Thermal requirements of differents strains of Telenemus podisi (Hymenoptera: Platygastridae), in Oebalus insularis (Heteroptera: Pentatomidae) eggs

The Telenomus podisi presents promising biological characteristics for the egg control of Oebalus insularis. The present study determines the thermal inferior limits, for the development of three strains of T. podisi reared in O. insularis eggs. Also the number of generations per year, for the parasitoids was calculated based on the thermal constant (K) and the degree days (DD), considering  the isotherm of the rice areas, in Chepo, Panama. With this objective, the O. insularis eggs were submitted to T. podisi parasitism, under controlled conditions of temperature (25±1°C), relative humidity (80 ±5%) and 12 hours photophase, for posterior transfer to climate chambers, regulated at different temperatures (18, 20, 22, 25, 28, 30 and 32°C). The biological cycle (egg to adult), survival rate and sex proportions were assessed daily. The T. podisi strains considered were: a) T.p. 1 (Chichebre, Panama, IDIAP-38); b) T.p. 2 (Juan Hombrón, Cocle, IDIAP-38); c) T.p. 3 (Calesa, Panama, Estrella-92). The experimental design completed random considering three masses of 20 parasitized eggs by temperatura. The thermal inferior limit (T_b), as well as the thermal constant (K) and the degree days (DD), was determinate by means of the hyperbola method. The thermal inferior limit for the strains T.p. 1, T.p. 2 and T.p. 3 was 12.2, 13.1 and 12.9 °C, respectively. According to isotherm (26.8 to 27.0 °C), registered at the rice productions areas, in Panama, it was determinate 25.5, 24.9 and 25.2 generations per year, for the strains T.p. 1, T.p. 2 and T.p. 3, respectively. These results, associated to the survival rates (94%) and the female proportions (0.68/1.00), suggests the success of T. podisi release to the O. insularis control.