Methodology for studying the relationship between Entomopathogenic Nematodes and Gonipterus platensis in field

Gonipterus platensis, an Australian eucalyptus defoliating insect that has been present in Brazil for over 40 years, returned to cause damage in several producing regions. Entomopathogenic nematodes (EPNs), Steinernema and Heterorhabditis genera, are options for controlling soil phases pests. Aiming to develop methodologies for G. platensis pupae and NEPs studies in field, this research was conducted. Pupae of G. platensis were individualized in 50 mL plastic pots containing 30 g of autoclaved sieved sand and 3 mL of distilled water, these were: M1 - the contents of the cup were poured into a wire trap and buried in the ground; M2 – it was the same of M1, but instead of wire trap, they were wrapped in voile fabric; M3 - individualized pupae in plastic cups with holes in the bottom and filled with 30 g of sieved and autoclaved sand, this cup was buried in the ground. Ten pupae with 17 days of development were used for each method (M1, M2, M3). The control consisted of 10 pupae kept in plastic pots and transferred to the soil according to M1, but without the application of NEPs. Heterorhabditis amazonensis were applied (400 nematodes/pupae) on the litter on the area where they were buried, with a manual sprayer flowed rate of 4.5/10⁴ L/min. After one week, the treatments were removed from the field, the dead pupae were placed in White traps and placed in incubator chambers at 18oC and 70% RH. White trap suspensions were collected daily for 15 days, when the nematodes were counted in Peters plates. The adult insects were kept in wooden cages (40 x 45 x 80 cm) lined with voile and fed with Eucalyptus urophylla, where they performed oviposition. The percentage of mortality of G. platensis pupae was 9.0, zero, 40.0 and 40.0; in control, M1, M2 and M3, respectively. However, EPNs emerged only from M3 pupae. So, M3 is considered the most appropriate methodology for studying the relationship between G. platensis and EPNs in field.