The isolating effect of greenhouses on arthropod pests [and its significance for integrated pest management] : a case-study on Clepsis spectrana (Lepidoptera: Tortricidae)

Chapter 1: the environmental conditions in greenhouses differ in many respects from those in the open field. Both the climate and the crops are different. A free exchange between the fauna of the greenhouses and the open air is hampered by the glass walls and roofs. The isolating effect of greenhouses on arthropod pests contributes to the effectiveness of control measures, but also to the development and maintenance of pesticide resistance in greenhouses. Because of the special conditions a specific fauna exists in greenhouses, and the use of exotic predators and parasites for biological control is possible. The greenhouse environment acts as a "sieve" only allowing such species to thrive that are adapted to these special conditions. These are sometimes exotic species that cannot thrive in the open in the Dutch climate. Native species may penetrate into greenhouse cultures, but to pass the "sieve" they have to adapt to greenhouse conditions.The leaf-roller Clepsis spectrana Tr. is native in the Netherlands. It gives an example of the development of a greenhouse-adapted biotype. In Dutch greenhouses, especially on roses, it causes much damage. In heated greenhouses, where artificial illumination is not given, growth and reproduction of C. spectrana continue without diapause during winter, which is advantageous for the species in this environment, where the difference between summer and winter temperatures does not exceed a few degrees and suitable food is available all the year round.Chapter 2 deals with the morphology, bionomics, host plant range, and distribution area of C. spectrana. Chapter 3 describes the materials and methods.Chapter 4: the number of larval instars from egg hatching to pupation varied between 4 and 8 in both field and greenhouse strains. Each larval growth type had its own specific progression of head capsule width. The difference in head capsule width between the 4- and 5-instar type was already evident in the 1st instar, between the Sand 6-in
Beschrijving van het aan de omstandigheden van Nederlandse kassen aangepaste biotype van de bladroller (Clepsis spectrana) wat betreft morfologie, fenologie, reactie op daglengte, samenstelling van geslachtsferomonen en kruisbaarheid met veldpopulaties