The Compared Efficiency of the Traditional Method, Radiography without Contrast and Radiography with Contrast in the Determination of Infestation by Weevil (Sitophilus zeamais) in Maize Seeds

Abstract

Technologies that increase safety and efficiency, while facilitating and streamlining the work of seed analysts, are increasingly required by the seed industry. X-ray image analysis is a technique that has been used in the analysis of grain and seeds because it is fast, accurate and non-destructive. The traditional method to verify the presence of insect damage in seeds involves manual cutting of the seeds, which endangers the safety of the analyst and is time-consuming and repetitive work that leads to visual fatigue. The objective of this study was to compared the efficiency of radiographic analysis with and without contrast in the determination of infestation by Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae), at different stages of development, in maize seeds, compared to the traditional method required by seed legislation, which consists of cutting and visual evaluation. Seeds were evaluated regarding the presence of eggs/oviposition signs, larvae, pupae, adult insects, insect damage in five infestation periods (5, 18, 33 and 35 days after infestation), while evaluating the total number of seeds infested, comparing the three methods. For characterization of the oviposition stage, the use of contrast was best at all times of infestation. For the larval stage, there was no difference between the evaluation methods; however, at 18 days, larger infestations were observed by the traditional method. At 5 days, the identification of pupae was better by the traditional method and radiography without contrast, while for the identification of adult insects the best method was the use of radiography without contrast. The characterization of the level of infestation with maize weevil damage was best verified using contrast radiography. Radiographic analysis is efficient in the detection of damage caused by S. zeamais in maize seeds. This method of radiographic analysis (with or without contrast) is thus an auxiliary tool to assess the damage and presence of S. zeamais in maize seeds.

Determination of Sitotroga cerealella infestation in wheat seeds by radiographic and multispectral images

“…The proximity of insect infestation results obtained from contrast x-rays, and from the conventional cutting methodology was demonstrated by Carvalho et al (2019). The accuracy of contrast radiography in detecting infestation is related to the fact that chloroform penetrates damaged areas of the seed and generates differences in tissue density so that areas affected by the insect appear brighter (light gray) on radiographs (Carvalho et al, 2019;Simak, 1957).…”

“…It is noteworthy that even using x-rays with and without contrast, it is possible that signs of oviposition and larvae F I G U R E 3 Characterization of wheat seeds undamaged and with presence of Angoumois grain moth infestation in the developmental stages as signs of eggs/oviposition, larvae, pupae and internal galleries, found by cutting the seeds with a blade, x-rays with and without contrast, and multispectral images. The yellow and orange on seed are areas non-infested by insect, whereas light to dark blue represent infestation or damage by insect go unnoticed in the analysis of these images, which may be a result of the quality of the radiographs, the moisture content of the seeds evaluated, the distance between the seeds and the x-ray emitting source, analyst interpretation, and even radiographic noise (Al-Mezeini et al, 2016;Carvalho et al, 2019;Pedersen & Brown, 1960). Alternatively, such identification problems have been solved by either segmenting radiographs, using algorithms, and in the F I G U R E 4 (a) Representation of marginal means of percentage of infested seeds considering the methodology used and data evaluation according to Tukey test.…”

“…In the traditional "infested seed examination" methodology, the analyst inspects 200 seeds individually, using sharp tools and observing signs of insect infestation on the external surface and damages to the internal structures of the seed. It is a time-consuming methodology, which leads to the analyst's visual fatigue, ergonomic problems, possible risks to the analyst's health due to the use of sharp blades, and compromises the quality of the analyses (Carvalho et al, 2019;França-Silva et al, 2019;Gomes-Junior, 2019).…”

“…The main challenge in seed technology and crop production is the increase in crop yield associated with costs rationalization in inputs and management. To meet these requirements, researchers have sought to develop assets with high productive yield, which can generate goodlooking seeds, with attributes of physical, physiological and sanitary quality, especially with tolerance and resistance to the major diseases and insect pests (Carvalho et al, 2019;Kist et al, 2019;Tavares, Mendonça, Gadotti, & Villela, 2016).…”