Age‐dependent effect of methyl eugenol on male mating success of the peach fruit fly, Bactrocera zonata

Abstract

The peach fruit fly, Bactrocera zonata (Saunders) (Diptera: Tephritidae), is a pest of economic importance, endemic to South and South‐East Asia. It is highly invasive and due to its quarantine pest status, it interferes with horticultural trade. Males of many Bactrocera species are strongly attracted to methyl eugenol (ME) [1,2‐dimethoxy‐4‐(2‐propenyl) benzene], a phenylpropanoid compound naturally occurring in many plant species. Feeding on ME is also reported to enhance male mating success in several Bactrocera species. Such an effect can increase the effectiveness of the sterile insect technique (SIT). The current study was designed to identify the sexual maturity age of males of B. zonata, the relation between male age and attraction to ME, and the effect of ME on male mating success. The results showed that males initiated their mating at 8 days of age and attained the highest mating success at 16 days of age. The percentage of immature males responding to ME increased with age and the maximum response was observed during the age of sexual maturity. Methyl eugenol treatment at sexual maturity significantly enhanced male mating success over untreated males. The males treated with ME at a sexually immature age (5 days old) achieved significantly higher mating success after reaching sexual maturity. These findings suggested that B. zonata males can be treated with ME at the age of 5 days in sterile‐male ‘holding and release’ facilities and thereafter released in the field, where they are expected to achieve higher mating success after attaining sexual maturity. The results are discussed as a valid approach for enhancing the effectiveness of SIT application against B. zonata.

Methyl eugenol aromatherapy: a delivery system facilitating the simultaneous application of male annihilation and sterile insect technique against the peach fruit fly

“…Holding maturing males beyond 4-5 days until their maturity would add costs to the programme and may decrease the quality of males as a consequence of overcrowded conditions. 51 Rasool et al 33 demonstrated that 5-day-old B. zonata males treated with ME by feeding had a mating advantage over untreated males in mating trials conducted at the onset of sexual maturity (8 days old) and older. However, holding males for 8-9 days for ME treatment is not practicable owing to financial costs, yet treating males at 5 days of age and releasing them at 6 days of age, with males gaining the mating advantage at 8-9 days of age, seems practicable.…”

“…The males and females were separated within 24 h of emergence, well before attaining sexual maturity at 8 days of age. 33 Flies used for experiments were maintained in a separate room at 25 ± 2 °C temperature, 60 ± 5% relative humidity (RH) and 14 h:10 h, light:dark photoperiod, matching the conditions in the colony holding room.…”

“…The age of the males was either 5 or 15 days. These ages were selected, because earlier work 33 showed that 5-day-old males did not mate when provided with virgin, mature females and 15-dayold males showed maximum mating propensity. Based on these observations, 5-day-old males were here termed 'immature' and 15-day-old males were termed 'mature'.…”

“…32 Compared to B. dorsalis, little is known about the effects of ME on B. zonata, available data suggest that pre-release ME exposure might be more easily incorporated into SIT efforts against this species. In particular, Rasool et al 33 demonstrated that B. zonata males fed ME at 5 days of age (when sexually immature) had a mating advantage over untreated males when tested after attaining sexual maturity. As noted above, holding adult Bactrocera males for 4-5 days postemergence is standard protocol in SIT operational programmes, 34,35 and the enhanced mating success of B. zonata males fed ME when 5 days old opens the opportunity of releasing sterile males treated with ME.…”

Less is more: Fewer attract-and-kill sites improve the male annihilation technique against Bactrocera dorsalis (Diptera: Tephritidae)

“…Around 84 species of dacine fruit flies are known responders to ME [45]. Among these, ME response varies across the Bactrocera dorsalis sibling species complex, manifested through both dose sensitivity and age of males [46][47][48]. Differences in responsiveness to ME are discrete enough that they can be used as a behavioral parameter to distinguish among species in the complex [49].…”