Overlooking the Alaka‘i Plateau from the Alaka‘i Swamp trailhead, Kaua‘i, Hawai‘i.
Dennis LaPointe (Former Employee)
Science and Products
eDNA to Inform Invasive Mosquito Distribution
We are using environmental DNA samples to assess habitat occupancy of the invasive southern house mosquito in Kīpahulu Valley, Maui. An understanding of mosquito distribution is critical to developing and implementing tools to prevent the transmission of avian malaria, a primary threat to Hawaiian forest birds.
Identifying Genetic Diversity of Wolbachia Bacteria for Mosquito Control
We are sequencing the DNA of Wolbachia bacteria found in mosquito populations in Hawai’i and those used for mosquito control. We are also developing sample processing techniques to increase the efficiency and accuracy of monitoring mosquito control efforts to help long-term survival and restoration of Hawaiian forest bird populations.
Predicting and Mitigating the Threat of Avian Disease to Forest Birds at Hakalau Forest National Wildlife Refuge
Hawaiʻi’s native forest birds are known worldwide for their diversity and beauty. Unfortunately, many species are heading towards extinction because of bird malaria spread by mosquitoes introduced over a century ago. Remaining populations of these highly threatened forest birds tend to be at high elevations near the tree line on mountains, where cooler temperatures limit mosquitoes and...
New Technologies and Groundwork for Mosquito Control in the Alakai Plateau
Introduced mosquito-borne avian diseases, avian pox and avian malaria, are key limiting factors for endemic Hawaiian forest birds and are, in part, likely responsible for past extinctions and the continued decline of extant species populations. In the last 40 years on the island of Kaua‘i a number of species have become increasingly rare and several are now presumed extinct. Coinciding with these...
Avian Pathogens and Vectors - Kahuku Unit of Hawaii Volcanoes National Park
While the Hawaiian avian disease system has been well-studied in the forests of the older section of Hawai‘i Volcanoes National Park (HAVO), and in many other locations throughout the state, nothing was known about avian disease in the new Kahuku Unit of Hawai‘i Volcanoes National Park and the adjacent Kau Forest Reserve. The high elevation forests of Kahuku are the only habitat located on...
Mosquito Vectors of Dengue and Zika Viruses in Hawaii National Parks
Six species of biting mosquitoes have been introduced to the Hawaiian Islands since Western contact, two of which are vectors of dengue, chikungunya, and Zika viruses. Environmental conditions favorable for the transmission of dengue and Zika occur year-long across Hawai‘i’s coastline. To better understand the ecology of vector mosquitoes and support public health efforts, mosquito monitoring at...
Disease Ecology In the Pacific Basin: Wildlife and Public Health Concerns
Both wildlife and human health in Hawai‘i and other island ecosystems in the Pacific Basin face continued threats from introductions of diseases and vectors. Accidental introduction of mosquito-borne avian malaria and pox virus to Hawai‘i is an outstanding example of how biological invasions can have a profound effect on endemic wildlife. The geographic distribution, density, and community...
Upper Waiākea Forest Reserve, Island of Hawai'i, Trap Efficacy and Mark-Release-Recapture Trial of Culex quinquefasciatus, 2020-2024
This USGS data release consists of five data sets and accompanying metadata for an experimental mark-release-recapture (MMR) study of adult Culex quinquefasciatus conducted in a montane rainforest in Upper Waiākea Forest Reserve on the Island of Hawai'i from October-December 2020 and laboratory survivorship studies and analysis from 2021- 2024. Culex quinquefasciatus is the vector of the...
Kīpahulu Valley, Haleakalā National Park, Maui Seasonal Distribution and Relative Abundance of the Mosquito Culex quinquefasciatus, 2022-2023
This USGS data release consists of six data sets and accompanying metadata for a year-long study on the seasonal distribution and relative abundance of the southern house mosquito Culex quinquefasciatus in Kīpahulu Valley, Haleakalā National Park, critical habitat for two endangered Maui endemic forest birds. Culex quinquefasciatus is the vector of the avian malaria Plasmodium relictum...
Island of Hawaii bird, mosquito, and avian malaria infection data 2001-2004
This data publication contains data files collected as part of a field, laboratory, and modeling effort aimed at uncovering ecological drivers of avian malaria transmission and impacts on Hawaiian honeycreepers across an elevational gradient on the eastern flank of Mauna Loa and Kilauea volcanoes on Hawaii Island. From 2001-2004, mosquito and bird data were collected at nine sites...
