This study describes the development of acetylcholinesterase (AChE), carboxylesterases (CaE1, CaE2, CaE3), glutathion-S-transferase (GST), alkaline phosphatase (ALP) and catalase (CAT) as enzyme biomarkers of exposure to xenobiotics such as thiamethoxam in the honey bee Apis mellifera. Extraction efficiency, stability under freezing and biological variability were studied. The extraction procedure achieved good recovery rates in one extraction step and ranged from 65 percent (AChE) to 97.3 percent (GST). Most of the enzymes were stable at -20°C, except ALP that displayed a slight but progressive decrease in its activity. Modifications of enzyme activities were considered after exposure to thiamethoxam at the lethal dose 50 percent (LD(50), 51.16 ng bee(-1)) and two sublethal doses, LD(50)/10 (5.12 ng bee(-1)) and LD(50)/20 (2.56 ng bee(-1)). The biomarker responses revealed that, even at the lowest dose used, exposure to thiamethoxam elicited sublethal effects and modified the activity of CaEs, GST, CAT and ALP. Different patterns of biomarker responses were observed: no response for AChE, an increase for GST and CAT, and differential effects for CaEs isoforms with a decrease in CaE1 and CaE3 and an increase in CaE2. ALP and CaE3 displayed contrasting variations but only at 2.56 ng bee(-1). We consider that this profile of biomarker variation could represent a useful fingerprint to characterise exposure to thiamethoxam in the honey bee A. mellifera. This battery of honey bee biomarkers might be a promising option to biomonitor the health of aerial and terrestrial ecosystems and to generate valuable information on the modes of action of pesticides.

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The present study was intended to evaluate the responses of enzymes in the honeybee Apis mellifera after exposure to deltamethrin, fipronil, and spinosad and their use as biomarkers. After determination of the median lethal doses (LD50), honeybees were exposed at doses of 5.07 ng/bee and 2.53 ng/bee for deltamethrin, 0.58 ng/bee and 0.29 ng/bee for fipronil, and 4.71 ng/bee and 2.36 ng/bee for spinosad (equivalent to 1/10th [LD50/10] and 1/20th [LD50/20] of the LD50, respectively). The responses of acetylcholinesterase (AChE), carboxylesterases (CaEs-1-3), glutathione-S-transferase (GST), catalase (CAT), and alkaline phosphatase (ALP) were assessed. The results showed that deltamethrin, fipronil, and spinosad modulated these biomarkers differentially. For the enzyme involved in the defense against oxidative stress, fipronil and spinosad induced CAT activity. For the remaining enzymes, 3 response profiles were identified. First, exposure to deltamethrin induced slight effects and modulated only CaE-1 and CaE-2, with opposite effects. Second, spinosad exhibited an induction profile for most of the biomarkers, except AChE. Third, fipronil did not modulate AChE, CaE-2, or GST, increased CAT and CaE-1, and decreased ALP. Thus, this set of honeybee biomarkers appears to be a promising tool to evaluate environmental and honeybee health, and it could generate fingerprints to characterize exposures to pesticides.

Pesticides are considered the first line of defense for the control of pests and diseases. At least in the short and medium term, the use of pesticides will remain an important strategy for pest management, allowing growers to produce crops of sufficient quality at low costs. A broad approach known as Integrated Pest Management (IPM) combines several different pest-control strategies, among which the combination of chemical and biological control stands out. It requires pesticides that achieve optimal control of target pests with minimal impact on the activity of biological control agents. Because of the dynamics of pest infestations, IPM routines are continuously adjusted by growers, requiring comprehensive information about pesticide effects on natural enemies. However, this information is not always available and often contradictory, which constrains the design of field recommendations. In this review, we focused on the importance of selective pesticides in IPM programs, and the effects of chemical pesticides on parasitoids, predators, and entomopathogenic fungi. We provided a detailed discussion of the challenges and constraints for research on pesticide effects on natural enemies, as well as for the resulting field recommendations.

