Morphological characteristics of Bracon hebetor (Hymenoptera: Braconidae), a larval parasitoid of coconut Black Headed Caterpillar Opisina arenosella Walker (Lepidoptera: Xyloryctidae)

Abstract

The Bracon hebetor is an essential natural enemy in suppressing the coconut black-headed caterpillar (BHC) Opisina arenosella, which was common in coconut field in Ben Tre province. Under laboratory conditions, with six-instar larvae of BHC as a host, the adult body of B. hebetor was yellow-brown and the male’s antennae were longer than those of the female, with oblong and rectangular shapes consisting of 17 - 20 segments, while the female’s antennae were square-shaped with 11 - 14 segments. The abdomen of B. hebetor was pale yellow, with its last segment being dark brown. Females of B. hebetor were larger than males. The average body length of female and male was 3.2 ± 0.17 mm and 3.0 ± 0.18 mm, respectively. The average body length of 2-day-old pupae was 3.0 ± 0.20 mm and that of 3-day-old ones was 3.5 ± 0.21 mm. The average egg length was 0.7 ± 0.07 mm. The findings of this study helped provide information on the identification of B. hebetor larval parasitic wasps on the BHC host, aiding in the search for natural enemies of BHC in coconut fields. Additionally, the research also facilitated the exploration of the biological and ecological aspects of this natural adversary in Vietnam.