Alakai Plateau, Kauai, and Volcano Village,Hawaii biopesticides and traps for the control of Culex quinquefasciatus, 2017-2018
This USGS data release consists of seven data sets and accompanying metadata for studies on the efficacy of adult mosquito traps and lures for monitoring populations of the invasive mosquito Culex quinquefasciatus and the efficacy of the biopesticide VectoMax FG for control of larval Culex quinquefasciatus in Hawaiian forest bird habitat. Culex quinquefasciatus is the vector of the avian...
Hawaii Island, modelled density of malaria-resistant and -susceptible Iiwi following release of malaria-resistant birds under three climate change projections, 2030-2100
This data set provides the simulated results of releasing malaria-resistant Iiwi into existing populations of wild birds on the Island of Hawaii. Resistant birds are released into mid- and high-elevation forests at different densities at 10-year intervals from 2030 to 2070. Populations of both malaria-resistant and susceptible Iiwi are then predicted at 10-year intervals from release...
Overlooking the Alaka‘i Plateau from the Alaka‘i Swamp trailhead, Kaua‘i, Hawai‘i.
Filter Total Items: 51
Assessing mosquito populations to limit the spread of avian disease and inform the conservation of Hawaiian forest birds
The introduced mosquito-borne avian malaria, Plasmodium relictum, along with its mosquito vector, Culex quinquefasciatus, are key limiting factors for endemic Hawaiian forest birds and are, in part, responsible for past extinctions and continued population declines of extant species. In the last 10 years steep declines in forest bird populations have been documented on Kaua`i and Maui...
Authors
Dennis Lapointe
Environmental and geographical factors influence the occurrence and abundance of the southern house mosquito, Culex quinquefasciatus, in Hawai‘i
Hawaiian honeycreepers, a group of endemic Hawaiian forest birds, are being threatened by avian malaria, a non-native disease that is driving honeycreepers populations to extinction. Avian malaria is caused by the parasite Plasmodium relictum, which is transmitted by the invasive mosquito Culex quinquefasciatus. Environmental and geographical factors play an important role in shaping...
Authors
Oswaldo Villena, Katherine Maria McClure, Richard J. Camp, Dennis Lapointe, Carter T. Atkinson, Helen Sofaer, Lucas Fortini
Hawai‘i forest review: Synthesizing the ecology, evolution, and conservation of a model system
As the most remote archipelago in the world, the Hawaiian Islands are home to a highly endemic and disharmonic biota that has fascinated biologists for centuries. Forests are the dominant terrestrial biome in Hawai‘i, spanning complex, heterogeneous climates across substrates that vary tremendously in age, soil structure, and nutrient availability. Species richness is low in Hawaiian...
Authors
Kasey Barton, Andrea Westerband, Rebecca Ostertag, Elizabeth Stacy, Kawika Winter, Don Drake, Lucas Fortini, Dennis Lapointe, Susan Cordell, Paul D. Krushelnycky, Kapua Kawelo, Kealoha Feliciano, Gordon D. Bennett, Tiffany M. Knight
Field trials to test new trap technologies for monitoring Culex populations and the efficacy of the biopesticide formulation VectoMax® FG for control of larval Culex quinquefasciatus in the Alaka'i Plateau, Kaua'i, Hawaii
Mosquito-borne avian malaria Plasmodium relictum is a key limiting factor for endemic Hawaiian forest birds. In the past decade, populations of Kaua‘i’s endemic forest birds have been in a steep decline due to an increase in malaria transmission. To evaluate the use of available biopesticides for short-term mosquito control we tested the efficacy of the biopesticide VectoMax® FG against...
Authors
Dennis Lapointe, Theodore Black, Michael Riney, Kevin W. Brinck, Lisa H. Crampton, Justin M. Hite
Fostering real-time climate adaptation: Analyzing past, current, and forecast temperature to understand the dynamic risk to Hawaiian honeycreepers from avian malaria
Various vector control options are increasingly being considered to safeguard forest birds in their natural habitats from avian malaria transmission. However, vector control options require localized deployment that is not logistically, ethically, ecologically, nor economically viable everywhere and all the time. Based on thermal tolerances of the sporogonic stages of avian malaria...
