Multiplicação de Ooencyrtus submetallicus em ovos de Euschistus heros armazenados em baixa temperatura e seu parasitismo em ovos de Dichelops melacanthus em laboratório e semi-campo

Abstract

Parasitoids are regulators of insect populations. The objective of this study was to verify if eggs of Euschistus heros (Fabricius, 1974) can be stored at low temperature for multiplication of Ooencyrtus submetallicus (Howard, 1897) for commercial scale production, and to compare biological aspects of 0 submetallicus in Dichelops melacanthus (Dallas, 1851) eggs, under laboratory and semi-field conditions. The experiment was carried out in the Laboratdrio de Controle Biologico de Insetos (LECOBIOL) of the Faculdade de Ciencias biologicas e Ambientais and in greenhouse the Faculdade de Cioncias Agrarias of the Universidade Federal da Grande Dourados. E. heros eggs were collected, packed in petri dishes in: technique I in the refrigerator, H technique in the freezer; technique III in the freezer; technique IV in liquid nitrogen at -196 ° C and without storage (control). After 30 days, these eggs were placed in glass tubes and offered to parasitoid females with 120h old. Twenty-five adults of parasitoid females with 24h old were individualized in glass tubes with 6 eggs of D. melacanthus with until to 168h of age. The parasitism was allowed for 24h, 25 ± 2 ° C in both cases, 80 ± 10% and 70 ± 10% relative humidity, respectively, and photophase 14h, in laboratory conditions. In the semi-field conditions, the treatment with 25 parasitoid females were individualized in pots (5L) containing corn plants, 6 eggs of D. melacanthus and covered with organza type fabric. The parasitism was allowed for 24h, 23.07 ± 2°C, 78.37 ± 10% relative humidity and 12.2h photophase, semi-field conditions. The highest percentages of parasitism and emergence were 58.89 ± 9.47 and 80.00 ± 9.51, 80.00 ± 10,69 and 86.67 ± 9.09 obtained in techniques I and IV, respectively. The duration of the parasitoid cycle was practically similar, with an overall mean of 17.86 ± 0.08 days. The highest total progeny was 11.15 ± 0.97 individuals obtained in technique IV. The highest longevity was 18.75 ± 0.79 days obtained in technique II. Parasitism and emergence were similar higher than 71% in laboratory and semi-field, respectively. The parasitoid cycle duration was lower in the laboratory. The number of individuals per egg was 1.74 in the laboratory. Longevity was similar in both conditions. The sex ratio was always 1 for all treatments. The presence of immature parasitoids was not observed. All storage techniques were feasible, with techniques I and IV being the best techniques. 0. submetallicus parasitized and developed into D. melacanthus eggs successfully under laboratory and semi-field conditions.