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Herbivores select host plants depending on plant quality and the presence of predators and competitors. Competing herbivores change host plant quantity through consumption, but they can also change plant quality through induction of plant defences, and this affects the performance of herbivores that arrive later on the plant. Some herbivores, such as the spider mite Tetranychus evansi, do not induce, but suppress plant defences, and later-arriving herbivores can profit from this suppression. It has been suggested that the dense web produced by this spider mite serves to prevent other herbivores to settle on the plant and benefit from the suppressed defences. Here, we confirmed this by studying the preference and performance of the whitefly Bemisia tabaci, a generalist herbivorous pest. To disentangle the effects through changes in plant defences from the effects of spider-mite web, we included treatments with a strain of the closely-related web-producing spider mite T. urticae, which induces plant defences. Whiteflies did perform worse on plants with defences induced by T. urticae, but, in contrast to other herbivores, did not perform better on plants with defences suppressed by T. evansi. Moreover, the web of both spider mites reduced the juvenile survival of whiteflies, and whiteflies avoided plants that were covered with web. Hence, whitefly performance was not only affected by plant quality and induced plant defences, but also through the web produced by spider mites, which thus serves to protect against potential competitors, especially when these could profit from the suppression of plant defences by the mites.

Plant quality for herbivores is usually evaluated with molecular and physiological techniques and with herbivore performance bioassays. These performance assays are usually done either on intact plants or on detached plant parts, such as leaves, leaflets, and leaf discs. It is thus far unclear how performance experiments on intact plants and on plant parts compare. Plant quality may change in detached plant parts because of the mechanical wounding inflicted, which may induce plant defences. Moreover, plant defences are often systemic, i.e., involving the entire plant, and may not be fully expressed in leaf discs. We investigated the effects of plant quality on the performance of a phytophagous mite on intact plants and on leaf discs. Plant quality was manipulated by infesting intact tomato plants (Solanum lycopersicum L., Solanaceae) either with a strain of the spider mite Tetranychus urticae Koch (Acari: Tetranychidae) that induces plant defences, or with Tetranychus evansi Baker & Pritchard, which suppresses defences, and using uninfested tomato plants as control. We subsequently evaluated the oviposition rate and survival of individual females of T. evansi on intact plants and on leaf discs as a measure of herbivore performance. The mites produced fewer eggs on detached leaf discs than on intact plants. However, the oviposition rate of T. evansi was lower on plants infested with the inducer T. urticae than on plants infested with the suppressor T. evansi, and than on uninfested plants, both on leaf discs and on intact plants. We conclude that both intact plants and leaf discs can be used to evaluate the effects of plant quality on performance of this herbivore.

The cultivation of peppers in northern Brazil has grown recently influenced by the increase in consumption, culinary usefulness, and medicinal features. However, pest insects damage plants and fruits, impairing production. This work investigates the management of pepper pests by intercropping plants that provide multiple ecosystem services, especially conservative biological control of pests. The experiment was carried out at the Federal Institute of Pará, Campus Rural de Marabá, Pará. The experimental design consisted of randomized blocks, with four treatments and five replications. Each plot contained thirty plants. The sampling of arthropods was carried out weekly in the useful portion of each treatment, through direct counting (visual analysis) and tapping plants on a white tray. The average abundance of arthropods in each functional group was calculated over the sampling weeks. We counted the number of fruits and bored fruits per plant to evaluate the effect of treatments on pepper yield. The abundance of pollinators differed significantly among treatments. Intercropping may favor the establishment of natural enemies and reduce the impacts of chemical insecticides. El cultivo de pimentos comerciales en la región Norte há ido creciendo em los últimos años influenciando por el consumo y su versatilidade em la cocción y sus características medicinales. Entre los obstáculos para su produccion se encuentra el ataque de insectos plagas, que provocam daños a la planta y al fruto. Em este trabajo se estudió uma estratégia para el manejo de plagas del pimiento, mediante la Asociación de plantas que brindan múltiples servicios ecosistémicos, com énfasis em el control biológico conservador de plagas. El experimento se realizo em el Instituto Federal do Pará, Campus Rural de Marabá, Pará. Se utilizo um diseño de bloques comletos al azar com cuatro tratamentos y cinco repeticiones. Cada parcela contenía treinta plantas. El muestro de artrópodos se realizo semanalmente em la porción útil de cada tratamento, mediante recuento directo (análisis visual) y golpeteo de las plantas em la bandeja blanca. Los promedios de los indivíduos em cada grupo funcional se calcularon durante las semanas de muestreo. Para evaluar el efecto de los tratamientos sobre el redimento de pimiento, se calculó el número de frutos por planta y el número de frutos aburridos. Hubo uma diferencia significativa em los polinizadores em los tratamientos de cultivos intercalados. Se observo que la presencia de consórcios puede contribuir positivamente al estabelecimento de enemigos naturales, incluída la reducción de los impactos com la aplicación de insecticidas químicos em el manejo de plagas de artópodos. O cultivo de pimentas comerciais na região Norte vem crescendo nos últimos anos influenciado pelo consumo e sua versatilidade na culinária e pelas suas características medicinais. Entre os entraves à sua produção está o ataque de insetos-praga, os quais causam danos à planta e aos frutos. Neste trabalho foi estudada uma estratégia para o manejo de pragas da pimenta, através da associação de plantas provedoras de múltiplos serviços ecossistêmicos, com ênfase ao controle biológico conservativo de pragas. O experimento foi conduzido no Instituto Federal do Pará, Campus Rural de Marabá (PA). Utilizou-se o delineamento experimental de blocos casualizados, com quatro tratamentos e cinco repetições. Cada parcela continha trinta plantas. As amostragens dos artrópodes foram realizadas semanalmente na parcela útil de cada tratamento, através de contagem direta (análise visual) e batidas das plantas na bandeja branca. Foram calculadas as médias de indivíduos de cada grupo funcional ao longo das semanas de amostragem. Para avaliar o efeito dos tratamentos sobre a produtividade da pimenta, foi calculado o número de frutos por planta e o número de frutos brocados. Houve diferença significativa de polinizadores nos tratamentos consorciados. Foi observado que a presença de consórcios pode contribuir, positivamente, ao estabelecimento de inimigos naturais, inclusive, reduzindo os impactos associados à aplicação de inseticidas químicos no manejo de artrópodes-praga.