Authors
Lucas B. Fortini, Lauren R. Kaiser, Dennis Lapointe
Facilitated adaptation for conservation – Can gene editing save Hawaii's endangered birds from climate driven avian malaria?
Avian malaria has played a significant role in causing extinctions, population declines, and limiting the elevational distribution of Hawaiian honeycreepers. Most threatened and endangered honeycreepers only exist in high-elevation forests where the risk of malaria infection is limited. Because Culex mosquito vectors and avian malaria dynamics are strongly influenced by temperature and...
Authors
Michael Samuel, Wei Liao, Carter T. Atkinson, Dennis Lapointe
Relationships between soil macroinvertebrates and nonnative feral pigs (Sus scrofa) in Hawaiian tropical montane wet forests
Nonnative feral pigs (Sus scrofa) are recognized throughout the New World as a highly significant introduced species in terms of ecosystem alteration. Similarly, nonnative soil macroinvertebrates (e.g. earthworms, ground beetles) invade and alter the structure and function of native habitats globally. However, the relationship between feral pigs and soil macroinvertebrates remains...
Authors
Nathaniel H. Wehr, Dennis Lapointe, Noa K Lincoln, Steve C. Hess
Large-scale tree mortality from Rapid Ohia Death negatively influences avifauna in lower Puna, Hawai‘i Island, USA
‘Ōhi’a lehua (Metrosideros polymorpha) is the principle tree species in forests across the Hawaiian Islands and provides critical foraging and nesting habitat for native passerines. Rapid Ohia Death (ROD), caused by the vascular wilt fungus Ceratocystis lukuohia and the canker pathogen C. huliohia, was first detected in the Puna District of Hawaii Island in 2010. It affects all life...
Authors
Richard J. Camp, Dennis Lapointe, Patrick E. Hart, Daniel E Sedgwick, Lisa K Canale
Seasonal surveillance confirms the range expansion of Aedes japonicus japonicas (Theobald) (Diptera: Culicidae) to the Hawaiian Islands of Oahu and Kauai
The Asian bush mosquito, Aedes japonicus japonicus (Theobald) was not known to occur in the Hawaii archipelago until it was identified on the island of Hawaii in 2003. This mosquito species remained undetected on the neighboring islands for 8 years before it was discovered at the Honolulu International Airport on Oahu in 2012. By 2015, four Ae. j. japonicus mosquitoes were collected in...
Authors
James Harwood, Jodi Fiorenzanoa, Elizabeth Gerardoa, Theodore Black, Jeomhee Hasty, Dennis Lapointe
The epidemiology of avian pox and interaction with avian malaria in Hawaiian forest birds
Despite the purported role of avian pox (Avipoxvirus spp.) in the decline of endemic Hawaiian birds, few studies have been conducted on the dynamics of this disease, its impact on free‐living avian populations, or its interactions with avian malaria (Plasmodium relictum). We conducted four longitudinal studies of 3–7 yr in length and used generalized linear models to evaluate cross...
Authors
Michael Samuel, Bethany L. Woodworth, Carter T. Atkinson, Patrick E. Hart, Dennis Lapointe
Biogeographical variation of plumage coloration in the sexually dichromatic Hawai‘i ‘Amakihi (Chlorodrepanis virens)
Plumage coloration in birds can be of major importance to mate selection, social signaling, or predator avoidance. Variations in plumage coloration related to sex, age class, or seasons have been widely studied, but the effect of other factors such as climate is less known. In this study, we examine how carotenoid-based plumage coloration and sexual dichromatism of the Hawai‘i ‘Amakihi...
Authors
Jacqueline M. Gaudioso-Levita, Patrick E. Hart, Dennis Lapointe, Anne Veillet, Esther Sebastián-González
Mitigating future avian malaria threats to Hawaiian forest birds from climate change
Avian malaria, transmitted by Culex quinquefasciatus mosquitoes in the Hawaiian Islands, has been a primary contributor to population range limitations, declines, and extinctions for many endemic Hawaiian honeycreepers. Avian malaria is strongly influenced by climate; therefore, predicted future changes are expected to expand transmission into higher elevations and intensify and lengthen...
