Host preference and survivorship ofEuschistus heros(Hemiptera: Pentatomidae) strains on cotton and soybean

Abstract

The Neotropical brown stink bug Euschistus heros (Fabricius) (Hemiptera: Pentatomidae) is a key pest of soybeans, Glycine max, and recently became an economically important pest of cotton, Gossypium hirsutum. This stink bug has two allopatric strains, one prevalent in southern Brazil (SS), and another in the north (NS). The two strains hybridize in central Brazil. Knowledge of host preferences and host suitability of these strains can clarify the contribution of the different gene pools to contemporary adaptive features such as the ability to harm cotton crops. We tested the attraction of the E. heros strains and reciprocal hybrids [NS female crossed with SS male (HNS) and SS female crossed with NS male (HSN)] to soybean and cotton plants and evaluated the nymph development and survivorship of the two strains and reciprocal hybrids fed on soybean or cotton. We conducted host-choice experiments with 4th instars and adult females and evaluated the survival of immatures on soybean and cotton plants in laboratory conditions. The SS strain preferred soybean over cotton. NS and hybrid strains chose randomly between soybean and cotton plants. All strains developed on soybean, with similar survival rates. On cotton, the pure strains did not reach adulthood; however, the hybrids developed on cotton but with a survival rate less than 1%. Our results showed that E. heros SS was more attracted to soybeans, and NS and hybrid strains had a polyphagous choice behavior, suggesting that current host selection has been mediated by historical and, mainly, contemporary relationships of E. heros strains with these hosts.

The first extensive analysis of species composition and abundance of stink bugs (Hemiptera: Pentatomidae) on soybean crops in Brazil

“…A similar trend was found in a recent survey carried out in the central and southern regions of Brazil 37 . Factors that could explain these results include the superior capability of Euschistus heros among native species to survive in agroecosystems and the efficient use of soybean plants (an exotic host) as a food resource 20,40,41 …”

“…The stink bug must undergo a complex adaptation process, including the recognition of soybean as a host and dealing with morphological and chemical soybean defenses against herbivory. 40,41 We confirmed that Euschistus heros is the main soybean pest in Brazil, with minor alterations in seasonal dynamics among soybean macroregions. The high prevalence of adults over nymphs during the R1 and R2 stages is possibly related to adults moving continuously to soybean fields in search for food resources.…”

“…37 Factors that could explain these results include the superior capability of Euschistus heros among native species to survive in agroecosystems and the efficient use of soybean plants (an exotic host) as a food resource. 20,40,41 We also observed, and consider it worth noting, that the total abundance of Euschistus heros was 5-6 times higher in MR2 than in other soybean macroregions, suggesting that the climatic characteristics and/or agricultural landscape of MR2 favor this species in comparison to other stink bug species. Indeed, this region has ideal thermal requirements for stink bug species, allowing more generations per year.…”

“…Such numbers indicate that using soybean plants, an exotic host, as a resource is not trivial. The stink bug must undergo a complex adaptation process, including the recognition of soybean as a host and dealing with morphological and chemical soybean defenses against herbivory 40,41 …”