Performance of reproductive system of Dichelops melacanthus (Hemiptera: Pentatomidae) subjected to buprofezin and pyriproxyfen: morphological analysis of ovarioles and testes

Abstract

The use of insecticides known as insect growth regulators, which are considered more selective to natural enemies, may be an alternative to integrated pest management of stink bugs of the main crops in Brazil. The objective of this study was to evaluate histological changes in the reproductive system of Dichelops melacanthus as well as female fecundity and egg fertility after use of growth-regulating insecticides. The insecticides used were buprofezin (a chitin biosynthesis inhibitor) at a sublethal concentration (LC 30 of 2.99 g L -1 ) and pyriproxyfen (a juvenile hormone analog) at a sublethal concentration (LC 30 of 8.35 mL L -1 ). A completely randomized experimental design was used, with 10 repetitions and 10 insects per experimental unit. Two bioassays were performed: in the first bioassay, fecundity (eggs/ female) and fertility (nymph eclosion) of the insects that survived the insecticides were evaluated; in the second bioassay, morphological alterations of the ovarioles of adult females and of the testes of adult male insects that survived the insecticides were evaluated. Buprofezin and pyriproxyfen did not affect the adult sex ratio or female fecundity. Pyriproxyfen reduced the percentage of ecloded nymphs (71.6%) compared with that of the control and buprofezin (96.4 and 90.6%, respectively) treatments and had an ovicidal effect, with direct and indirect action on embryogenesis. Morphological changes were observed in both treatments with buprofezin and pyriproxyfen. The alterations observed in female and male reproductive systems may occur by the action of buprofezin and pyriproxyfen on the morphology of both ovarioles and testes. Key words: Dose-response curve. Endocrine disruption. Green-belly stink bug. Insect growth regulators. Reproductive organ morphology. ResumoA utilização de inseticidas conhecidos como reguladores de crescimento dos insetos, considerados mais seletivos a inimigos naturais, pode ser uma alternativa no manejo integrado no que se refere ao controle de percevejos-pragas das principais culturas no Brasil. Os objetivos deste trabalho foram avaliar alterações histológicas causadas no aparelho reprodutor de Dichelops melacanthus e a fecundidade das fêmeas e fertilidade de ovos, após o uso de inseticidas reguladores de crescimento. utilizados foram buprofezina (inibidor da biossíntese de quitina), na concentração subletal CL 30 2,99 g L -1 , e o piriproxifem (análogo do hormônio juvenil) na concentração subletal CL 30 8,35 mL L -1 . O delineamento experimental foi inteiramente casualizado, com 10 repetições e 10 insetos por repetição. Foram realizados dois bioensaios: no primeiro foi avaliada a fecundidade (número de ovos/fêmea) e a fertilidade (número de ninfas eclodidas) dos insetos que sobreviveram aos produtos. No segundo bioensaio, foram avaliadas as alterações morfológicas de ovaríolos de fêmeas e testículo de machos de percevejos adultos, que sobreviveram à ação dos inseticidas. Buprofezina e piriproxifem não afetaram a razão sexual de adultos ou mesmo a fecundidade das ...

A synopsis of the numbers of testicular follicles and ovarioles in true bugs (Heteroptera, Hemiptera) – sixty-five years of progress after J. Pendergrast’s review

“…Species identification was made by authors or collectors (in case of donated material). Voucher samples are deposited in the insect collections of the National Museum of Natural et Freitas et al 2007aFreitas et al , b, 2008Freitas et al , 2010Freitas et al , 2012Mróz 2007Mróz , 2012Ogorzałek 2007;Pires et al 2007;Esquivel 2009;Marchini et al 2009;Ogorzałek and Trochimczuk 2009;Souza et al 2009;Chiang 2010Chiang , 2013Van Doesburg et al 2010;Horton and Lewis 2011;Mróz and Wojciechowski 2011;Souza et al 2011Souza et al , 2014Uceli et al 2011;Chiang et al 2012;Patial 2012, 2016;Soto et al 2012;Gomes et al 2013;Özyurt et al 2013a, b, 2014a, b, 2015Pluot-Sigwalt and Chérot 2013;Jyoti et al 2015;Pereira et al 2015;Cremonez et al 2017Cremonez et al , 2019Elelimy et al 2017a, b;Novais et al 2017;Candan et al 2018;Mahmood et al 2018;Grodowitz et al 2019Grodowitz et al , 2020Khandelwal et al 2019;Koçakoğlu et al 2019;Xia 2019;…”

Effect of sublethal concentrations of insecticides associated with NaCl and KCl on feeding behavior and mortality of Euschistus heros and Diceraeus melacanthus (Hemiptera: Pentatomidae)

“…Sublethal (LC 25 ) and median lethal (LC 50 ) concentrations of each insecticide were pre-determined following the methodology described in Cremonez et al (2017). Briefly, six base concentrations for each insecticide were defined, with the highest concentration based on the maximum label rate registered for the stink bugs or a closely related pest in soybean when not registered (e.g., the whitefly Bemisia tabaci).…”

“…Due to their selective mode of action on insect-specific physiological mechanisms, these products may represent an efficient alternative for the control of pest resistant populations (Ishaaya et al, 2005;Liang et al, 2016;Sun et al, 2015), especially for possible use of integrating rotation schemes (Sparks et al, 2021). For stink bugs, previous studies have been conducted using sublethal doses of insect growth regulators (IGRs), or growth disruptors, for lower dosage effects on reproduction parameters, with reports of reduced fertility and fecundity (Cremonez et al, 2017) and internal morphological alterations in the reproductive organs of surviving adults (Cremonez et al, 2019;Matsumoto et al, Semina: Ciênc. Agrár.…”

Anatomy of male and female reproductive organs of stink bugs pests (Pentatomidae: Heteroptera) from soybean and rice crops

“…The comparative morphology of the reproductive tract in male and female stink bugs has already been described in several Pentatomidae species, and males generally exhibit a pair of testes, deferent ducts, ejaculatory bulb complex, paired accessory glands, and an ejaculatory duct (Pendergrast 1956, Adams 2001, Lemos et al 2001, Candan et al 2010, Araújo et al 2011, Özyurt et al 2013a, 2013b, Cremonez et al 2017). On the other hand, females exhibit a pair of ovaries connected to the lateral oviducts by the pedicels of ovarioles, a common oviduct, and a spermatheca (Lemos et al 2005, Candan et al 2010, Cremonez et al 2017. Insect ovaries and ovarioles can be classified into two types according to the presence (or absence) of nurse cells.…”