RT Dissertation/Thesis
T1 Modeling population dynamics and dispersion of Codling moth Cydia pomonella L. (Lepidoptera, Tortricidae)
A1 Gharehkhani,Gholamhossein
WP 2010/04/22
AB The study of insect dispersal plays an essential role in estimating the spread of damage caused by a newly invaded pest or the spatial distribution of an insect during the active period in growing season. Moreover concerning dispersal, quantitative information performs a crucial role in the evaluation and implementation of pest control. Since rearing clean and healthy insects in sufficient numbers is the most important prerequisite for many basic research programs and for developing pest control strategies, mass rearing of the Codling moth on the artificial diet carried out as the first step at optimum conditions. With regard to the fundamental function of feeding and  pre-releasing handling on insect biological attributes, we intended to evaluate the individual marking influence on longevity of Codling moths in the next step. For this purpose, one day old adult male and female moths were kept three and five minutes at -20°C to make them motionless, then immediately marked  individually with felt tip pens and coded by the different colors, maintained under optimum condition and checked daily for 13 days.
The proposed linear model accounted for 89 % of the variations. Numbing and marking process influenced of the moths longevity regardless of their sex while the duration of the anesthetize does not affect the survival of moths meaningfully. Regarding the obstacles associated with egg and pupa storage of Codling moth, we examined the possibility of adult moth?s storage in low temperature in order to evaluate its effect on longevity of moths. Adult 12-24 h old male and female moths were treated separately and maintained in 4 ◦C and (0:24 h, L:D) photoperiod during the entire adult life. The survival rate  evaluated with two days interval throughout 27 days. The effects of day and treatment were significant. It seems that the female moths tolerate the cold condition better and further than the male moths and live longer. Additionally the proposed models accounted for 71 % and 57 % of the variations for male and females respectively as verified more affection and debility of the males by the storage condition. Disadvantages of individual marking led us to test the mass marking and it?s influence on the survival of the moths. One-day-old moths were marked with fluorescent powder. Mortality of the males and females recorded daily for a 20 days period. Results indicated that the effects of the sex, the replications and interaction of them were significant as well as the effect of the day. The model accounted for 96 % of the variations. This study indicated that male and female moths were influenced by the fluorescent powder. Findings of this study may facilitate the improvement of mark-release experiment results and interpretation more precisely in particular for dispersal studies. In the field experiments, firstly trade off trap structure in assessing the horizontal and vertical distribution of Codling moth carried out as well as outward and inward dispersal. Three different types of the traps including Delta pheromone traps, Delta Pear ester trap and Cylinder shape Pear ester traps were used in the research station of the Hohenheim University. Ninety six traps were suspended in eight compass directions in order of four traps per direction, at three heights in random arrangement in outward dispersal. In inward dispersal study the traps arrangement and number was the same but dissimilarly the  releasing site was from borders of directions SW, NW, W, E, and SE. The traps were checked daily and followed nine days after release. Results demonstrated no
significant differences between three types of traps in attracting the marked and feral females ?Fn?. Meanwhile significant dissimilarity in marked and feral male ?Mn? catches were traced. Reaction of the moths to the traps elevation was not similar in the vertical distribution study. whereas marked female moths exhibited significant differences to different heights, marked and feral male and ?Fn? moths revealed no difference reaction to traps in different heights.In horizontal distribution study marked female moths ?Fr? exhibited significant differences. It is revealed that dominant directions for marked and feral moths were different. Concerning inward distribution, both marked male ?Mr? and female demonstrated significant differences in their direction and distances. In regard to this findings and priceless and effortless manufacturing of the Cylinder traps, utilization of this trap in mark-release-recapture studies of female and male Codling moths is recommended. Effect of apple cultivar on pheromone and Pear ester trap efficiency studied as the next tread. In this experiment 32 Delta pheromone traps and 32 Cylinder-shape Pear ester traps impartially mounted on different varieties of apple trees. Artificially reared and marked 24 to 26 h old moths were released at 1 m height from a central point. Among the simple effects the most important explanatory variable for the response variables ?Mn? and ?Fn? moths was sampling dates of moths, while the variety and distance from the releasing point for ?Mn? and the variety and trap height for ?Fn? were the second and third influential variables respectively. Moreover among the nested effects the interaction of distance-height-variety was the most influential one for ?Mn? likewise the interactions of date, release point, direction and trap height with the variety were the most influential for ?Fn?. For the ?Mr? and ?Fr? moths releasing date was the most important influential variable, while the trap type and variety for ?Mr? and variety and trap height for the ?Fr? were the second and third influential variables respectively. Current study revealed that dispersal of the feral and marked-released male and female Codling moths influenced by host cultivars distinctly and decidedly. Meanwhile, quantifying these relationships and propose distinct model for marked and feral male and female moths are the exclusive characteristics of present findings.
The next stage of present study related to study of climatic factors on dispersal of Codling moth. In this study, Hohenheim station climatic data were used. Several climatic elements including temperature, relative humidity, precipitation, wind speed in two different heights (2.5 m and 10 m), Day Degree, twilight temperature, wind speed and precipitation were utilized in the analysis. Diversity and high number of variables led us to use AIC method for  selecting of appropriate regressors and fitted model. The main regressors that inföuenced the ?Fr? were flight height, ageing, twilight wind speed (2.5 m heights) and precipitation. For the ?Mr? the same regressors plus the
distance from the releasing point were the best subset. In the case of the feral moths the flight height, relative humidity, Day Degree, twilight temperature and wind speed were the best subset regressors. Comprehensively we concluded that present study provides new knowledge in basic as well as in applied science. Twilight temperature, rainfall, wind speed and Day Degree impress the distribution of the moths in a superior way than the circadian weather data. This knowledge could mitigate confusion which arises from observations of erratic flight patterns and could lead to fewer treatment decision errors in the future. Also may accelerate and strengthen forecasting programs of this key pest as well as the related management tactics.
The combination of mark-release-recapture and diffusion models have been shown to be effective for measuring insect dispersal. We attempted to measure the Codling moth dispersal using traps placed at different distances and heights. Diffusion coefficient calculated for horizontal and vertical dispersal of male and female moths distinctly using direct and indirect methods and resulting models were compared. We fitted the non-linear regression using the iterative process and estimating the parameters accuracy were tested according to the default asymptotic 95 % confidence intervals calculation in non-linear regression. Considering the overall models, suitability of three factors
fitted models was more convincible than that of two factors model particularly for male moths.
Meanwhile we found great difference in the diffusion coeffcient of direct and indirect methods. Regardless of the model type, the R2 was relatively high in our experiments which evaluate how well the model fits data. We have shown that the diffusion model leads to powerful techniques for the analysis of dispersal data at least for one economically important insect. In conclusion, the
present study provides an estimate of population spread by Codling moth using estimated rates of reproduction and dispersal, quantified the association between various key factors and Codling moth movement for the first time using the diffusion model. By including additional parameter to the diffusion model the predictive explanatory potential of this method was improved for dispersal
studies at least for a cosmopolitan and critical insect.
K1 Modellierung
K1 Populationsdynamik
K1  Verbreitung 
K1 Apfelwickler
PP Hohenheim
PB Kommunikations-, Informations- und Medienzentrum der Universität Hohenheim
UL http://opus.uni-hohenheim.de/volltexte/2010/437