Brazil is the country which has produced the most coffee for over 150 years, and to achieve high productivity, pesticides are the most common control measure for pests. Due to the need to adopt less impactful control practices, natural enemies or insecticides of botanical origin have been studied as alternatives to synthetic insecticides. However, botanical pesticides can negatively affect some natural enemies, and the effect depends on the formulation and concentration. The objective of this study was to estimate the survival of green lacewing larvae, Chrysoperla externa (Hagen), exposed to different doses of neem-based products, whose active ingredient is azadirachtin (Azamax®: 0 (control treatment with distilled water), 12, 24, 36, 48, 60, 72, 84, 96, and 108 mg a.i. L−1; Organic neem®: 0, 3.3, 6.6, 9.9, 13.2, 16.5, 19.8, 23.1, and 26.4 mg a.i. L−1; Natuneem®: 0, 3.8, 7.5, 10.5, 15.0, 18.8, 22.5, 26.3, 30.0, and 33.8 mg a.i. L−1), using a parametric approach. Predator larvae were exposed to neem-based insecticides and evaluated for 20 days. Survival curves estimated by the models—Log-logistic for Azamax®, Weibull for Organic neem®, and Log-normal for Natuneem®—demonstrated an inverse relationship between increasing doses and survival time. These concluded that the application dose should be less than 84 mg a.i. L−1 for Azamax®, 19.8 mg a.i. L−1 for Organic neem®, and 26.3 mg a.i. L−1 for Natuneem® to keep 50% of the green lacewings alive for 13 days, which is the average time for the larval cycle of C. externa.

In natural ecosystems, arthropod predation on herbivore prey is higher at lower latitudes, mirroring the latitudinal diversity gradient observed across many taxa. This pattern has not been systematically examined in human-dominated ecosystems, where frequent disturbances can shift the identity and abundance of local predators, altering predation rates from those observed in natural ecosystems. We investigated how latitude, biogeographical, and local ecological factors influenced arthropod predation in

Plant diversification is a strategy for pest management in agroecosystems. However, a major hurdle in the adoption of this management practice by farmers is related to doubts concerning its effects on crop productivity. Here we assess coffee production and natural control of coffee pests in the presence or absence of leguminous trees bearing extrafloral nectaries (Inga edulis). We compared coffee yield, coffee damage caused by coffee leaf miners (Leucoptera coffeella) and coffee berry borers (Hypothenemus hampei) and parasitism and predation of coffee leaf miners in a replicated field experiment. To evaluate the effect of proximity of the nectar source on natural control, we also assessed pest control and production along transects of 50 m extending from the Inga trees. Production per coffee plant was equal in both systems but coffee fruits were heavier in coffee consorted with Inga trees. In the most productive year, coffee production was higher on plants closer to the Inga trees. Damage caused by coffee leaf miners and coffee berry borers was lower in coffee with Inga trees and increased with distance from the trees. Parasitism of coffee leaf miners and predation by wasps did not increase in coffee consorted with Inga, neither decreased with distance from the trees. Therefore, Inga trees enhanced coffee production and increased natural control of coffee pests.

It is known that many social insects and arthropod predators and parasitoids can learn the association between a resource and volatile cues. Although there are various studies on the effect of experience in immature arthropods on behavior later in adult life, not much is known about the effects of such experiences on immature behavior. This was investigated here in the lacewing Ceraeochrysa cubana (Hagen) (Neuroptera: Chrysopidae). Whereas adults of this lacewing feed on plant‐provided food and honeydew, larvae are voracious polyphagous predators of several insect pests, and therefore important for biological control. Hence, studying the foraging behavior and the effects of learning in immatures of this species is important. We exposed immatures to the volatile methyl salicylate (MeSA), which was either associated with food or with the absence of food. Subsequently, their response to this volatile was tested in an olfactometer. Immatures that had experienced the association of MeSA with food were attracted to it and immatures that were exposed to MeSA during food deprivation were repelled. Subsequently, predator immatures that had experienced the association between MeSA and food were released on a plant without food and were found to use this volatile in locating patches with food. In contrast, larvae without such experience were found equally on food patches with and without the volatile. We conclude that these immature predators are capable of learning the association between volatiles and food, or the absence of food, and use this during foraging.

