Trade-Offs between Temperature and Fitness in Euschistus heros (Fabricius) (Hemiptera: Pentatomidae): Implications for Mass Rearing and Field Management

Abstract

The brown stink bug, Euschistus heros (Fabricius, 1798) (Hemiptera: Pentatomidae), is one of the most abundant soybean stink bug pests in Brazil. Temperature is a key factor that affects its development and reproduction, and fluctuating temperatures may impact the development and reproduction of E. heros differently from those under constant temperatures. The objective of this study was to evaluate the influence of constant and fluctuating temperature on the biological characteristics of E. heros in three successive generations. Treatments consisted of six constant temperatures (19 °C, 22 °C, 25 °C, 28 °C, 31 °C and 34 °C) and four fluctuating temperatures (25:21 °C, 28:24 °C, 31:27 °C, and 34:30 °C) evaluated for three successive generations. Second-stage nymphs were evaluated daily, and after they reached the adult stage, they were separated by sex, and the individual weight (mg) and pronotum size (mm) were recorded. After pair formation, eggs were collected to evaluate the pre-oviposition period, total number of eggs, and egg viability. The duration of the nymphal stage was reduced with an increase in both constant and fluctuating temperatures; however, at constant temperatures of 19 °C, 31 °C and 34 °C and fluctuating temperatures of 28:24 °C, there was no reproduction in adults. The base temperature and total degree day requirement for nymphal development were 15.5 °C and 197.4 dd, respectively. Pre-oviposition period (d), number of eggs per female, and viability of eggs (%) were affected by temperature across the generations. The multiple decrement life table analysis revealed that mortality was highest during the molting of the second-stage nymphs. These findings have important implications for E. heros’ laboratory mass-rearing programs and for its management in fields.

Optimizing the Release Pattern of Telenomus podisi for Effective Biological Control of Euschistus heros in Soybean

“…The number of eggs offered (about 1890 eggs per plot), the time allowed for parasitism (24 h) and the use of cryopreserved eggs as sentinels might also explain the low parasitism rate observed. The number of eggs and distance might exceed T. podisi ’s parasitism capacity in 24 h. Although in applied inundative biological control programs, the parasitism capacity holds greater significance than the lifespan of females in the field [ 8 ], T. podisi females might have needed more than 24 h for the pre-reproductive period to reach its full parasitism capacity in the field [ 34 ]. Bueno et al [ 2 ] reported a 70% parasitism rate in soybean fields after T. podisi release; however, this was after three parasitoid releases and over a period of 27 days.…”

“…Populations of E. heros are affected by diseases, other natural enemies [ 41 , 42 , 43 , 44 ] and by abiotic factors [ 45 ]. Barrufaldi et al [ 34 ] documented 40% mortality just from molting in E. heros with the highest mortality occurring between the first and second-stage nymphs. At these stages, the stink bug does not compromise soybean yield or quality [ 46 ].…”

Effects of Temperature and Host Plant on Hedgehog Grain Aphid, Sipha maydis Demographics

“…We determined the effects of temperature on life history using constant temperatures maintained in the growth chambers for each temperature rather than in replicated chambers. Previous studies have demonstrated the potential limitation of this approach and additional assessment and refinement of temperature requirements, including the effects of fluctuating temperatures on HGA development, is warranted [48].…”