Effect of Lure Combination on Fruit Fly Surveillance Sensitivity.

Surveillance for invading insect pests is costly and the trapper usually finds the traps empty of the target pest. Since the successful establishment of new pests is an uncommon event, multiple lures placed into one trap might increase the efficiency of the surveillance system. We investigated the effect of the combination of the Tephritidae male lures - trimedlure, cuelure, raspberry ketone and methyl eugenol - on catch of Ceratitis capitata, Zeugodacus cucurbitae, Bactrocera tryoni, B. dorsalis, B. aquilonis and B. tenuifascia in Australia and the USA (not all species are present in each country). The increase in trap density required to offset any reduction in catch due to the presence of lures for other Tephritidae was estimated. The effect of increasing trap density to maintain surveillance sensitivity was modelled for a hypothetical population of B. tryoni males, where the effective sampling area of cuelure traps for this species has been estimated. The 3-way combination significantly reduced the catch of the methyl eugenol-responsive B. dorsalis. Unexpectedly, we found that trimedlure-baited traps that contained methyl eugenol had ×3.1 lower catch of C. capitata than in trimedlure-only-baited traps in Australia, but not in Hawaii where no difference in catch was observed, we cannot satisfactorily explain this result. Based on the data presented here and from previous research, combinations of some male lures for the early detection of tephritid flies appear compatible and where there is any reduction in surveillance sensitivity observed, this can be offset by increasing the density of traps in the area.

Low Dose Gamma Irradiation Does Not Affect the Quality or Total Ascorbic Acid Concentration of "Sweetheart" Passionfruit (Passiflora edulis).

Passionfruit (Passiflora edulis, Sims, cultivar "Sweetheart") were subject to gamma irradiation at levels suitable for phytosanitary purposes (0, 150, 400 and 1000 Gy) then stored at 8 °C and assessed for fruit quality and total ascorbic acid concentration after one and fourteen days. Irradiation at any dose (≤1000 Gy) did not affect passionfruit quality (overall fruit quality, colour, firmness, fruit shrivel, stem condition, weight loss, total soluble solids level (TSS), titratable acidity (TA) level, TSS/TA ratio, juice pH and rot development), nor the total ascorbic acid concentration. The length of time in storage affected some fruit quality parameters and total ascorbic acid concentration, with longer storage periods resulting in lower quality fruit and lower total ascorbic acid concentration, irrespective of irradiation. There was no interaction between irradiation treatment and storage time, indicating that irradiation did not influence the effect of storage on passionfruit quality. The results showed that the application of 150, 400 and 1000 Gy gamma irradiation to "Sweetheart" purple passionfruit did not produce any deleterious effects on fruit quality or total ascorbic acid concentration during cold storage, thus supporting the use of low dose irradiation as a phytosanitary treatment against quarantine pests in purple passionfruit.

Development of phytosanitary cold treatments for oranges infested with Bactrocera invadens and Bactrocera zonata (Diptera: Tephritidae) by comparison with existing cold treatment schedules for Ceratitis capitata (Diptera: Tephritidae).

Phytosanitary cold treatments were tested for Bactrocera invadens Drew, Tsuruta, and White and Bactrocera zonata (Saunders) using comparisons with Ceratitis capitata (Wiedemann). Oranges were infested by puncturing holes in the peel and allowing tephritids to oviposit in the holes. The treatments were initiated when the larvae reached late third instar because previous research had shown that stage to be the most cold tolerant for all three species. Results show that B. invadens is not more cold tolerant than C. capitata and B. zonata at 1.0 +/- 0.1 degrees C and lend support to the use of C. capitata cold treatment schedules for B. invadens. It cannot be concluded that B. zonata is not more cold tolerant than C. capitata.

Comparison of in vitro heat and cold tolerances of the new invasive species Bactrocera invadens (Diptera: Tephritidae) with three known tephritids.

Bactrocera invadens Drew, Tsuruta & White (Diptera: Tephritidae) is spreading throughout central Africa attacking a variety of fruit; quarantines are placed on fruit from this region that are considered hosts. The only phytosanitary treatment that is commercially available is an ionizing irradiation treatment for all Tephritidae at 150 Gy. The development of other treatments, such as heat, cold, or fumigation, usually requires testing tens of thousands of insects at a dose that provides efficacy and may take several years. It may be possible to shorten the time required to develop treatments by comparing tolerance of a new quarantine pest to tolerances of pests with similar behaviors and modes of infestation for which treatment schedules are available. Cold and heat tolerance ofB. invadens was compared with tolerance of Anastrepha ludens (Loew), Bactrocera dorsalis (Hendel), and Ceratitis capitata (Wiedemann) in vitro. Third-instar B. invadens was no more cold tolerant than the other species when treated in diet at 0.94 +/- 0.65 degrees C and no more heat tolerant than C. capitata when immersed in vials in water at 44.7 +/- 0.1 degrees C. The data at 0.94 +/- 0.65 degrees C was used to include B. invadens in a USDA cold treatment schedule for citrus fruit from Africa so that trade would not be interrupted while protecting U.S. agriculture from this invasive pest.