RESUMO
An important concern with the use of genetically modified (GM) plants expressing Bacillus thuringiensis (Bt) insecticidal toxins is the deleterious effect on non-target organisms. The predatory stink bug Podisus nigrispinus (Dallas) (Hemiptera: Pentatomidae) is used in biological control programs and may be exposed to Bt toxins. This study evaluated the indirect effects of different Cry proteins on P. nigrispinus with the prey Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae), fed on simple or pyramided Bt maize genotypes. The experiment was carried out in a completely randomized design with three treatments: i) Isohybrid (not Bt), ii) Herculex® (transgenic maize encoding Cry1F protein) and iii) PowerCore® (pyramidal transgenic maize encoding the Cry1F, Cry1A.105, and Cry2Ab2 proteins), which were used to feed S. frugiperda for 48 h. The caterpillars were used as prey by P. nigrispinus females. We evaluated the presence of Cry proteins, consumed prey biomass (predation), oviposition period, number of postures, number of eggs, number of eggs per posture, number of nymphs, egg viability, embryonic period, female longevity and development, and survival rates of immature. The results show that different Cry proteins move through the food chain of P. nigrispinus and provide evidence that the ingestion of three different proteins does not lead to unexpected synergistic effects. However, Cry toxins promoted histopathological changes in midgut cells of P. nigrispinus.
Assuntos
Animais , Comportamento Predatório/efeitos dos fármacos , Controle Biológico de Vetores , Plantas Geneticamente Modificadas/toxicidade , Spodoptera , Cimicidae , Toxinas de Bacillus thuringiensis/análise , Zea maysRESUMO
The extensive use of insecticides can cause adverse side effects on pollinators, which negatively impact crop productivity. The pollination carried out by the honeybee Apis mellifera L. (Hymenoptera: Apidae) is crucial in increasing the productivity of the melon (Cucumis melo L.). The main objective of this study was to assess if insecticides applied in the cultivation of cantaloupe melon exhibit significant levels of toxicity toward A. mellifera. We tested the toxicity of azadirachtin, pyriproxyfen, chlorantraniliprole, and imidacloprid, which are commonly sprayed to manage melon pests such as the whitefly Bemisia tabaci (Genn.) (Hemiptera: Aleyrodidae), the pickleworm Diaphania nitidalis (Stoll) and the melonworm Diaphania hyalinata (L.) (Lepidoptera: Pyralidae). Three treatments were carried out, 0.0×, 0.1x and 1.0x the concentration recommended by the manufacturer for the control of those pests. Repellency tests, analysis of mortality through contact and ingestion, and flight tests were performed. The insecticide imidacloprid caused mortality rates above 90% in all tested exposure pathways, displaying high residue persistence on plants. Although not causing significant mortality in the ingestion test, pyriproxyfen caused significant mortality after exposure through contact, and change in flight ability. Azadirachtin caused mortality in the ingestion test and impaired the flight ability of bees, while chlorantraniliprole only impaired the flight ability. Moreover, bees were not repelled by these insecticides, suggesting that they may collect contaminated food in the field while foraging. Altogether, ecofriendly, alternative pest control options should be developed, as well as the adoption of more selective insecticides, in order to reduce the non-target effects on honeybees and guarantee their pollination services.
Assuntos
Abelhas/fisiologia , Inseticidas/toxicidade , Controle de Pragas/métodos , Animais , Abelhas/efeitos dos fármacos , Brasil , Cucurbitaceae , Voo Animal/efeitos dos fármacos , Lepidópteros , Limoninas , Neonicotinoides , Nitrocompostos , Polinização , PiridinasRESUMO
The spotted lanternfly, Lycorma delicatula, is an introduced plant hopper that causes significant damage to host plants in the United States. Because of its affinity for tree of heaven, Ailanthus altissima, control efforts have focused on the use of the systemic insecticide, dinotefuran, in designated trap trees. There is concern about exposure to this pesticide by non-target species, especially honey bees, Apis mellifera, via lanternfly honeydew. Therefore, honey bee colonies were established in areas of high densities of trap trees and samples of honey, bees, and beeswax were collected in May, July, and October of 2017 for analysis. Samples were extracted by the QuEChERS method and analyzed using high-performance liquid chromatography with tandem mass spectrometry to determine the presence and quantity of dinotefuran. Additionally, honeydew from lanternflies was analyzed for dinotefuran and informal observations of trap tree visitors were made. None of the worker bee, wax, or honey samples indicated detectable levels of dinotefuran; however, honeydew samples collected did contain dinotefuran above the detection limit with amounts ranging from 3 to 100 ng per sample. The lack of dinotefuran in honey bee products matches the general absence of honey bees at trap trees in informal observations.
Assuntos
Hemípteros , Himenópteros , Animais , Abelhas , Guanidinas , Neonicotinoides , Nitrocompostos , ÁrvoresRESUMO
Rough rice grains are often stored for extended periods before they are used or consumed. However, during storage, the rough rice is vulnerable to insect infestation, resulting in significant economic loss. Previous studies have shown that volatiles cues, physical characteristics, and taste chemicals on the grains could be the important key behavior factors for storage insect pests to locate the hosts and select oviposition sites. It is also well known that the transgenic Bt rough rice line T1C-19, which expresses a cry1C(â) gene has a high resistance to Lepidoptera pests. However, there were no evidences to show the consequences of host preference for non-target insect pests after growing Bt transgenic rice. In this study, the potential key factors of Bt rough rice were investigated for their impacts on the behaviors of non-target pest lesser grain borer Rhyzopertha dominica, the main weevil pest of grain and its parasitic wasps Anisopteromalus calandrae, the natural enemy of the beetle. Both electronic nose and electronic tongue analyses showed that the parameters of Bt rough rice were analogous to those of the non-Bt rough rice. The volatile profiles of Bt and non-Bt rough rice examined by gas chromatographic mass spectrometry (GC-MS) were similar. For most volatile compounds, there were no significantly quantitative differences in compound quantities between Bt and non-Bt rough rice. The densities of sclereids and trichomes on the rough rice husk surface were statistically equal in Bt and non-Bt rough rice. The non-target pest, R. dominica, and its parasitoid wasp, A. calandrae, were attracted to both rough rice and could not distinguish the transgenic T1C-19 from the isogenic rough rice. These results demonstrated that Bt rough rice has no negative impacts on the host preference behaviors of non-target stored product pest R. dominica and its parasitoid A. calandrae.