Factors influencing the responsiveness of male oriental fruit fly, Bactrocera dorsalis, to Methyl Eugenol (3, 4 Dimethoxyalyl Benzene)

Abstract

The parapheromone, methyl eugenol (ME) (3, 4 dimethoxyalyl benzene), occurring in a variety of plant species, is the most effective known lure attracting the male oriental fruit fly, Bactrocera dorsalis (Hendel). Bioassays were carried out in a wind tunnel under laboratory conditions, to evaluate behavioural responses of male flies to seven concentrations of ME, diurnal pattern of male responsiveness and age of responsiveness to methyl eugenol and the factors influencing the responsiveness of males to ME. Attraction of male flies to ME was assessed by monitoring three behavioural parameters namely the number of flies performing upwind zigzagging anemotactic flights over at least 50cm to the ME source, total number of flies landing on the source and the total number of flies moved into the upwind section of the wind tunnel after 20 minutes. The responsiveness of males to ME increased with the increase of the concentration, 0.0001µl eliciting the lowest and 5.0µl producing the highest attraction in males. All the males which were attracted exhibited a feeding response and no other behavioural response was observed. Male responsiveness to ME was not uniform throughout the day. The responses were highest during the morning (82.6%), declined to a lower level in the afternoon (41.8%) and then dropped markedly at the 'dusk' period (11.4%). This decline in response to ME suggested an inverse relationship to the time of peak mating activity in the male. Male responsiveness to ME was found to be age-dependent. The response to the attractant increased with the age of the flies indicating a relationship between responses to ME and sexual maturity of the flies. No significant responses were evident when males were 1, 3 and 5 days old. Males were strongly attracted to ME by the time they were 10d-old and the highest attraction was observed in 15d-old males. Attraction to ME was still considerably high even when they were 25 and 30d-old.

BdorOBP2 plays an indispensable role in the perception of methyl eugenol by mature males of Bactrocera dorsalis (Hendel)

“…Immature male flies were obviously not attracted to ME, but the highest attraction was observed in 15-day-old males, a result consistent with Karunaratne and Karunaratne 40 . That BdorOBP2 was abundantly expressed in the mature male antennae agrees with prior findings by Zheng et al .…”

“…Notably, the responsiveness to ME in B. dorsalis males was not uniform throughout the day: it peaked in the morning, declined in the afternoon, and it then dropped markedly at dusk 40 . This daily fluctuation in the male responsiveness to ME suggests an inverse relationship with the daily cycle of their mating behaviour.…”

“…The Oriental fruit fly is a biologically interesting and economically relevant insect herbivore, whose mature males are effectively trapped by ME. Over the past few decades, numerous studies have been focused on the factors influencing the ME-luring efficiency on males, and the metabolic pathways or metabolites of ME after feeding by B. dorsalis adults 7 , 9 , 12 , 40 . However, the molecular mechanisms underlying the olfactory perception of ME remain poorly understood.…”

Proteomics/qPCR protocol to estimate physical ages of wild male oriental fruit flies, Bactrocera dorsalis (Hendel)

“…It was within the range of the estimated physical age based on qPCR approach of 12.03+ 5.46-d-old. This confirmed the statement of Karunaratne and Karunaratne (2012) that no significant responses to ME were evident when males were 1, 3 and 5 days old. Males were strongly attracted to ME by age 10 d old and the highest attraction was observed in 15 d old males.…”

BdorOR88a Modulates the Responsiveness to Methyl Eugenol in Mature Males of Bactrocera dorsalis (Hendel)

“…Bioassays were performed in the laboratory following a method similar to that of Karunaratne and Karunaratne (2012) and Liu H. et al (2017) . For the assessment of effects of age on the male responses to ME, each sample of 2-day- and 10-day-old males (200 of each) were randomly selected as the test subjects and released into a screened cage (1.0 m × 1.0 m × 1.0 m) without a trap.…”