The in vivo treatment with the plant urease "Jack Bean Urease" in females of Rhodnius prolixus (Hemiptera: Reduviidae).

FRUTTERO LL; MOYETTA, NATALIA R.; CANAVOSO LE

La Plata

Congreso; II Congress of the Latin American Society for Vector Ecology; 2022

Latin American Society for Vector Ecology

Ureases are enzymes that catalyze the hydrolysis of urea to carbon dioxide and ammonia. Inrecent decades, it has been postulated that plant ureases are also defense proteins againstphytophagous insect species with potential biotechnological application. Previous reportsdemonstrated that the injection of "Jack Bean Urease" (JBU), the major isoform of ureasefrom the legume Canavalia ensiformis, into the hemocele of triatomine insects, resulted inseveral toxic effects including activation of the immune response. Although the insecticidaleffect of JBU was described several years ago, many aspects of its mechanism of action aswell as the target organs remains largely uncharacterized. In particular, the effects of JBU onthe female reproductive system and the consequences of sublethal doses have not beenstudied. In this work, we employed the Chagas disease vector Rhodnius prolixus as a modelto study the effects of JBU on survival, ovarian development and oviposition of females. Forthe experiments, insects were injected with different doses of JBU in phosphate buffer.Control insects were treated with the same volume of vehicle. The results show for the firsttime that a sublethal dose of JBU impaired different reproductive parameters of R. prolixusfemales. All doses tested (0.01, 0.025 and 0.05 μg JBU/mg body weight) significantlydecreased the number of eggs and the highest dose tested of 0.05 μg/mg delayed the onsetof oviposition and hatching. However, only the dose of 0.01 μg JBU/mg did not cause insect mortality. Surprisingly, this sublethal dose that decreased the number of eggs resulted inincreased insect longevity. Ovarian development of JBU-treated females was markedlydelayed compared to controls. The ovaries exhibited ovarioles with atretic terminal follicles,which by high-resolution light microscopy showed cellular disorganization and vacuolization.Transmission electron microscopy displayed vacuolization and swelling of the nuclearmembrane and mitochondria, being these findings compatible with cell death by necrosis.The reported findings are particularly relevant considering that reproduction and theachievement of a successful oogenesis are of key importance in the population dynamics ofinsect vector and pest species.