Effects Of Exogenous Jasmonic Acid Induced Resistance And Phenolic Acid To Gypsy Moth And Pathogenicity Of LdNPV

Lymantria dispar L. is a one of the most important phytophagous pests which has a worldwide distribution, multiple host plants. It could cause great losses to the economy and ecological construction. Lymanria dispar nucleopolyhedrosivirus(LdNPV) is one of an important pathogenic microorganisms of gypsy moths and often has an effect on the populatin dynamic of gypsy moths. The occurrence of LdNPV has something to do with the midgut intestinal environment of host insects. After a larva eats the plants which defensive compound may affect the intestinal environment thereby lessening virulence of the virus. This paper uses Populus cathayana by jasmonic-induced resistance and selects four phenolic acids which were researched the effects on pathogenicity of LdNPV and the development of gypsy moths. Analyze the pathology manifest of midgut slice through phenolic acid and virus. We investigate the relation of plant induced-resistance-insect-insect viruses. The results are as follows:1. Effects of induced resistance of exogenous JA on pathogenicity of LdNPV to the gypsy moth.The mortalities of the 2ndlarvae rearing on the induced-poplar of 5d or 10 d was much higher than that of control, it was increened about 13.3% or 20.1%, respectively(P<0.05).The mortalities of the 2nd larvae reared on the induced 1, 5, and 10 d poplar was much higher than that of larvae reared on the artifical diet, 25.8, 14.3, 29.6, and 33.8%(P<0.05)higher than that of the artificial rearing. The development duration of the 2nd larvae rearing on poplar was prolonged, 1.4days longer than that of the normal(P<0.05).The mortalities of 2ndlarvae by rearing poplar 0.1mmol/L concentration JA induced the 1, 5, and 10 d were 25.9, 28.1 and 28.9% compared with normal poplar respectively(P<0.05). The mortalities of 2nd larvae rearing induced-poplar of 5d-induced than control high about 19.0%(P<0.05). Viral mortalities reared by poplar of normal and induced 1, 5,and 10 d were 25.8, 40.9, 34.9, and 41.4% higher than artificial rearing(P<0.05). The development duration of 2nd larvae rearing poplar saw no significant changes with CK, but their time was prolonged.2. Effects of exogenous JA-induced resistance and LdNPV on the growth and development and food utilization of gypsy moth.There was significant effects of JA-induced poplar resistance and LdNPV on larvalgrowth and nutritional utilization of gypsy moth. The larval weight was lower than that of the control significantly when infected with Ld NPV and fed on the induced poplar by JA.The development duration was lengthened, and 1.0day, 1.2 day and 1.7 day longer than that of control when fed on the poplar after induced 1day, 5 days and10 days, respectively.The food consumption was significantly decreased by 21.6% compared with control and by 24.2% compared with LdNPV infection when fed on the poplar after induced 5days, but there was no significant change when fed on the poplar after induced 1days and 10 days.The relative growth rate was lower than that of control and that of LdNPV infection significantly. The approximate digestibilities(AD) of gypsy moth larvae infected by LdNPV and fed on poplar after induced 1day, 5days and10 days were decreased by 4.3%,7.5% and 7.4% than that of control, respectively; the efficiency of conversion of ingested food(ECI) decreased by 17.4%, 22.0% and 25.1%,respectively; efficiency of conversion of digested food(ECD) reduced 18.0%, 23.0% and 27.1%, respectively. Those three nutritional utilization indices increased as time after the JA induction prolonged, but there was no significant difference from the point of statistics. The results suggested that induced resistance of poplar by exogenous JA may enhance the effects of nucleopolyhedrovirus on the nutritional utilization of gypsy moth larvae.3. Effects of plant phenolic acids and LdNPV on the development and reproduction of gypsy moth larvae.Phenolic acid alone. Tannic acid and chlorogenic acid had comparatively large affected to young age of larva. Tannic acid caused the larval mortality of 22.2% on the 12 th day after feeding, which was significantly higher than the mortality in the control(larvae fed on normal artificial diet)(3.3%)(P < 0.01). Both tannic acid and chlorogenic acid reduced the larval weight and prolonged the developmental duration, frequently causing incomplete ecdysis, even all died, at the 4th instar larval stage. The larvae fed on the diet containing salicylic acid or syringic acid pupated and grew to adults, and the pupal weight of females increased significantly but the number of eggs laid per female and fertilization rates of eggs decreased obviously. Compared with the control, syringic acid caused a decrease of 90 eggs in the number of eggs laid per female, a 35% decrease in the fertilization rate of eggs, and also a reduction in the proportion of female adults.Phenolic acids and LdNPV. Treating with the syringic acid, tannic acid and chlorogenic acid for 4 to 12 days found that cloves acids led to a mortality rate of larvae up to 57.8% at the 12 th day, significantly higher than that of CK, 3.3%(P<0.01)and that of CK+V(P<0.05), 16.7%. Those viruses treated by tannic acids and chlorogenic acids had askyrocketing mortality which eventually reached 100%. And larvae treated by the two kinds of acids undergone significantly longer development period with slim bodies and skulls that are not easy to fall off. But at the 4th instar, they all died. Salicylic acids and syringic acids brought a remarkably lower emergence rate, fecundity rate and fertility rate to the infected gypsy moths compared with those treated with CK+V. The rates were far different from those resulting from CK. The fecundity and egg fertilization rate ratio of larvae treated with syringic acids were respectively about 400 fewer and 43% lower than those treated with CK. The syringic acid also reduced the proportion of adult females by a large margin.4. Histo-pathological effects of phenolic acids and LdNPV on midgut cells of gypsy moth larvae.Midgut cells fed on the chlorogenic acid and tannic acid had lined up untidily,columnar cells and goblet cells had begun to deformities at 12 hour. At 24 hour, microvilli falling off. At 48 hour, entocoele of goblet cells had intumescentia. And microvilli began to desquamate abundantly at 72 hour. Finally the cell was unclear, beginning to melt at 96 hour. The cell of larval midgut infected virus alone had deformed at 12 hours. At 24 hour the intercellular space had enlarged. At 48 hour nucleus of columnar cell had swelled. And the cells was unclear at 72 hour. Virus particles were seen within cells at 96 hour. Midgut cells of larvae fed phenolic acid or Ld NPV alone which pathological changes time had happened early. And the speed of pathological changes was quick, degree was severity.Especially, whey they were fed with the chlorogenic acid and tannins had seen within organelles finally.