Evaluation of entomopathogenic nematodes to control pineapple weevil in Tachira state Venezuela

Abstract

The pineapple, Ananas comosus L., known as the queen of the fruits, is used for fresh consumption, alcoholic drinks, pharmaceutical use, and fiber production. However, its production is affected by the incidence of various insect pests including Metamasius dimidiatipennis, known as the pineapple weevil. This insect infests the crop by perforating stems and leaves. For controlling this insect, native and foreign strains of entomopathogenic nematodes of the genus Steinernema and Heterorhabditis (Strains 044, 037, 075, SCALL, and HP88) were used under laboratory conditions at the INIA Táchira. Larvae of the insect in its last two stadia were collected from infested plants at Libertad County in Táchira. Lethal times (TL50 and TL95), lethal doses (DL50 and DL95) and a regression model of time Vs mortality were determined for each strain of entomopathogenic nematodes (EPNs) in its infective juvenile stage (IJ) at different concentrations: 0, 100, 300, 500, 700 and 1000 IJ/ml. Four replicates with 5 larvae each were placed in Petri dishes along with the suspension of IJ added at each dose. The number of individuals killed was counted every 24 hours for 6 days. The nematode infested dead larvae were recognized for its soft consistency and no stinking smell. The native strain 075 gave the best performance with a DL50 and TL50 of 500 IJ/ml and 2,05 days, respectively, followed by strains 044 and 037, all in the genus Steinernema.