Thermal Requirements of Ooencyrtus submetallicus (Hym.: Encyrtidae) and Telenomus podisi (Hym.: Platygastridae) Parasitizing Euschistus heros Eggs (Hem.: Pentatomidae)

Abstract

Temperature is one of the abiotic factors that strongly influences the biology and behavior of insects. In this study, we assessed the development of egg parasitoids Ooencyrtus submetallicus and Telenomus podisi parasitizing Euschistus heros eggs at different temperatures, and estimated the average number of generations for seven representative soybean-producing regions in Brazil. A comparative biology study was conducted, where the percentage of parasitism and emergence, life cycle duration (egg–adult), and longevity were found to be similar between O. submetallicus and T. podisi. The sex ratio and the number of individuals emerged from parasitized egg were higher in O. submetallicus in all regions. In the study of thermal requirements, temperatures of 16, 19, 22, 25, 28, 31, and 33 °C were tested. O. submetallicus and T. podisi developed at temperatures between 16 and 31 °C. The base temperature (Tb) for O. submetallicus and T. podisi was 9.3 and 6.7 °C, respectively; the thermal constant (K) was 336.9 and 272.7 degree-days, respectively. The estimated average number of annual generations of both parasitoids was higher than the host. O. submetallicus and T. podisi have the same ability to parasitize and develop in eggs of E. heros under the conditions studied. Both parasitoids exhibited satisfactory development and parasitism at temperatures between 19 and 31 °C. The development of both parasitoids was faster than their host, and the number of generations was higher for the seven studied localities.

Optimizing Mass Rearing of the Egg Parasitoid, Telenomus podisi, for Control of the Brown Stink Bug, Euschistus heros

“…Values of K , T min , T max , and T opt vary according to the type of host used, species of parasitoid, and adjusted model for the analyses, potentially relating our results to those of other studies [ 22 , 34 , 35 , 54 , 55 , 56 , 57 ]. Since T2 presented T min of 16 °C and was composed of a natural diet (little variety of ingredients) and cryopreserved eggs, the nutritional aspect of the eggs from this diet was potentially inferior compared to the other treatments, influencing T min .…”

“…As observed in most insects, the increase in temperature results in a decreased lifespan. This can be explained by increases in the insect’s metabolic rate at high temperatures and decreased metabolism at low temperatures [ 34 , 35 ]. Similar effects of high temperatures on survivorship and parasitism capacity were found for several other parasitoids species [ 34 , 36 , 37 , 38 , 39 , 40 ].…”

“…E. heros , the preferred host for T. podisi , has a K of 327 degree-days [ 35 ], which is significantly higher than all treatments. This is a good indication that, in favorable situations in the field, the parasitoid will complete its cycle faster than the host, further contributing to pest management [ 34 , 53 ].…”

Release of Adults and Pupae of T<em>elenomus podisi</em> (Hymenoptera: Scelionidae) For the Management of <em>Euschistus heros</em> (Hemiptera: Pentatomidae) In Soybean

“…Given the efficiency of T. podisi parasitism on eggs of pest pentatomids, especially E. heros [13], the difference in the total and male population of brown stink bugs between areas can best be explained by the density of parasitoids released in the field. In general, it is recommended to release at least 15,000 T. podisi females per hectare throughout the season, which can be divided into three or four applications [14].…”

“…The rearing of T. Podisi was maintained under controlled conditions of light (14:10 L:D), relative air humidity (70±5%) and temperature (25±2°C). The parasitoids were reared in E. heros eggs, the preferred host [13]. The rearing of E. heros was carried out under the same conditions at the same site of the parasitoids.…”