Use of nonlinear models in determining the temperature thresholds of olive fruit fly Bactrocera oleae (Rossi) in the Tarom sofla region

Olive fruit fly Bactrocera oleae (Rossi) (Dip.: Tephritidae), is the main and considerable damaging pest on olive trees (Olea europaea, Oleaceae) and causes huge economic losses. In this study, the effect of temperature on developmental rate of the Olive fruit fly was studied at 7 constant temperatures,10, 15, 20, 24, 28, 32, and 35 °C, 60-70% RH, and a photoperiod of (L:D) 16:8h. 26 nonlinear models were evaluated to determine development rate of olive fruit flies at different temperatures and to estimate the thermal developmental thresholds.Among evaluated nonlinear models, Lactin-2 and Briere-2 were the best fitting models for all immature stages considering the statistical criteria and biological significance of the estimations. Accordingly, the lower temperature threshold values (T0) estimated using Briere-2 model for incubation period, egg+ larval period, pupal period and the total period of immature stages, 5- 5.001, 5- 9.16, 7.19- 9.76, and 7.69- 8.68 °C respectively. In addition, the values of the upper temperature threshold (TU) for the mentioned developmental stages estimated 32- 43.42, 32.04- 36.23, 32.03- 36.42, and 34.03- 34.4 °C, respectively. Furthermore, estimated values for the optimal temperature (Topt) for the same mentioned developmental stages were 27.99- 30.09, 24.43- 28.04, 25.82- 30.32, and 25.94- 26.86 °C, respectively. Finally the values of lethal temperature threshold (Tl) for the mentioned developmental stages by using Lactin-2 model estimated as 34.31- 43.8, 37.44- 39.53, 33.67- 45, and 37.93- 40.13°C, respectively. The findings of the present study are useful for predicting the population dynamics of olive fruit flies and can be effective in developing optimal management strategies of B. oleae.