Near Infrared Imaging As a Method of Studying Tsetse Fly (Diptera: Glossinidae) Pupal Development

Abstract

Near infrared (NIR) photography and video was investigated as a method for observing and recording intrapuparial development in the tsetse fly Glossina palpalis gambiensis and other Muscomorpha (Cyclorrhapha) Diptera. We showed that NIR light passes through the puparium, permitting images of the true pupae and pharate adult to be captured. Various wavelengths of NIR light from 880 to 1060 nm were compared to study the development of tsetse fly pupae from larviposition to emergence, using time-lapse videos and photographs. This study was carried out to advance our understanding of tsetse pupal development, specifically with the goal of improving a sorting technique which could separate male from female tsetse flies several days before emergence. Separation of the sexes at this stage is highly desirable for operational tsetse sterile insect technique control programmes, as it would permit the easy retention of females for the colony while allowing the males to be handled, irradiated and shipped in the pupal stage when they are less sensitive to vibration. In addition, it presents a new methodology for studying the pupal stage of many coarctate insects for many applications. NIR imaging permits observation of living pupae, allowing the entire development process to be observed without disruption.

Multispectral imaging for quality control of laboratory‐reared Anastrepha fraterculus (Diptera: Tephritidae) pupae

“…Previous studies have shown the potential of imaging systems in entomological studies. Moran and Parker (2016) used NIR imaging to study the intrapupal development of Tsetse fly (Diptera: Glossinidae), and to distinguish males from females several days before emergence. Hyperspectral imaging (HSI) spectroscopy was evaluated for determining the age and species of blowfly (Diptera: Calliphoridae) (Voss, Magni, Dadour, & Nansen, 2017).…”

Detection of live larvae in cocoons of Bathyplectes curculionis (Hymenoptera: Ichneumonidae) using visible/near‐infrared multispectral imaging

“…A higher female to male wasp ratio is desirable for achieving higher parasitism because only females can oviposit eggs onto the host larvae. A previous study showed that the gender of the tsetse fly ( Glossina palpalis gambiensis ) (Diptera: Glossinidae) could be identified at the pupal stage using NIR imaging . This study did not consider determining the gender of larvae in cocoons, however, we assume that the MS imaging system would have a similar ability for the studied parasitoid.…”

“…A recent study on the identification of rice weevil species, Sitophilus (Coleoptera: Curculionidae), used an MS imaging approach by selecting only images of the useful wavelengths from an originally visible/NIR hyperspectral image . A similar approach was used to study pupal development in the tsetse fly ( Glossina palpalis gambiensis ) (Diptera: Glossinidae) using NIR hyperspectral imaging . These studies involving hyperspectral imaging have highlighted the MS imaging system as a prospective technology with practical application, primarily due to a significant reduction in image size and rapid analysis .…”

“…20 A similar approach was used to study pupal development in the tsetse fly (Glossina palpalis gambiensis) (Diptera: Glossinidae) using NIR hyperspectral imaging. 24 These studies involving hyperspectral imaging have highlighted the MS imaging system as a prospective technology with practical application, primarily due to a significant reduction in image size and rapid analysis. 13,20,24 The potential of the MS imaging system to evaluate seed viability, 23,25 for varietal identification of seeds 26 or to detect adulteration in meat has already been demonstrated.…”

“…24 These studies involving hyperspectral imaging have highlighted the MS imaging system as a prospective technology with practical application, primarily due to a significant reduction in image size and rapid analysis. 13,20,24 The potential of the MS imaging system to evaluate seed viability, 23,25 for varietal identification of seeds 26 or to detect adulteration in meat has already been demonstrated. 27 The method has shown potential in the rapid determination of species of blowfly puparias (Diptera: Calliphoridae) and their age.…”