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Queensland lemons are exported at low (i.e. <3°C) temperature to meet market access protocols. While the fruit generally tolerate these conditions, skin damage consistent with chilling injury (CI) is occasionally encountered and results in significant economic and reputational loss. The robustness of fruit to withstand export handling is inherently variable and difficult to predict. This study evaluated the potential of hyperspectral imaging to detect and predict CI in fruit before it was visible to the human eye. Seeded and seedless Eureka lemons were sourced from a north Queensland orchard. They were treated with either 2.6 or 18.5 parts per million (ppm) ethylene gas at 20.4 or 28.9oC for 5 days to hasten the loss of green skin colour, as per commercial degreening practice. The degreened fruit were stored at 1.9oC for 5 weeks to simulate seafreight to export markets, followed by 10 days at 20oC to assess CI under typical retail display conditions. Spectral data was collected within 2-3 h after harvest, degreening or cold storage. Three near infrared (NIR) devices were used; Bruker Matrix-F for spot assessment; Pika NIR 320 and Pika XC2 for hyperspectral imaging, covering wavelengths from 830-2500 nm, 900-1700 nm and 400-1000 nm, respectively. The supervised classification method of linear discriminate analysis was applied to the spectra collected from the Bruker Matrix-F, whereas partial least squares discriminant analysis (PLS-DA) was used to analyse spectra and images obtained from the Pika XC2 and NIR 320 instruments. The results showed that there is potential for NIR hyperspectral imaging to predict CI in seeded and seedless Eureka lemons, when assessed after degreening and particularly after cold shipment. Spectra collected after degreening and cold storage demonstrated reasonable levels (i.e. 70%) of correct classification. The highest correct classification was obtained for scans taken after storage and is likely due to CI having been induced in the fruit.

Queensland lemons are exported at low (i.e. <3°C) temperature to meet market access protocols. While the fruit generally tolerate these conditions, skin damage consistent with chilling injury (CI) is occasionally encountered and results in significant economic and reputational loss. The robustness of fruit to withstand export handling is inherently variable and difficult to predict. This study evaluated the potential of hyperspectral imaging to detect and predict CI in fruit before it was visible to the human eye. Seeded and seedless Eureka lemons were sourced from a north Queensland orchard. They were treated with either 2.6 or 18.5 parts per million (ppm) ethylene gas at 20.4 or 28.9oC for 5 days to hasten the loss of green skin colour, as per commercial degreening practice. The degreened fruit were stored at 1.9oC for 5 weeks to simulate seafreight to export markets, followed by 10 days at 20oC to assess CI under typical retail display conditions. Spectral data was collected within 2-3 h after harvest, degreening or cold storage. Three near infrared (NIR) devices were used; Bruker Matrix-F for spot assessment; Pika NIR 320 and Pika XC2 for hyperspectral imaging, covering wavelengths from 830-2500 nm, 900-1700 nm and 400-1000 nm, respectively. The supervised classification method of linear discriminate analysis was applied to the spectra collected from the Bruker Matrix-F, whereas partial least squares discriminant analysis (PLS-DA) was used to analyse spectra and images obtained from the Pika XC2 and NIR 320 instruments. The results showed that there is potential for NIR hyperspectral imaging to predict CI in seeded and seedless Eureka lemons, when assessed after degreening and particularly after cold shipment. Spectra collected after degreening and cold storage demonstrated reasonable levels (i.e. 70%) of correct classification. The highest correct classification was obtained for scans taken after storage and is likely due to CI having been induced in the fruit.

Queensland lemons are exported at low (i.e. <3°C) temperature to meet market access protocols. While the fruit generally tolerate these conditions, skin damage consistent with chilling injury (CI) is occasionally encountered and results in significant economic and reputational loss. The robustness of fruit to withstand export handling is inherently variable and difficult to predict. This study evaluated the potential of hyperspectral imaging to detect and predict CI in fruit before it was visible to the human eye. Seeded and seedless Eureka lemons were sourced from a north Queensland orchard. They were treated with either 2.6 or 18.5 parts per million (ppm) ethylene gas at 20.4 or 28.9oC for 5 days to hasten the loss of green skin colour, as per commercial degreening practice. The degreened fruit were stored at 1.9oC for 5 weeks to simulate seafreight to export markets, followed by 10 days at 20oC to assess CI under typical retail display conditions. Spectral data was collected within 2-3 h after harvest, degreening or cold storage. Three near infrared (NIR) devices were used; Bruker Matrix-F for spot assessment; Pika NIR 320 and Pika XC2 for hyperspectral imaging, covering wavelengths from 830-2500 nm, 900-1700 nm and 400-1000 nm, respectively. The supervised classification method of linear discriminate analysis was applied to the spectra collected from the Bruker Matrix-F, whereas partial least squares discriminant analysis (PLS-DA) was used to analyse spectra and images obtained from the Pika XC2 and NIR 320 instruments. The results showed that there is potential for NIR hyperspectral imaging to predict CI in seeded and seedless Eureka lemons, when assessed after degreening and particularly after cold shipment. Spectra collected after degreening and cold storage demonstrated reasonable levels (i.e. 70%) of correct classification. The highest correct classification was obtained for scans taken after storage and is likely due to CI having been induced in the fruit.

