Pest potencial of Sitophilus zeamais on Brazil nut under storage conditions

The Brazil nut, fruit of Bertholletia excelsa H.B.K., a native plant of the Amazon region and may be considered one of the main extractivist products of countries like Bolivia, Colombia, Guyana, Venezuela, Peru and Brazil. In Brazil this plant can be found in the states of Acre, Amapá, Amazonas, Mato Grosso, Pará, Rondônia, Roraima and Tocantins. Species of the Coleoptera and Lepidoptera, have been classified as pest potentials of Brazil nut under storage conditions. Sitophilus zeamais (Coleoptera: Curculionidae) is one of the main insect pests attacking grain stores worldwide. This specie may be observed attacking grains in the field and in storage facilities (cross-infestation), presenting a wide variety of hosts. The purpose of this study was to assess the potential of adults of this species feed on Brazil nuts, and also to identify the type of injury as well as the life span of this coleopteran exposed to the meat of the Brazil nut. No feeding injury was observed on the surface of Brazil nuts and the life span of the insects was similar in treatments both with and without this food source in all populations evaluated. Due to the fact that S. zeamais adults do not injure, or feed on the Brazil nut, this beetle is not able to colonize this product and therefore may be considered a non-pest insect for stored Bertholletia excelsa almonds stored

Efeitos toxicológicos do fipronil no intestino médio e cérebro da abelha sem ferrão Partamona helleri Friese (Hymenoptera: Apidae)

Partamona helleri Friese is a stingless bee that pollinates native and cultivated plants in Brazil. The general decline of the bee population has been associated with many factors, including exposure to insecticides. Among insecticides used in agriculture and forestry in Brazil, fipronil is particularly important due to its toxicity to non-target organisms, including bees. In this context, this study aimed to evaluate the side effects of fipronil LC 50 on the midgut and brain of P. helleri workers after oral exposure. In chapter 1, the fipronil effects on the midgut morphology, antioxidant activity, and some pathways of cell death, cell proliferation and differentiation in the workers were evaluated. Fipronil caused disorganization of the midgut epithelium and increased the activities of the detoxification enzymes superoxide dismutase, catalase and glutathione S-transferase. In addition, there was an increase in the signaling-pathway proteins caspase-3, peroxidase, and ERK 1/2 in the midgut of exposed bees, but a decrease in the proteins JNK, Wg, Armadillo, Notch, and Prospero, indicating the induction of cell death and impairment of the midgut epithelial renewal. In chapter 2, the effects of fipronil on the behavior, brain morphology, antioxidant activity, and proteins related to cell signaling pathways on workers' brains were evaluated. The insecticide ingestion caused hyperactivity in the bees and damaged the brain. Fipronil also decreased the activity of catalase but increased the activity of glutathione S-transferase. Furthermore, exposed bees showed an increase in the number of positive cells for caspase-3 and peroxidase but a reduction in positive cells for ERK 1/2, JNK, and Notch, suggesting neuron death and impaired brain function. Together, these results demonstrate that fipronil significantly affects the morphology and physiology of two important organs of the stingless bee P. helleri, which may threaten the individuals and colonies of this important Neotropical pollinator. Keywords: Pollinator. Midgut. Brain. Fipronil. Signaling pathways.Partamona helleri Friese é uma abelha sem ferrão que poliniza plantas nativas e cultivadas no Brasil. O declínio geral da população de abelhas tem sido associado a muitos fatores, incluindo a exposição a inseticidas. Dentre os inseticidas usados na agricultura e silvicultura no Brasil, o fipronil é particularmente importante devido à sua toxicidade para organismos não-alvo, incluindo as abelhas. Nesse contexto, o presente estudo teve como objetivo avaliar os efeitos colaterais da LC 50 do fipronil no intestino médio e cérebro de operárias de P. helleri após exposição oral. No capítulo 1, foram avaliados os efeitos do inseticida sobre a morfologia do intestino médio, atividade antioxidante e algumas vias de morte celular, proliferação e diferenciação celular nas operárias. O fipronil causou desorganização do epitélio do intestino médio e aumentou a atividade das enzimas de desintoxicação superóxido dismutase, catalase e glutationa S-transferase. Além disso, houve um aumento nas proteínas da via de sinalização caspase-3, peroxidase e ERK 1/2 no intestino médio de abelhas expostas, mas uma diminuição nas proteínas JNK, Wg, Armadillo, Notch e Prospero, indicando a indução de morte celular e comprometimento da renovação epitelial do intestino médio. No capítulo 2, foram avaliados os efeitos do fipronil sobre o comportamento, morfologia cerebral, atividade antioxidante e proteínas relacionadas às vias de sinalização celular no cérebro das operárias. A ingestão do inseticida causou hiperatividade nas abelhas e danificou o cérebro. O fipronil também diminuiu a atividade da catalase, mas aumentou a atividade da glutationa S-transferase. Além disso, as abelhas expostas mostraram um aumento no número de células positivas para caspase-3 e peroxidase, mas uma redução nas células positivas para ERK 1/2, JNK e Notch, sugerindo morte de neurônios e função cerebral prejudicada. Juntos, esses resultados demonstram que o fipronil afeta significativamente a morfologia e a fisiologia de dois importantes órgãos da abelha sem ferrão P. helleri, o que pode ameaçar os indivíduos e as colônias deste importante polinizador Neotropical. Palavras-chave: Polinizador. Intestino médio. Cérebro. Fipronil. Vias de sinalização

