En Brazil los pequeños agricultores producen el piñón Jatropha curcas L. asociado con plantaciones de zapallo, maíz, y muchas veces con malezas. Evaluamos la adecuación del polen de zapallo y maíz, así como de la maleza (Peltaea riedelli), frecuente en los cultivos del piñon, como fuente de alimento alternativo para los ácaros E. concordis y I. zuluagai. Estas especies son los enemigos naturales de Polyphagotarsonemus latus y Tetranychus bastosi, dos principales ácaros plagas de plantas de jatropha. La tasa de sobrevivencia y desove de los ácaros E. concordis y I. zuluagai fue evaluada por un período de cinco días en discos de hojas provistas con polen de zapallo, maíz o de P. riedelii. Polen de la planta Ricinus communis fue previsto para los depredadores, como control de alimentación adecuada. No hubo diferencia estadística en la tasa del desove de ambos I. zuluagai y E. concordis cuando alimentados con el polen de las especies evaluadas. No obstante, la fuente de polen afecta la sobrevivencia de los ácaros depredadores. El polen de zapallo fue el peor alimento para ambos ácaros depredadores, contrario al del maíz y la maleza P. riedelii, que fueron los mejores. Los resultados indican que el polen de zapallo es inadecuado como alimento alternativo para I. zuluagai y E. concordis. El maíz y la maleza P. riedelli representan una fuente alimenticia suplementaria para los ácaros depredadores y puede ser importante para sustentar poblaciones de depredadores, por lo menos algunos días, cuando la presa está ausente o escasa.

In Brazil, smallholders produce the physic nut Jatropha curcas in association with crops such as pumpkin and corn, besides weeds. We evaluated the suitability of pumpkin and corn pollens, as well as pollen from a weed species (Peltaea riedelii), present in physic nut crop, as alternative food to predatory mites Euseius concordis and Iphiseiodes zuluagai. These species are natural enemies of Polyphagotarsonemus latus and Tetranychus bastosi, two important mite pests on J. curcas plants. The survival and oviposition rate of E. concordis and I. zuluagai were evaluated for five days on leaf discs supplied with pollen of pumpkin, corn or P. riedelii. Castor bean pollen (Ricinus communis) was provided to the predators as a control of suitable food. No significant difference on the oviposition rate of both I. zuluagai and E. concordis was observed when they fed with pollen from the three plants. However, the source of pollen affected the survival of the predatory mites. Pumpkin pollen was the worst food for both predatory mites while corn and P. riedelii was a better food. These results indicate the non-suitability of pumpkin pollen as alternative food to I. zuluagai and E. concordis. Corn and P. riedelli are sources of supplementary food to the predatory mites and can sustain predator populations when prey is scarce.

El control biológico a través de predadores es observado como una alternativa promisoria al control químico de plagas. Phytoseiulus macropilis se ha encontrado asociado a poblaciones del ácaro rayado Tetranychus urticae en plantaciones de fresa en el estado de Minas Gerais, Brasil. En este trabajo se evaluó a través de experimento de olfatometria los efectos subletales de la azadirachtina sobre la capacidad de P. macropilis en detectar volátiles de plantas de fresa infestadas con T. urticae. Los resultados muestran que el ácaro predador P. macropilis puede diferenciar entre olores de plantas de fresa no atacadas y plantas de fresa atacadas por T. urticae. La azadirachtina en la concentración de 0,31 mg i.a/L no interfirió en la respuesta olfativa de P. macropilis alimentado de presas asperjadas.

The biological control through predators is seen as a promising alternative to chemical insect pest control. Phytoseiulus macropilis has been found associated with populations of the striped mite, Tetranychus urticae in strawberry plantations in the state of Minas Gerais, Brazil. In this work, the sublethal effects of azadirachtina on the natural ability of P. macropilis to detect volatile compounds from strawberry plants infested with T. urticae was evaluated by using olfactometry assays. The results show that P. macropilis predatory mite can distinguish odors from non-attacked strawberry plants and those from strawberry plants attacked by T. urticae. Azadirachtina at a concentration of 0.31 mg i.a/L did not interfere in the olfactory response of P. macropilis fed with sprinkled striped mites.