The physic nut ( Jatropha curcas ) is a potential plant for biofuel production. However, its productivity is limited by pests such as the broad mite ( Polyphagotarsonemus latus ) and the red spider mite ( Tetranychus bastosi ). Despite the problems resulting from their misuse, chemicals are currently the primary method of controlling these herbivorous mites, but biological control by native organisms represents an alternative approach. The predatory mite Typhlodromus transvaalensis (Acari: Phytoseiidae) was collected from J. curcas plants associated with P. latus and T. bastosi in the state of Tocantins, Brazil. We studied predation rates, biological parameters and reproduction of T. transvaalensis feeding on P. latus and T. bastosi as well as the effects of adding pollen from corn ( Zea mays ), physic nut ( J. curcas ) and castor bean ( Ricinus communis ) to the diet. Adult female T. transvaalensis were more efficient at predating all stages of P. latus than T. bastosi . The T. transvaalensis life cycle was shorter with diets including R. communis pollen, but Z. mays pollen was also suitable for reproduction. The results indicate that T. transvaalensis is a generalist predator with high potential for controlling P. latus in J. curcas plantations and that the presence of R. communis and Z. mays crops boosts its development and reproduction.

Pest control is an important ecosystem service that can be enhanced by increasing plant diversity. One of the simplest forms of plant diversification is making use of the occurring weeds that may benefit natural enemies of crop pests. We investigated the interaction between tomato plants, beggar-ticks (Bidens pilosa, Asteraceae), a common weed in Brazil and elsewhere, and the native ladybird beetle Cycloneda sanguinea, an important predator of aphids. The predators occurred on beggar-ticks in the field, independent of the presence of aphids, confirming that they obtained some benefit other than aphid prey from the plants. Predators were attracted to volatiles of clean, flowering beggar-ticks, and volatiles of flowering tomato plants plus flowering beggar-ticks were more attractive than volatiles of tomato plants alone. In the absence of aphids, C. sanguinea did not oviposit on tomato plants, beggar-ticks, or a combination of the two plants, but adult survival was higher on a combination of both plants than on tomato plants alone. These results show that the management of an abundant plant species in agricultural crops has potential for increasing pest control.

Orius insidiosus is economically important for biological control of pests of vegetable and ornamental crops. To improve pest control with this predator, its densities in the crops can be enhanced by the provision of alternative foods, especially when prey are scarce. We therefore compared the performance of O. insidiosus on three alternative foods (Ricinus sp. pollen, bee pollen and the mixed stages of the astigmatid prey Tyrophagus putrescentiae) that are cheaper than frozen eggs of Ephestia kuehniella. Juvenile development was significantly shorter on E. kuehniella and T. putrescentiae than on Ricinus sp. pollen and on bee pollen and lowest without food. Female bugs had a higher oviposition rate when fed either E. kuehniella or T. putrescentiae, but produced fewer eggs when feeding on bee pollen and Ricinus sp. pollen. This shows that T. putrescentiae can possibly be used as cheap alternative food to boost predator populations in periods of low prey densities.

Intraguild predation is a mix of competition and predation and occurs when one species feeds on another species that uses similar resources. Theory predicts that intraguild predation hampers coexistence of species involved, but it is common in nature. It has been suggested that increasing habitat complexity and the presence of alternative food may promote coexistence. Reciprocal intraguild predation limits possibilities for coexistence even further. Habitat complexity and the presence of alternative food are believed to promote coexistence. We investigated this using two species of predatory mites, Iphiseiodes zuluagai and Euseius concordis, by assessing co‐occurrence in the field and on arenas differing in spatial structure in the laboratory. The predators co‐occured on the same plants in the field. In the laboratory, adults of the two mites fed on juveniles of the other species, both in the presence and the absence of a shared food source, showing that the two species are involved in reciprocal intraguild predation. Adults of I. zuluagai also attacked adults of E. concordis. This suggests limited possibilities for coexistence of the two species. Indeed, E. concordis invariably went extinct extremely rapidly on arenas without spatial structure with populations consisting of all stages of the two predators and with a shared resource. Coexistence was prolonged on host plant leaves with extra food sources, but E. concordis still went extinct. On small, intact plants, coexistence of the two species was much longer, and ended with the other species, I. zuluagai, often going extinct. These results suggest that spatial structure and the presence of alternative food increase the coexistence period of intraguild predators.

Ricoseius loxocheles (De Leon) (Acari: Phytoseiidae) is often found in coffee crops and is known to feed on coffee leaf rust, Hemileia vastatrix Berkeley and Broome (Uredinales). As the occurrence of coffee leaf rust is limited primarily to the rainy season, the mite may use other food sources to survive during the periods of low pathogen prevalence. It is well known that phytoseiid mites can survive on a variety of food sources, such as herbivorous mites, fungi and pollen. We evaluated the ability of R. loxocheles to survive and reproduce on a diet of Brevipalpus phoenicis Geijskes (Acari: Tenuipalpidae), cattail pollen (Typha spp.), clover rust (Puccinia oxalidis), bee pollen (Santa Barbara® dehydrated pollen, Santa Barbara, MG, Brazil) and coffee leaf rust. Ricoseius loxocheles did not survive or reproduce on any B. phoenicis stages tested (egg, larva, adult). The survival and oviposition of R. loxocheles were directly affected by the presence of coffee rust urediniospores, but not by the presence of the prey. Survival and oviposition of the phytoseiid were similar when fed cattail pollen, clover rust and coffee leaf rust but was lower when fed bee pollen. Our results show that R. loxocheles is not a predator of B. phoenicis but it is able to utilize other resources besides coffee leaf rust.

