Browsing by Subject "Apfelwickler"

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Modeling population dynamics and dispersion of Codling moth Cydia pomonella L. (Lepidoptera, Tortricidae)
(2009) Gharehkhani, Gholamhossein; Zebitz, Claus P. W.
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.
Prüfung von Citral als Zusatzstoff zu Pheromon zur Bekämpfung des Apfelwicklers Cydia pomonella L. (Lepidoptera, Tortricidae) und des Apfelbaumglasflüglers Synanthedon myopaeformis Borkh. (Lepidoptera, Sesiidae)
(2003) Hapke, Christine; Zebitz, Claus P. W.
In the years 1998 til 2000, a modification of the confusion technique was tested against two pest insects in apple, the Codling moth Cydia pomonella L. and the Apple clearwing Synanthedon myopaeformis Borkh. The respective pheromone was combined with the tentative monoterpene synergist Citral, and applied in the orchard at a density of 125 per hectare as recommended. Laboratory tests were conducted to characterize the effects of Citral mode on individuals of the pests. Field tests with Codling moth revealed no essential differences in the efficiency between the common confusion method with 500 pheromondispensers per hectare and the new technology with Citral (125 dispensers/ha) as expressed in numbers of male caught in pheromone traps or in percent fruit damage under low pest pressure. Both methods failed under high pest pressure. Weighing the dispensers weekly followed up the release of Citral and the pheromone. In semi-field tests in large cages (2 m  2 m  2 m) pest population density seemed to have no impact on control success. In small cages (30 cm height, 30 cm ) the copulation rate in the pheromone plot was significantly lesser than in the Citral-treated atmosphere and in the untreated control plot. Using a laboratory wind tunnel undiluted and 10-1 diluted Citral resulted in a significant decrease of the attractiveness of pheromone. After 24 hours this effect diminished. Half-life of released Citral was approximately two hours. After four hours about 100 µg/h 10-1 diluted Citral was still released into the tunnel. Electroantennogrammes of both, male and female antennae of C. pomonella showed a strong reaction to Citral. The reaction of the antennas to pheromone was strongly overlaid by Citral. In laboratory tests in a closed system, copulation of the moths could be prevented starting from a Citral concentration of 2000 mg/l. Male moths, previously exposed to Citral for 24 h, were not able to copulate with mature, unmated females. Citral-exposed females (24 h exposure time), however, were successfully mated by mature untretaed males. Any impact of Citral in concentrations up to 1,500 mg/l on oviposition could not be proven. Furthermore, first larvae of the Codling moth were not prevented to penetrate into an apple with up to 5,000 mg/l Citral. Field tests with the Apple clearwing proved significantly lesser pheromone trap catches in the Citral-treated plots than in the control plots on five alternatively six test orchards. The plots with 500 and 250 pheromone dispensers per hectare also exerted rates of confusion of up to 100 %. In a plot with 250 Citral dispensers per hectare, an effect of confusion could not be observed. Catches in lure pots showed no difference in the amount of mated or unmated females between plots. The amount of mated females in all plots was much higher than those of the unmated. The amount of fresh frass in treated and untreated plots was too small for proving a success of control. The quantitative preparation of the larvae in coincidentally selected trees on a plant showed a significant difference between the Citral-treated plot and the untreated control plot. However this difference is based only on a reduced number of larvae up to 7 mm body length. Tests with S. myopaeformis in a laboratory wind tunnel were not successful, because the attractiveness of the traps baited with pheromone were not very high. Investigating the environmental conditions for a successful copulation of S. myopaeformis the light intensity did not prove to play the major role. Temperature and wind velocity seem to possess a substantial meaning, dominating light. The copulation rate in small cages (30 cm height, 30 cm ) generally hardly reached 50 % and was very small thereby. In the laboratory moths of the apple clearwing could not be brought to copulation. Synergisation of pheromones with Citral seem to be not recommendable under practical conditions.