Resource information
This audiotutorial unit (cassette, printed script, 70 color slides, study guide, self-evaluation test), prepared by the Communications Support Unit at CIAT, is available for use with a manually or automatically synchronized slide projector/cassette tape recorder. Each unit is available from the Distribution Office at a cost of US$ 50; photocopies of the study guide alone can be obtained from the Cassava Information Center. Data are given on the biology of the hornworm, its economic importance and possible methods of control. Integrated control of Erinnyis ello should begin immediately after the previous harvest, applying cultural practices such as plowing between rows and weed control. Biological control should be continuous even though severe attacks do not occur; a good option is the combined use of egg parasites (Trichogramma spp.) with larval predators (Polistes sp.) and parasites (Apanteles sp. and Euplecirus sp.). The farmer should keep constant track of the no. of parasitized and nonparasitized eggs, especially in young plantations. If the no. of nonparasitized eggs increases, there will be an increased no. of larvae. In this case Trichogramma wasps should be released in the field (10-20 (in.)2/ha), or the crop should be sprayed with Bacillus thuringiensis (350-400 g/ha). Chemical control should be avoided since its continued use wiil upset the balance between the pest population, the natural enemies and the fauna in general, intensifying later attacks. Therefore, chemical contTrol should be used only when there is a very severe attack (high larval populations/plant) and when the plants are young (up to 6 mo). (CIAT)
