Development of Eulophidae (Hymenoptera) parasitoids in Diatraea saccharalis (Lepidoptera: Crambidae) pupae exposed to entomopathogenic fungi

Abstract

Palmistichus elaeisis Delvare and LaSalle, Tetrastichus howardi (Olliff), and Trichospilus diatraeae Cherian and Margabandhu (Hymenoptera: Eulophidae) are promising candidates for the control of sugarcane borer, Diatraea saccharalis (Fabricius) (Lepidoptera: Crambidae). The fungi Beauveria bassiana (Balsamo) Vuillemin (Cordycipitaceae) and Metarhizium anisopliae (Metchnikoff) Sorokin (Clavicipitaceae) also can be used to control sugarcane borers plus leafhoppers (Hemiptera: Cercopidae) in sugarcane. This observation motivated us to investigate whether entomopathogenic fungi can affect biological aspects of these parasitoids. Diatraea saccharalis pupae (24 hours in age) were exposed to parasitism by three females of each eulophid species for 72 hours and then placed in small tubes. A contact surface treated with 1 mL of fungal suspension was placed inside each tube with the parasitised pupae at concentrations of 1 × 10 9 , 5 × 10 9 , or 10 × 10 9 conidia mL −1 of M. anisopliae and B. bassiana. Exposure to fungi reduced emergence of adult P. elaeisis, but not of T. howardi and T. diatraeae. Life cycle duration, progeny, and sex ratio of P. elaeisis were not affected by exposure. Exposure was associated with decreased longevity for both sexes of T. howardi and in males of P. elaeisis, but not at levels expected to affect their performance as biocontrol agents. In general, the exposure of eulophid species developing in pupae of D. saccharalis exposed to entomopathogenic fungi, did not compromise the biological aspects of these parasitoids.