Queensland lemons are exported at low (i.e. <3°C) temperature to meet market access protocols. While the fruit generally tolerate these conditions, skin damage consistent with chilling injury (CI) is occasionally encountered and results in significant economic and reputational loss. The robustness of fruit to withstand export handling is inherently variable and difficult to predict. This study evaluated the potential of hyperspectral imaging to detect and predict CI in fruit before it was visible to the human eye. Seeded and seedless Eureka lemons were sourced from a north Queensland orchard. They were treated with either 2.6 or 18.5 parts per million (ppm) ethylene gas at 20.4 or 28.9oC for 5 days to hasten the loss of green skin colour, as per commercial degreening practice. The degreened fruit were stored at 1.9oC for 5 weeks to simulate seafreight to export markets, followed by 10 days at 20oC to assess CI under typical retail display conditions. Spectral data was collected within 2-3 h after harvest, degreening or cold storage. Three near infrared (NIR) devices were used; Bruker Matrix-F for spot assessment; Pika NIR 320 and Pika XC2 for hyperspectral imaging, covering wavelengths from 830-2500 nm, 900-1700 nm and 400-1000 nm, respectively. The supervised classification method of linear discriminate analysis was applied to the spectra collected from the Bruker Matrix-F, whereas partial least squares discriminant analysis (PLS-DA) was used to analyse spectra and images obtained from the Pika XC2 and NIR 320 instruments. The results showed that there is potential for NIR hyperspectral imaging to predict CI in seeded and seedless Eureka lemons, when assessed after degreening and particularly after cold shipment. Spectra collected after degreening and cold storage demonstrated reasonable levels (i.e. 70%) of correct classification. The highest correct classification was obtained for scans taken after storage and is likely due to CI having been induced in the fruit.

Queensland lemons are exported at low (i.e. <3°C) temperature to meet market access protocols. While the fruit generally tolerate these conditions, skin damage consistent with chilling injury (CI) is occasionally encountered and results in significant economic and reputational loss. The robustness of fruit to withstand export handling is inherently variable and difficult to predict. This study evaluated the potential of hyperspectral imaging to detect and predict CI in fruit before it was visible to the human eye. Seeded and seedless Eureka lemons were sourced from a north Queensland orchard. They were treated with either 2.6 or 18.5 parts per million (ppm) ethylene gas at 20.4 or 28.9oC for 5 days to hasten the loss of green skin colour, as per commercial degreening practice. The degreened fruit were stored at 1.9oC for 5 weeks to simulate seafreight to export markets, followed by 10 days at 20oC to assess CI under typical retail display conditions. Spectral data was collected within 2-3 h after harvest, degreening or cold storage. Three near infrared (NIR) devices were used; Bruker Matrix-F for spot assessment; Pika NIR 320 and Pika XC2 for hyperspectral imaging, covering wavelengths from 830-2500 nm, 900-1700 nm and 400-1000 nm, respectively. The supervised classification method of linear discriminate analysis was applied to the spectra collected from the Bruker Matrix-F, whereas partial least squares discriminant analysis (PLS-DA) was used to analyse spectra and images obtained from the Pika XC2 and NIR 320 instruments. The results showed that there is potential for NIR hyperspectral imaging to predict CI in seeded and seedless Eureka lemons, when assessed after degreening and particularly after cold shipment. Spectra collected after degreening and cold storage demonstrated reasonable levels (i.e. 70%) of correct classification. The highest correct classification was obtained for scans taken after storage and is likely due to CI having been induced in the fruit.

Queensland fruit fly, Bactrocera tryoni, is one of Australia’s most damaging fruit fly pests. Male Annihilation Technique (MAT) is a method used to manage fruit fly populations by luring and killing male flies, which limits population growth by preventing female flies from mating. MAT devices consist of an attractant and a toxicant, such as maldison or fipronil. Fipronil has a slow knockdown effect, which has been exploited to induce indirect toxicity of a number of insect pests, including cockroaches and termites. This indirect effect, called horizontal transfer, is facilitated through the sharing of food or contact with exposed individuals. Horizontal transfer has been reported in Queensland fruit fly, where exposed males have transferred lethal doses of fipronil to virgin females during courtship and mating. In the present study, we explored three possible modes of horizontal transfer of fipronil against Queensland fruit fly under laboratory conditions. These included: (1) direct contact of females with exposed males (2) contact of males to the regurgitant of exposed males and (3) contact of males with dead exposed males. Our results demonstrated that lethal doses of fipronil were not transferred from males to females during courtship and mating. Male flies that were exposed to fipronil one and six hours prior to dusk were all knocked down, moribund or dead at dusk and therefore did not participate in courtship displays or mating. However, we found that horizontal transfer and subsequent death occurred in males that fed on the regurgitant of exposed males, and in males that were in contact with dead exposed males. Therefore, MAT devices that contain fipronil should not be used as a standalone treatment but rather be used in combination with other control methods, such as protein bait sprays to ensure the control of female flies.

