UVM Theses and Dissertations
Format:
Print
Author:
Izzo, Victor Michael
Dept./Program:
Plant and Soil Science
Year:
2014
Degree:
PhD
Abstract:
Seasonal changes in abiotic conditions within temperate climates require the development and/or adaptation of life history traits to synchronize invading populations within their new environments. These ecophysiological adaptations are essential for the success of expanding populations and may ultimately determine the likelihood of establishment.
Using a common agricultural pest, the Colorado potato beetle, Leptinotarsa decemlineata Say, as a model, we conducted a regional comparison of cold hardiness and overwintering success among ancestral (southern Mexico) and derived (Vermont and Kansas, USA) L. decemlineata populations. To determine if ancestral and derived beetle populations vary physiologically for cold hardiness, we compared supercooling points (SCPs) of 'three geographic populations of L. decemlineata. We also tested if ancestral and derived beetle populations differed in their overwintering behavior. Ancestral and derived populations did not express different physiological responses (Le. SCPs) to freezing temperatures. Ancestral and derived populations responded differently to the onset of winter conditions. The majority of ancestral beetles failed to initiate diapause and dug upward within experimental mesocosms. Derived populations also displayed higher overwintering survivorship when compared with ancestral populations.
We investigated the effect of plant-mediated photoperiod cues on diapause initiation within the Colorado potato beetle, Leptinotarsa decemlineata. Analyses revealed a significant effect of short-day (8:16 L:D and 10:14 L:D) photoperiod growth regimens on both nitrogen content in potato leaves and diapause initiation within L. decemlineata. Potato plants grown under short day conditions displayed significantly higher levels of leaf nitrogen compared with long day treated plants. Over 65% of beetles feeding upon short-day treated plants initiated diapause compared with <20% of beetles placed upon long-day treated plants.
To test for regional differences in host preference and performance among both ancestral and derived L. decemlineata populations, we performed choice and no-choice experiments using individual beetle~ throughout the North American assemblage of the beetle. Vermont pest populations exhibited a markedly greater host breadth whern compared with all other regional populations. Beetles from Vermont performed equally well on all host types and failed to display any significant preference for any particular host type. The expanded diet breadth and increased performance on all host types underscores the virulence of the pest form of the beetle.
The colonization and establishment of L. decemlineata within northern agroecosystems involved the development of various ecophysiological adaptations. It is evident that research exploring the interaction of the ecological factors and evolutionary processes is necessary to fully realize the dynamics of biological invasions.
Using a common agricultural pest, the Colorado potato beetle, Leptinotarsa decemlineata Say, as a model, we conducted a regional comparison of cold hardiness and overwintering success among ancestral (southern Mexico) and derived (Vermont and Kansas, USA) L. decemlineata populations. To determine if ancestral and derived beetle populations vary physiologically for cold hardiness, we compared supercooling points (SCPs) of 'three geographic populations of L. decemlineata. We also tested if ancestral and derived beetle populations differed in their overwintering behavior. Ancestral and derived populations did not express different physiological responses (Le. SCPs) to freezing temperatures. Ancestral and derived populations responded differently to the onset of winter conditions. The majority of ancestral beetles failed to initiate diapause and dug upward within experimental mesocosms. Derived populations also displayed higher overwintering survivorship when compared with ancestral populations.
We investigated the effect of plant-mediated photoperiod cues on diapause initiation within the Colorado potato beetle, Leptinotarsa decemlineata. Analyses revealed a significant effect of short-day (8:16 L:D and 10:14 L:D) photoperiod growth regimens on both nitrogen content in potato leaves and diapause initiation within L. decemlineata. Potato plants grown under short day conditions displayed significantly higher levels of leaf nitrogen compared with long day treated plants. Over 65% of beetles feeding upon short-day treated plants initiated diapause compared with <20% of beetles placed upon long-day treated plants.
To test for regional differences in host preference and performance among both ancestral and derived L. decemlineata populations, we performed choice and no-choice experiments using individual beetle~ throughout the North American assemblage of the beetle. Vermont pest populations exhibited a markedly greater host breadth whern compared with all other regional populations. Beetles from Vermont performed equally well on all host types and failed to display any significant preference for any particular host type. The expanded diet breadth and increased performance on all host types underscores the virulence of the pest form of the beetle.
The colonization and establishment of L. decemlineata within northern agroecosystems involved the development of various ecophysiological adaptations. It is evident that research exploring the interaction of the ecological factors and evolutionary processes is necessary to fully realize the dynamics of biological invasions.