1.Mixing of prey that differ in nutrient content or toxic compounds (dietary mixing) may allow synovigenic predatory arthropods to balance their diet or dilute toxins of different prey items to maximize performance: dietary mixing may therefore explain the prevalence of polyphagy in this functional group.2.Several predatory arthropods can redress nutritional imbalances in their diet by actively mixing different diets, based on experiments with artificial diets or with prey that were manipulated to contain different nutrients.3.Evidence is also accumulating that predator species perform better on a mixed diet of several different prey species, but evidence that they actively forage for different prey species is scarce.4.Thus, evidence that predators actively forage for a mixed diet consisting of natural, non-manipulated prey to increase their performance is still rare. Here, we investigate whether arthropod predators invest in achieving an optimal diet by active mixing of different prey species or by simply eating what they encounter.5.Females of two species of plant-inhabiting predatory mites produced significantly more eggs when feeding on a prey mixture of co-occurring phytophagous mites than when feeding on either of the two prey species separately.6.When the two prey species were offered on two separate, connected patches at some distance from each other, predators commuted significantly more between the two patches to obtain a mixed diet and had a significantly increased egg production than predators that were offered a single prey species on two patches.7.Thus, predators actively commuted between patches to balance their diet. We propose that active dietary mixing can have synergistic effects on predator fitness and has the potential to explain polyphagy in this functional group.

Many herbivorous arthropods construct shelters on their host plant that offer protection against natural enemies. This has resulted in selection on natural enemies to enter these shelters, where they can feed on prey that are inaccessible for competing predators and parasitoids. The spider mite Tetranychus evansi produces a shelter consisting of a dense web that is impenetrable for most predators; the only known natural enemy that can penetrate the web and can forage efficiently on this pest is Phytoseiulus longipes. We show that this predator preferentially foraged and oviposited in the web of its prey. Moreover, intraguild predation on juveniles of these predators was significantly higher outside this web and in the less dense web of a closely related prey species (T. urticae) than inside the web of T. evansi. Although the production of shelters by herbivores may be profitable at first, their adapted natural enemies may reap the benefit in the end.

A cultura da melancia Citrullus lunatus (Thunberg, Matsumura & Nakai) abriga uma grande diversidade de artropodes, cada um desempenhando um papel especifico. Apesar de alguns desses artropodes serem considerados pragas, outros sao responsaveis pela aeracao do solo, liberacao de nutrientes e predacao das especies-praga, sendo, dessa forma, considerados beneficos as culturas. A agricultura intensiva praticada no Brasil para o cultivo da melancia e baseada no uso dos inseticidas como tiamethoxam e deltametrina, que pode nao so matar as pragas, mas tambem organismos nao-alvo. Pesquisas relacionadas a influencia de inseticidas sobre artropodes beneficos na cultura da melancia sao escassas. Este estudo foi realizado com o objetivo de avaliar o efeito dos inseticidas deltametrina e thiamethoxam na comunidade de artropodes existentes na superficie do solo, bem como naqueles artropopodes que habitam o dossel das plantas na cultura da melancia. Este estudo foi realizado no Estado do Tocantins, Brasil. Embora as aplicacoes de thiamethoxam e deltametrina foram eficientes no controle de populacoes de Aphis gossypii , como era esperado, os inseticidas afetaram negativamente artropodes nao-alvo como insetos detritivoros, insetos de dossel e da superficie do solo. Implicacoes ecologicas do impacto dos pesticidas sobre as especies de artropodes beneficos sao discutidos.

Watermelon Citrullus lunatus (Thunberg, Matsumura & Nakai) is an ecosystem having a variety of arthropods, each one playing a specific role. Although some of them are considered pest to crops, some others are responsible for soil aeration, nutrient release and predation of pest species and are, therefore, considered beneficial to crops. The intensive farming practiced for watermelon cultivation in Brazil is based on the use of tiamethoxam and deltamethrin, which may not only kill target but also nontarget organisms such as beneficial arthropods. Research data regarding the influence of insecticides on arthropods in watermelon cropping is scarce. This study aimed to evaluate the effect of the insecticides deltamethrin and thiamethoxam on soil surface and watermelon canopy arthropod community. The study was carried out in the State of Tocantins, Brazil. Although the application of thiamethoxam and deltamethrin was efficient in controlling populations of Aphis gossypii (Glover), as we expected, they negatively affected non-target arthropods such as detritivores insects in the canopy and soil surface. Ecological implications of the impact of such pesticides on beneficial arthropod species are discussed.A cultura da melancia Citrullus lunatus (Thunberg, Matsumura & Nakai) abriga uma grande diversidade de artrópodes, cada um desempenhando um papel específico. Apesar de alguns desses artrópodes serem considerados pragas, outros são responsáveis pela aeração do solo, liberação de nutrientes e predação das espécies-praga, sendo, dessa forma, considerados benéficos às culturas. A agricultura intensiva praticada no Brasil para o cultivo da melancia é baseada no uso dos inseticidas como tiamethoxam e deltametrina, que pode não só matar as pragas, mas também organismos não-alvo. Pesquisas relacionadas à influência de inseticidas sobre artrópodes benéficos na cultura da melancia são escassas. Este estudo foi realizado com o objetivo de avaliar o efeito dos inseticidas deltametrina e thiamethoxam na comunidade de artrópodes existentes na superfície do solo, bem como naqueles artropópodes que habitam o dossel das plantas na cultura da melancia. Este estudo foi realizado no Estado do Tocantins, Brasil. Embora as aplicações de thiamethoxam e deltametrina foram eficientes no controle de populações de Aphis gossypii, como era esperado, os inseticidas afetaram negativamente artrópodes não-alvo como insetos detritívoros, insetos de dossel e da superfície do solo. Implicações ecológicas do impacto dos pesticidas sobre as espécies de artrópodes benéficos são discutidos.

