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Toxicidade do extrato aquoso de Simarouba sp. em Plutella xylostella, Apis mellifera e Melipona quadrifasciata

Fri, 10 Apr 2026 00:00:00 GMT

Título: Toxicidade do extrato aquoso de Simarouba sp. em Plutella xylostella, Apis mellifera e Melipona quadrifasciata Autor(es): Souza , Silvana Aparecida de Primeiro Orientador: Mussury , Rosilda Mara Abstract: Botanical extracts are natural chemical products derived from plants, whose synergistic action of secondary metabolites can interfere with the biological characteristics of insect pests. Thus, they represent a promising alternative for the control of species resistant to synthetic insecticides, such as Plutella xylostella (Linnaeus, 1758) (Lepidoptera: Plutellidae). Commonly known as the diamondback moth, this species is one of the main lepidopteran pests of brassicas and stands out for its resistance to several registered active ingredients. Additionally, botanical extracts are known for their lower environmental persistence and, in general, lower risk to human health. However, the scarcity of information on their effects on non-target organisms, such as pollinators and natural enemies, hinders the safe application of botanical insecticides in crop areas. In this context, the objective of the present study was to evaluate the mode of action of the aqueous extract of Simarouba sp. (EAS), at different concentrations, on Plutella xylostella, with emphasis on alterations in the midgut (Chapter I), as well as to investigate the selectivity of the extract to Apis mellifera and Melipona quadrifasciata (Chapter II). For the histological analyses, second-instar larvae were exposed for 48 h to kale leaves (Brassica oleracea var. acephala) treated with the botanical extract at concentrations of 0.01%, 0.05%, 0.1%, 1%, 5%, and 10%, in addition to the control treatment, which consisted of distilled water. After exposure, caterpillars were randomly collected from each treatment for histological processing and evaluation. For the selectivity tests in bees, workers of A. mellifera and M. quadrifasciata were exposed to EAS at concentrations of 0.01% and 0.05% by oral and topical routes. Survival was evaluated over 96 h. Sublethal effects on locomotion were analyzed by video tracking using the EthoVision XT system. The highest concentrations of the aqueous extract of Simarouba sp. (10% and 5%) caused marked alterations in the midgut of P. xylostella, with impairment of the intestinal epithelium. The main alterations observed included cellular disorganization, presence of vacuoles, and protrusions and extrusions toward the lumen. In addition, at the highest concentrations, it was not possible to identify the presence of the peritrophic membrane, suggesting impairment of the structure responsible for protecting the intestinal epithelium. Regarding selectivity, in A. mellifera, EAS caused low impact on survival after oral exposure, with high survival throughout the evaluation period, whereas, after topical exposure, the concentration of 0.05% promoted mortality close to 50% at the end of 96 h. In M. quadrifasciata, the effects were more evident after oral exposure, in which EAS at 0.05% caused mortality of at least 50% of individuals at the end of 96 h, allowing the estimation of the LT50, whereas, after topical exposure, all treatments showed survival above 70%. Regarding locomotor activity, EAS altered the movement pattern in both species, mainly affecting mean speed, mean distance, and locomotion intensity. In M. quadrifasciata, it also caused resting periods, indicating absence of movement. In summary, our results demonstrate that the aqueous extract of Simarouba sp. promotes significant alterations in the midgut of P. xylostella, highlighting its potential as a promising alternative for the ecological management of insect pests. However, EAS also showed lethal and sublethal effects on bees, depending on the species, exposure route, and concentration, with 0.05% being more toxic than 0.01%. These findings indicate that, although botanical extracts have potential for pest control, they may also pose risks to non target organisms, such as pollinators, reinforcing the need to develop appropriate protocols for assessing the toxicity of plant-derived products. Editor: Universidade Federal da Grande Dourados Tipo: Tese

Epizootia do fungo entomopatogênico Moelleriella Bres. sp. sobre mosca-branca e cochonilha: primeiro registro, avaliação do potencial biológico e desenvolvimento in vitro

Mon, 20 Apr 2026 00:00:00 GMT

Título: Epizootia do fungo entomopatogênico Moelleriella Bres. sp. sobre mosca-branca e cochonilha: primeiro registro, avaliação do potencial biológico e desenvolvimento in vitro Autor(es): Mesa, Natalia Elizabeth Soto Primeiro Orientador: Loureiro, Elisangela de Souza Abstract: The use of entomopathogenic fungi as biological control agents represents a sustainable alternative to the use of agrochemicals in agriculture. In this context, the genus Moelleriella (Clavicipitaceae, Hypocreales, Ascomycota) has been little studied, despite its potential for controlling insect pests, such as whiteflies and mealybugs, and its potential as an endophyte of associated plants. The present study aimed to evaluate the growth of colonies, conidial production, and germination of Moelleriella sp. in different culture media under laboratory conditions. To this end, the fungus was isolated from infected insects in a remnant of the Atlantic Forest in Brazil, morphologically identified, and cultured on five culture media (AN, MEA, SAB, BDA, and YEAST). Radial colony growth, conidial production, and germination percentage were evaluated. The data were analyzed using analysis of variance (ANOVA) and Tukey’s test (α = 0.05). The results showed significant differences among treatments, with the Yeast Extract (YEAST) medium standing out for promoting the highest mycelial growth, as well as the highest conidia production and germination (F₄,₄₀ = 71.22; p < 0.001). These results suggest that the nutritional composition of the medium, particularly its content of carbon and nitrogen sources, directly influences the physiological performance of the fungus. In conclusion, Moelleriella sp. shows high potential as a biological control agent, and the YEAST medium stands out as an efficient alternative for its production under laboratory conditions. This study provides relevant information for optimizing cultivation systems and lays the groundwork for future research aimed at its application in Integrated Pest Management programs. Editor: Universidade Federal da Grande Dourados Tipo: Dissertação