Morphology of ovary and spermatheca of the phorid parasitoid Eibesfeldtphora tonhascai Brown (Diptera: Phoridae)

O forídeo Eibesfeldtphora tonhascai (Diptera: Phoridae) é um parasitoide das formigas cortadeiras Atta sexdens Forel e Atta laevigata Smith (Hymenoptera: Formicidae). Os estudos sobre este parasitoide estão restritos ao seu comportamento de parasitismo. Além disso, não há estudos sobre a reprodução deste parasitoide e neste caso, a morfologia é usualmente a ferramenta mais adequada para propor hipóteses funcionais sobre a reprodução. Assim, o objetivo deste trabalho foi descrever a morfologia do ovário e espermateca de E. tonhascai. As amostras foram processadas segundo a metodologia convencional para microscopia de luz e microscopia eletrônica de transmissão. Eibesfeldtphora tonhascai tem um par de ovários do tipo meroístico politrófico e duas espermatecas. O ovócito em estágios iniciais de desenvolvimento apresentou formato esférico e tamanho pequeno. O tamanho de toda a câmara ovocítica aumentou como resultado do acúmulo de vitelo no citoplasma do ovócito. As células foliculares iniciaram a deposição das camadas do córion e após sua deposição, essas células se degeneraram. Os ovócitos maduros possuíam formato elíptico e citoplasma repleto de grânulos. A parede do reservatório da espermateca de E. tonhascai tem células glandulares com citoplasma contendo abundantes ribossomos livres e retículo endoplasmático rugoso. O lúmen da espermateca é revestido por uma fina cutícula. A secreção elétron-densa das células glandulares pode ser observada dentro do lúmen da espermateca, do ducto glandular e em vesículas. A compreensão da organização e função do sistema reprodutivo feminino pode contribuir para o entendimento dos detalhes sobre a reprodução de forídeos. Além disso, pode ser usado como base para futuros estudos sobre vários aspectos da biologia reprodutiva desses inimigos naturais.The phorid Eibesfeldtphora tonhascai (Diptera: Phoridae) is a parasitoid of the leaf cutting ants Atta sexdens Forel and Atta laevigata Smith (Hymenoptera: Formicidae). The studies about this parasitoid are limited to its parasitism behavior. Furthermore, there are no studies about the reproduction of this parasitoid and in this case, morphology is usually the most adequate tool to propose functional hypotheses about reproduction. Thus, the aim of this work was to describe the morphology of ovary and spermatheca of E. tonhascai. The samples were processed according to the conventional methodology for light microscopy and transmission electron microscopy. Eibesfeldtphora tonhascai has a pair of ovaries of meroistic-polytrophic type and two spermatheca. The oocyte at the early stages of development had a spherical shape and small size. The size of entire oocyte chamber increased due to the accumulation of yolk in the oocyte cytoplasm. The follicular cells initiated the deposition of the chorion layers and after their deposition, these cells degenerated. The mature oocytes had an elliptical shape and cytoplasm filled with granules. The reservoir wall of the E. tonhascai spermatheca has glandular cells with abundant free ribosomes and rough endoplasmic reticulum. The lumen of the spermatheca is covered by a thin cuticle. Glandular cells secretion can be observed within the lumen of spermatheca, glandular duct and inside vesicles. Understanding the female reproductive system organization and function can contribute to understand details of phorids reproduction. Furthermore, it can be used as a basis for future studies about several aspects of reproductive biology of these natural enemies.Coordenação de Aperfeiçoamento de Pessoal de Nível Superio

