Abstract
The study of the interaction between parasitoid and host, especially the age of these organisms, is an important step towards the implementation of biological control programs. Therefore, we investigated the performance of Ooencyrtus submetallicus (Hymenoptera: Encyrtidae) and Trissolcus sp. aff. urichi (Hymenoptera: Scelionidae) parasitizing eggs of Nezara viridula (Hemiptera: Pentatomidae), considering different ages of the parasitoids and the host. We performed four laboratory bioassays: two using females of O. submetallicus and Trissolcus sp. aff. urichi at 24, 48, 72, 96, 120, or 144 hours of age exposed to parasitism in N. viridula eggs (24 h) and two trials with N. viridula eggs at 24, 48, 72, 96, 120, or 144 hours exposed to the parasitism of O. submetallicus and Trissolcus sp. aff. urichi (24 h). We evaluated the percentage of parasitism and emergence, life cycle length, progeny, sex ratio, and the longevity of the parasitoids. The parasitism of O. submetallicus in N. viridula eggs was influenced by the age of the parasitoid, 120 hours being the minimum to obtain better parasitism. From this age on, there is interference in the longevity of the progeny. Trisolcus sp. aff. urichi, at all ages, parasitized N. viridula eggs relatively well, but with almost no emergence of the parasitized eggs. Females of O. submetallicus parasitized and developed in eggs of N. viridula of all ages. Females of Trissolcus sp. aff. urichi parasitized their host, but there was barely any emergence. These pieces of information regarding the breeding methodology contribute to the implementation of new protocols for the multiplication of these parasitoids in the laboratory, and later, their release in the field.
Highlights
Biological control is an environmentally friendly and affordable management alternative, adopted to reduce insect populations considered pests for their natural enemies (Parra et al, 2002)
Parasitism progressively increased with the age of females of O. submetallicus in N. viridula eggs, going from 40.00±20.00% at 24 hours to 97.33±1.82% at 144 hours (F = 41.2610, p ≤ 0.0001 and Rtrat = 0.83) (Figure 2)
The emergence percentage of O. submetallicus in N. viridula eggs was not a significant factor when related to the ages of this parasitoid, it remained high during the six days (144 h), presenting an overall average of 94.52±1.61 % (p > 0.05) (Table 1)
Summary
Biological control is an environmentally friendly and affordable management alternative, adopted to reduce insect populations considered pests for their natural enemies (Parra et al, 2002). Species of the Pentatomidae complex are controlled with synthetic insecticides, both in seed treatment and in aerial application at the initial stages of crop development (Chiesa et al, 2016) This management method has been associated with the emergence of insect populations resistant to the main groups of insecticides adopted, the reduction of natural control agents, as well as other implications for the agroecosystem (Sosa-Gómez et al, 2001; Sosa-Gómez et al, 2010, Turchen et al, 2016)
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