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.
SPIDER COMMUNITIES AFFECTED BY EXCLUSION NETS
Spiders are one of the most abundant natural enemies in apple orchards and have an important role in the biological control of harmful arthropods. Recently, coloured shade nets were introduced into management practices to improve the utilization of solar radiation by fruit trees and to exclude pest species. While the coloured netting in apple orchards had a positive effect on fruits, the secondary aim of our research was to analyse the influence the nets had on spider diversity and species composition. In this study we sampled the ground dwelling spider assemblage by pitfall trapping and identified spiders to species. Traps were placed under trees covered by four types of exclusion photo selective nets and uncovered (control) trees in an untreated experimental plot of an apple orchard. In total 456 individuals belonging to 13 families and 26 species of spiders were collected. Two wolf spider (Araneae, Lycosidae) species dominated the assemblages; Trochosa robusta (Simon, 1876) and Hogna radiata (Latreille, 1819) comprised 45% of the total adult catch. Spider abundance showed a declining trend over season in all treatments. Most importantly, there was no difference either between the abundance, species richness or the species composition of spiders in the treatments. The study strongly indicates that insect exclusion nets have no negative effect on ground dwelling spider assemblages.
Overwintering of Codling Moth (Lepidoptera: Tortricidae) Larvae in Apple Harvest Bins and Subsequent Moth Emergence
Abstract Codling moths, Cydia pomonella (L.), have long been suspected of emerging from stacks of harvest bins in the spring and causing damage to nearby apple and pear orchards. With increased use of mating disruption for codling moth control, outside sources of infestation have become more of a concern for growers using pheromone based mating disruption systems. Studies were designed to provide information on bins as a source of codling moth and the pattern of codling moth emergence from stacks of bins. In these studies, codling moth larvae colonized wood harvest bins at a much higher frequency than harvest bins made of injection molded plastic (189 moths emerged from wood compared with five from plastic). There was no statistical difference in the number of moths infesting bins that had been filled with infested fruit compared with bins left empty at harvest. This suggests that codling moth enter the bins during the time that the bins are in the orchard before harvest. Emergence of laboratory reared adult codling moth from wood bins placed in stacks was found to be prolonged compared with field populations. Temperature differences within the bin stacks accounted for this attenuated emergence pattern. Covering bin stacks with clear plastic accelerated codling moth development in the upper levels of the stack. Codling moth emergence patterns from plastic-covered stacks more closely coincided with male flight in field populations. This information could be important in developing a technique for neutralizing codling moth-infested bins, and in understanding how infested bins may influence pest management in fruit orchards that are located near bin piles. Implications for control of codling moth in conventional orchards and in those using mating disruption as the principal component of an integrated pest management system include increased numbers of treatments directed at areas affected by infested bins.