Influence of Different Netting Structures on Codling Moth and Apple Fruit Damages in Northwest Croatia
During the vegetation season of 2015 exclusion nets were set up in IPM apple orchard in Krapina (Croatia) to test their effectiveness in preventing the attack of codling moth to apple fruits. Nets were the same in mesh size (2.4 x 4.8 mm) but different in color (white, red, yellow) in order to examine their effect on vegetative growth and quality of apples. To assess the presence of pest, weekly sampling of codling moth on pheromone traps in protected and unprotected (control) net rows was conducted. Single row netting structures resulted in a highly significant reduction of codling moth catches on pheromone traps in comparison to the unprotected control in the experimental orchard. The percentage of codling moth infested fruits during the harvest time was considerably lower, in the protected net rows in comparison with unprotected rows. The lowest percentage of damaged fruits was recorded under the red net (0.96%), followed by white net (1.04%) and yellow net (2.86%). Percentage of damaged fruits in unprotected row amounted to 11.39%. Considering the fact that the mean net efficiency amounted to almost 90%, these results confirm the effectiveness of netting structures in the protection of apple fruits from CM damages.
Exclusion netting may alter reproduction of the codling moth (Cydia pomonella) and prevent associated fruit damage to apple orchards
Insecticide‐based management programmes targeting codling moth, Cydia pomonella L. (Lepidoptera: Tortricidae: Olethreutinae), in apple orchards in southern France have incurred increasing levels of fruit injury in recent years. An alternative programme incorporating the use of exclusion netting named Alt'carpo has been developed. This study aimed at studying its efficiency and gaining more insight into its mode of action. This was achieved through laboratory and field behavioural tests and observations in a network of commercial orchards in southern France. The moths were able to lay eggs through the nets and escape from net cages in the laboratory. Male moths released in the netted rows were poorly recaptured using sexual pheromone trapping, whereas over 20% of the released males were recaptured in unprotected rows. The netting reduced fruit injury by up to 91% compared to the unprotected rows in the experimental orchard. The efficacy of this netting was even higher in commercial orchards in which fruit injury did not exceed 0.1% without any application of specific insecticide. These results lead us to assume that netting alters the reproduction of the pest, mainly by preventing it from flying over the canopy to find mates.
Cold hardiness adaptations of codling moth, cydia pomonella
The cold hardiness adaptations of natural and laboratory reared populations of the codling moth, Cydia pomonella, were examined. Hemolymph, gut, and whole body supercooling points (SCPs), 24-h LT50s, polyhydroxy alcohol concentrations, hemolymph freezing points, and hemolymph melting points were determined. Nondiapausing codling moth larvae do not have appreciable levels of ice nucleators in the hemolymph or gut. Whole body supercooling points were higher than hemolymph supercooling points. For nondiapausing larvae, LT50s were significantly higher than both the whole body and the hemolymph supercooling points, indicating the presence of chill sensitivity. As the larvae left the food source and spun a cocoon, both hemolymph and whole body SCPs decreased. Diapause destined larvae had significantly lower hemolymph SCPs than nondiapausing larvae, but whole body SCPs were not significantly different from nondiapausing larvae of the same age. The LT50s of diapause destined and diapausing larvae were significantly lower than that of nondiapausing larvae. Codling moths are freezing intolerant, with LT50s close to the average whole body supercooling point in diapause destined and diapausing larvae. The overwintering, diapausing larvae effectively supercool to avoid lethal freezing by removal of ice nucleators from the gut and body without appreciable increase of antifreeze agents such as polyols or antifreeze proteins.