Release density, dispersal capacity, and optimal rearing conditions for Telenomus remus, an egg parasitoid of Spodoptera frugiperda, in maize

Abstract

ABSTRACT We determined the release density, dispersal capacity, and optimal storage conditions for the parasitoid Telenomus remus Nixon to control Spodoptera frugiperda (J.E. Smith). Each of eighty plants within an 829-m2 plot were artificially infested with one S. frugiperda egg mass in a maize field. These plants were distributed evenly along four concentric squares which allowed for 14 different distances from a central release point (range 3.6–20.3 m). Egg parasitoids were released at four densities (0; 100,000; 150,000; and 200,000 adults/ha) in two vegetative maize growth stages (V4-5 and V8-9). After a 48-h exposure, egg masses were retrieved to evaluate parasitism rates. Spodoptera frugiperda egg parasitism by T. remus did not differ among the three parasitoid release densities. Egg parasitism decreased linearly with increasing distance from the release point, but this was influenced by the crop’s phenological stage. Egg parasitism was 28% higher at the older than younger growth stages, and dispersal distance and area of dispersal were 35% and 16% lower, respectively, at the older stage. In the laboratory, we evaluated the effects of six storage periods (0, 3, 6, 9, 12, and 15 days) of S. frugiperda eggs at four temperatures (5, 10, 15, and 20°C) on T. remus adult emergence. Our results showed the highest emergence when eggs were stored at 15°C for ≤9 days. Altogether, we identified important mass release and rearing parameters for augmentative biocontrol of T. remus on S. frugiperda eggs that may help reduce production and marketing costs.