Thermal requirements of Fidiobia dominica (Hymenoptera: Platygastridae) and Haeckeliania sperata (Hymenoptera: Trichogrammatidae), two exotic egg parasitoids of Diaprepes abbreviatus (Coleoptera: Curculionidae)

Abstract

Diaprepes abbreviatus is an exotic root weevil occurring in southern US. It is a highly polyphagous species which can complete its entire life cycle on citrus and several woody ornamental plants. The lack of native egg parasitoids for this wwvil in citrus orchards has triggered efforts to evaluate condidate egg parasitoids from the Caribbean Region into Florida. The egg parasitoids Fidiobia dominica and Haeckeliania sperata are two exotic natural enemies of D. abbreviatus recently introduced in the US in a classical biological control program. The therminal requierements of both parasitoids were studied in the laboratory. The upper development threhold (UDT) of F. dominica was 30.0ºC, its maximal development rate (MDR) occurred at 27.6ºC, its lower development threshold (LDT) was 9.6ºC and its thermal constant (K) for development from egg to adult was 293.1 DD. For H. sperata, UDT was 35.0ºC, MDR occurred at 31.0ºC, LDT was arround 15ºC and K was 188.1 DD. Based on these results, both species would be able to complete 17 to 18 generations annually in southern Florida. However, host availability during critical periods could severely impair the ability og these egg parasitoids to establish and successfully control D. abbreviatus in areas where winter temperatures fluctuate around 12ºC, the LDT for this pest