The development of new strategies to control pest insects is required, in combination with conventional pesticides or replacing them. Essential oils produced from botanical extracts used in management programs should be effective against pests and selective to natural enemies. Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is one of the most destructive pests of solanaceous crops in the world, and a possible management strategy consists of releases of the predator Nesidiocoris tenuis (Hemiptera: Miridae), along with botanical applications. The objective of this study was to evaluate the effects of Prev-am ® oil on T. absoluta offspring, either with or without the predator N. tenuis, as well as the oil's effects on N. tenuis predatory behavior and longevity. The oil's effects were compared with distilled water (control) and a synthetic pesticide (lambdacyhalothrin). The response of populations to lambda-cyhalothrin was similar to that with Prev-am ® , compared to the control, showing that N. tenuis had higher capacity to reduce T. absoluta populations. The survival analysis of predators exposed to Prev-am ® indicates that none of the concentrations differed significantly from the control. In addition, the canonical variate analysis indicated significant overall differences in the predator behavior submitted to different treatments, suggesting that synthetic pesticide treatment affected predator behavior when compared to control and Prev-am ® . Reduction in predatory voracity of N. tenuis adults exposed to leaves treated with pesticide and biopesticide was significant compared to the control treatment. The results obtained could improve IPM programs against T. absoluta through the Prev-am ® applications and N. tenuis releases.Keywords Natural product · Predatory mirid · South American tomato pinworm · Ecotoxicology · Biological control Key message• New strategies based on the use of natural enemies and biopesticides to control Tuta absoluta are desirable for integrated pest management (IPM). • The combination of Nesidiocoris tenuis with Prev-am ® (at half of the recommended concentration) showed enhanced efficacy against T. absoluta. • Presence of N. tenuis significantly reduced T. absoluta population growth. • Lambda-cyhalothrin and Prev-am ® could disturb behavioral response of N. tenuis.

Influência do Silício na Interação Tritrófica: Plantas de Trigo, Pulgão-Verde Schizaphis graminum (Rondani) (Hemiptera: Aphididae) e seus Inimigos Naturais Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae) e Aphidius colemani Viereck (Hymenoptera: Aphidiidae)RESUMO -Estudou-se a interação tritrófica: trigo, pulgão-verde Schizaphis graminum (Rondani) e seus inimigos naturais-chave Chrysoperla externa (Hagen) e Aphidius colemani Viereck, em plantas com ou sem adubação de silício. Os tratamentos consistiram em: 1) aplicação de silício via foliar; 2) aplicação de silício no solo e 3) testemunha (sem aplicação). As avaliações consistiram: a) teste de preferência do pulgão com chance de escolha em laboratório e b) aspectos biológicos das fases imaturas do predador C. externa, alimentado com pulgões criados em plantas dos diferentes tratamentos. Para a realização dos bioensaios com A. colemani foram realizados dois tratamentos: 1) aplicação de silício no solo e 2) testemunha (sem aplicação). As características biológicas avaliadas foram: duração da fase imatura, longevidade, razão sexual, ciclo total e porcentagem de parasitismo. Verificou-se que a aplicação de silício aumentou o grau de resistência das plantas de trigo diminuindo a preferência do pulgão-verde em relação à testemunha. Esse resultado pode estar relacionado à barreira mecânica proporcionada pela deposição de sílica na parede celular, o que dificultaria a penetração do estilete no tecido da planta, como também ao aumento na síntese de compostos de defesa da planta. Entretanto, não foi observado nenhum efeito indireto da aplicação de silício nas características biológicas tanto do predador como do parasitóide.PALAVRAS-CHAVE: Insecta, Triticum aestivum, resistência, predador, parasitóide ABSTRACT -We studied the tritrophic interaction: wheat, greenbug Schizaphis graminum (Rondani) and its key natural enemies, Chrysoperla externa (Hagen) and Aphidius colemani Viereck, in plants with or without silicon fertilization. Treatments consisted of: 1) silicon application via the leaves; 2) silicon application in the soil 3) control (no application). The evaluations consisted of: a) free-choice aphid preference test in the laboratory, from the 35 th day after plant emergence, and b) biological aspects of the immature stages of predator C. externa, feeding on aphids reared on plants from the different treatments. Two treatments were tried in the bioassays involving A. colemani: 1) silicon application in the soil, and 2) control (no application). The biological traits evaluated were: duration of the immature stage, longevity, sex ratio, total developmental time, and percentage parasitism. Silicon application increased the degree of resistance in wheat plants, decreasing greenbug preference in relation to the control. This result could be related to the mechanical barrier provided by silica deposition in the cell wall, which would make it difficult for the stylet to penetrate the plant tissue, as well as an increase in the synthesis of plant defense compounds. Howev...

