Doctor of Philosophy / Department of Entomology / Raymond A. Cloyd / Western flower thrips, Frankliniella occidentalis, is one of the most destructive insect pests in greenhouse production systems due to direct and indirect plant damage resulting in substantial economic losses. In addition, western flower thrips has developed resistance to many insecticides. Therefore, alternative plant protection strategies are warranted, such as augmentative biological control. This research was designed to evaluate 1) the effect of different absolute numbers of predator (rove beetle, Dalotia coriaria) and prey (western flower thrips) on predation efficacy of rove beetle under laboratory conditions; 2) the effect of western flower thrips pupal stage, predator-prey ratio, predator-prey number, and searchable area on predation efficacy of rove beetle in the laboratory; and 3) the effectiveness and cost of integrating the entomopathogenic fungus, Beauveria bassiana, and the rove beetle, D. coriaria, in suppressing western flower thrips populations under greenhouse conditions. Three laboratory experiments were conducted to assess predation efficacy of rove beetle adults on three western flower thrips pupal stages [prepupa, pupa, and prepupa-pupa combination (50%:50%)]. In each experiment, there were six numbers (0, 1, 2, 3, 4, and 5) of rove beetle adults and four initial numbers (15, 20, 25, and 30) of one western flower thrips pupal stage. This treatment configuration allowed for assessing the effect of predator-prey ratios (1:5, 1:10, and 1:15), accounting for different initial prey numbers, on predation efficacy of the rove beetle. Overall, for each pupal stage, the estimated mean probability of western flower thrips adults captured on yellow sticky cards decreased as the number of rove beetle adults released increased from 1 to 3, although the effect of additional rove beetle adult releases was not apparent. Furthermore, across the pupal stages considered in this study, in general, there was no evidence of any differences due to predator-prey ratios or initial prey numbers within each predator-prey ratio. Two laboratory experiments were conducted to assess the effects of western flower thrips pupal stage, predator-prey ratio, predator-prey number, and searchable area on predation efficacy of rove beetle adults. In experiment 1, there were two western flower thrips pupal stages (prepupa and pupa), three predator-prey ratios (rove beetle:western flower thrips—1:5, 1:10, and 1:15), and three predator-prey numbers (2, 3, and 4 times). Experiment 2 evaluated the latter two factors in combination with searchable area defined by container sizes [15.2 cm (1,834.82 cm3) and 11.5 cm (701.79 cm3)]. The estimated mean probability of western flower thrips adults captured on yellow sticky cards was significantly higher for the 1:5 predator-prey ratio [61.1% (48.5-72.4%)] than 1:10 [39% (28.1-51.2%)] and 1:15 predator-prey ratio [34.7% (24.7-46.3%)]. The estimated mean probability of western flower thrips adults captured on yellow sticky cards for 2 times the predator-prey number [57% (44.3-68.8%)] was significantly higher than 3 [37.2% (26.6-49.3%)] and 4 [40.6% (30-52.3%)] times the predator-prey number. In addition, a significantly higher estimated mean probability of western flower thrips adults was captured on the yellow sticky cards in the 15.2 cm than 11.5 cm containers. Two greenhouse experiments were conducted that evaluated five treatments: combination of insecticides (spinosad, pyridalyl, chlorfenapyr, and abamectin), B. bassiana, D. coriaria, B. bassiana and D. coriaria combination, and a water control. Overall, the estimated mean number of western flower thrips adults captured on yellow sticky cards was significantly lower for the insecticide treatment (mean range: 0, 46) than for the B. bassiana and D. coriaria combination (mean range: 0.3, 105.1) over eight weeks. There were no significant differences in final foliage quality of chrysanthemum, Dendranthema x grandiflorum, plants among the five treatments in experiment 1, but there were significant differences in experiment 2. However, in experiment 2, the chrysanthemum plants across all treatments were not marketable due to substantial feeding damage by western flower thrips. The cost of the insecticide treatment was nearly twice that of the B. bassiana and D. coriaria combination ($963.50 vs. $495.67) and was over twice that of the B. bassiana only treatment ($963.50 vs. $417.04). The D. coriaria only treatment was the least expensive at $78.63. The results of the research provide insight into the predatory behavior of D. coriaria on western flower thrips pupal stages, which may have practical implications for greenhouse production systems. However, predation efficacy of rove beetle adults on western flower thrips is influenced by predator-prey ratio, predator-prey number, and searchable area. Finally, greenhouse producers must initiate insecticide applications or release rove beetle adults early in the production cycle when western flower thrips populations are low to minimize plant damage.

