Researches On The Population Spatial Patterns, Prediction And Forecast And Control Techniques Of Pseudorobitis Gibbus Redtenbacher (Coleoptera: Apionidae)

In the paper, we investigated the spatial pattern, prediction and forecast ofPseudorobitis gibbus Redtenbacher from the point of ecology and prevention and treatment.We used various methods, such as the indoor toxicities, field investigations, field effect andso on, to study the characteristics of spatial pattern, control et al. of P. gibbus. Throughanalyzing the results the prediction and forecast of the pest are summarized. And the resultare as follow:Through the field survey, we calculate the adults’population aggregation indices byaggregation index methods. And the results showed that the spatial pattern of the adultsbelonged to aggregated distribution, the east of the tree distribute a bit more insect, then thesouth, followed by west, and the north is the least. The vertical distribution of the adultsmainly at the top half of Lagerstroemia indica, more higher more aggregated. And thepopulation’s aggregation reason arose from its some bionomics and behaviors, maybe alsorelate to the environmental factors.The spatial pattern of Pseudorobitis gibbus adults on Lagerstroemia indica was alsoanalyzed by using the geostatistics. And the results showed that the best fitting models for thefive different sampling data in June4, June16, June29, July25and August22wereGaussian, Gaussian, Linear, Gaussian and Linear models, respectively, but random models inJuly12and August7. All the results showed that the spatial distribution of the pest wasaggregated on the whole, and there existed a spatial correlation in the adult population. Thespatial correlation ranges of adults in different dates varied from1.68m to9.79m.Through the field phenological periods observation of different plants and the fieldsurvey of the population, the prediction and forecast of P. gibbus was summarized. The adultbeginning emergence period synchronized with full-bloom stage of Melia azedarach andWeigela florida cv. Red Prince, peaked in the full bloom of Hibiscus syriacus, and the lateperiod of occurence of the adult was at the early flowering of Cottonrose hibiscus. The eggemergence period was in the bloom period of Rudbeckia hirta, the fastigium was in the fullbloom of Koelreuteria paniculata, Physostegia virginiana and H. syriacus, and the telophasewas in the late period of bloom of H. syriacus. The larva beginning emergence period was inthe period of bloom of Sophora japonica and Canna indica, peaked in the full bloom ofBougainvillea spectabilis and Camellia sasanqua, and the late period was in full bloom of Punica granatum. The pupa beginning emergence period was in the end-flower stage ofMalus halliana, peaked in the full bloom of Kolkwitzia amabilis Graebn and Medicago sativacomes to bloom, and the late period was in full bloom of Ligustrum lucidum and Albiziajulibrissin.We set16,21,25,28and30℃five temperatures to determine the developmentalthreshold of the pupae of P. gibbus on different constant temperatures. The result show that inthe temperatures setted, the developmental threshold of the pupae and the temperature’s risingwas inverse ratio. The effective accumulated temperature for the pupae of P. gibbus were8.00℃and114.70degree, respectively, by using of the least squares method. According tomonthly mean temperature of the soil surface from2009to2011in Tai’an, and by using theeffective accumulated temperature formula and the confidence interval, we predicted that theoverwintering adult emergence would firstly occur from10th to21st of May in the field.Compared with the practical emergence date in2011, the forecasting result was proved to bemore accurate.On the basis of the population dynamics of adult P. gibbus, the adult number wasgradually increase with its eclosion from the end of May to the mid-June. While the adultnumber in the early to mid-July was declined sharply, then rapid increase to the early August,followed by tapering, until the early September rise a little then taper off. The fastigium of theP. gibbus is from the mid to end-June to the early August, so there should be grasp the time toprevent the pest widespread damage and spread.Eight insecticides were chosen to research the indoor toxicities of P. gibbus by themethod of immersion. According to the indoor toxicities of8pesticides, we selected3highertoxicity pesticides to conduct the field efficacy. The result showed that10%imidacloprid EC,20%sumicidin and1%Emamectin benzoate had better indoor toxicities to against P. gibbus,and their LC50were1.52,2.87and1.16mg/L at12h; and0.593,3.513and2.524mg/L at24h;0.407,6.094and5.985mg/L at48h;10.68,4.286and5.441mg/L at72h, respectively. Andthe three pesticides also had better field efficacy, and their corrected mortalities were morethan95%, after10days of the field control of the P. gibbus.The behavior responses of the adults of P. gibbus to sex pheromone was determined byY-shaped olfaction instrument. The results showed that female pheromone could attract themale adult, and the highest response to30females. Also the male pheromone could attract the female, the highest response to20males. And further more, female pheromone’s attractionsto the male as a whole were lower than the male pheromone to the female. The attractions ofmultiplicate pheromone to the female or the male were far below the single pheromone.These preliminary results could serve as the basis to isolate and identify the attractivecompounds, which may provide useful information of studying new methods to monitoringcontrolling the adults of P. gibbus.