Experimental approaches comparing the magnetoreception capabilities of two sister storage mite species Tyrophagus putrescentiae (Schrank) and Tyrophagus longior (Gervais) (Acari: Acaridae)
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- Tyrophagus, Mites, Magnetoreception, Orientation, Alignment, Compass
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Abstract
Animal magnetoreception is a biological mystery that has maintained its intrigue and complication from the very first study. Evidence from the literature suggests that various species of birds, mammals, reptiles, invertebrates and fish have been able to detect and utilise magnetic fields to gain directional information to navigate their respective environments. Regarding the literature focussing on animal magnetoreception, it is evident that the class Arachnida has been considerably overlooked. Acariformes are some of the most diverse organisms within Arachnida, however their magnetoreception capabilities have not yet been investigated. This study focusses on two specific species of storage mites Tyrophagus putrescentiae and Tyrophagus longior, both of which can be pests found in anthropogenic habitats. These two species were selected as they are sister species and of the two of them, only Tyrophagus putrescentiae possesses eyes. The mites were put through several experiments which were slightly altered each time using trial and error to perfect the experimental design each time. The mites were introduced to petri dishes atop a dyed filter paper base dipped in a whole wheat flour solution to keep the mites interested in remaining within the experimental arena. These arenas were placed in a blackened box with an artificial light to ensure that the light was as homogenous as possible (see Figure 1). The mites were allowed approximately 24 hours to move around freely within the petri dishes before they were dispatched using a freezer. These mites were individually counted in their directional groups using a microscope and fine paint brush so that there could be no miscounts. The data that was yielded was analysed using the Rayleigh z test for uniformity from 10 observations per species (n = 10). Results suggest that Tyrophagus longior is capable of orientating using the Earth’s magnetic field as they predominantly gravitate towards the South-South West compass points (p = 0.02). However, results gathered from Tyrophagus putrescentiae suggest that their directional behaviour is predominantly uniform, suggesting randomness and an inability to follow the Earth’s magnetic field (p = 0.414). These results indicate that T. longior relies on magnetoreception to compensate for its inability to visually perceive its environment to maintain sporadic colony structure. T. putrescentiae on the other hand, may still use visual cues to sense larger or more desirable items of food, whilst still being able to maintain a compact, unpredictable colonial structure. This study indicates that these mite species can be used as cheap and effective model species in future magnetoreception studies involving invertebrates. The mechanism(s) that this species uses to sense these magnetic fields, however, is still unknown and yet unstudied.
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Original language | English |
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Award date | 13 Oct 2021 |