La concentración letal (CL) es usada para estimar la toxicidad de plaguicidas a artrópodos. Sin embargo, la CL es una medida incompleta de los efectos de los productos sobre poblaciones, pues analiza solamente la mortalidad como parámetro de toxicidad. Se sabe que individuos que sobreviven a la exposición a plaguicidas pueden sufrir efectos subletales. Objetivo: En este trabajo fue estudiado en laboratorio los efectos letales y subletales del caldo sulfocálcico en el crecimiento poblacional de los ácaros T. evansi y T. urticae. Metodología: Los efectos letales fueron estimados a través de test de toxicidad aguda con obtención de curvas dosis-respuesta y sus respectivas concentraciones letales, y los efectos subletales a través de la estimativa de la tasa instantánea de crecimiento poblacional (ri). Resultados: Las concentraciones letales y subletales del caldo sulfocálcico para T. evansi fueron 0,2 y 1,03% del producto, respectivamente, mientras que para T. urticae fueron 5,68 y 23,44% del producto. Conclusiones: El caldo sulfocálcico se presenta como una alternativa para el control de T. evansi, mientras que para T. urticae no es viable económicamente su utilización.

The lethal concentration (CL) is used to estimate the toxicity of pesticides for arthropods. However, the CL is an incomplete measurement of the effects of products on populations because it analyzes only mortality as a parameter of toxicity. It is known that individuals that survive to exposure of pesticides may suffer sub-lethal effects. Objective: The lethal and sublethal effects of lime sulfur on the population growth of dust mites T. evansi and T. urticae were studied in laboratory conditions. Methodology: Lethal effects were estimated by using acute toxicity tests to obtain dosage-response curves and their respective lethal concentrations and sub-lethal effects were estimated by means of the instantaneous population growth rate (ri). Results: The lethal and sub-lethal concentrations of lime sulphur against T. evansi were 0.2 and 1.03%, respectively, whereas for T. urticae, concentrations were 5.68 and 23.44%. Conclusions: Lime sulfur represents a valuable alternative for T. evansi control; while for T. urticae is not a viable economically option to be recommended.

El ácaro fitófago Tetranychus evansi posee una alta capacidad reproductiva, llevándolo a alcanzar altas poblaciones en muy corto tiempo, ocasionando daños económicos. El objetivo de este trabajo fue evaluar productos comerciales a base de Azadirachtina y caldo sulfocálcico para el control de T. evansi en invernadero. Fueron estudiados en el laboratorio: la toxicidad letal y los efectos subletales en el crecimiento poblacional (r i) de T. evansi, de los productos Neem Pro (0,08 y 0,07 mg i.a/L de azadirachtina), Natuneem (1,4 y 0,89 mg i.a/L), Organic Neem (0,37 y 0,28 mg i.a/L) y caldo sulfocálcico (1,0 y 0,6% a 31,5 °Bé). Posteriormente, en invernadero, se evaluó el potencial de control de dosis correspondientes a CL95 de los productos y aquellos donde el crecimiento de la población quedo estable (r i= 0). El diseño experimental utilizado, fue completamente al azar, con tres repeticiones. Después de 1, 5, 7 y 10 días de la aplicación de los productos, fueron realizadas las evaluaciones poblacionales de los ácaros en las plantas y los debidos análisis de mortalidad. La aplicación de los productos resultó en una mayor eficiencia de control a lo largo del tiempo y dicha eficiencia aumento con el período de exposición. El porcentaje de reducción poblacional del ácaro fitófago, fue superior a 98%, después de diez días de la aplicación. El manejo de T. evansi en tomate con productos alternativos a base de Azadirachtinay el caldo sulfocálcico.

