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Papers by Thalia Sachtleben
BioControl
The release of Tamarixia triozae (Burks) (Hymenoptera: Eulophidae), a parasitoid of the potato ps... more The release of Tamarixia triozae (Burks) (Hymenoptera: Eulophidae), a parasitoid of the potato psyllid, Bactericera cockerelli (Šulc) (Hemiptera: Triozidae), resulted in the successful establishment of the parasitoid in New Zealand. The parasitoid was released at more than 30 sites by the final year of the three-year study throughout New Zealand. Its continued presence over the three-year study was confirmed in two regions (Hawke’s Bay and Canterbury). At one site in Canterbury, the parasitoid was released only in the first summer of this study (Nov. 2017–Feb. 2018). It was recovered from potato psyllid infested African boxthorn (Lycium ferocissimum Miers) foliage in the second and third summers at this site, demonstrating the parasitoid’s ability to survive over successive winters. We found T. triozae parasitized nymphs at 24 sites of the 86 potato psyllid host plant sites surveyed within a 25 km radius of known release sites in Hawke’s Bay. The parasitoid was found up to 24 km fro...
... I thank my committee (Julie Savidge, Alan Franklin, and Ruth Hufbauer), David Anderson, Sarah... more ... I thank my committee (Julie Savidge, Alan Franklin, and Ruth Hufbauer), David Anderson, Sarah Converse, Aaron Ellingson, Paul Lukacs, Tom Stanley, Gary White, and the members of ... Blakesley, Tina de Cruz, Brett Dickson, and Mike Wunder. Heartfelt thanks to Nathan ...
New Zealand Journal of Ecology, 2010
Reliable information about population density and trends is essential for making valid inferences... more Reliable information about population density and trends is essential for making valid inferences regarding conservation management. The suitability of point counts using distance sampling was examined as a means of monitoring a population of kaka (Nestor meridionalis septentrionalis), a large forest-dwelling parrot, inhabiting the Waipapa Ecological Area in the central North Island of New Zealand. Counts were conducted on 13 occasions between 2000 and 2007. The sampling design was tailored to maximise the detectability of kaka and to minimise violations of the four most important assumptions of distance sampling. Location errors and subsequent distance estimation errors were most likely to bias density estimates despite our attempts to minimise failures of this assumption. Densities estimated from counts conducted in October were similar between 2000 and 2007 (approximately 0.5 kaka ha -1 ) with no evidence of either a positive or negative trend. Densities derived from counts in Fe...
New Zealand Journal of …, 2010
Reliable information about population density and trends is essential for making valid inferences... more Reliable information about population density and trends is essential for making valid inferences regarding conservation management. The suitability of point counts using distance sampling was examined as a means of monitoring a population of kaka (Nestor meridionalis septentrionalis), a large forest-dwelling parrot, inhabiting the Waipapa Ecological Area in the central North Island of New Zealand. Counts were conducted on 13 occasions between 2000 and 2007. The sampling design was tailored to maximise the detectability of kaka and to minimise violations of the four most important assumptions of distance sampling. Location errors and subsequent distance estimation errors were most likely to bias density estimates despite our attempts to minimise failures of this assumption. Densities estimated from counts conducted in October were similar between 2000 and 2007 (approximately 0.5 kaka ha-1) with no evidence of either a positive or negative trend. Densities derived from counts in February or March were more erratic and seemed to reflect variation in the frequency and success of the preceding breeding season. Given the frequency of kaka breeding, the pest control regime during the study period, and our attempts to minimise violations of distance sampling assumptions, we are confident that the reported trends in density are realistic. Although distance sampling was found to give reliable density estimates of kaka at Waipapa, this may not be the case at other sites, particularly where kaka density is low, location error is high, forest structure or topography are more complex, or surveys of kaka are made part of more extensive multi-species surveys.
The Wilson Journal of Ornithology, 2006
... FIG. 2. Micronesian Honeyeater (Myzomela rubratra saffordi) nest photographed on Saipan,Maria... more ... FIG. 2. Micronesian Honeyeater (Myzomela rubratra saffordi) nest photographed on Saipan,Mariana Is ... DISCUSSION Prior to our study, nests of Micronesian Honeyeaters had been found on Guam (Har tert 1898, Seale 1901, Yamashina 1932, Jen kins 1983; N. Drahos pers. ...
New Zealand Journal of Ecology
Reliable information about population density and trends is essential for making valid inferences... more Reliable information about population density and trends is essential for making valid inferences regarding conservation management. The suitability of point counts using distance sampling was examined as a means of monitoring a population of kaka (Nestor meridionalis septentrionalis), a large forest-dwelling parrot, inhabiting the Waipapa Ecological Area in the central North Island of New Zealand. Counts were conducted on 13 occasions between 2000 and 2007. The sampling design was tailored to maximise the detectability of kaka and to minimise violations of the four most important assumptions of distance sampling. Location errors and subsequent distance estimation errors were most likely to bias density estimates despite our attempts to minimise failures of this assumption. Densities estimated from counts conducted in October were similar between 2000 and 2007 (approximately 0.5 kaka ha -1 ) with no evidence of either a positive or negative trend. Densities derived from counts in February or March were more erratic and seemed to reflect variation in the frequency and success of the preceding breeding season. Given the frequency of kaka breeding, the pest control regime during the study period, and our attempts to minimise violations of distance sampling assumptions, we are confident that the reported trends in density are realistic. Although distance sampling was found to give reliable density estimates of kaka at Waipapa, this may not be the case at other sites, particularly where kaka density is low, location error is high, forest structure or topography are more complex, or surveys of kaka are made part of more extensive multi-species surveys.
