Evaluation of the potencial of the entomogenous nematod Steinernema Carpocapsae Weiser (Rhabditida: Steinernematidae) for the control of Cyrtomenus bergi Froeschner (Hemiptera: Cydnidae) under laboratory condicionts

Abstract

The potential for the control of Cyrtomenus bergi by the entomopathogenic nematode, Steinernema carpocapsae in the laboratory was evaluated. Three methodologies, using all instars of C. bergi, were evaluated: a) Petri dishes (100x15mm) with filter paper and with unsterilized soil, with one insect per unit and one dose of 6.788.800 nematodes/ml. Results confirmed that C. bergi was infected by S. carpocapsae at 5 and 8 days after exposure; b) the second experiment used plastic cups (7x7x10cm) containing unsterilized soil in Petri dishes containing 10 insects of the same stage of development and doses of 2.000, 4.000, and 6.000 nematodes/ml. No clear ten­dency in parasitism was observed 2 and 8 days after exposure; c) the third experiment used plastic cups (3.Sx4x5cm) containing 10 g of sterile sand with 3% RH and one insect per cup, with 2.000, 4.000, 6.000, 8.000 and 10.000 nematodes/ml. Results showed that the adult stage is the most sensitive at all doses with 58.6% parasitism after 10 days; the least sensitive is the first and second instars with 17 and 31% parasitism, respectively. An ad­ditional experiment using the afore-described methodology evaluated the six nematode doses with adults. Probit analysis showed that an average dose of 192 nematodes/ml is required to obtain 50% parasitism, 10 days after inocu­lation. Plastic cups with sterile soil was the most successful experiment unit. Results showed that S. carpocapsae is a potential bio­logical control agent of C. bergi.