Ecological and biological studies on the parasitoids of the cabbage white butterfly, Pieris rapae (L.) (Lep., Pieridae) in winter cabbage at Mansoura
1992
Ragab, M.E. (Mansoura Univ. (Egypt). Plant Protection Dept.)
Field and laboratory studies on the parasitoids of Pieris rapae (L.) in cabbage in winter season of 1989/90 at Mansoura district were carried out. No parasitoids emerged from the larvae of the host. Pteromalus puparum (L.), Brachymeria femorata Panz. and Exorista larvarum (L.) (Tachina larvarum) only emerged from the pupae of the host. General rate of parasitism induced by the three parasitoids together reached 49.69 %. The most common parasitoid was P. puparum followed by B. femorata, while E. larvarum considered to be of little importance. The total developmental period of P. puparum lasted 32.57 plus-minus 0.84 and 11.2 plus-minus 0.29 days at 18.6 degrees C and 27 degrees C, respectively. The highest number of adult P. puparum that emerged from a single parasitized host pupa was obtained at 27 degrees C, with the lowest sex ratio of 2.5 females per male. Its lowest number was recorded at 18.6 degrees C, with the highest sex ratio of 7.5 females per male. Survival rate of the adult females of this parasitoid refrigerated at 10 degrees C exceeded 84 % after 14 days and sharply decreased to 4 % and 0 % after 21 and 28 days, respectively
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