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The burrower bug Scaptocoris castanea is an important soybean and pasture pest in Brazil, with an underground habit feeding directly on the sap of the roots. Underground habit hinders control and knowledge of the biology and physiology of this pest. This study describes the anatomy, histology, ultrastructure and symbionts of the midgut of S. castanea. The midgut of S. castanea is anatomically divided into five regions (ventricles). Ventricles 1-3 are similar between males and females, with cells specialized in digestion and absorption of nutrients, water transport and homeostasis. Ventricle 4 has squamous epithelium forming crypts and harboring bacteria in the lumen. Ventricle 5 of males is small with cells containing apical microvilli and broad basal folds with many openings for hemocoel, while in females, this region of the midgut is well developed and colonized by intracellular bacteria, characterizing bacteriocytes. The main bacteria are Gammaproteobacteria. The results show sexual dimorphism in ventricle 5 of the midgut of S. castanea, with formation of bacteriocytes in the females, while the other regions are involved in digestive processes in both sexes.

BACKGROUND: The peanut burrower bug, Pangaeus bilineatus is a major crop pest of peanuts in the southern United States. Peanuts infested by P. bilineatus exhibit weight and quality losses and could be discounted by ≤50% of the prevailing market price. Control of this pest is difficult because it attacks peanut pods underground, thus rendering foliar pesticide applications ineffective. Integration of entomopathogenic fungi and nematodes (EPF/EPNs) with chemical insecticides in the management of P. bilineatus was investigated as a potential integrated pest management containment tool. RESULTS: The nymphs were less susceptible than adults of P. bilineatus to EPNs. Comparison of six strains of both Heterorhabditis spp. and Steinernema spp. demonstrated that Steinernema carpocapsae (All) was the most virulent EPN, causing 75.54% mortality of P. bilineatus adults after 7 days postinoculation (dpi), whereas the mortality generated by the application of the rest of the nematodes ranged between 17.03% (H. bacteriophora ‐ Lewis) and 50% (H. bacteriophora VS). Application of imidacloprid by itself at ½FR (field rate) did not result in any significant mortality of P. bilineatus adults but application of chlorpyrifos at 1/8FR caused significant mortality (27.41–61.35%) at 7–14 dpi. However, combined applications of S. carpocapsae and imidacloprid resulted in significant mortality starting at 3 dpi. The interactions between S. carpocapsae and imidacloprid were synergistic at 3–5 dpi, but became additive at 7–14 dpi. Both chlorpyrifos and imidacloprid did not negatively impact the reproduction of S. carpocapsae. CONCLUSION: The compatibility between S. carpocapsae and imidacloprid makes a case for the combination to be used for the management of P. bilineatus. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The peanut burrower bug, Pangaeus bilineatus (Say), is an important pest of peanut (Arachis hypogaea L.) in the southern United States. Current control methods for this pest, which are based on the use of chemical insecticides, have not been successful. Our objective was to determine if entomopathogens applied alone or in combination with a standard chemical insecticide would provide superior levels of P. bilineatus mortality compared with the standard chemical applied alone. Specifically, we investigated the efficacy of an entomopathogenic nematode, Heterorhabditis bacteriophora Poinar (Oswego strain), and a fungus, Beauveria bassiana (Balsamo) Vuillemin (GHA strain), applied alone or in combination with chlorpyrifos. When applied as single treatments, the two entomopathogens were not pathogenic, that is, they did not cause mortality in P. bilineatus adults that was different from the nontreated control. However, 3 and 7 d posttreatment, the combination of the H. bacteriophora and chlorpyrifos caused higher mortality than the nematode, fungus, or insecticide alone, or the combination of chlorpyrifos and B. bassiana. The nature of the interaction between H. bacteriophora and chlorpyrifos was synergistic, which is of particular interest, given that this is the first time a synergy is being reported between a nematode that was not pathogenic when applied alone and a chemical insecticide. B. bassiana and its combination with the chlorpyrifos did not significantly increase insect mortality compared with chlorpyrifos alone or the control. Based on the observation of synergy, the combination of H. bacteriophora and chlorpyrifos should be investigated further for potential adoption in the management of P. bilineatus. [ABSTRACT FROM AUTHOR]

The evolution of life history characters, including parental care behaviors, depends on costs and benefits. When offspring can influence parental behaviors, parent-offspring conflict over parental care can occur, but only if these parental behaviors are costly. Mother burrower bugs (Sehirus cinctus) exhibit extended and complex care of offspring. Mothers guard eggs until hatching and then attend and provision offspring for approximately 2 weeks after hatching.Using four experimental treatments, we attempted to identify the costs associated with specific components of these behaviors. Under laboratory conditions, egg guarding increases inter-clutch interval, but provisioning does not appear to be very costly. We discuss additional ecological factors that may be important in mediating provisioning costs under natural conditions. Through analysis of individual maternal performance, we find no evidence for trade-offs between successive clutches. These data suggest that variation in overall condition may obscure variation in allocation strategies. [ABSTRACT FROM AUTHOR]