BioControl
The release of Tamarixia triozae (Burks) (Hymenoptera: Eulophidae), a parasitoid of the potato ps... more The release of Tamarixia triozae (Burks) (Hymenoptera: Eulophidae), a parasitoid of the potato psyllid, Bactericera cockerelli (Šulc) (Hemiptera: Triozidae), resulted in the successful establishment of the parasitoid in New Zealand. The parasitoid was released at more than 30 sites by the final year of the three-year study throughout New Zealand. Its continued presence over the three-year study was confirmed in two regions (Hawke’s Bay and Canterbury). At one site in Canterbury, the parasitoid was released only in the first summer of this study (Nov. 2017–Feb. 2018). It was recovered from potato psyllid infested African boxthorn (Lycium ferocissimum Miers) foliage in the second and third summers at this site, demonstrating the parasitoid’s ability to survive over successive winters. We found T. triozae parasitized nymphs at 24 sites of the 86 potato psyllid host plant sites surveyed within a 25 km radius of known release sites in Hawke’s Bay. The parasitoid was found up to 24 km fro...
... I thank my committee (Julie Savidge, Alan Franklin, and Ruth Hufbauer), David Anderson, Sarah... more ... I thank my committee (Julie Savidge, Alan Franklin, and Ruth Hufbauer), David Anderson, Sarah Converse, Aaron Ellingson, Paul Lukacs, Tom Stanley, Gary White, and the members of ... Blakesley, Tina de Cruz, Brett Dickson, and Mike Wunder. Heartfelt thanks to Nathan ...
New Zealand Journal of Ecology, 2010
Reliable information about population density and trends is essential for making valid inferences... more Reliable information about population density and trends is essential for making valid inferences regarding conservation management. The suitability of point counts using distance sampling was examined as a means of monitoring a population of kaka (Nestor meridionalis septentrionalis), a large forest-dwelling parrot, inhabiting the Waipapa Ecological Area in the central North Island of New Zealand. Counts were conducted on 13 occasions between 2000 and 2007. The sampling design was tailored to maximise the detectability of kaka and to minimise violations of the four most important assumptions of distance sampling. Location errors and subsequent distance estimation errors were most likely to bias density estimates despite our attempts to minimise failures of this assumption. Densities estimated from counts conducted in October were similar between 2000 and 2007 (approximately 0.5 kaka ha -1 ) with no evidence of either a positive or negative trend. Densities derived from counts in Fe...
New Zealand Journal of …, 2010
Reliable information about population density and trends is essential for making valid inferences... more Reliable information about population density and trends is essential for making valid inferences regarding conservation management. The suitability of point counts using distance sampling was examined as a means of monitoring a population of kaka (Nestor meridionalis septentrionalis), a large forest-dwelling parrot, inhabiting the Waipapa Ecological Area in the central North Island of New Zealand. Counts were conducted on 13 occasions between 2000 and 2007. The sampling design was tailored to maximise the detectability of kaka and to minimise violations of the four most important assumptions of distance sampling. Location errors and subsequent distance estimation errors were most likely to bias density estimates despite our attempts to minimise failures of this assumption. Densities estimated from counts conducted in October were similar between 2000 and 2007 (approximately 0.5 kaka ha-1) with no evidence of either a positive or negative trend. Densities derived from counts in February or March were more erratic and seemed to reflect variation in the frequency and success of the preceding breeding season. Given the frequency of kaka breeding, the pest control regime during the study period, and our attempts to minimise violations of distance sampling assumptions, we are confident that the reported trends in density are realistic. Although distance sampling was found to give reliable density estimates of kaka at Waipapa, this may not be the case at other sites, particularly where kaka density is low, location error is high, forest structure or topography are more complex, or surveys of kaka are made part of more extensive multi-species surveys.
The Wilson Journal of Ornithology, 2006
... FIG. 2. Micronesian Honeyeater (Myzomela rubratra saffordi) nest photographed on Saipan,Maria... more ... FIG. 2. Micronesian Honeyeater (Myzomela rubratra saffordi) nest photographed on Saipan,Mariana Is ... DISCUSSION Prior to our study, nests of Micronesian Honeyeaters had been found on Guam (Har tert 1898, Seale 1901, Yamashina 1932, Jen kins 1983; N. Drahos pers. ...
New Zealand Journal of Ecology
Reliable information about population density and trends is essential for making valid inferences... more Reliable information about population density and trends is essential for making valid inferences regarding conservation management. The suitability of point counts using distance sampling was examined as a means of monitoring a population of kaka (Nestor meridionalis septentrionalis), a large forest-dwelling parrot, inhabiting the Waipapa Ecological Area in the central North Island of New Zealand. Counts were conducted on 13 occasions between 2000 and 2007. The sampling design was tailored to maximise the detectability of kaka and to minimise violations of the four most important assumptions of distance sampling. Location errors and subsequent distance estimation errors were most likely to bias density estimates despite our attempts to minimise failures of this assumption. Densities estimated from counts conducted in October were similar between 2000 and 2007 (approximately 0.5 kaka ha -1 ) with no evidence of either a positive or negative trend. Densities derived from counts in February or March were more erratic and seemed to reflect variation in the frequency and success of the preceding breeding season. Given the frequency of kaka breeding, the pest control regime during the study period, and our attempts to minimise violations of distance sampling assumptions, we are confident that the reported trends in density are realistic. Although distance sampling was found to give reliable density estimates of kaka at Waipapa, this may not be the case at other sites, particularly where kaka density is low, location error is high, forest structure or topography are more complex, or surveys of kaka are made part of more extensive multi-species surveys.