Authors
Wei Liao, Carter T. Atkinson, Dennis Lapointe, Michael Samuel
Science and Products
eDNA to Inform Invasive Mosquito Distribution
We are using environmental DNA samples to assess habitat occupancy of the invasive southern house mosquito in Kīpahulu Valley, Maui. An understanding of mosquito distribution is critical to developing and implementing tools to prevent the transmission of avian malaria, a primary threat to Hawaiian forest birds.
Identifying Genetic Diversity of Wolbachia Bacteria for Mosquito Control
We are sequencing the DNA of Wolbachia bacteria found in mosquito populations in Hawai’i and those used for mosquito control. We are also developing sample processing techniques to increase the efficiency and accuracy of monitoring mosquito control efforts to help long-term survival and restoration of Hawaiian forest bird populations.
Predicting and Mitigating the Threat of Avian Disease to Forest Birds at Hakalau Forest National Wildlife Refuge
Hawaiʻi’s native forest birds are known worldwide for their diversity and beauty. Unfortunately, many species are heading towards extinction because of bird malaria spread by mosquitoes introduced over a century ago. Remaining populations of these highly threatened forest birds tend to be at high elevations near the tree line on mountains, where cooler temperatures limit mosquitoes and...
New Technologies and Groundwork for Mosquito Control in the Alakai Plateau
Introduced mosquito-borne avian diseases, avian pox and avian malaria, are key limiting factors for endemic Hawaiian forest birds and are, in part, likely responsible for past extinctions and the continued decline of extant species populations. In the last 40 years on the island of Kaua‘i a number of species have become increasingly rare and several are now presumed extinct. Coinciding with these...
Avian Pathogens and Vectors - Kahuku Unit of Hawaii Volcanoes National Park
While the Hawaiian avian disease system has been well-studied in the forests of the older section of Hawai‘i Volcanoes National Park (HAVO), and in many other locations throughout the state, nothing was known about avian disease in the new Kahuku Unit of Hawai‘i Volcanoes National Park and the adjacent Kau Forest Reserve. The high elevation forests of Kahuku are the only habitat located on...
Mosquito Vectors of Dengue and Zika Viruses in Hawaii National Parks
Six species of biting mosquitoes have been introduced to the Hawaiian Islands since Western contact, two of which are vectors of dengue, chikungunya, and Zika viruses. Environmental conditions favorable for the transmission of dengue and Zika occur year-long across Hawai‘i’s coastline. To better understand the ecology of vector mosquitoes and support public health efforts, mosquito monitoring at...
Disease Ecology In the Pacific Basin: Wildlife and Public Health Concerns
Both wildlife and human health in Hawai‘i and other island ecosystems in the Pacific Basin face continued threats from introductions of diseases and vectors. Accidental introduction of mosquito-borne avian malaria and pox virus to Hawai‘i is an outstanding example of how biological invasions can have a profound effect on endemic wildlife. The geographic distribution, density, and community...
Upper Waiākea Forest Reserve, Island of Hawai'i, Trap Efficacy and Mark-Release-Recapture Trial of Culex quinquefasciatus, 2020-2024
This USGS data release consists of five data sets and accompanying metadata for an experimental mark-release-recapture (MMR) study of adult Culex quinquefasciatus conducted in a montane rainforest in Upper Waiākea Forest Reserve on the Island of Hawai'i from October-December 2020 and laboratory survivorship studies and analysis from 2021- 2024. Culex quinquefasciatus is the vector of the...
Kīpahulu Valley, Haleakalā National Park, Maui Seasonal Distribution and Relative Abundance of the Mosquito Culex quinquefasciatus, 2022-2023
This USGS data release consists of six data sets and accompanying metadata for a year-long study on the seasonal distribution and relative abundance of the southern house mosquito Culex quinquefasciatus in Kīpahulu Valley, Haleakalā National Park, critical habitat for two endangered Maui endemic forest birds. Culex quinquefasciatus is the vector of the avian malaria Plasmodium relictum...
Island of Hawaii bird, mosquito, and avian malaria infection data 2001-2004
This data publication contains data files collected as part of a field, laboratory, and modeling effort aimed at uncovering ecological drivers of avian malaria transmission and impacts on Hawaiian honeycreepers across an elevational gradient on the eastern flank of Mauna Loa and Kilauea volcanoes on Hawaii Island. From 2001-2004, mosquito and bird data were collected at nine sites...
