Rectal gland exudates and emissions of Bactrocera bryoniae: chemical identification, electrophysiological and pheromonal functions

Abstract

Bactrocera bryoniae is a polyphagous and economically significant fruit fly found in Indonesia, Papua New Guinea and Australia. To understand chemical-mediated sexual communication, and the potential for novel pheromone-based attractants for monitoring and mass-trapping of B. bryoniae, rectal gland exudates and emissions from sexually mature males and females were investigated. Gas chromatography-mass spectrometry showed that male rectal glands contained six compounds, of which 1,7-dioxaspiro [5,5]undecane elicited electroantennographic (EAD) and electropalpographic (EPD) responses in both sexes, ethyl 3-acetoxybutanoate elicited EPD responses in both sexes, N-(3-methylbutyl)acetamide elicited EAD response from males and 4-hydroxy-1,7-dioxaspiro[5.5]undecane elicited EAD responses in males and females and EPD responses in females. Female rectal glands contained 23 compounds with the esters ethyl laurate and ethyl myristate as major components. Amongst the female rectal gland constituents, ethyl laurate, ethyl myristate and ethyl palmitate elicited EAD responses in males and females, N-(3-methylbutyl)acetamide elicited EAD responses in males only, (E,E)-2,8-dimethyl-1,7-dioxaspiro[5.5]undecane elicited EAD responses in males and EPD responses in females, and 2,7-dimethyl-1,6-dioxaspiro[4.5] decane, (E,E)-2-ethyl-7-methyl-1,6-dioxaspiro[4.5]decane, (E,E)-2-ethyl-8-methyl-1,7-dioxaspiro[5.5]undecane, (Z,Z)-2,8-dimethyl-1,7-dioxaspiro[5.5]undecane, (E,E)-2-propyl-8-methyl-1,7-dioxaspiro[5.5]undecane and ethyl caprate elicited EPD responses in females only. Y-tube bioassays indicated that male rectal gland extracts and headspace volatiles attracted females and males, while female rectal gland extracts and headspace volatiles only attracted males. The results suggest that ethyl 3-acetoxybutanoate, 1,7-dioxaspiro [5,5]undecane and 4-hydroxy-1,7-dioxaspiro[5.5]undecane may be components of male-produced sex pheromone in B. bryoniae while (E,E)-2,8-dimethyl-1,7-dioxaspiro [5.5]undecane, N-(3-methylbutyl) acetamide, ethyl laurate, ethyl myristate and ethyl palmitate may be components of female-produced sex pheromone. Ethyl 3-acetoxybutanoate, N-(3-methylbutyl) acetamide, 1,7-dioxaspiro [5,5]undecane and 4-hydroxy-1,7-dioxaspiro[5.5]undecane may be components of male aggregation pheromone. These findings contribute to the understanding of pheromone communication in B. bryoniae and provide a foundation for developing pheromone-based monitoring and control methods.

Electrophysiological Responses of Bactrocera kraussi (Hardy) (Tephritidae) to Rectal Gland Secretions and Headspace Volatiles Emitted by Conspecific Males and Females

“…The major compounds ethyl dodecanoate ( 19 ) and ethyl tetradecanoate ( 25 ) in the present study have also been reported as the major constituents of the rectal glands and headspace volatiles of females in several other Bactrocera [ 8 , 22 , 23 , 26 , 34 ]. The esters of saturated/unsaturated fatty acids and several acids are female specific and have also been reported in other Bactrocera species but in different proportions in each species [ 8 , 22 , 23 , 24 , 26 , 34 , 35 , 36 ]. Interestingly, ethyl dodecanoate ( 19 ) comprised 39.1% in rectal gland samples but 70.2% in headspace samples.…”

“…Although less common, aromatic compounds are also found in Zeugodacus cucurbitae [ 15 ]. The most commonly reported compound in Bactrocera and Zeugodacus rectal gland secretions is ( E , E )-2,8-dimethyl-1,7-dioxaspiro[5.5]undecane [ 8 , 15 , 16 , 19 , 20 , 22 , 23 , 24 , 25 , 26 ]. This compound is also known to occur in other insects, such as Polistes wasps and Ontholestes beetles [ 27 , 28 ].…”

“…This compound is also known to occur in other insects, such as Polistes wasps and Ontholestes beetles [ 27 , 28 ]. N- (3-Methylbutyl)acetamide is a major component in Bactrocera tryoni male rectal glands [ 14 , 23 ] and is also widely reported in other Bactrocera and Zeugodacus species [ 15 , 16 , 22 , 23 , 25 , 26 ]. Female Bactrocera and Zeugodacus have been found to produce the esters of medium chain fatty acids [ 8 , 15 , 22 , 23 , 26 ].…”

Diversity and sex differences in rectal gland volatiles of Queensland fruit fly, Bactrocera tryoni (Diptera: Tephritidae)

“…Conversely, the disproportionately high number of female-biased compounds that are long-Rt suggests that some of those compounds could be involved in shorter range communication. The potential pheromonal function of identified compounds can now be tested in laboratory and field enclosure assays of Qfly behaviours associated with mate attraction and choice [ 18 , 94 , 95 ].…”

Olean (1,7-dioxaspiro[5.5]undecane): A Novel Intraspecific Chemical Cue in Coraebus undatus (F.) (Coleoptera: Buprestidae)

“…Here, we report for the first time the release, and the electroantennographic and behavioral activity, of olean on both sexes of the FOB. This spiroacetal compound has been previously detected only in fruit fly species (Diptera: Tephritidae), and in the stingless bee Partamona cupira (Smith) (Hymenoptera: Apidae) [36][37][38]. Biologically active spiroacetals have been also described as part of the pheromonal communication system of some bark beetles (Coleoptera: Curculionidae), such as (2S,5S)-chalcogran [(2S,5S)-2-ethyl-1,6-dioxaspiro [4.4]nonane] in the genus Pityogenes Bedel [39][40][41], and (5S,7S)-conophthorin [(5S,7S)-7-methy1-1,6-dioxaspiro [4.5]decane] in Pityophthorus carmeli Swaine [42], among others.…”