O conhecimento das características morfológicas das plantas é de grande relevância para o estudo das interações entre plantas, herbívoros e inimigos naturais. Variações nessas características são determinantes na ocorrência, abundância e diversidade de organismos que exploram esse habitat. Caracterizou-se a superfície foliar de quatro espécies de pimentas do gênero Capsicum e elaborou-se uma proposta de classificação das folhas com base nos critérios de presença ou ausência, densidade e distribuição de tricomas para domácias, visando a utilização dessas informações em estudos de resistência de plantas a artrópodes. A contagem dos tricomas foi feita em uma área de 5 cm²,no terço médio das folhas, sendo contabilizados os tricomas do limbo, das nervuras e das domácias. As espécies de pimenta diferiram significativamente quanto à densidade de domácias e tricomas presentes na nervura e no limbo de suas folhas. Também foi observada diferença significativa na densidade total de tricomas/cm² e no número de tricomas por domácia. Das quatro espécies de pimenta avaliadas, apenas C. baccatum var. pendulum (pimenta com ardume variedade dedo-de-moça) não possui domácias nem tricomas em qualquer região de suas folhas. A maior densidade de domácias foi observada em C. baccatum var. praetermissum, espécie em que se observou as maiores densidades de tricomas em todas as regiões da folha e a única com densidade significativa de tricomas no limbo. As variações quanto à presença, distribuição e densidade de tricomas e domácias podem ser determinantes na ocorrência de ácaros predadores e fitófagos nas plantas. Com base na caracterização efetuada foi proposta uma escala de classificação da superfície foliar das plantas, variando de 1 a 5, em função do número e da densidade de tricomas e domácias observados.The knowledge of morphological characteristics of plant leaves is important to study the interactions among plants, herbivores and natural enemies. Variations on such characteristics are determinant on the occurrence, abundance and diversity of organisms that exploit that habitat. The leaf surface of four Capsicum pepper species was characterized, focusing on the presence of trichomes and domatia. The objective is to identify possible mite resistance mechanisms on these plants. The classification key of pepper leaves was based on presence/absence, density and distribution of trichomes. The counting of trichomes was done in an area of 5 cm², from the medium third of each leaf. We assessed the trichomes from the limb, ribs and domatia. The pepper species significantly differed on the density of domatia and trichomes present on the ribs and limbs of their leaves. A significant difference was observed on the total density of trichomes/cm² and on the number of trichomes/domatia. From the five Capsicum species evaluated, only C. baccatum var. pendulum (hot pepper, variety girl finger pepper) does not have domatia neither trichomes in any part of its leaves. The highest domatia density was found on C. baccatum var. praetermissum, which has the highest trichome density in all leaf parts and the only one with significant density of limb trichomes. The variation of the presence, distribution and density of trichomes and domatia may be determinant on the occurrence of herbivorous and predatory mites on plants. Such structures can act as a resistance mechanism against herbivore mites or may favor the presence of predatory and fungivorous mites due to provision of shelter sites. We propose here a surface classification scale of chili pepper leaves varying from 1 to 5 taking into account the number and density of observed trichomes and domatia.

The attack of phytophagous mites may induce plants to produce volatiles, which in turn may attract predators. The occurrence of multiple phytophagous infestations on plants may influence predator response. In this paper, we investigated whether the attraction of the predatory mite Phytoseiulus macropilis (Banks) to phytophagous-infested plants would change with the simultaneous presence of two tetranichid mites Oligonychus ilicis (McGregor) and Tetranychus urticae Koch. While the former species is rarely found on strawberry plants and is only occasionally found in association with P. macropilis, the latter is commonly found on strawberry plants and is frequently found in association with P. macropilis. Y-tube olfactometer test assays demonstrated that the predator preferred plants infested with T. urticae, avoided plants infested with O. ilicis, and had no preference for plants infested with both phytophagous mite species. These results indicated that the presence of a non-prey species (O. ilicis) on a given plant can alter the response of the predator to one of its prey (T. urticae). The consequences of the predatory behavior determined in this study on the predator ability to control T. urticae population on strawberry plants are discussed.

