Olfactory Cues from Pathogenic Fungus Affect the Direction of Motion of Termites, Coptotermes formosanus

Abstract

Formosan subterranean termites, Coptotermes formosanus, tend to avoid pathogen odors when tested in Y-tube olfactometers, but approach and groom exposed nestmates to remove pathogens from their cuticle and maintain a healthy population. To better understand their differential reaction to pathogens and their odors, the relationship between odor cues and direction of motion was examined with the fungus Isaria fumosorosea K3 strain. The results indicate that nestmate odor was strongly attractive only in tests where fungal odors were present in both branches of the olfactometer. Termites generally avoid fungal odors when offered a choice without fungal odor. We also tested termite aversion to 3-octanone and 1-octen-3-ol, major surface chemical compounds of I. fumosorosea K3, and estimated the total mass of these compounds present on the conidial surface by direct extraction method. The total quantity of these chemicals on the surface of fungal conidia was estimated to be approximately 0.01 ng per 107 conidia. This study demonstrates a context dependent behavioral change in termites in response to the odors of pathogenic fungi.Electronic supplementary materialThe online version of this article (doi:10.1007/s10886-015-0649-8) contains supplementary material, which is available to authorized users.

Volatiles of bacteria associated with parasitoid habitats elicit distinct olfactory responses in an aphid parasitoid and its hyperparasitoid

“…While gustatory information may indicate the quality of food, mates or egg deposition sites after contact, both visual and olfactory cues provide information about where to search in the first place (Wäckers & Lewis, ). Likewise, several insects use olfaction to avoid threats and risks associated with toxic environments, pathogens or predators (Stensmyr et al, ; Yanagawa, Imai, Akino, Toh, & Yoshimura, ).…”

The Effects of Trichoderma Fungi on the Tunneling, Aggregation, and Colony-Initiation Preferences of Black-Winged Subterranean Termites, Odontotermes formosanus (Blattodea: Termitidae)

“…In addition, termites rely on altered behaviors to protect themselves from microbial pathogens. For example, the odor of entomopathogenic fungi has been shown to trigger alarm responses [7,8], grooming [8][9][10][11], attacking and cannibalism [12], cadaver burying [13], and spatial avoidance [14][15][16][17] in termites. These anti-pathogen responses, referred as "behavioral immunity" or "social immunity," have received increasing attention in recent years [18][19][20][21].…”

Fungal volatile organic compounds show promise as potent molluscicides

“…The VOCs of Metarhizium and other fungi are repellents for several invertebrates including store grain pests ( Sitophilus zeamais Motschulsky) , and termites ( Coptotermes formosanus Shiraki) . Repellency is dependent upon the target since some insects are tolerant of higher quantities than others.…”

“…39 The VOCs of Metarhizium and other fungi are repellents for several invertebrates including store grain pests (Sitophilus zeamais Motschulsky), and termites (Coptotermes formosanus Shiraki). 21,27,28 Repellency is dependent upon the target since some insects are tolerant of higher quantities than others. For example, mushroom pests such as the phorid fly, Megaselia halterata Wood, are tolerant of relatively high levels of 1-octen-3-ol.…”

“…[21][22][23] Most notable are 1-octen-3-ol, 3-octanone and 1-octene, which are produced by a wide range of fungi including saprophytic molds, mushrooms and entomopathogenic fungi including species of Beauveria and Metarhizium. [24][25][26][27][28] Exactly why entomopathogenic fungi produce these compounds is unclear but the fact that so many insects exhibit avoidance behavior suggest that they are responding to VOCs. 20,29 This paper reports that these compounds are highly repellent or toxic to slugs and snails.…”