Monitoring the Neotropical brown stink bug Euschistus heros (F.) (Hemiptera: Pentatomidae) with pheromone-baited traps in soybean fields

The effectiveness of the synthetic sex pheromone of the Neotropical brown stink bug, Euschistus heros, was evaluated both in laboratory and in field assays. Lures loaded with 1 mg of methyl 2,6,10-trimethyltridecanoate (TMTD) continuously attracted female bugs for more than 30 days to pheromone-baited traps in field trials. The pheromone-baited traps were effective in field tests even at low bug population densities, as compared with the usual monitoring technique, shake cloth sampling. Traps around borders or in the centre of soybean fields caught similar numbers of bugs. Trap captures showed a positive relationship with field populations, as monitored with the shake cloth technique, during the reproductive phase of the soybean crop, i.e. from the R1-R5 developmental stage (pod formation to pod fill). The physiological state of the trapped migrating insects was determined. The first insects arriving in the field had fewer eggs in the reproductive tract compared to later arrivals. Some cross-attraction was also observed, with Piezodorus guildinii and Edessa meditabunda also being caught in pheromone-baited traps, suggesting that these insects respond to the sex pheromone or to the defensive compounds released by E. heros captured in traps. In brief, the results showed that traps baited with 1 mg of the sex pheromone efficiently caught bugs, that the lures lasted for more than 1 month under field conditions and that placement of traps around the borders of the crop area was as effective as placement inside the crop area. Border-placed traps were effective at a density of one trap every 200 m.