Variações nas características morfológicas das plantas podem ter efeito imediato sobre a preferência alimentar, escolha de sítios de oviposição e vulnerabilidade de herbívoros a inimigos naturais. A longo prazo, podem ter consequências sobre a dinâmica populacional desses organismos, já que atuam sobre seu desenvolvimento, sobrevivência e reprodução. Neste trabalho, avaliou-se o desenvolvimento de Polyphagotarsonemus latus (Banks) em cinco espécies de Capsicum com diferentes densidades de tricomas. Testou-se a hipótese de que o crescimento populacional de P. latus nessas plantas apresenta relação negativa com o aumento da densidade de tricomas nas folhas. Observou-se um padrão decrescente na taxa intrínseca de crescimento (r m) de P. latus com o aumento da densidade de tricomas nas folhas. O menor r m foi obtido em folhas de C. praetermissum (r m = 0,46), que apresenta a maior densidade de tricomas entre as espécies de Capsicum avaliadas. Os maiores valores de r m foram observados em espécies de Capsicum com densidade intermediária de tricomas nas folhas, Capsicum frutescens (r m = 0,77) e Capsicum chinense (r m = 0,76). Os tricomas de Capsicum spp. atuaram como fator limitante ao desenvolvimento de P. latus à medida que se apresentaram em maiores densidades e mais bem distribuídos na superfície foliar. Foi discutido ainda o papel da defesa morfológica e química de plantas de Capsicum sobre o desenvolvimento de P. latus. Plant morphology traits can affect the feeding preference, oviposition choice and the vulnerability of herbivores to natural enemies. At long term, these plant variations may influence herbivore population dynamics due to the interference on their development, survival and reproduction. In this paper, the development of the broad mite Polyphagotarsonemus latus (Banks) was evaluated on five species of Capsicum with different density of trichomes. We tested the hypothesis that P. latus population growth has a negative relationship with the increase trichome density on leaves. It was assessed a decrease in the intrinsic growth rate (r m) of P. latus with the increase of trichome density on the leaves tested. The lower r m was measured in leaves of C. praetermissum (r m = 0.46), which has the highest trichome density among the assessed Capsicum species. The highest values of r m were observed on Capsicum species with intermediate densities of trichomes on leaves such as Capsicum frutescens (r m = 0.77) and Capsicum chinense (r m = 0.76). Capsicum spp. trichomes acted as a limiting plant trait for the development of P. latus when they were in higher densities and better distributed on the leaf surface. We also discuss the role of morphologic and chemical plant defenses on P. latus development.

O morangueiro, Fragaria x ananassa, pode ser atacado por diferentes espécies de ácaros fitófagos, dentre elas o ácaro-vermelho, Oligonychus ilicis McGregor, e o ácaro-rajado, Tetranychus urticae Kock. Essas espécies são encontradas juntas, alimentando-se, com maior freqüência, sobre a epiderme adaxial e abaxial das folhas, respectivamente. Neste trabalho estudou-se o padrão de escolha de O. ilicis e T. urticae por sítio de alimentação em plantas de morangueiro. Duas hipóteses foram formuladas: a primeira, que a escolha por sítios de alimentação estaria relacionada à aptidão das espécies; a segunda, que esta escolha seria determinada pela presença do heteroespecífico. Com o objetivo de testar tais hipóteses, avaliou-se a preferência, biologia e sucesso reprodutivo de O. ilicis e T. urticae sobre a face abaxial e adaxial de folhas de morangueiro infestadas ou não pelo heteroespecífico. O. ilicis preferiu permanecer sobre a face adaxial enquanto T. urticae preferiu permanecer sobre a face abaxial de folhas de morangueiro. A preferência pelas faces foliares correlacionou-se com o sucesso reprodutivo das espécies, avaliado pela taxa intrínseca de crescimento populacional (r m). O padrão de escolha não se alterou quando as espécies foram submetidas ao teste de escolha entre as faces foliares previamente infestadas pelo heteroespecífico. É discutida a possibilidade de T. urticae induzir defesas da planta capazes de reduzir a aptidão de O. ilicis e vice-versa. A possibilidade dessas espécies permanecerem juntas sobre plantas de morangueiro aumenta a capacidade de dano à cultura. Many phytophagous mites can attack strawberry plants, Fragaria x ananassa, among them the southern red mite, Oligonychus ilicis McGregor, and the two-spotted spider mite, Tetranychus urticae Koch. They are found together feeding on the same plant on the upper and underside of the leaves, respectively. Here we studied the choice for feeding sites of O. ilicis and T. urticae on strawberry plants. The first hypothesis tested whether the feeding site choice would be related to the fitness of the species. The second hypothesis dealt whether the feeding site would be determined by the presence of a heterospecific mite. We evaluated the preference, biology and reproductive success of O. ilicis and T. urticae on the under and upper side surface of strawberry leaves infested or not by the heterospecific. O. ilicis preferred to stay on the upper side surface while T. urticae preferred the underside. The preference for the leaf surface correlated with the reproductive success of the species (measured by the intrinsic growth rate). The choice pattern of feeding sites did not alter when the choice test was applied using sites previously infested by heterospecific. Although O. ilicis and T. urticae, apparently, do not interact directly for feeding sites, there is a chance that the first species induces defenses in strawberry plant enabling to reduce the fitness of the second species. The possibility of those species stay together on strawberry plant increases the damage capacity to the culture.

