Near-infrared imaging for automated tsetse pupae sex sorting in support of the sterile insect technique
Argilés-Herrero Rafael,
Salvador-Herranz Gustavo,
Parker Andrew G.,
Zacarés Mario,
Fall Assane G.,
Gaye Adji M.,
Nawaz Arooj,
Takáč Peter,
Vreysen Marc J.B.,
de Beer Chantel J.
Affiliations
Argilés-Herrero Rafael
Joint FAO/IAEA Centre of Nuclear Techniques in Food and Agriculture, Insect Pest Control Laboratory, Department of Nuclear Sciences and Applications, International Atomic Energy Agency
Salvador-Herranz Gustavo
Instituto Universitario de Investigación en Tecnología Centrada en el Ser Humano. Universitat Politècnica de València, Camino de Vera, s/n
Parker Andrew G.
Roppersbergweg 15
Zacarés Mario
Departamento de Ciencias Básicas y Transversales. Facultad de Veterinaria y Ciencias Experimentales, Universidad Católica de Valencia San Vicente Mártir
Fall Assane G.
Institut Sénégalais de Recherches Agricoles, Laboratoire National de l’Élevage et de Recherches Vétérinaires, Service de Bio-écologie et Pathologies Parasitaires
Gaye Adji M.
Ministère de l’Élevage et des Productions animales, Sphères Ministérielles de Diamniadio
Nawaz Arooj
Joint FAO/IAEA Centre of Nuclear Techniques in Food and Agriculture, Insect Pest Control Laboratory, Department of Nuclear Sciences and Applications, International Atomic Energy Agency
Takáč Peter
Institute of Zoology, Slovak Academy of Sciences
Vreysen Marc J.B.
Joint FAO/IAEA Centre of Nuclear Techniques in Food and Agriculture, Insect Pest Control Laboratory, Department of Nuclear Sciences and Applications, International Atomic Energy Agency
Joint FAO/IAEA Centre of Nuclear Techniques in Food and Agriculture, Insect Pest Control Laboratory, Department of Nuclear Sciences and Applications, International Atomic Energy Agency
Tsetse flies are the cyclical vectors of African trypanosomes and one of several methods to manage this vector is the sterile insect technique (SIT). The ability to determine the sex of tsetse pupae with the objective to separate the sexes before adult emergence has been a major goal for decades for tsetse management programmes with an SIT component. Tsetse females develop faster and pharate females inside the pupae melanise 1–2 days before males. This earlier melanisation can be detected by infrared cameras through the pupal shell, and the newly developed Near InfraRed Pupae Sex Sorter (NIRPSS) takes advantage of this. The melanisation process is not homogeneous for all fly organs and the pupa needs to be examined ventrally, dorsally and laterally to ensure accurate classification by an image analysis algorithm. When the pupae are maturing at a constant temperature of 24 °C and sorted at the appropriate age, 24 days post-larviposition for Glossina palpalis gambiensis, the sorting machine can efficiently separate the sexes. The recovered male pupae can then be sterilised for field releases of males, while the rest of the pupae can be used to maintain the laboratory colony. The sorting process with the new NIRPSS had no negative impact on adult emergence and flight ability. A mean male recovery of 62.82 ± 3.61% was enough to provide sterile males to an operational SIT programme, while mean contamination with females (4.69 ± 3.02%) was low enough to have no impact on the maintenance of a laboratory colony.
