none Opisina arenosella; HYMENOPTERAN-PARASITES; Bracon brevicornis & Pediobius imbreus; Parasitoid & hyperparasitoid interrelationships; HYPERPARASITISM-; KERALA-; Hymenopteran parasitoid & hyperparasitoid interrelationships Bracon brevicornis; HYMENOPTERAN-PARASITES; Pediobius imbreus; LEPIDOPTERAN-HOSTS; Opisina arenosella; Interactions with Pediobius imbreus hyperparasitoid; HYPERPARASITISM-; Interactions with Pediobius imbreus; KERALA-; Parasitoid & hyperparasitoid interactions, lepidopteran host Pediobius imbreus; FECUNDITY-; LIFE-CYCLE; Bionomics; DEVELOPMENT-; Duration, effect of temperature; LONGEVITY-; Temperature effects; HYMENOPTERAN-HOSTS; Bracon brevicornis; Parasitoid & hyperparasitoid interactions, lepidopteran hosts, Kerala; TEMPERATURE-; Development duration & longevity, relationships. Pediobius imbreus (Walker), (Hymenoptera: Eulophidae) is an important hyperparasitoid of Opisina arenosella the black-headed caterpillar pest of coconut. The female of this hyperparasitoid during its life time laid a maximum number of 160 eggs. Temperature profoundly influences the duration of its immature stages: at 20 degree C it required 34.8 days, while at 35 degree C it was completed within 13.65 days. Owing to its high host searching capacity, P. imbreus parasitized most of the cocoons of Bracon brevicornis in the field, thus reducing the efficiency of the latter as a successful biocontrol agent.