Parasitoids as a bioagent to eliminate the insecticides to control the main pests-infested economic crops

Hemipterous insects are one of the important pests that attack different economic plants. A study was conducted to evaluate the biological control potential of these pests by augmentation with parasitoids, such as Microterys flavus (Howard), Metaphycus lounsburyi Howard (Encyrtidae), Encarsia sophia (Girault and Dodd), Coccophagus scutellaris (Dalman), Aphytis melinus DeBach (Aphelinidae) and Aphidius ervi Haliday (Braconidae). All the species were mass reared and monthly releases were made in fields of citrus, olive, tomato, sugar cane, mango and squash during each of 11 consecutive years (1999–2009). About 5,830,000 individuals of M. flavus, M. lounsburyi, E. sophia, C. scutellaris, A. melinus and A. ervi were released in the fields of Gharbiya, Marsa Matrouh, Daqahlyia, Qena, Qalyubiya and Behira governorates in Egypt on citrus, olive, tomato, sugar cane, mango and squash which were naturally infested by Ceroplastes floridensis Comstock, Saissetia oleae (Olivier) (Coccidae), Bemisia tabaci (Gennadius) biotype Q (Aleyrodidae), Pulvinaria tenuivalvata (Newstead) (Coccidae), Aulacaspis tubercularis (Newstead) (Diaspididae) and Aphis craccivora Koch (Aphididae), respectively. Population of the parasitoids and parasitism increased in field plots where releases were made when compared with where no releases were made. The maximum rate of parasitism reached 61.4, 92.1, 45.7, 59, 91 and 55.2% in the field treatment where releases were made, while parasitism peaked at 8.2, 13.5, 6, 2, 16 and 17.5% where no releases were made. The populations of M. flavus, M. lounsburyi, E. sophia, C. scutellaris, A. melinus, A. ervi were significantly correlated with the populations of C. floridensis, S. oleae, B. tabaci, P. tenuivalvata, A. tubercularis and A. craccivora during the field seasons. Additional parasitism was caused by natural infestations of Metaphycus helvolus (Compere) and M. lounsburyi (Howard) (C. floridensis), Scutellista cyanea (Motschulsky) (S. oleae), Encarsia lutea (Masi) and Eretmocerus mundus (Mercet) (B. tabaci biotype Q), Encarsia citrina (Craw) (A. tubercularis) and Aphelinus demyaati Abd-Rabou (A. craccivora). These observations enhance the understanding of the usefulness of these parasitoids after augmentation in the field.