Parasitóides associados a Spodoptera frugiperda (Smith, 1797) em cultivos de milho (Zea mays) no Estado do Maranhão

Abstract

The losses caused by Spodoptera frugiperda (Smith,1797) vary between 17 and 37,8 %, what tums it one the main pest of the comJts control is based in the use of Chemical insecticides, which cause damages to the environment and to men.The present work aimed to indentify and quantify the emerged parasitoids from larvas collected in agricultural fields at São Luis, Formosa da Serra Negra and Urbano Santos, Maranhão States, evaluate the dependence between number of larvas collected and the number of emerged parasitoids and evaluate the preference of parasitoids for different larvals development stages.The caterpillars collected were isolated and grown in artificial diet.The caterpillars were conditioned in climatic with temperature of 25°C, relative humidity of ± 10 % and “photophase” of 14 hours, remaining till emergency of S. frugiperda or parasitoids adults. 1173 larvae were collected, with parasitism of 17,81 %, varying 12,42 % in 2002/2003 and 24,48 % in 2003/2004, which had great representativity when compared with the total mortality rate. The emerged parasitoids belonged to the orders Diptera and Hymenoptera. With prevalence for Chelonus insularis (Cresson) (Chelonidae) that represented 34,66 % of the sample obtained in the year of 2003/2004 and Tachinideos Lespesia lanei (Guimarães) and Archyta incertus (Macquard), that represented 25,92 % and 24,07 % respectively, in the years of 2004/2003. Was observed the occurrence of the hymenopteran Eiphosoma laphymae (Costa Lima), Chelonus texanus (Cressson), Cotesia sp., Macrocentrus sp. and Brachymeria sp. and the dipteran Lespesia affins (Riley), Archytas incansanus (Townseard) and Archytas sp. The hymenopteran presented preference for the first instars larvae and the dipteran for the last ones and for the pupa phase, not being verified, therefore, competition for the phase of development of Spodoptera frugiperda