I investigated the effects ofhabitat loss and subsequent restoration on invertebrate community structure and ecosystem functioning in a mined peat bog in the North Island, New Zealand. In an experimental trial, the impact of peat bog habitat loss and isolation on the invertebrate community associated with Sporadanthus ferrugineus (Restionaceae) was investigated. Potted S. ferrugineus plants were exposed to invertebrates at various distances up to 800 m from an intact habitat (the presumed source population) over 18 weeks. Invertebrates rapidly colonised the experimental plants, with all major Orders and trophic groups present on Sc ferrugineus within 6 weeks. However. with increasing distance away from the undisturbed habitat, there was a significant decrease in total richness and abundance of invertebrates associated with the potted plants. Additional tests showed that even a moderate degree of isolation (i.e. greater than 400 m) from the intact habitat caused an almost complete failure of 'Batrachedra' sp. to colonise its host plant, at least in the short-term, The density of eggs and larvae, and the average larval size of 'Batrachedra' sp. (Lepidoptera: Coleophoridae) colonising Si ferrugineus plants, as well as the proportion of Si ferrugineus stems damaged by 'Batrachedra' sp. herbivory, all decreased logarithmically with increasing distance from the intact habitat. Surprisingly, though, the rate of recovery of the insect-plant interaction following experimental habitat restoration was remarkably rapid (i.e. between 3Y2 and 6 years). After just 6 years there was no significant difference in insect-plant interactions between the intact peat bog sites and any of the experimentally restored sites up to 800 m away. These results suggest that the degree of isolation from undisturbed habitat has a major impact on the rate and patterns of restoration recovery in the invertebrate community and that some insect-plant interactions can recover rapidly from habitat loss with restoration management. Restoration of mined peat bogs in northern New Zealand is initiated by establishing a native vegetation cover to minimize further peat degradation. The effects of various restoration techniques on litter decomposition, microbial community activity and beetle community composition were investigated within an experimental trial, These treatments included translocation ofpeat bog habitat (direct transfer of islands), milled peat islands with no seed and milled peat islands with seed, and were compared with an unrestored mined site and an undisturbed peat bog. In all the response variables measured, the undisturbed peat bog sites had significantly higher decomposition rates and microbial respiration rates, and significantly higher abundance and species richness of beetles than any of the restoration treatments. Inaddition, the technique used to restore mined peatlands had a significant effect on the beetle community composition and litter decomposition processes. Despite a rapid initial change in the beetle community following habitat translocation, the direct transfer islands were still the most similar in beetle species composition to the undisturbed peat bog. Microbial activity and decomposition rates were higher in the direct transfer and mined peat surface after 6 months. However, even after 12 months, decomposition rates in the restored habitats were still far from reaching the levels recorded in the undisturbed peat bog. The results suggest that beetle community structure and ecosystem processes such as decomposition and microbial activity rates may be able to recover faster with certain restoration techniques, such as direct transfer of intact habitat islands. Subsequently, I examined long-term beetle community reassembly on islands that had been restored by creating raised areas ofprocessed peat with the addition of Leptospermum scoparium seed. Monitoring of different-aged restored islands representing the full range of restoration ages (up to 6 years) available at the peat mine, indicated that as the peat islands became older and the vegetation structure became more complex, the abundance, species richness and composition of the beetle community became increasingly similar to the community in the undisturbed peat bog. Despite this, distinct differences between the intact peat bog and older restored peat islands still persisted, even after 6 years, particularly at an individual species level. However, it is predicted that within 12 years the restored peat islands will share 100% ofbeetle species in common with the undisturbed peat bog. Taken together, these results indicate that restoration is effective in initiating the recovery of beetle assemblages and ecosystem processes (such as litter decomposition and microbial community activity) in cut-over peat bogs. However, it is estimated to take at least 12 years before pre-mining communities and functions are attained, and ongoing monitoring to develop an understanding of the longer-term dynamics of such ecosystems and processes is clearly required.