Alakai Plateau, Kauai, and Volcano Village,Hawaii biopesticides and traps for the control of Culex quinquefasciatus, 2017-2018
This USGS data release consists of seven data sets and accompanying metadata for studies on the efficacy of adult mosquito traps and lures for monitoring populations of the invasive mosquito Culex quinquefasciatus and the efficacy of the biopesticide VectoMax FG for control of larval Culex quinquefasciatus in Hawaiian forest bird habitat. Culex quinquefasciatus is the vector of the avian...
Hawaii Island, modelled density of malaria-resistant and -susceptible Iiwi following release of malaria-resistant birds under three climate change projections, 2030-2100
This data set provides the simulated results of releasing malaria-resistant Iiwi into existing populations of wild birds on the Island of Hawaii. Resistant birds are released into mid- and high-elevation forests at different densities at 10-year intervals from 2030 to 2070. Populations of both malaria-resistant and susceptible Iiwi are then predicted at 10-year intervals from release...
Overlooking the Alaka‘i Plateau, Kaua‘i
Overlooking the Alaka‘i Plateau from the Alaka‘i Swamp trailhead, Kaua‘i, Hawai‘i.
Overlooking the Alaka‘i Plateau from the Alaka‘i Swamp trailhead, Kaua‘i, Hawai‘i.
Filter Total Items: 51
Assessing mosquito populations to limit the spread of avian disease and inform the conservation of Hawaiian forest birds
The introduced mosquito-borne avian malaria, Plasmodium relictum, along with its mosquito vector, Culex quinquefasciatus, are key limiting factors for endemic Hawaiian forest birds and are, in part, responsible for past extinctions and continued population declines of extant species. In the last 10 years steep declines in forest bird populations have been documented on Kaua`i and Maui...
Authors
Dennis Lapointe
Environmental and geographical factors influence the occurrence and abundance of the southern house mosquito, Culex quinquefasciatus, in Hawai‘i
Hawaiian honeycreepers, a group of endemic Hawaiian forest birds, are being threatened by avian malaria, a non-native disease that is driving honeycreepers populations to extinction. Avian malaria is caused by the parasite Plasmodium relictum, which is transmitted by the invasive mosquito Culex quinquefasciatus. Environmental and geographical factors play an important role in shaping...
Authors
Oswaldo Villena, Katherine Maria McClure, Richard J. Camp, Dennis Lapointe, Carter T. Atkinson, Helen Sofaer, Lucas Fortini
Hawai‘i forest review: Synthesizing the ecology, evolution, and conservation of a model system
As the most remote archipelago in the world, the Hawaiian Islands are home to a highly endemic and disharmonic biota that has fascinated biologists for centuries. Forests are the dominant terrestrial biome in Hawai‘i, spanning complex, heterogeneous climates across substrates that vary tremendously in age, soil structure, and nutrient availability. Species richness is low in Hawaiian...
Authors
Kasey Barton, Andrea Westerband, Rebecca Ostertag, Elizabeth Stacy, Kawika Winter, Don Drake, Lucas Fortini, Dennis Lapointe, Susan Cordell, Paul D. Krushelnycky, Kapua Kawelo, Kealoha Feliciano, Gordon D. Bennett, Tiffany M. Knight
Field trials to test new trap technologies for monitoring Culex populations and the efficacy of the biopesticide formulation VectoMax® FG for control of larval Culex quinquefasciatus in the Alaka'i Plateau, Kaua'i, Hawaii
Mosquito-borne avian malaria Plasmodium relictum is a key limiting factor for endemic Hawaiian forest birds. In the past decade, populations of Kaua‘i’s endemic forest birds have been in a steep decline due to an increase in malaria transmission. To evaluate the use of available biopesticides for short-term mosquito control we tested the efficacy of the biopesticide VectoMax® FG against...
Authors
Dennis Lapointe, Theodore Black, Michael Riney, Kevin W. Brinck, Lisa H. Crampton, Justin M. Hite
Fostering real-time climate adaptation: Analyzing past, current, and forecast temperature to understand the dynamic risk to Hawaiian honeycreepers from avian malaria
Various vector control options are increasingly being considered to safeguard forest birds in their natural habitats from avian malaria transmission. However, vector control options require localized deployment that is not logistically, ethically, ecologically, nor economically viable everywhere and all the time. Based on thermal tolerances of the sporogonic stages of avian malaria...
