Browsing by Subject "Cydia pomonella"

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Impact of plastic rain shields and exclusion netting on pest dynamics and implications for pesticide use in apples
(2025) Bischoff, Robert; Piepho, Hans-Peter; Scheer, Christian; Petschenka, Georg
Apple production is among the most pesticide-intensive cultures. Recently, plastic rain shields and pest exclusion netting have emerged as potential measures to reduce the heavy reliance on chemical pesticides in apple, due to their inhibitory effect on pathogen and pest infestations. In a field trial, we compared yields, pest, and pathogen abundance in an orchard consisting of four plots, where two plots were covered with anti-hail net covers, one with plastic rain shields only, and one with plastic rain shields and exclusion netting. Pests and pathogens were assessed visually, and beating tray samples were collected to compare overall arthropod diversity between plots. We observed virtually no scab infections in both plastic rain shield plots, despite a more than 70% reduction of fungicides applied, when compared to anti-hail plots. Although no codling moth insecticides were sprayed in the plot with exclusion netting we found significantly reduced damage here, when compared to the anti-hail plots. However, likely due to microclimatic changes, we observed an increase of powdery mildew, woolly apple aphids, and spider mites under plastic rain shields. Modeling of metabolic rates of arthropod herbivores and predators revealed that there is an increased potential of herbivory under plastic rain shields. However, in terms of plant protection, the net effect of plastic rain shields and exclusion netting was a substantial reduction in chemical pesticide use, demonstrating that they represent a promising approach to minimize the use of chemical pesticides in apple production.
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.