I investigated the effects ofhabitat loss and subsequent restoration on invertebrate community structure and ecosystem functioning in a mined peat bog in the North Island, New Zealand. In an experimental trial, the impact of peat bog habitat loss and isolation on the invertebrate community associated with Sporadanthus ferrugineus (Restionaceae) was investigated. Potted S. ferrugineus plants were exposed to invertebrates at various distances up to 800 m from an intact habitat (the presumed source population) over 18 weeks. Invertebrates rapidly colonised the experimental plants, with all major Orders and trophic groups present on Sc ferrugineus within 6 weeks. However. with increasing distance away from the undisturbed habitat, there was a significant decrease in total richness and abundance of invertebrates associated with the potted plants. Additional tests showed that even a moderate degree of isolation (i.e. greater than 400 m) from the intact habitat caused an almost complete failure of 'Batrachedra' sp. to colonise its host plant, at least in the short-term, The density of eggs and larvae, and the average larval size of 'Batrachedra' sp. (Lepidoptera: Coleophoridae) colonising Si ferrugineus plants, as well as the proportion of Si ferrugineus stems damaged by 'Batrachedra' sp. herbivory, all decreased logarithmically with increasing distance from the intact habitat. Surprisingly, though, the rate of recovery of the insect-plant interaction following experimental habitat restoration was remarkably rapid (i.e. between 3Y2 and 6 years). After just 6 years there was no significant difference in insect-plant interactions between the intact peat bog sites and any of the experimentally restored sites up to 800 m away. These results suggest that the degree of isolation from undisturbed habitat has a major impact on the rate and patterns of restoration recovery in the invertebrate community and that some insect-plant interactions can recover rapidly from habitat loss with restoration management. Restoration of mined peat bogs in northern New Zealand is initiated by establishing a native vegetation cover to minimize further peat degradation. The effects of various restoration techniques on litter decomposition, microbial community activity and beetle community composition were investigated within an experimental trial, These treatments included translocation ofpeat bog habitat (direct transfer of islands), milled peat islands with no seed and milled peat islands with seed, and were compared with an unrestored mined site and an undisturbed peat bog. In all the response variables measured, the undisturbed peat bog sites had significantly higher decomposition rates and microbial respiration rates, and significantly higher abundance and species richness of beetles than any of the restoration treatments. Inaddition, the technique used to restore mined peatlands had a significant effect on the beetle community composition and litter decomposition processes. Despite a rapid initial change in the beetle community following habitat translocation, the direct transfer islands were still the most similar in beetle species composition to the undisturbed peat bog. Microbial activity and decomposition rates were higher in the direct transfer and mined peat surface after 6 months. However, even after 12 months, decomposition rates in the restored habitats were still far from reaching the levels recorded in the undisturbed peat bog. The results suggest that beetle community structure and ecosystem processes such as decomposition and microbial activity rates may be able to recover faster with certain restoration techniques, such as direct transfer of intact habitat islands. Subsequently, I examined long-term beetle community reassembly on islands that had been restored by creating raised areas ofprocessed peat with the addition of Leptospermum scoparium seed. Monitoring of different-aged restored islands representing the full range of restoration ages (up to 6 years) available at the peat mine, indicated that as the peat islands became older and the vegetation structure became more complex, the abundance, species richness and composition of the beetle community became increasingly similar to the community in the undisturbed peat bog. Despite this, distinct differences between the intact peat bog and older restored peat islands still persisted, even after 6 years, particularly at an individual species level. However, it is predicted that within 12 years the restored peat islands will share 100% ofbeetle species in common with the undisturbed peat bog. Taken together, these results indicate that restoration is effective in initiating the recovery of beetle assemblages and ecosystem processes (such as litter decomposition and microbial community activity) in cut-over peat bogs. However, it is estimated to take at least 12 years before pre-mining communities and functions are attained, and ongoing monitoring to develop an understanding of the longer-term dynamics of such ecosystems and processes is clearly required.

No description available.