Temperature-dependent development of two neotropical parasitoids of Liriomyza sativae (Diptera: Agromyzidae)

We studied two species of neotropical parasitoids that occur naturally in northeastern Brazil and are associated with Liriomyza sativae (Blanchard): Opius (Gastrosema) scabriventris Nixon (Hymenoptera: Braconidae) and Chrysocharis vonones (Walker) (Hymenoptera: Eulophidae). We evaluated the influence of seven temperatures on the duration of the egg-adult period and on the survivorship of the immature stages of the parasitoids. A temperature increase from 15 to 30°C shortened the egg-adult period of O. scabriventris and C. vonones. However, at 32°C, the developmental time for the braconid was prolonged, and no difference was observed for the eulophid, compared with 30°C. The highest temperature, 35°C, proved to be lethal for both species. At 15°C, C. vonones pupal survivorship was drastically reduced, whereas that of O. scabriventris was unaffected. At most temperatures, the eulophid had an egg-adult period shorter than or similar to the braconid, except at 15°C. The threshold temperature (Tt) of the egg-adult period for O. scabriventris was 7.3°C with a thermal constant (K) of 257.1 degree days (DD). For C. vonones the Tt was 7.4°C for the total cycle and 6.2°C for the pupal stage, with a thermal constant of 246.3 and 140.3 DD, respectively. These data allow an estimate of 29.4 annual generations for O. scabriventris and 30.5 for C. vonones in a melon production region in northeastern Brazil, values that are equivalent to 4.9 and 6.0 more generations than the host. These results demonstrate that both species have potential for application in biological control programs against the leafminer fly L. sativae.