368.2 - Functional Morphology of Sensory Organs of the House Cricket, Acheta domesticus (L.): A Morphological and Physiological Investigation

Vonnie Shields (Towson University, Fisher College of Science and Mathematics), Cameron Weaver (Towson University, Fisher College of Science and Mathematics), Shannon Farmer (Towson University, Fisher College of Science and Mathematics)

Insects have paired antennae that bear many sensory organs or sensilla. These sensilla allow them to gather information about olfactory, gustatory, and mechanosensory environmental cues. Both antennae of male and female house crickets, Acheta domesticus, bear approximately 200 segments. The first aim of this study was to morphologically characterize the sensillum types on the antennae. Scanning and transmission electron microscopy studies revealed that each antennal segment bears seven sensillum types. Four types have external morphological features suggestive of olfactory sensilla, namely an abundance of cuticular pores. Two of these types resemble short to medium-sized pegs, a third resembles a short peg with longitudinal ridges or “fingers,” while a fourth resembles a short peg recessed in a deep pit. Each antenna also bears two sensillum types devoid of external cuticular pores, suggestive of a mechanosensory function. One of these types is a long hair-like sensillum with conspicuous ridges, while the other is a small circular depression on the antennal surface. Another medium-sized sensillum bears diagonal circular ridges and a single apical pore, indicative of a gustatory function.

The second aim of this study was to determine which odorants elicited positive or negative anemotaxis (orientation toward or away from a food source, respectively), suggestive of possible food lures or repellents. Odorants permeate through the environment and bind to receptor sites in olfactory neurons. Once these molecules bind, chemical signals are converted to electrical ones. Olfactory signals are then transmitted to higher-order olfactory processing centers in the insect’s brain. Depending on the odorant, this may trigger a behavioral response(s). Odorants may be used to detect and identify food, mating partners, and avoidance of predators. Previous studies in the lab have focused on odorants associated with some fruits, vegetables, and proteins. In this study, we tested some odorants associated with amines derived from ammonia. We hypothesized that such odorants would elicit negative anemotaxis. We carried out each experiment over a 24-hour period in plastic bins. We found that the crickets elicited positive anemotaxis to the odorants tested, leading us to reject our hypothesis. These findings are important as house crickets are pests and known to contaminate food sources. This finding raises concerns about foodborne illnesses associated with microbial pathogens and can create health concerns especially in developing countries. The results of this study may prove to be helpful in the suggestion of lures as effective biocontrol measures against pests.

Supported by NIH Grant R-25-GMO5826416 and NSF MRI Grant 1626326.