Bactrocera tryoni is a polyphagous fruit fly that is predicated to have continuous breeding in tropical and subtropical Australia as temperature and hosts are not limiting. Nevertheless, in both rainforest and tropical agricultural systems, the fly shows a distinct seasonal phenology pattern with an autumn decline and a spring emergence. Temperature based population models have limited predictive capacity for this species and so the driver(s) for the observed phenology patterns are unknown. Using a demographic approach, we studied the age-structure of B. tryoni populations in subtropical Australia in an agricultural system, with a focus on times of the year when marked changes in population abundance occur. We found that the age-structure of the population varied with season: summer and autumn populations were composed of mixed-age flies, while late-winter and early-spring populations were composed of old to very old individuals. When held at a constant temperature, the longevity of adult reference cohorts (obtained from field infested fruits) also showed strong seasonality; the adults of spring and early autumn populations were short-lived, while late autumn and late winter adults were long-lived. While still expressing in modified landscapes, the data strongly suggests that B. tryoni has an endogenous mechanism which would have allowed it to cope with changes in the breeding resources available in its endemic monsoonal rainforest habitat, when fruits would have been abundant in the late spring and summer (wet season), and rare or absent during late autumn and winter (dry season).

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The surveillance and management of Dacini fruit fly pests are commonly split by fly gender: male trapping focuses on the dacine ‘male-lures’, whereas female trapping focuses on lures based on host-fruit volatiles. Although the males of several Dacini species have been reported to be attracted to host fruit volatiles, the option of using host-fruit traps for males has, to date, been ignored. Males of the cue-lure responsive fruit fly Bactrocera tryoni (Froggatt) have been recorded as responding to host-fruit volatile blends, but it is not known how frequently this happens, if it is age-dependent, or the strength of the response relative to cue-lure throughout the year. Here, we conducted an olfactometer experiment to test the lifetime (weeks 1–15) response of B. tryoni males to the odor of tomato, a known host of this fly, and compare catches of wild males to tomato-based traps and cue-lure traps in the field. Bactrocera tryoni males started to respond to tomato odor as they sexually matured (2 to 3 wk olds) and thereafter showed consistent olfactory response until advanced age (15 wk). In the field, wild males were captured by tomato-based traps throughout the year at a level not significantly different from cue-lure traps. The reason for the consistent B. tryoni male response to host fruit odor at this stage is not known, but it certainly occurs at a level greater than can be continued to be ignored for both basic and applied research.

ABASTRACTA comparative efficacy of five essential oils (EOs) of cardamom (Elettaria cardamomum Maton), Cinnamon (Cinnamomum zeylanicum Blume), Clove (Syzygium aromaticum L.), Eucalyptus (Eucalyptus spp.), and Jasmine (Jasminum spp.) was assessed against two-spotted spider mite (TSSM), Tetranychus urticae. The mites were reared under laboratory conditions and oils were procured from market. Fumigation experiment was done in a glass jar making it airtight. The mortality of mites was recorded after 48 hours of treatment. The result showed that the most potent fumigant was cardamom with highest LC 50 values 180.57nlcm -3 , 199.45 nlcm -3 and 395.36 nlcm -3 for protonymph, deutonymph and adult respectively. Jasmine (354.05 nlcm -3 ), cinnamon (659.13nlcm -3 ) and eucalyptus (1033.7 nlcm -3 ) were least effective oils for protonymh, deutonymph and adult stages accordingly. All the oils used in the current study have a variable degree of toxicity on different stages of TSSM life cycle . In case of all tested oils, protonymph showed 50% mortality at lower doses(range of value was 180.57 to 354.05 nlcm-3 ) but adult needed two to three fold higher doses( range of value was 395.36 to 1033.7 nlcm-3 ) than protonymh. The result has revealed that, all these oils have great potentiality to be used as an acaricide in pests control program.