Queensland fruit fly, Bactrocera tryoni, is one of Australia’s most damaging fruit fly pests. Male Annihilation Technique (MAT) is a method used to manage fruit fly populations by luring and killing male flies, which limits population growth by preventing female flies from mating. MAT devices consist of an attractant and a toxicant, such as maldison or fipronil. Fipronil has a slow knockdown effect, which has been exploited to induce indirect toxicity of a number of insect pests, including cockroaches and termites. This indirect effect, called horizontal transfer, is facilitated through the sharing of food or contact with exposed individuals. Horizontal transfer has been reported in Queensland fruit fly, where exposed males have transferred lethal doses of fipronil to virgin females during courtship and mating. In the present study, we explored three possible modes of horizontal transfer of fipronil against Queensland fruit fly under laboratory conditions. These included: (1) direct contact of females with exposed males (2) contact of males to the regurgitant of exposed males and (3) contact of males with dead exposed males. Our results demonstrated that lethal doses of fipronil were not transferred from males to females during courtship and mating. Male flies that were exposed to fipronil one and six hours prior to dusk were all knocked down, moribund or dead at dusk and therefore did not participate in courtship displays or mating. However, we found that horizontal transfer and subsequent death occurred in males that fed on the regurgitant of exposed males, and in males that were in contact with dead exposed males. Therefore, MAT devices that contain fipronil should not be used as a standalone treatment but rather be used in combination with other control methods, such as protein bait sprays to ensure the control of female flies.

Queensland fruit fly, Bactrocera tryoni, is one of Australia’s most damaging fruit fly pests. Male Annihilation Technique (MAT) is a method used to manage fruit fly populations by luring and killing male flies, which limits population growth by preventing female flies from mating. MAT devices consist of an attractant and a toxicant, such as maldison or fipronil. Fipronil has a slow knockdown effect, which has been exploited to induce indirect toxicity of a number of insect pests, including cockroaches and termites. This indirect effect, called horizontal transfer, is facilitated through the sharing of food or contact with exposed individuals. Horizontal transfer has been reported in Queensland fruit fly, where exposed males have transferred lethal doses of fipronil to virgin females during courtship and mating. In the present study, we explored three possible modes of horizontal transfer of fipronil against Queensland fruit fly under laboratory conditions. These included: (1) direct contact of females with exposed males (2) contact of males to the regurgitant of exposed males and (3) contact of males with dead exposed males. Our results demonstrated that lethal doses of fipronil were not transferred from males to females during courtship and mating. Male flies that were exposed to fipronil one and six hours prior to dusk were all knocked down, moribund or dead at dusk and therefore did not participate in courtship displays or mating. However, we found that horizontal transfer and subsequent death occurred in males that fed on the regurgitant of exposed males, and in males that were in contact with dead exposed males. Therefore, MAT devices that contain fipronil should not be used as a standalone treatment but rather be used in combination with other control methods, such as protein bait sprays to ensure the control of female flies.

Queensland fruit fly, Bactrocera tryoni, is one of Australia’s most damaging fruit fly pests. Male Annihilation Technique (MAT) is a method used to manage fruit fly populations by luring and killing male flies, which limits population growth by preventing female flies from mating. MAT devices consist of an attractant and a toxicant, such as maldison or fipronil. Fipronil has a slow knockdown effect, which has been exploited to induce indirect toxicity of a number of insect pests, including cockroaches and termites. This indirect effect, called horizontal transfer, is facilitated through the sharing of food or contact with exposed individuals. Horizontal transfer has been reported in Queensland fruit fly, where exposed males have transferred lethal doses of fipronil to virgin females during courtship and mating. In the present study, we explored three possible modes of horizontal transfer of fipronil against Queensland fruit fly under laboratory conditions. These included: (1) direct contact of females with exposed males (2) contact of males to the regurgitant of exposed males and (3) contact of males with dead exposed males. Our results demonstrated that lethal doses of fipronil were not transferred from males to females during courtship and mating. Male flies that were exposed to fipronil one and six hours prior to dusk were all knocked down, moribund or dead at dusk and therefore did not participate in courtship displays or mating. However, we found that horizontal transfer and subsequent death occurred in males that fed on the regurgitant of exposed males, and in males that were in contact with dead exposed males. Therefore, MAT devices that contain fipronil should not be used as a standalone treatment but rather be used in combination with other control methods, such as protein bait sprays to ensure the control of female flies.

