Studies on Pediobius bruchicida (Rond.) (Hym., Eulophidae) a hyperparasitoid of Sesamia cretica Led. (Lep., Noctuidae)

Abstract

AbstractCocoons of the primary parasitoid Bracon brevicornis, turned black 5–7 days after invasion by the eulophid, Pediobius bruchicida and served as a clue to presence of the hyperparasitoid. Pediobius female was not able to parasitize every cocoon within a given mass of cocoons resulting in “partial parasitism” of those present, in the laboratory. However, certain cocoon masses were found in which all cocoons were parasitized by wasp(s) resulted in “complete parasitism”, in the field. Parasitism of P. bruchicida was estimated by 3 methods, in the field. Pediobius females were observed to have high searching ability to forage sorghum stalks and attack Bracon cocoons even they were inside tunnels of the phytophagous borer larvae.The emergence of Bracon individuals occurred significantly earlier than of Pediobius. Time‐distance between emergence increased (from 10 to 18 days) as the time of Pediobius exposure was delayed. Average total developmental period was 14 and 21 for Bracon and Pediobius, respectively. Pediobius females attacked new as well as old cocoons of Bracon and the development rate of progeny was the same.When reared in the laboratory, the adults of primary parasitoid altered their color from black to yellow. However, Pediobius adults retained the initial color (black). The eulophid wasp proved to be solitary and endopupal parasitoid of the braconid, B. brevicornis.ZusammenfassungUntersuchungen über Pediobius bruchicida (Rond.) (Hym., Eulophidae), einen Hyperparasiten von Sesamia cretica Led. (Lep., Noctuidae)Die Kokons des Primärparasiten Bracon brevicornis verfärbten sich 5–7 Tage nach Befall durch den Hyperparasiten Pediobius bruchicida schwarz. Das Pediobius‐Weibchen war nicht imstande, im Labor jeden Bracon‐Kokon in einer gegebenen Kokonmenge zu parasitieren (partieller Parasitismus). Jedoch wurden mehrere Kokonmengen im Freiland gefunden, die 100%ig hyperpa‐rasitiert waren (vollständiger Parasitismus). Die Pediobius‐Weibchen zeigten eine hohe Suchfähigkeit und spürten Bracon‐Kokons selbst dann auf, wenn diese sich im Inneren der Larvengänge von Sesamia cretica in Sorghum‐Stengel befanden.