Morphology of ovary and spermathecae of the parasitoid Eibesfeldtphora tonhascai Brown (Diptera: Phoridae)

Eibesfeldtphora tonhascai (Diptera: Phoridae) is a parasitoid of leaf-cutting ants and a potential biological control agent against these insect pests. This study describes the morphology of the ovary and spermatheca of E. tonhascai. The female reproductive tract of this parasitoid has a pair of meroistic polytrophic ovaries, two lateral oviducts that open into a common oviduct, an elongated accessory gland, and two spermathecae. Young oocytes are small and spherical, and their size increases as yolk is stored in the cytoplasm. This process is followed by chorion production by follicular cells. Mature oocytes are elliptical or torpedo-shaped. The reservoir wall of the spermatheca has type III glandular cells with cytoplasm rich in free ribosomes, rough endoplasmic reticulum, and secretory vesicles. The apical surface of these cells has microvilli associated with mitochondria. The reservoir lumen is lined by a cuticle and filled with spermatozoa. This is the first report of the ovary and spermatheca morphology of E. tonhascai and contributes to the comprehension of the reproductive biology of this parasitoid of leaf-cutting ants

Bioindicadores ambientais: insetos como um instrumento desta avaliação

Atividades agrícolas, florestais e do setor imobiliário vêm, ao longo do tempo, modificando ambientes ecologicamente estruturados. As consequências são drásticas e, por isso, faz-se necessária a busca por ferramentas e instrumentos para diagnosticar e monitorar a diversidade biológica desses locais. Os insetos têm-se destacado como potenciais organismos bioindicadores e isso se deve ao fato de apresentarem grande capacidade perceptiva, no que se refere a alterações do meio ambiente, principalmente por seu apurado sistema sensorial, que lhes permite qualificar condições ambientais em determinadas situações e, ainda, quantificar danos causados ao meio. Um dos problemas que podem ser associados a este setor é a falta de padronização e definição de protocolos de coleta e avaliação da biodiversidade, para que esses resultados possam ser analisados e extrapolados para diferentes ambientes antropizados. Neste trabalho, é contextualizada a importância da entomofauna como bioindicadora, em ecossistemas

Parasitism, sexual dimorphism and effect of host size on Apocephalus attophilus offspring, a parasitoid of the leaf-cutting ant Atta bisphaerica.

Atta bisphaerica (Forel) is a leaf-cutting ant that specializes on grass and causes productivity losses in sugar cane fields and pastures. Three phorid species, Apocephalus attophilus (Borgmeier), Myrmosicarius grandicornis (Borgmeier) and Eibesfeldtphora bragancai (Brown), have been found parasitizing A. bisphaerica workers. These parasitoids can reduce plant material transported into the nests and ant traffic on the trails. Therefore, phorid flies have been considered potential biological control agents for leaf-cutting ants. Here, we evaluated which parasitoid species attack the leaf-cutting ant A. bisphaerica in pasture areas of a Brazilian Savannah-Atlantic Forest ecotone, parasitism rate, effect of host size, sexual dimorphism and sex ratio of the emerged parasitoids. Four nests of A. bisphaerica were selected in pasture areas from August 2016 to August 2017, with 400 workers collected from each colony monthly. A total of 23,714 A. bisphaerica workers were collected during the study, of which 236 (0.99%) were parasitized by phorid parasitoids. Apocephalus attophilus, E. bragancai and M. grandicornis parasitized 217, 17 and 2 ants, respectively. The higher parasitism rate was found in the hottest/rainy season of the year. Non-parasitized ants survived longer than those parasitized by A. attophilus. The larval and pupal periods of this parasitoid were 2.2 ± 0.8 and 16 ± 1.4 days, respectively, and the number of pupae per parasitized ant ranged from 1 to 7. The number of A. attophilus pupae per host increased with the host head size. Likewise, the size of the adult parasitoids also increased according to the host ant. Apocephalus attophilus females were larger than males and the sex ratio (male: female) did not differ from 1: 1. Our results showed that A. attophilus would be a potential biocontrol agent of leaf-cutting ants because it produces multiple larvae per host, allowing a great production of parasitoids with short developmental time and kills the host ant faster than other phorids