Queensland fruit fly, Bactrocera tryoni, is one of Australia’s most damaging fruit fly pests. Male Annihilation Technique (MAT) is a method used to manage fruit fly populations by luring and killing male flies, which limits population growth by preventing female flies from mating. MAT devices consist of an attractant and a toxicant, such as maldison or fipronil. Fipronil has a slow knockdown effect, which has been exploited to induce indirect toxicity of a number of insect pests, including cockroaches and termites. This indirect effect, called horizontal transfer, is facilitated through the sharing of food or contact with exposed individuals. Horizontal transfer has been reported in Queensland fruit fly, where exposed males have transferred lethal doses of fipronil to virgin females during courtship and mating. In the present study, we explored three possible modes of horizontal transfer of fipronil against Queensland fruit fly under laboratory conditions. These included: (1) direct contact of females with exposed males (2) contact of males to the regurgitant of exposed males and (3) contact of males with dead exposed males. Our results demonstrated that lethal doses of fipronil were not transferred from males to females during courtship and mating. Male flies that were exposed to fipronil one and six hours prior to dusk were all knocked down, moribund or dead at dusk and therefore did not participate in courtship displays or mating. However, we found that horizontal transfer and subsequent death occurred in males that fed on the regurgitant of exposed males, and in males that were in contact with dead exposed males. Therefore, MAT devices that contain fipronil should not be used as a standalone treatment but rather be used in combination with other control methods, such as protein bait sprays to ensure the control of female flies.

Queensland fruit fly, Bactrocera tryoni, is one of Australia’s most damaging fruit fly pests. Male Annihilation Technique (MAT) is a method used to manage fruit fly populations by luring and killing male flies, which limits population growth by preventing female flies from mating. MAT devices consist of an attractant and a toxicant, such as maldison or fipronil. Fipronil has a slow knockdown effect, which has been exploited to induce indirect toxicity of a number of insect pests, including cockroaches and termites. This indirect effect, called horizontal transfer, is facilitated through the sharing of food or contact with exposed individuals. Horizontal transfer has been reported in Queensland fruit fly, where exposed males have transferred lethal doses of fipronil to virgin females during courtship and mating. In the present study, we explored three possible modes of horizontal transfer of fipronil against Queensland fruit fly under laboratory conditions. These included: (1) direct contact of females with exposed males (2) contact of males to the regurgitant of exposed males and (3) contact of males with dead exposed males. Our results demonstrated that lethal doses of fipronil were not transferred from males to females during courtship and mating. Male flies that were exposed to fipronil one and six hours prior to dusk were all knocked down, moribund or dead at dusk and therefore did not participate in courtship displays or mating. However, we found that horizontal transfer and subsequent death occurred in males that fed on the regurgitant of exposed males, and in males that were in contact with dead exposed males. Therefore, MAT devices that contain fipronil should not be used as a standalone treatment but rather be used in combination with other control methods, such as protein bait sprays to ensure the control of female flies.

Queensland fruit fly, Bactrocera tryoni, is one of Australia’s most damaging fruit fly pests. Male Annihilation Technique (MAT) is a method used to manage fruit fly populations by luring and killing male flies, which limits population growth by preventing female flies from mating. MAT devices consist of an attractant and a toxicant, such as maldison or fipronil. Fipronil has a slow knockdown effect, which has been exploited to induce indirect toxicity of a number of insect pests, including cockroaches and termites. This indirect effect, called horizontal transfer, is facilitated through the sharing of food or contact with exposed individuals. Horizontal transfer has been reported in Queensland fruit fly, where exposed males have transferred lethal doses of fipronil to virgin females during courtship and mating. In the present study, we explored three possible modes of horizontal transfer of fipronil against Queensland fruit fly under laboratory conditions. These included: (1) direct contact of females with exposed males (2) contact of males to the regurgitant of exposed males and (3) contact of males with dead exposed males. Our results demonstrated that lethal doses of fipronil were not transferred from males to females during courtship and mating. Male flies that were exposed to fipronil one and six hours prior to dusk were all knocked down, moribund or dead at dusk and therefore did not participate in courtship displays or mating. However, we found that horizontal transfer and subsequent death occurred in males that fed on the regurgitant of exposed males, and in males that were in contact with dead exposed males. Therefore, MAT devices that contain fipronil should not be used as a standalone treatment but rather be used in combination with other control methods, such as protein bait sprays to ensure the control of female flies.