Revista Brasileira de Milho e Sorgo (Apr 2007)
EFFECT OF NEEM EXTRACTS AND APPLICATION METHODS ON THE DAMAGE AND DEVELOPMENT OF FALL ARMYWORM, Spodoptera frugiperda, ON MAIZE
Abstract
The neem tree has a recognized insecticidal activity against insects that damage several crops. The objective of this study was to evaluate the effect of neem exctracts and application methods on the damage and development of Spodoptera frugiperda larvae on maize. Two experiments were carried out at Embrapa Milho e Sorgo, Sete Lagoas, MG, Brazil, under greenhouse conditions. Maize leaves were sprayed varying the neem extracts, sprayer nozzles, concentration and number of application. In the first experiment, the results showed the smallest damage to chlorpyrifos (2.00) and for the aqueous extracts from neem leaves (2.50) applied three times through flat nozzles. The commercial extract did not protect maize leaves from larval damage (7.22 to 7.90). The larval development showed consistent with the low leaves damage, resulting in the low larval weight (97.41 mg). In the second experiment, the smallest leaves damage (2.62and 2.65) were observed in three applications of the aqueous extract, using 80.01/80.04/ 80.01 nozzles, 10,000 and 7,500 ppm, respectively. The highest extract concentration provided low larval weight (60.21 mg). In conclusion, the three applications of neem leaves extract (10,000 ppm), using 80.01/80.04/80.01 nozzles, is most effective to protect maize from fall armyworm damage. All the extract concentrations evaluated affect the larval development.
