Estimation of the lower temperature threshold and thermal requirement of olive fruit fly Bacterocera oleae Rossi. (Dip:Tephritidae) using Degree-Day and Ikemoto linear models

Olive fruit fly, Bactrocera oleae (Rossi) (Dip: Tephritidae), is one of the most important and main pests that attack olives around the world, especially in Mediterranean countries. The fly larvae seriously reduces olive production, and in some successful years due to the favorable weather conditions, they cause high economic damage to olives. This pest typically reduces the measurable quantity and superior quality of canned olives as well as olive oil after attacking olive fruits. In this study, the desired effect of specific temperatures was studied as the key environmental factor undoubtedly affecting the continuous growth of olive fruit flies. Development time of incubation period for egg, larva, pupal stage, as well as total immature stages of the olive fruit fly were recorded in temperatures ranging 10-30°C, 60-70% RH, and a photoperiod of 16: 8 h (L:D). Based on the ANOVA, the specific temperature along the growth period inevitably affected significantly developmental time of the olive fruit fly at 5% probability level and the increase in temperature allegedly followed a decrease in developmental time. Degree-Day and Ikemoto linear models were used to describe temperature-dependent development of the olive fruit fly. Based on the obtained results in Siahpoush, Qushchi and Kallaj regions, the heat requirements for embryonic development of eggs were obtained 63.45, 71.28 and 63.68 days-degrees, for the egg+ larva stage were 209.18, 215.83 and 159.68 days-degrees, pupae stage were obtained 159.44, 183.15 and 175.55 days-degrees and the total immature stages were 348.51, 396.94 and 338.40 days-degrees, respectively, using Ikemoto model. In addition, the low threshold temperature of growth which estimated using Ikemoto linear model for the points mentioned were as follow: for embryonic developmental stages of eggs were 6.67, 6.33 and 6.71°C, for the egg + larva stage were 8.04, 6.96 and 9.43°C, for pupa stage were 9.72, 9.35 and 9.45°C and for the total immature stages were 9.31, 8.41 and 9.39°C, respectively.