Authors
Lucas B. Fortini, Lauren R. Kaiser, Dennis Lapointe
Facilitated adaptation for conservation – Can gene editing save Hawaii's endangered birds from climate driven avian malaria?
Avian malaria has played a significant role in causing extinctions, population declines, and limiting the elevational distribution of Hawaiian honeycreepers. Most threatened and endangered honeycreepers only exist in high-elevation forests where the risk of malaria infection is limited. Because Culex mosquito vectors and avian malaria dynamics are strongly influenced by temperature and...
Authors
Michael Samuel, Wei Liao, Carter T. Atkinson, Dennis Lapointe
Relationships between soil macroinvertebrates and nonnative feral pigs (Sus scrofa) in Hawaiian tropical montane wet forests
Nonnative feral pigs (Sus scrofa) are recognized throughout the New World as a highly significant introduced species in terms of ecosystem alteration. Similarly, nonnative soil macroinvertebrates (e.g. earthworms, ground beetles) invade and alter the structure and function of native habitats globally. However, the relationship between feral pigs and soil macroinvertebrates remains...
Authors
Nathaniel H. Wehr, Dennis Lapointe, Noa K Lincoln, Steve C. Hess
Large-scale tree mortality from Rapid Ohia Death negatively influences avifauna in lower Puna, Hawai‘i Island, USA
‘Ōhi’a lehua (Metrosideros polymorpha) is the principle tree species in forests across the Hawaiian Islands and provides critical foraging and nesting habitat for native passerines. Rapid Ohia Death (ROD), caused by the vascular wilt fungus Ceratocystis lukuohia and the canker pathogen C. huliohia, was first detected in the Puna District of Hawaii Island in 2010. It affects all life...
Authors
Richard J. Camp, Dennis Lapointe, Patrick E. Hart, Daniel E Sedgwick, Lisa K Canale
Seasonal surveillance confirms the range expansion of Aedes japonicus japonicas (Theobald) (Diptera: Culicidae) to the Hawaiian Islands of Oahu and Kauai
The Asian bush mosquito, Aedes japonicus japonicus (Theobald) was not known to occur in the Hawaii archipelago until it was identified on the island of Hawaii in 2003. This mosquito species remained undetected on the neighboring islands for 8 years before it was discovered at the Honolulu International Airport on Oahu in 2012. By 2015, four Ae. j. japonicus mosquitoes were collected in...
Authors
James Harwood, Jodi Fiorenzanoa, Elizabeth Gerardoa, Theodore Black, Jeomhee Hasty, Dennis Lapointe
The epidemiology of avian pox and interaction with avian malaria in Hawaiian forest birds
Despite the purported role of avian pox (Avipoxvirus spp.) in the decline of endemic Hawaiian birds, few studies have been conducted on the dynamics of this disease, its impact on free‐living avian populations, or its interactions with avian malaria (Plasmodium relictum). We conducted four longitudinal studies of 3–7 yr in length and used generalized linear models to evaluate cross...
Authors
Michael Samuel, Bethany L. Woodworth, Carter T. Atkinson, Patrick E. Hart, Dennis Lapointe
Biogeographical variation of plumage coloration in the sexually dichromatic Hawai‘i ‘Amakihi (Chlorodrepanis virens)
Plumage coloration in birds can be of major importance to mate selection, social signaling, or predator avoidance. Variations in plumage coloration related to sex, age class, or seasons have been widely studied, but the effect of other factors such as climate is less known. In this study, we examine how carotenoid-based plumage coloration and sexual dichromatism of the Hawai‘i ‘Amakihi...
Authors
Jacqueline M. Gaudioso-Levita, Patrick E. Hart, Dennis Lapointe, Anne Veillet, Esther Sebastián-González
Mitigating future avian malaria threats to Hawaiian forest birds from climate change
Avian malaria, transmitted by Culex quinquefasciatus mosquitoes in the Hawaiian Islands, has been a primary contributor to population range limitations, declines, and extinctions for many endemic Hawaiian honeycreepers. Avian malaria is strongly influenced by climate; therefore, predicted future changes are expected to expand transmission into higher elevations and intensify and lengthen...
Authors
Wei Liao, Carter T. Atkinson, Dennis Lapointe, Michael Samuel