Studies on Behavioral Responses of Adult Fruit Flies to Food and Sex Lures in Relation to Their Management

Fruit flies (Diptera: Tephritidae) has been recognized as a cosmopolitan pest of fruits and vegetables. In Pakistan, it is a serious pest of mango, melons, citrus and guava and a major threat to export of these commodities. The pesticides used for this pest leave residues, which are not acceptable for many buyers under WTO agreement. Studies were undertaken to get more precise information on behavioral aspects of fruit flies and to devise management techniques with integrated approach. Field studies on population fluctuation of Bactrocera zonata (Diptera: Tephritidae) were monitored in mango (Mangifera indica) orchards, located at 2 different ecological zones; Dera Ismail Khan and Paniala for three consecutive years, using methyl euginol baited traps. Abiotic weather factors were correlated with population fluctuation. The population density data at both locations showed two prominent peaks with some variations, first in late spring and second and larger one in late summer or early fall. The population builds up of flies in the early spring were found associated with off-host fruits [Ber (Ziziphus jujuba) and Guava (Psidium guajava)] shifted to mango. The second and larger peak was associated with mid and late mango varieties like Chounsa, Fajri. Overall, a positive correlation of population fluctuation in relation to abiotic factors exists. However, inverse relation was found significant in relative humidity (RH). In a series of experiments, comprised of lures (food and sex), and neem extracts was tested in comparison with untreated check to devise the IPM model for fruit fly management in mango orchards. The IPM model reduced the infestation to 0.4 and 0.8% in dropped and harvested fruits respectively in comparison with that of farmers practice where it was 7% in dropped fruits and 10.5% in harvested fruits. The experiments to evaluate the management techniques revealed bait (Protein hydrolysate) application technique (BAT) and crop hygiene (CH) equally effective to that of synthetic insecticide (Diptrex 80SP). In other experiments, BAT + CH and neem oil reduced 87.27 and 75.11% infestation of fruit fly, as compared to Diptrex 80SP (2.42%). Turmeric oil was less effective than neem oil. The integration of crop hygiene (removal of weed flora and burying of damaged fruits) with intermittent spray of bait and one neem application on and around the field significantly reduced the fruit fly infestation. The farmers practice fields had 25.3% fruit fly infestation whereas it was 3.6% where IPM model was applied. In a series of experiments, infective capabilities of entomopathogenic nematodes (EPN) were evaluated against fruit flies under lab conditions. Results indicated Hetrerorhabditis bacteriophora and S. feltiae with 97.6 and 85.10% infection and were leading EPN among the tested nematodes. In addition, the fly emergence was better option for EPN evaluation than dissection of insect. EPN showed comparatively less infectiveness towards fruit fly pupae and only 60% infection was caused due to S. feltiae followed by 58% due to H. indica. The progeny development experiment with three nematode species viz. S. carpocapsie, S. feltiae and H. bacterophora, in the lab, showed J3 started emerging in all nematode after day 11. The J3 production increased until day 13 for S. feltaie and ends on day 23. H. bacterophora produced 697 progeny in 16 days. Progeny production as unit body weight, S. carocapsae produced 784 J3/mg followed by H. bacterophora and S. feltiae with 580 and 221/mg body weight of fruit fly. In another experiment, LC50 for S. feltiase was 516 J3/ml and H. bacterophora was 600 J3. Fruit fly Bactrocera zonata pupation habitat preference was evaluated in two lab experiments. In first experiment, three soil types were tested for preferred pupation depth by late instar fruit fly larvae. Results revealed more than 57% of the pupae preferred 2.54 - 5.02 cm depth for pupation comparing with 20% in the top 2.53 cm, 17.7% in the 5.03 - 7.67 cm and only 2.1% in the 7.67 - 10.23 cm. The experiment regarding soil particle sizes was evaluated for pupation depth preference. Results indicated 2.53 - 5.03 cm is the preferred depth for all particles sized except for the 13 - 25 particle size where pupae preferred top 2.54 cm to other two depths tested. In another experiment with neem as additive adult diet, showed adult feeding on ground neem seed kernel with sugar and yeast hydrolysate arrested the egg laying capacity significantly.