O objetivo deste trabalho foi avaliar, em laboratório, os efeitos do extrato de semente de nim sobre uma praga da pimenteira, o pulgão-verde Myzus persicae (Sulzer), e seu predador Eriopis connexa (Germar). Folhas de pimenteira foram imersas em solução aquosa de extrato de semente de nim (1% de azadiractina) a 0,5%, 1%, em acefato (0,75 g L-1) e em água. Fêmeas do pulgão foram transferidas para essas folhas e, após seis dias, avaliou-se a população final. Larvas de quarto ínstar do predador foram colocadas em plantas de pimenteira infestadas com pulgões e pulverizadas com solução aquosa de nim a 0,25 e, 0,5%, em acefato (0,75 g L-1) e em água. Após 48 horas, as larvas foram transferidas para tubos de plástico e alimentadas com pulgões. A mortalidade larval, a viabilidade pupal e a emergência de adultos foram avaliadas. A população de pulgões foi significativamente menor em folhas tratadas com nim e com acefato do que nas tratadas com água. A mortalidade de larvas do predador foi maior em plantas tratadas com acefato do que com nim. No entanto, somente 9,1 e 10% das larvas em plantas tratadas com nim a 0,25% e a 0,5%, respectivamente, formaram pupas e não houve emergência de adultos. Apesar do potencial do nim em reduzir a população de M. persicae, o produto apresenta efeitos nocivos a E. connexa. The aim of this work was to assess, in laboratory, the effects of neem seed extract on chilli pepper pest, the green peach aphid Myzus persicae (Sulzer) and on its predator Eriopis connexa (Germar). Chilli pepper leaves were treated with an aqueous solution of neem seed extract (1% of azadiractin) at concentrations of 0.5 and 1.0%, using acephate (0.75 g L-1) and water. Aphid females were transferred to treated leaves and after six days the aphid population was checked. Fourth-instar larvae of E. connexa were placed on pepper seedlings infested with aphids and sprayed with an aqueous solution of neem at 0.25 and 0.5%, using acephate (0.75 g L-1) and water. After 48 hours, larvae were transferred to plastic tubes and fed aphids. Larval mortality, pupal viability and adult emergence were evaluated. Aphid population was significantly lower on leaves treated with neem and acephate than on water treated plants. Mortality of E. connexa larvae was higher on plants treated with acephate than on neem treated plants. However, only 9.1 and 10% of larvae on plants treated with neem at 0.25 and 0.5%, respectively, reached the pupal phase and there was no adult emergence. In spite of the potential of neem to reduce M. persicae population, the product shows deleterious effects on E. connexa.

A survey of the seasonal occurrence of stink bug egg parasitoids was carried out in soy bean fields in the Triangulo Mineiro region, Minas gerias state Brazil A survey of the seasonal occurrence of stink bug egg parasitoids was carried out in soy bean fields in the Triangulo Mineiro region, Minas gerias state Brazil

A ação letal e subletal de defensivos alternativos sobre o ácaro-branco Polyphagotarsonemus latus (Banks) foi avaliada em laboratório. Plantas de pimenta "Malagueta" (6 cm de altura) foram pulverizadas, nas dosagens recomendadas para hortaliças, com os seguintes produtos: biofertilizante "Supermagro", "Calda Viçosa", calda sulfocálcica, acaricida abamectina e água. Após a pulverização, foram transferidas dez fêmeas de P. latus para cada planta. Seis dias após, avaliou-se o número de ácaros por planta e calculou-se a taxa instantânea de crescimento populacional (r i). A população final de P. latus em plantas tratadas com a calda sulfocálcica, com a "Calda Viçosa" e com o acaricida abamectina foi significativamente menor do que em plantas tratadas com água e com "Supermagro". Foram obtidos valores negativos para a r i de P. latus em plantas tratadas com a calda sulfocálcica (r i = -0,2922) e com a "Calda Viçosa" (r i = -0,0301). Valores positivos para a r i foram obtidos para ácaros em plantas tratadas com "Supermagro" (r i = 0,2373) e com água (r i = 0,1971), indicando aumento da população de P. latus nessas plantas. Não foi possível o cálculo do r i para ácaros em plantas tratadas com abamectina devido a morte de todas as fêmeas no inicio do experimento. A "Calda Viçosa" e a calda sulfocálcica apresentaram potencial de controle para o ácaro branco P. latus em pimenta.Lethal and sublethal effects of alternative pesticides on the broad mite Polyphagotarsonemus latus were evaluated. Chilli pepper plants (6 cm high) were sprayed with one of the following treatments: biofertilizer "Supermagro", "Viçosa mixture" (a nutrient amended Bordeaux mixture), lime sulfur, abamectin and water. After spraying, 10 females of P. latus were transferred to each plant. Six days after, the number of mites per plant was counted and the instantaneous rate of increase (r i) was evaluated for each treatment. The population of P. latus on plants treated with lime sulfur, "Viçosa mixture" and abamectin was significantly lower than on plants treated with biofertilizer and water. Negative values of the instantaneous rate of increase (r i), were obtained for P. latus on plants treated with lime sulfur (r i = -0.2922) and with "Viçosa mixture" (r i = -0.0301). Positive values were obtained for mites on plants treated with biofertilizer (r i = 0.2373) and water (r i = 0.1971), which indicate increase of P. latus population on these plants. It was not possible to calculate r i for mites on abamectin treated plants, because all females died at the beginning of the experiment. Lime sulfur and "Viçosa mixture" showed potential for controlling broad mite P. latus on chilli pepper "Malagueta".

