Dispersal capacity of the egg parasitoid Telenomus remus Nixon (Hymenoptera: Platygastridae) in maize and soybean crops

Abstract

This study examined the dispersal capacity of the parasitoid Telenomus remus Nixon (Hymenoptera: Platygastridae) in soybean and maize crops. Knowledge on mobility and dispersal capacity of parasitoids is crucial for the implementation of successful biological control strategies using this biological control agent. Experiments were conducted at the experimental farm of Embrapa Soja located in Londrina, PR (−51°11′0.54″ Long.; −23°11′58.94″ Lat.) in the crop seasons of 2012, 2012/13 and 2013 at different plant phenological stages. Experimental plots consisted of six concentric circles with radii of 5, 10, 15, 20, 25, and 30 m, with 8, 24, 40, 56, 72 and 88 parasitoid traps per circle, respectively. Host eggs were placed on each plant as parasitoid traps. Approximately 150,000 newly emerged (up to 24 h old) adults of T. remus reared on eggs of Corcyra cephalonica Stainton (Lepidoptera: Pyralidae) or Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae) were released at the central point of each circle. Parasitism by T. remus decreased with increasing distance to the release points regardless of host, phenological stage, crop or season. Our findings allow the conclusion that T. remus should be released at a minimum density of 35 points/hectare in soybean crops and 34 points/hectare in maize crops to ensure T. remus dispersal over 100% of the area in the worst case scenario. Since wind direction influences the dispersal pattern of T. remus, the release methodology should be determined according to wind conditions, possibly with preference for a perimetric distribution of the released insects.