The Population Dynamics And Spatial Distribution Of Lithocolletis Ringoniella And Effect Of Low Temperature On The Overwintering Pupae And Pupa Postnatal Development

【Objective】The aim of this experiment was to investigate the population dynamics andspatial distribution of Lithocolletis ringoniella in apple orchard and the aim of thisexperiment was to examine the effect of low temperature on the overwintering pupae andpupa postnatal development of Lithocolletis ringoniella, and to further reveal activity laws.【Method】In apple orchards in Yangling, Shaanxi, China, five point sampling methodwas used to find target trees. One tree was selected in each point, and in one tree, thecanopy was divided into20resource units, where50pieces of leaves damaged byLithocolletis ringoniella were randomly selected to record the number of Lithocolletisringoniella. Pupae and leaves with pupae of L. ringoniella were stored and compared undernatural outdoor and indoor (i.e., constant low temperature of4±0.5℃) conditions,respectively. The pupae and leaves with pupae were sampled10times (i.e.,15,30,45,60,75,90,105,120,135, and150d after the onset of the low temperature treatment) during theoverwintering period. Five biological parameters of the moths (i.e., developmental durationafter storage before adult emergence, the emergence rate, abnormal emergence rate, andlongevity and sex ratio of the adults) were examined under25℃，70%，14L:10D condition inthe study.【Result】The overwintering pupae of Lithocolletis ringoniella number change wasdivided into three stages, rise period (October26to November23), stable phase (November23to next year January4) and the descent phase (January4to April25). The survival ofoverwintering pupae was most greatly affected by the rise of natural temperature in spring.Different low temperature treatment had different influence on the development duration, forthe outdoor condition, the duration of Lithocolletis ringoniella pupae was extended firstly andthen shorten while the storage time increasing. In refrigerated condition, the duration of pupaeextended while the refrigerated time increased. The eclosion rate and abnormal eclosion rateexpressed same under different low temperature, as long as the time of low temperatureincreased, the eclosion rate decreased and abnormal eclosion rate increased. From75stored days to120stored days, the abnormal eclosion rate was: leaves within pupa in outdoor>pupa in outdoor>refrigerated leaves within pupa> refrigerated pupa. In the same treatment,the longevity of the male was shorter than the longevity of the female. And after refrigeratedstorage of the pupae in45days, both male and female had longest mean longevities,(13.67±2.02) d and (6.67±1.45)d, respectively. Sex ratio increased as the refrigerated daysincreased. The number of the first generation and overwintering generation were big and tidy,so it was the better time to control the Lithocolletis ringoniella. The spatial distributionpattern of5generations of Lithocolletis ringoniella was aggregated, and the basic componentof the distribution was individual colony, and the aggregation intensity was increased withpopulation density. By using the Bray-Curtis Measure coefficient to calculate the similarityindex, the5generations of Lithocolletis ringoniella constituted population sub-layer structureat different levels.【Conclusion】the occurred number of5generations of Lithocolletis ringoniella and thenumber distribution at different orientation were different. Proper prevention and cure time isthe effective way to control Lithocolletis ringoniella. Low temperature treatment hassignificantly affected the pupa development before the adult emergence. The leaves withpupae were greatly affected by the rise of natural temperature in the later portion of outdoorsin terms of the development duration after the low-temperature storage treatment. The adulteclosion rate and abnormal eclosion rate indicated that the leaves with pupae can be stored fora period of low temperature (60d) under outdoor conditions. In contrast, when the leaves withpupae were stored under indoor conditions for120d at4℃constant temperature, theeclosion rate was greater than58%, the abnormal eclosion rate was lower than20%, and thelongevity and sex ratio of adults was the same as the control.