Multiplicação do parasitoide Ooencyrtus submetallicus (Hymenoptera: Encyrtidae) em ovos de hospedeiros alternativos

Abstract

The use of parasitoids in biological control programs depends on studies of their bioecology in natural and alternative hosts and their production in large quantities to meet the demands due to the high reproductive capacity of pest insects. Ooencyrtus submetallicus (Hymenoptera: Encyrtidae) has been reported in the literature, occurring naturally in eggs of several pentatomids such as Ne- zara viridula, Piezodorus guildinii and Edessa meditabunda (Hemiptera: Heteroptera). This parasi- toid has also been reported to occur in lepidoptera eggs. The cryopreservation of hosts has enabled the use of parasitoids in a timely manner. What motivated us to compare the biology of O. subme- tallicus in eggs of Helicoverpa armigera (Lepidoptera: Noctuidae), Bombyx mori (Lepidoptera: Bombycidae), Spodoptera Frugiperda (Lepidoptera: Noctuidae) and eggs of Podisus nigrispinus (Hemiptera: Pentatomidae) in liquid nitrogen at -196 ° C for different periods. The experiment was carried out at the Biological Insect Control Laboratory (LECOBIOL) of the Faculty of Biological and Environmental Sciences (FCBA). To this end, ten eggs of each species of lepidopteran from the farms were collected and pasted in cartons of sky blue cardboard with 10% arabic gum and these were individualized in glass tubes and offered to a 120 hours old female O. Submetallicus age. Parasitism was allowed for 24 h. After this period, the parasitized eggs were kept in a climate chamber at 25 ± 2ºC, 70 ± 10% relative humidity and 14h photophase, until the emergence of the offspring for subsequent recording of biological characteristics. H. armigera and S. frugiperda eggs were not parasitized by O. submetallicus females. Parasitism and emergence percentages, number of parasitoid individuals per egg, life cycle length (days), sex ratio and longevity of adult females (days) of O. submetallicus in B. mori eggs were 90 ± 5.53; 26.33 ± 8.24; 1.56 ± 0.21; 18.20 ± 0.55 (days); 1.0; 17.73 ± 2.20 days, respectively, whereas in P. nigrispinus eggs the percentage of parasitism was higher when eggs were stored for 60 days, with 70.00 ± 8.94% res- pectively. Sex ratio was 1 for all treatments. The number of individuals of O. submetallicus per P. nigrispinus egg was 1.53 ± 0.04; 1.39 ± 0.04; 1.39 ± 0.03; 1.22 ± 0.01 and 1.54 ± 0.11, being sta- tistically equal for all storage periods evaluated. B. mori eggs can be used as an alternative host and P. nigrispinus can be stored in liquid nitrogen at -196°C for up to 60 days and subsequently used without compromising the main biological characteristics of O. submetallicus.