Seletividade de inseticidas (microbiológico e alternativo) à adultos de Chrysoperla externa (Hagen, 1861) (Neuroptera: Chrysopidae)

Mon, 02 Feb 2026 00:00:00 GMT

Título: Seletividade de inseticidas (microbiológico e alternativo) à adultos de Chrysoperla externa (Hagen, 1861) (Neuroptera: Chrysopidae) Autor(es): Almeida , Adner Wilian Fernandes de Primeiro Orientador: Silva , Rosilda Mara Mussury Franco Abstract: The intensification of insecticide use in maize (Zea mays L.) cultivation has increased the need to assess their compatibility with natural enemies used in integrated pest management (IPM). Chrysoperla externa (Hagen, 1861) is one of the main predators associated with maize in Brazil; however, most studies on selectivity focus on immature stages, and there is limited information available on the effects of phytosanitary products on adults. Based on a structured theoretical framework regarding the biology, development, and behavior of the species, this study aimed to experimentally evaluate the lethal and sublethal effects of different products used in maize pest management on adults of C. externa. Bioassays were conducted under controlled conditions using the ASPECLE system, with four treatments: acephate, Isaria fumosorosea, aqueous extract of Simarouba sp., and distilled water as control. Mortality was corrected using Abbott’s formula, and the products were classified according to IOBC/WPRS criteria, in addition to evaluating sublethal effects on survival and oviposition. Acephate caused total mortality and was classified as harmful (Class 4). Isaria fumosorosea exhibited a slightly harmful effect (Class 2), whereas the Simarouba sp. extract was considered harmless (Class 1), with survival and oviposition rates similar to those of the control. The results indicate that Chrysoperla externa is highly compatible with biological agents and plant extracts, reinforcing its potential as a biological control agent in maize and highlighting the importance of prioritizing selective inputs in IPM programs. Editor: Universidade Federal da Grande Dourados Tipo: Dissertação

Óleos essenciais como alternativa de controle de Callosobruchus maculatus (Fabr., 1775) (Coleoptera: Chrysomelidae, Bruchinae) em grãos de feijão-caupi (Vigna unguiculata): toxicidade, efeito subletal e qualidade dos grãos

Sat, 28 Feb 2026 00:00:00 GMT

Título: Óleos essenciais como alternativa de controle de Callosobruchus maculatus (Fabr., 1775) (Coleoptera: Chrysomelidae, Bruchinae) em grãos de feijão-caupi (Vigna unguiculata): toxicidade, efeito subletal e qualidade dos grãos Autor(es): Santos , Bruno Pereira dos Primeiro Orientador: Silva, Gutierres Nelson Abstract: Callosobruchus maculatus (Fabricius, 1775) (Coleoptera: Chrysomelidae: Bruchinae) is one of the main directives of stored cowpea, causing significant losses in weight, nutritional quality and grain predictions, especially in low-technology storage systems. In search of sustainable alternatives to the use of synthetic insecticides, essential oils are highlighted as promising tools in the management of stored product directives. The present study aimed to evaluate the contact toxicity, fumigant activity and repellent effect of essential oils from Origanum vulgare L., 1753, Hyssopus officinalis L., 1753, Syzygium aromatic (L.) Merr. & L.M. Perry, 1939, and Plukenetia volubilis L., 1753 on C. maculatus adults. The bioassays were prolonged under controlled conditions of temperature, humidity and photoperiod at the Insect-Plant Interaction Laboratory at the Federal University of Grande Dourados (UFGD). In the contact toxicity test, beans treated with different concentrations of essential oils were offered to insects, therefore lethal concentrations (LC₅₀ and LC₉₅) were estimated. In fumigation tests, insects were exposed to oil vapors in airtight chambers to assess respiratory mortality. The repellent effect was determined through choice arenas, calculating the repellency index (RI). Additionally, the instantaneous population growth rate and the quality of the treated grains were evaluated. The results revealed that essential oils have different efficiency depending on their chemical composition and route of exposure. O. vulgare oil showed greater contact toxicity, with lower LC₅₀ and LC₉₅ values. H. officinalis stood out for its greatest fumigant and repellent effect, with a repellency index of less than 1. S. aromaticum showed moderate toxicity and a low repellent effect, while P. volubilis was the least efficient in all evaluations. In relation to sublethal effects, the reduction of the population growth rate in the most efficient treatments was encouraged, reducing interference in the development of the species. Regarding grain quality, no significant changes were observed in the evaluated parameters. Editor: Universidade Federal da Grande Dourados Tipo: Dissertação