Euschistus heros is an important pest in Brazilian agriculture growing importance in the general Neotropical realm. Its reproductive potential is the key factor for its characterization as a pest in major crops such as soybean and cotton. The aims of this study were to characterize morphometric parameters of testicles and testicular accessory cells-TACs nuclei of adults E. heros treated with chitin biosynthesis inhibitors (CBIs). The insecticides lufenuron (Match® 50 EC) and buprofezin (Applaud® 250 WP) were applied individually in 4th instar nymphs, remained in controlled conditions until the emergence of adult males. The testicles were identified and removed 72 h after emergency, fixed, photographed for anatomic analysis, and processed for morphometric analyses of the TACs nuclei. It was possible to observe that lufenuron and buprofezin decreased the testicular area. Buprofezin decreased the mean nuclear area analyzed in the TACs, and nuclear hypertrophy can indicate an activity on support and nutrition of germ line cells, presenting a possible effect on protein synthesis. The intense reaction for Fast green in control compared to buprofezin treatment may indicate that total protein (histones and non-histones) has been altered. The tested insecticides, with special focus on buprofezin may affect the final stages of reproductive development of E. heros, with potential to be used in field to the control of this pest.

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 ...

Cucurbit chlorotic yellows virus (CCYV) belongs to the genus Crinivirus and is part of a complex of whitefly-transmitted viruses that cause yellowing disease in cucurbits. In the southeastern USA, heavy incidences of CCYV have been observed on all cucurbits grown in the fall. CCYV was detected from wild radish (Raphanus raphanistrum L.), a common weed that grows in the southeastern USA by high-throughput sequencing as well as RT-PCR. CCYV sequence from wild radish was 99.90% and 99.95%, identical to RNA 1 and RNA 2 of cucurbit isolates of CCYV from the region. Transmission assays using whiteflies demonstrated that wild radish is a good host for CCYV. Whiteflies were also able to acquire CCYV from wild radish and transmit the virus to cucurbit hosts, which developed typical symptoms associated with CCYV. Using quantitative PCR, the titer of CCYV in wild radish was also estimated to be on par with that of cucurbit hosts of the virus. Whitefly bioassays revealed that wild radish is an acceptable feeding and reproductive host plant. These results indicate that wild radish could serve as a reservoir host for CCYV in the USA and other parts of the world where similar conditions exist.

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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 ...

The aim of this study was to determine the effect of the insecticide pyriproxyfen (Tiger™ 100 CE), juvenile hormone analogue, when applied in a sublethal LC30 concentration (0.668 mL a. i. L-1), on the morphological and morphometric parameters of external and internal connective tissue (CT) of the Neotropical-brown stink bug Euschistus heros testicles. The insecticide was applied on nymphs from the 4th instar using a Potter tower with a working pressure of 82.73 kPa (12 lb pol-²) and 1 mL of the emulsion per replicate. A completely randomized experimental design was used, consisting of two treatments (control and pyriproxyfen-treated), five repetitions, and 10 adults of E. heros per experimental unit. The insects were maintained under controlled conditions until the emergence of adults. After 48 h of emergence of adults, the testicles were collected, fixed, and processed for morphological and morphometric analyses. A change was observed in the collagen fibers of the CT of treated insects when compared with those of controls. It was also observed that both types of CT (dense irregular and loose) over the internal tunic of the treated insect were thinner than those in control insects. The analysis showed that pyriproxyfen significantly reduced the external and internal CT width and the conformation of its fibers in all the observed regions when compared with the controls; this may affect the production of the three different types of sperm present in this species.

Stink bugs are important pests of highly profitable agricultural crops worldwide, and the use of insecticides remains the main strategy for their control. The objectives of this study were to evaluate the behavioral aspects of Euschistus heros and Diceraeus melacanthus through feeding after exposure to chloride solutions (NaCl and KCl), as well as the control efficacy of insecticides in combination with salt. Two bioassays were performed with stink bugs exposed to treated substrate: i) feeding preference by salivary sheath counting in a free choice test for chloride solutions, using bean pod or corn seedling as counting substrate for newly emerged E. heros and D. melacanthus adults, respectively; and ii) comparative efficiency of five synthetic insecticides associated with NaCl or KCl in the mortality of 4th instar nymphs (N4). Pre-determined sublethal (LC25) and median lethal (LC50) concentrations of commercially available insecticides (Lfn), buprofezin (Bpf), pyriproxyfen (Ppx), chlorantraniliprole (Ctn) and spinosad (Spn) were used. For each species and insecticide, the treatments were pure LC25, LC25 + NaCl 5% m/m, LC25 + KCl 5% m/m, pure LC50, and distilled water (dH2O) as the control. Corn seedlings treated with 5% NaCl saline solution had reduced salivary sheaths from D. melacanthus. Ctn LC25 (0.63 mL L-1) + 5% NaCl and pure Ctn LC50 (1.16 mL L-1) were similar and more efficient in terms of mortality of D. melacanthus N4s than any other treatment. The association of Spn LC25 (0.37 mL L-1) + 5% NaCl and Spn LC50 only (0.90 mL L-1) was similar to that of E. heros N4s compared to other treatments. The insecticide concentrations used in this study have potential for stink bug pest control, thus the association of insecticides with commercially available, easy-to-find, and low-cost chloride salts may represent a good strategy for stink bug control.

Tuta absoluta (Meyrick) is considered a pest with high destructive potencial and its control depends mainly on successive applications of insecticides. Therefore, new alternatives for the control of the tomato leaf miner using plants with insecticidal potential have been examined. This study was aimed at evaluating the toxic effect of Annona mucosa extract on the developmental stages of T. absoluta. Larval survival bioassay was performed in which newly-hatched caterpillars were inoculated in tomato leaflets sprayed with A. mucosa extract in the LC50 and LC90 treatments and the insecticidal controls chlorfenapyr, methanol, and water. To identify the mode of action of the extract in caterpillars, histological analyzes of the integument and gut were carried out. To evaluate ovicidal activity and oviposition repellency, only the LC50 treatment and controls (water and methanol) were carried out. In the ovicidal bioassay 75 eggs/treatment were used, and for the oviposition repellency, 10 couples/treatment, with 10 replicates. In the larval survival bioassay, a significant difference among survival curves, and the crude extract of A. mucosa significantly reduced the survival of T. absoluta caterpillars. The mode of action of the extract occurred by contact and ingestion, as indicated by changes in the integument and gut. The extract of A. mucosa also interfered in the embryonic development of T. absoluta, with a viability of more than 90% of the eggs. Regarding the behavioral effect, the extract reduced oviposition rates of T. absoluta females. Thus, A. mucosa extract had toxic effects on the different stages of pest development.