Dimethyl disulfide and dimethyl trisulfide: so similar yet so different in evoking biological responses in saprophilous flies

Abstract

Dimethyl disulfide (DMDS) and dimethyl trisulfide (DMTS) are used by saprophilous insects to locate breeding sites (decaying organic matter), and by brood-site deceptive flowers to attract such insects. However, little is known about the relative importance of these two compounds in eliciting electrophysiological and behavioural responses in the insects. Here, we compared the relative attractiveness of DMDS and DMTS to saprophilous flies in field choice experiments and tested whether potential differences in field responses can be explained by differences in electrophysiological antennal responses to these compounds. Field experiments revealed that the attractiveness of a mixture of these compounds is due to DMTS alone. This result was confirmed by electroantennographic recordings in which flies of four tested species of Calliphoridae (Lucilia sericata, L. caesar, Calliphora vicina, Protocalliphora azurea) and one Muscidae (Musca domestica) respond clearly to DMTS, but not to DMDS. In house flies, however, DMTS elicited electrophysiological responses only, not reflected in behavioural assays. Despite the fact that DMTS and DMDS exhibit similar chemical structures, both the electroantennographic and field responses from saprophilous flies to these two compounds strongly differed. Our study suggests that oligosulfide-responsive saprophilous flies rely on DMTS and not DMDS for finding appropriate breeding sites and that DMTS and not DMDS could act as a key mediator for pollinator attraction in brood-site deceptive plants

Floral Volatiles in a Sapromyiophilous Plant and Their Importance in Attracting House Fly Pollinators

“…Even if DMTS elicited the strongest physiological response, it did not play any role in the attraction of house flies. A similar result recently has been shown by Zito et al (2014). This compound, therefore, seems generally not to elicit attractive responses in house flies despite being sensitively detected by their antennae.…”

“…This compound, therefore, seems generally not to elicit attractive responses in house flies despite being sensitively detected by their antennae. In other flies (Calliphoridae), however, this compound does elicit both antennal and positive behavioral responses (Zito et al 2014). In behavioral assays, Cossé and Baker (1996) showed that mixtures are better attractants for house flies looking for breeding sites than single compounds.…”

“…However, while nitrogen and sulfur containing compounds are reported in the literature in connection with deceitful attraction and in the syndrome of sapromyiophily (Woodcock et al 2014), only DMTS has been tested singly in behavioral experiments to confirm its biological activity. It is highly attractive to calliphorid flies (Zito et al 2014). Musca domestica is not the sole pollinator of P. laevigata.…”

“…Among these compounds are sulphur containing (e.g., DMTS) and nitrogen containing (e.g., indole) compounds as well as aliphatic acids, accompanied by aliphatic alcohols and esters. The function of these compounds/compound classes as pollinator attractants has been demonstrated in physiological and behavioral experiments although most studies have tested mixtures and not single components (Shuttleworth and Johnson 2010;Stensmyr et al 2002;van der Niet et al 2011;Zito et al 2014). Recently, Zito et al (2013) demonstrated that the sapromyiophilous flowers of Caralluma europaea attract Musca domestica by Bsweet^terpinolene, α-terpinene, and linalool.…”

The role of metals in mammalian olfaction of low molecular weight organosulfur compounds

“…15). 40,66a The homology model was felt to be appropriate because of the high sequence identity between the MOR244-3 and M2 receptor TM regions. A common structural feature of both MOR244-3 and the M2 receptor is an internal aqueous channel (Fig.…”