number of eggs and the hatching rate of larvae on guava.That reduces the harm of B.dorsalis.The effects of the extract of L.cubeba and azadirachtin on guava for the drill collar behavior of the larvae and the adult behavior of B.dorsalis were determined.Scanning electron microscopy was used to observe the effects and differences of the sensory structure of the head of the adult after contact with L.cubeba and azadirachtin.The results showed that the adult of B.dorsalis had self-harm and fighting behavior.At the same time,the damage to the sensor SC and MI is larger than contacting distilled water.Related studies have shown that long-term training of insect behavior can make it produce long-term memory.Establishing the relationship between the L.cubeba and azadirachtin on the behavior and memory of B.dorsalis,the effects of azadirachtin and L.cubeba on the memory gene and protein CREB expression in the head of B.dorsalis were determined by PCR and Western-blot.The results showed that after 24 hours of olfactory training,azadirachtin and L.cubeba had an effect on increasing the memory of B.dorsalis.After 48 h,the expression of CREB gene and protein was down-regulated,indicating that memory declined after 48 h.