Effect Of Fertilization On The Biological Characteristics Of Asian Citrus Psyllid,Diaphorina Citri Kuwayama

Asian citrus psyllid Diaphorina citri Kuwayama is the most important pest of citrus worldwide,because it serves as a vector of“Candidatus Liberibacter asiaticus”and“Ca L.americus”that cause Citrus Huanglongbing?HLB?.Fertilization in citrus orchard can affect the occurrence of citrus pests by changing the host nutrition.Therefore the relationship between fertilization of citrus and biological characteristics and behaviors has an important role in psyllid control and HLB management.In this thesis,the biological characteristics of D.citri feeding on Citrus reticulata cultivated by organic fertilizer?OF?,chemical fertilizer?CF?,mixed fertilizer?Mixture of organic fertilizer and chemical fertilizer,MF?and different nitrogen levels were studied.The preference of D.citri to different fertilizers-culture citrus was also observed.The main contents and results are as follows:1.The influence of fertilization on the biological characteristics of D.citriApplication of OF,CF,and MF had different effects on the biological characteristics of D.citri.There was no significant difference among the survival rates of D.citri on the three hosts.The durations of egg,1st instar and 2nd instar nymphs were also not significantly different.But the duration of the 3rd instar nymphs,4th instar nymphs in the OF treatment was shorter,and the 5th instar nymphs and the immature stage were significantly shorter than other treatments.There were no significant differences in the female's pre-oviposition period,the fecundity,the oviposition period,and the longevity on the three types of fertilizers.However,the amount of spawning,the shortest pre-oviposition duration,and the longest lifespan were all on the sweet C.reticulata with chemical fertilizers.In addition,there was no significant difference in the survival rates of overwintering D.citri adults among different hosts with different types of fertilizer.The net reproduction rate?R₀?,intrinsic rate of increase?r_m?,finite rate of increase???,and index of population trend?I?of D.citri were highest on the organic fertilizer treatment,followed by the mixed fertilizer treatment,and the fertilizer treatment group was the smallest.This result indicates that the application of organic fertilizer is most beneficial to the population growth of D.citri,while chemical fertilizer is worst.The results of leaf nutrition test of the three treatments showed that the nitrogen contents of OF,CF and MF treatments were 3.5%,3.9%,and 3.5%;the phosphorus contents were 0.45%,0.47%and 0.36%;and the potassium contents were 2.71%,4.17%,and 3.53%,respectively.The N/K of OF,CF and MF treatments were 1.29,0.94,0.99,respectively.The highest N/K level in OF treatment might contribute to the best population growth of D.citri on this treatment.The application of organic fertilizer treatment is more conducive to the growth of the wood lice population may be related to a higher N/K ratio.2.The effect of citrus fertilization on the host preference of D.citri adultsD.citri showed different preference to the C.reticulata young plants using OF,CF and MF.The number of D.citri adults feeding on the plants applying CF was significantly higher than others 1 hour post-release.The number of psyllid adults feeding on the C.reticulata with chemical fertilizers is the highest during the whole 96 hours.The result demonstrates that hostplant applying with chemical fertilizer is most attractive to D.citri adults.However,the egg quantity on the C.reticulata with OF,CF and MF were not significant.3.Effects of different nitrogen levels in host plants on the biological characteristics of D.citriDifferent amounts of nitrogen also affected the biological characteristics of D.citri.The duration of immature stage was shortest on the plants with medium nitrogen application,and longest on plants without nitrogen.Different nitrogen application rates had no significant effect on the survival rate of D.citri.The pre-oviposition period of D.citri with high nitrogen application rate and medium nitrogen application rate was shorter,but there was no significant difference with other treatments.The fecundity increased with the increase of nitrogen application rate except for no nitrogen fertilizer treatment,but the difference was not significant.The order of generation period?T?of D.citri with medium nitrogen application rate was shortest.The net reproduction rate?R₀?,intrinsic rate of increase?r_m?and finite rate of increase???were highest in medium nitrogen application rate?The index of population trend?I?of D.citri was increased with the amount of nitrogen applied to the hosts.This result indicates that high nitrogen level is beneficial to the population growth of D.citri.The results of leaf nutrient test showed that the nitrogen content of Without-N low-N,medium-N,and high-N applied treatments was 2.7%,2.9%,3.3%,and 3.5%,phosphorus content was<0.2%,0.65%,0.70%and 0.67%,and the potassium content was 1.59%,3.50%,3.79%and 4.02%,respectively.Leaves nitrogen content increased with the increased of the soil nitrogen application,which is conducive to the reproduction of the D.citri population.4.Effects of different nitrogen levels in host plants on the host preference of D.citri adultsThere was no significant difference in attraction effect of C.reticulata with different nitrogen application rates on D.citri adults.But the egg quantity on the C.reticulata with medium nitrogen application rate was highest,and significantly higher than that on the C.reticulata without nitrogen.