Response of phosphine-resistant and -susceptible Lasioderma serricorne adults to different light spectra

Authors: BALIOTA, GEORGIA - University Of Thessaly; ATHANASSIOU, CHRISTOS - University Of Thessaly; Cohnstaedt, Lee

Submitted to: Journal of Stored Products Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/10/2021
Publication Date: 5/28/2021
Citation: Baliota, G.V., Athanassiou, C.G., Cohnstaedt, L.W. 2021. Response of phosphine-resistant and -susceptible Lasioderma serricorne adults to different light spectra. Journal of Stored Products Research. 92:101808. https://doi.org/10.1016/j.jspr.2021.101808.
DOI: https://doi.org/10.1016/j.jspr.2021.101808

Interpretive Summary: The phototaxis behavior of insects or why insects move towards specific colors is important to understand because it allows us to design better surveillance traps and management practices. Understanding the behaviors allows us to take advantage of the insect's natural behaviors. The cigarette beetle is a significant pest of stored products ranging from tobacco to other durable food products. Our findings that ultraviolet light is the most attractive color to the beetles will help storage facilities more effectively manage infestations of this economically damaging insect pest. Furthermore, the results found specific life stages such as unmated males and mated females were most attracted to the ultraviolet color. On the other hand, dark areas were most attractive to the non-dispersing life history stages. This suggests the dispersal stages in the beetles life history are moving towards open spaces (most often associated with sunlight) and collecting these dispersing individuals will help limit the spread of the beetles to adjacent areas. Additionally, the beetles are not dispersing to find food because adding food to the arena did not change the attraction towards ultraviolet light. Lastly, insecticide resistance is always an important matter and if genes or behaviors associated with insecticide resistance are limiting the dispersal or attraction of insects, the most resistant insects will be the least likely to be managed by light traps. However, resistance to phosphine, a common stored product insecticide, did not alter the observed behavioral variation of the insects. This is interesting because insecticides narrow the genetic variation when they select for resistant individuals. However, this narrowing of genetic variation did not narrow the behavioral responses, suggesting a strong heritability and maintenance of variable phototaxis or movement to various colors of light.

Technical Abstract: Laboratory studies were conducted to evaluate the behavior of adults belonging to two different populations of the cigarette beetle, Lasioderma serricorne (F.) (Coleoptera: Anobiidae), one resistant and one susceptible to phosphine, towards specific LED light stimuli. This was done in conjunction with other factors, such as sex and mating, as well as the presence or absence of food. For this purpose, LED lights with wavelength of 400 nanometers (ultraviolet, UV), 460 nanometers (blue), 505 nanometers (green) and 660 nanometers (red) were incorporated in a structure made of transparent acrylic plastic, which served as an arena, while the response of the adults to the visual cues was recorded 24 h after their release. The attractiveness of the UV light was consistently higher than the other spectra, regardless of population, sex, mating status and the presence of food. We observed that the unmated males of the susceptible population showed a stronger flight response towards UV light compared with the unmated females that had a more static behavior, regardless of the presence of food. When mated adults of both sexes were released together in the arena, both populations had similar responses towards the light colors, regardless of the presence of food. Considering our findings, for the vast majority of the parameters tested, the natural behavioral variation in photoattraction was not affected by phosphine resistance. The evaluation of the phototactic responses in L. serricorne is of major importance, as light and pheromone traps for monitoring of the activity of this species have been widely adopted globally in different types of storage and processing facilities of durable commodities.