A ação letal e subletal de defensivos alternativos sobre o ácaro-branco Polyphagotarsonemus latus (Banks) foi avaliada em laboratório. Plantas de pimenta "Malagueta" (6 cm de altura) foram pulverizadas, nas dosagens recomendadas para hortaliças, com os seguintes produtos: biofertilizante "Supermagro", "Calda Viçosa", calda sulfocálcica, acaricida abamectina e água. Após a pulverização, foram transferidas dez fêmeas de P. latus para cada planta. Seis dias após, avaliou-se o número de ácaros por planta e calculou-se a taxa instantânea de crescimento populacional (r i). A população final de P. latus em plantas tratadas com a calda sulfocálcica, com a "Calda Viçosa" e com o acaricida abamectina foi significativamente menor do que em plantas tratadas com água e com "Supermagro". Foram obtidos valores negativos para a r i de P. latus em plantas tratadas com a calda sulfocálcica (r i = -0,2922) e com a "Calda Viçosa" (r i = -0,0301). Valores positivos para a r i foram obtidos para ácaros em plantas tratadas com "Supermagro" (r i = 0,2373) e com água (r i = 0,1971), indicando aumento da população de P. latus nessas plantas. Não foi possível o cálculo do r i para ácaros em plantas tratadas com abamectina devido a morte de todas as fêmeas no inicio do experimento. A "Calda Viçosa" e a calda sulfocálcica apresentaram potencial de controle para o ácaro branco P. latus em pimenta. Lethal and sublethal effects of alternative pesticides on the broad mite Polyphagotarsonemus latus were evaluated. Chilli pepper plants (6 cm high) were sprayed with one of the following treatments: biofertilizer "Supermagro", "Viçosa mixture" (a nutrient amended Bordeaux mixture), lime sulfur, abamectin and water. After spraying, 10 females of P. latus were transferred to each plant. Six days after, the number of mites per plant was counted and the instantaneous rate of increase (r i) was evaluated for each treatment. The population of P. latus on plants treated with lime sulfur, "Viçosa mixture" and abamectin was significantly lower than on plants treated with biofertilizer and water. Negative values of the instantaneous rate of increase (r i), were obtained for P. latus on plants treated with lime sulfur (r i = -0.2922) and with "Viçosa mixture" (r i = -0.0301). Positive values were obtained for mites on plants treated with biofertilizer (r i = 0.2373) and water (r i = 0.1971), which indicate increase of P. latus population on these plants. It was not possible to calculate r i for mites on abamectin treated plants, because all females died at the beginning of the experiment. Lime sulfur and "Viçosa mixture" showed potential for controlling broad mite P. latus on chilli pepper "Malagueta".

Current knowledge on coccinellids is primarily focused on their role as natural enemies of soft-bodied insects. However, there is a great diversity of coccinellid parasitoid species that are less studied. Here, we describe new records of coccinellid parasitoids with emphasis on new host–parasitoid interactions in 11 sample sites in Brazil. We collected 122 coccinellid individuals parasitized by six species of parasitoids in the Cerrado and in the Atlantic Rainforest biomes. New records of coccinellid parasitoids and host associations, expansion of habitat ranges and interactions are discussed focusing on the lack of basic information on these interactions in Brazil.

A toxicidade relativa dos extratos de folha, semente e óleo de torta de Azadirachta indica A. Juss (nim) ao ácaro predador Iphiseiodes zuluagai (Denmark & Muma) (Acari: Phytoseiidae) foi estudada em laboratório. Foram determinadas concentrações discriminatórias (CLs99) dos extratos de folha, semente e óleo de torta de nim para fêmeas adultas de Oligonychus ilicis (McGregor) (Acari: Tetranychidae), através de bioensaios de concentração-mortalidade. Arenas com 3,5 cm de diâmetro, confeccionadas com folhas de cafeeiro flutuando em água, foram impregnadas com resíduo seco dos extratos e usadas para se estimar a seletividade ao ácaro I. zuluagai. As concentrações dos extratos de nim que mataram 99% de O. ilicis, após 72h de exposição foram: 277,4; 520,9 e 10,9 mg/ml, para folha, semente e óleo de torta, respectivamente. A concentração discriminatória do extrato de óleo de torta de nim para fêmeas adultas de O. ilicis foi altamente tóxica ao ácaro I. zuluagai, as dos extratos de folha e de semente foram seletivos.

Studies on interactions among plants, herbivores and natural enemies are important for understanding population dynamics of species in food webs, but they are also important for the practice of pest control with natural enemies. Biological control programs heavily rely on the occurrence of trophic cascades, where the addition of one natural enemy causes a decrease of pest densities and an increase of plant biomass. However, when more that one natural enemy is used to control various pests in the same system, artificial food webs are created and simple tritrophic interactions change to more complicated ones. The occurrence of complex interactions and omnivory in these food webs may modify the sign and the strength of direct effects of natural enemies on pests. In this paper, we show and discuss the experimental results on interactions mediated by predators in an artificial food web that occurs on cucumber plants in greenhouses where biological control is applied. The two pests in this food web are the two-spotted spider mite Tetranychus urticae Koch, and the western flower thrips Frankliniella occidentalis (Pergande). The predatory mites Phytoseiulus persimilis Athias-Henriot and Neoseiulus californicus (McGregor) are used to control spider mites, and the generalist predatory bug Orius laevigatus (Fieber) and a specialist predatory mite Neoseiulus cucumeris (Oudemans) are predators of thrips. Results from behavioural studies showed that some of these species are attracted to the same patch and do not avoid each other's presence. We show some complex interactions arising from the meeting of these species: (a) the intraguild predation by O. laevigatus on P. persimilis, (b) the use of spider-mite web as a refuge by thrips larvae against their predators. The consequences of such interactions for population dynamics of predators and prey and their implications for success of biological control are discussed.