Evaluation of Franklinothrips vespiformis (Crawford) (Thysanoptera: Aeolothripidae) as a natural enemy of glasshouse pests
Author(s)
Larentzaki, Eleni
Type
Thesis
Abstract
Characteristics of Franklinothrips vespiformis (Crawford) (Thysanoptera: Aeolothripidae), a predatory thrips, were studied in order to aid its assessment as a potential biocontrol agent of glasshouse pests.
The effect or constant temperatures on preimaginal development and pre-oviposition of F. vespiformis reared on irradiated Ephestia kuehnie!la eggs was studied. About 294 degreedays above a threshold temperature of 12.3°C were required for F. vespiformis to complete development from egg to adult eclosion. Franklinothrips vespiformis intrinsic rate of increase (") was 0.16 allowing successful mass rearing and release in biocontrol programmes. Developmental times and reproductive potential on Heliothrips haemorrhoidalis (Bouche) and Tetranychus urticae Koch diets were significantly different and the spider mite diet was inadequate lo support adult reproduction. To facilitate short-term storage for the production and release or F. vespiformis, lif'c-history consequences of exposing eggs and adults to moderately low temperatures were evaluated. Temperatures above 7°C offered longer storage periods for adults without significantly affecting oviposition rates and fertility of stored adults. Low temperature and storage period affected egg viability and subsequent development of pre-imaginal stages. No eggs hatched after a 20-day period of storage at 5.5 and 7.0°C, whereas 12.5°C was suitable. Overwintering and establishment potential of F. vespiformis in the U.K were studied based on its cold tolerance. Larval stages survived longer than adults at -5, 0 and 5°C. Cold stress decreased the number of reproductive females and affected the number or viable eggs, reducing the establishment potential of the predator. Low availability and poor quality or rood and high densities increased larval cannibalistic behaviour whereas starved adults were prone to egg cannibalism of conspesific eggs. Oviposition site deprivation and starvation affected F. vespiformis adult female egg load and the oviposition behaviour of the predatory thrips was significantly affected by the presence of self-and conspecific eggs. Franklinothrips vespiformis appears a promising biocontrol agent for use in U.K. glasshouses with low risk of establishment and non-target effects.
The effect or constant temperatures on preimaginal development and pre-oviposition of F. vespiformis reared on irradiated Ephestia kuehnie!la eggs was studied. About 294 degreedays above a threshold temperature of 12.3°C were required for F. vespiformis to complete development from egg to adult eclosion. Franklinothrips vespiformis intrinsic rate of increase (") was 0.16 allowing successful mass rearing and release in biocontrol programmes. Developmental times and reproductive potential on Heliothrips haemorrhoidalis (Bouche) and Tetranychus urticae Koch diets were significantly different and the spider mite diet was inadequate lo support adult reproduction. To facilitate short-term storage for the production and release or F. vespiformis, lif'c-history consequences of exposing eggs and adults to moderately low temperatures were evaluated. Temperatures above 7°C offered longer storage periods for adults without significantly affecting oviposition rates and fertility of stored adults. Low temperature and storage period affected egg viability and subsequent development of pre-imaginal stages. No eggs hatched after a 20-day period of storage at 5.5 and 7.0°C, whereas 12.5°C was suitable. Overwintering and establishment potential of F. vespiformis in the U.K were studied based on its cold tolerance. Larval stages survived longer than adults at -5, 0 and 5°C. Cold stress decreased the number of reproductive females and affected the number or viable eggs, reducing the establishment potential of the predator. Low availability and poor quality or rood and high densities increased larval cannibalistic behaviour whereas starved adults were prone to egg cannibalism of conspesific eggs. Oviposition site deprivation and starvation affected F. vespiformis adult female egg load and the oviposition behaviour of the predatory thrips was significantly affected by the presence of self-and conspecific eggs. Franklinothrips vespiformis appears a promising biocontrol agent for use in U.K. glasshouses with low risk of establishment and non-target effects.
Version
Open Access
Date Awarded
2004
Advisor
Copland, Dr. M.I.W,
Powell, Dr. Glen
Sponsor
Greek State Scholarship Foundation (I.K.Y.)
Publisher Department
Department of Life Sciences
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)