Efecto de Bacillus thuringiensis var Kurstaki HD1 sobre larvas de Spodoptera frugiperda pertenecientes a dos grupos etarios

ALVAREZ, ANALÍA; VIRLA, EDUARDO G.; PERA, LICIA; BAIGORÍ, MARIO D.

Rosario, Santa Fé

Congreso; VIII Congreso nacional de maíz; 2005

AIANBA - MAIZAR

The fall armyworm, Spodoptera frugiperda (Sf) is one of the most important corn pest in tropical and subtropical América. Some microorganisms are important candidates for its control. Bacillus thuringiensis (Bt) has gained special attention due to its efficiency and low impact on natural enemies. The objective of this research was the evaluation of B. thuringiensis var kurstaki HD1 susceptibility on different initial age S. frugiperda larvae. Life cycle started with both III (group 1) and V (group 2) instar larvae were followed daily. Parameters like larval mortality, foliar consumption as well as sublethal responses of surviving larvae were determined. Larvae came from a laboratory colony. To start this colony, individuals were collected from Tucumán (Argentina) corn crops. After seven days of Bt ingestion, larval mortality of 60.0% and 6.7% was observed for group 1 and 2, respectively (F=10,27; gl=1; P=0,0108). Larval mortality was also statistically different between group 1 and its control (F=25,60; gl=1; P=0,0072) but not between group 2 and its control (F=4,00; gl=1; P=0,1161). Sublethal effects resulted in significantly increased group 2 larval and pupal mortality. This behavior was not observed in group 1 individuals. The impact of Bt exposure was finally visualized as a reduction of foliar consumption in both group.