Biological characteristics of Trissolcus urichi (Crawford) (Hymenoptera: Scelionidae) on Euschistus heros (Fabricius) and Dichelops melacanthus (Dallas) (Hemiptera: Pentatomidae) Eggs

Abstract

Species of the genus Trissolcus are effective as egg parasitoids of Euschistus heros and can potentially be used in a multispecies pest management approach. However, in order to successfully use those biocontrol agents in the field, previous detailed knowledge about their life history are necessary. therefore, we evaluate some biological characteristics of Trissolcus urichi on Euschistus heros and Dichelops melacanthus eggs. Three independent experiments were performed: (1) T. urichi host preference between E. heros and D. melacanthus eggs. (2) T. urichi eggs-adult period (days), number of parasitized eggs in 24 h, emergence rate (%) and sex ratio of the parasitoid in E. heros and D. melacanthus eggs. (3) Morphometric characteristics of T. urichi grown on E. heros and D. melacanthus eggs. Trissolcus urichi preferred to parasitize E. heros eggs, exhibiting a higher number of parasitized eggs, higher rate of emergence (%) and faster development, as well as producing progeny of larger size than the parasitoids emerged from eggs of D. melacanthus in relation to body length, wing length and width. thus, it can be concluded that T. urichi had better performance on E. heros eggs, although the parasitoid had also acceptable parasitism capacity and development in D. melacanthus eggs. Stink bugs are one of the most important groups of insects that cause yield losses in soybean (Glycine max) production in Brazil, Argentina and Uruguay 1. Not only have they damage soybean in South America but also in Arkansas and other states in the Mid-South of the United States 2. Because these insects feed directly on the soybean pods they seriously affect both yield and bean quality 1,3. Among the recorded stink bugs from soybean fields, there have been at least 54 different species belonging to the family Pentatomidae 4. The relative economic importance of each species might vary according to each country or its region 5. However, of the many species of stink bug, the Neotropical Brown Stink Bug, Euschistus heros (Fabricius) (Hemiptera: Pentatomidae) is the most frequent pest of field crops, mainly in the central region of Brazil at latitudes between 0° and 23°6. In addition, more recently, the Green-Belly Stink Bug, Dichelops melacanthus (Dallas) (Hemiptera: Pentatomidae), has become more abundant, increasing its significance to soybean and maize (Zea mays) production in the Neotropical region, especially in Brazil 7. This increase is mostly a consequence of the adopted production system in which soybean is cropped during summer immediately followed by maize in autumn. The resulting continuous food supply to the insects throughout the year, known as green bridge, has favored D. melacanthus outbreaks 8 .

Reproduction of Ooencyrtus submetallicus (Hymenoptera: Encyrtidae) and Trissolcus sp. aff. urichi (Hymenoptera: Scelionidae) in Eggs of Nezara viridula (Hemiptera: Pentatomidae) of Different Ages

“…aff. urichi and neither by the different ages of the eggs of N. viridula, being characterized by the presence of male and female individuals, which is similar to what was observed by Queiroz et al (2020b) through the emergence of individuals of both sexes of T. urichi in eggs of Pentatomidae hosts. From the results obtained and the discussion raised, this work provides grounds and opens the possibility for future studies about other stink bugs of the Pentatomidae complex, with the possibility of implementing new protocols for multiplication and for subsequent release of these species of parasitoids in a synchronized manner with the occurrence of stink bug populations in the field.…”