Differentiating Oriental Fruit Moth and Codling Moth (Lepidoptera: Tortricidae) Larvae Using Near-Infrared Spectroscopy

Abstract

Cydia pomonella (L.) and Cydia molesta (Busck) (Lepidoptera: Tortricidae) are two important lepidopteran pests that may co-occur in apple orchards and are difficult to differentiate in the larval stage. We investigate the possibility of using near-infrared spectroscopy (NIRS) coupled with partial least squares analysis to distinguish the larvae of the two species. We further assess whether wild individuals can be differentiated using laboratory strains of the two species for model calibration. The NIRS spectra of C. molesta and C. pomonella differed most in the wavelengths between 1,142 and 1,338 nm. Using these wavelengths, partial least squares analysis allowed the differentiation of C. molesta and C. pomonella at the larval stage with very low error, but only as long as both the calibration and prediction sets for individuals had the same origin (either both from the laboratory or both from the field). Errors that appeared when using laboratory individuals for calibration were owing to the divergence of the C. pomonella laboratory strain, most likely following evolution during rearing. Thus, NIRS appears to be a promising tool for the easy and rapid identification of individuals in the field, provided that it is calibrated based on a subset of field individuals.

Near‐infrared spectroscopy (NIRS) for taxonomic entomology: A brief review

“…Some change in cuticular composition was observed in the laboratory offspring of wild-caught flies, leading the authors to highlight the need to develop calibration models from the same population as the test population. Siegwart, Bouvier, Maugin, Lecomte, and Lavigne (2015) used NIRS (780-2,500 nm) with partial least squares discriminant analysis (PLS-DA) to distinguish larvae of two common pests of apple orchards, Cydia pomonella (L.) and Cydia molesta (Busck), with 100% accuracy. The wavelengths showing the greatest difference were between 1,142 and 1,338 nm, corresponding to carboxyl functional groups, presumably from cuticular hydrocarbons.…”

“…The main differences in NIR signatures were attributed to cuticular hydrocarbons. (Siegwart et al, 2015) Noctuidae 2 450-2,500 Supervised 93.4%-89.5% (Jia et al, 2007) Hymenoptera Braconidae 2 750-1,700 Supervised >85% (Cole et al, 2003) Trichogrammatidae 3 405-907 Supervised >90% (Nansen et al, 2014) a For field-collected specimen. Accuracy on laboratory-reared specimens was almost 100%…”

“…Siegwart, Bouvier, Maugin, Lecomte, and Lavigne () used NIRS (780–2,500 nm) with partial least squares discriminant analysis (PLS‐DA) to distinguish larvae of two common pests of apple orchards, Cydia pomonella (L.) and Cydia molesta (Busck), with 100% accuracy. The wavelengths showing the greatest difference were between 1,142 and 1,338 nm, corresponding to carboxyl functional groups, presumably from cuticular hydrocarbons.…”

Detecting Host-Plant Volatiles with Odorant Receptors from Grapholita molesta (Busck) (Lepidoptera: Tortricidae)

“…3 The adults can move between host plants, switching between different species or cultivars, such as peaches, nectarines, apples, and pears. 4,5 Changes in the components of host-plant volatiles are the primary reason that G. molesta switch among host plants. 6 G. molesta responds to a variety of host-plant volatiles, including alcohols, aldehydes, esters, terpenes, benzonitriles, and alkanes.…”

“…Grapholita molesta Busck (Lepidoptera: Tortricidae), known as the oriental fruit moth, is a common, economically important, multivoltine pest that causes serious damage to pome and stone fruits worldwide. , Its larvae cause damage by not only feeding on young twigs but also directly feeding on the pulp . The adults can move between host plants, switching between different species or cultivars, such as peaches, nectarines, apples, and pears. , Changes in the components of host-plant volatiles are the primary reason that G. molesta switch among host plants , Green-leaf volatiles and aromatics attract female G. molesta , whereas host-plant volatiles mixed with sex pheromones can enhance attractiveness to male G. molesta .…”