This study assessed the transgenerational effects of insecticides in developing Trichogramma galloi (Hymenoptera: Trichogrammatidae). Laboratory bioassays were performed in which five insecticides were sprayed on egg-larval, pre-pupal and pupal stages of the parasitoid. The interaction between insecticides and development stages of the parasitoid was not significant for the rate of F0 emergence. All insecticides significantly reduced the emergence of wasps, with the lowest emergence observed when they were applied to the pupal stage. For the sex ratio, only spinosad applied to the pre-pupal stage and triflumuron applied on the egg-larval and pre-pupal stages did not differ from the controls. Triflumuron applied to pre-pupae did not lead to any difference in the parasitism rate of the treated generation (F0) when compared to the control. There were no significant differences among survival curves for females of F0 when all insecticides were sprayed on the egg-larval stage. Both concentrations of lambda-cyhalothrin + thiamethoxam reduced female pre-pupal survival, and all treatments reduced female pupal survival. In addition, we observed a transgenerational effect of the insecticides on emergence and sex ratio of next generation (F1). Lambda-cyhalothrin + thiamethoxam (Min) applied to the pre-pupae and pupae, the maximum rate of the same insecticides applied to the egg-larvae and pre-pupae, and spinosad applied to pre-pupae all significantly reduced the adults emergence of T. galloi F1 generation. Only triflumuron did not alter the F1 sex ratio. These bioassays provide a basis for better understanding the effects of insecticide use on beneficial parasitoids.

A tactic for control to corn leaf Rhopalosiphum maidis (Fitch, 1856) would be the use of resistant materials, but, for not being a key pest of the crop, there are not yet corn genotypes availables with those characteristics. So, it was aimed in this work to evaluate the effect of silicon on the aphid's development on corn plants. Preference tests with leaves detached from the plants and on corn plants were accomplished. Its was found that the treatments where silicon was applied to the soil plus a foliar sprayed fertilization or through two foliar applications were the ones which contained a lower number of aphids, increasing the resistance of leaves and making the feeding of those insects difficult. In general, the results showed that silicon affected the leaf aphid's preference.Index terms: Insecta, resistance, IPM. RESUMOUma tática para o controle do pulgão-do-milho Rhopalosiphum maids (Fitch, 1856) seria a utilização de materiais resistentes, porém, por não se tratar de uma praga-chave da cultura, não há, ainda, disponibilidade de genótipos de milho com essas características. Assim com o presente trabalho objetivou-se avaliar o efeito do silício na preferência do pulgão-da-folha em plantas de milho. Os tratamentos consistiram na aplicação de silício via solo e/ou foliar e testemunha. Foram realizados testes de não-preferência com folhas destacadas e diretamente em plantas de milho. Verificou-se que os tratamentos nos quais o silício foi aplicado via solo mais uma adubação foliar, ou mediante duas aplicações foliares, foram os que apresentaram menor número de pulgões, aumentando a resistência das folhas e dificultando a alimentação desses insetos. De modo geral, o silício afetou a preferência do pulgão-da-folha.Termos para indexação: Insecta, resistência, MIP.