The phytophagous mite Tetranychus evansi is characterized by its high reproductive, capacity which allows for its ability to attain high populations in a short time and cause economic damage. The objective of this study was to evaluate commercial products based on Azadirachtina and syrup sulfocálcico to control T. evansi in greenhouses. Lethal toxicity and sublethal effects on population growth (r i) of T. evansi products Neem Pro (0.08 and 0.07 mg/L of Azadirachtina), Natuneem (1.4 and 0.89 mg ai/L), Organic Neem (0.37 and 0.28 mg ai/L) and lime sulphur (1.0 and 0.6% to 31.5 °Bé) were initially studied in the laboratory. Lethal toxicity and sublethal effects on population growth (r i) of T. evansi products Neem Pro (0.08 and 0.07 mg/L of Azadirachtina), Natuneem (1.4 and 0.89 mg ai/L), Organic Neem (0.37 and 0.28 mg ai/L) and lime sulphur (1.0 and 0.6% to 31.5 0Bé) were initially studied in the laboratory. Later in a greenhouse, the control potential for concentrations corresponding to the LC95 of the products was evaluated and those where population growth was stable (r i =0). Experimental design, was completely randomized, with three replicates. Application of the products resulted in the improved efficiency of control over time, and this efficiency increased with the duration of exposure. The reduction percentage of phytophagous mite population was over 98%, after ten days of application. The management of T. evansi on tomatoes could be made possible by the use of products based on Azadirachtina and syrup sulfocálcico.

El análisis de la composición química de los artrópodos es importante en la taxonomía, en el reconocimiento de especies de difícil diferenciación, en la ecología, en el comportamiento, en el estudio de la selectividad de compuestos naturales y artificiales y, por consiguiente, importante en el control de plagas. El objetivo de este trabajo fue estudiar la composición química de la cutícula de los ácaros T. urticae y T. evansi. Se realizaron análisis cromatográficos de los extractos por Cromatografía Gaseosa acoplada a Espectrometría de Gases (CGMS). La identificación de los compuestos fue realizada por comparación de los tiempos de retención con patrones, en el cálculo del índice de Kovats y análisis de los espectros de masa obtenidos para cada pico registrado en el cromatograma. Se evaluó la concentración relativa de los compuestos presentes en la cutícula, la polaridad de esos compuestos y su concentración total relativa, y la presencia diferencial de compuestos en la cutícula de las dos especies de ácaros. Los compuestos más abundantes en la cutícula de las dos especies de ácaros fueron el ácido hexadecanoico (ácido palmítico), ácido 9,12-octadecadienoico (ácido linoleico), ácido 9,12,15-octadecatrienoico-metil ester (metil linoleato) y ácido octadecanoico (ácido oleico o esteárico). La cutícula de T. urticae tiene de 2,07 a 3,67 veces más compuestos extraíbles por hexano que la cutícula de T. evansi. El total de compuestos polares fue 2,15 a 3,71 veces mayor en T. urticae y la cantidad de los compuestos más abundantes, presentes en las dos especies, fueron 2,34 a 5,66 veces mayor en T. urticae.

The analysis of arthropods chemical composition is important in taxonomy for recognition of species difficult to differentiate, in ecology, for behavioral analyses, and in selectivity studies of artificial and natural compounds, and, therefore, it is important for pest control. The objective of this study was to evaluate the chemical composition of the T. urticae and T. evansi mites cuticle. Chromatographic analyses of extracts were performed by gas chromatography coupled to mass spectrometry (CGMS). Identification of compounds was based on the comparison of retention times with standards, on the Kovats' index calculation and the analysis of mass spectra obtained for each registered peak on the chromatogram. Relative concentration of compounds present in the cuticle, the polarity of these compounds and their total relative concentration, and the differential presence of compounds in the cuticle of the two mite species were evaluated. The most abundant compounds in the cuticle of both mite species were hexadecanoic acid (palmitic acid), 9,12-octadecadienoico acid (linoleic acid), 9,12,15-octadecatrienoic acid-methyl ester (methyl linoleate) and octadecanoic acid (oleic acid or stearic). T. urticae cuticle has from 2.07 to 3.67 times more hexane extractable compounds than T. evansi cuticle . The total polar compound concentration was 2.15 to 3.71 times higher in T. urticae and the quantity of the most abundant compounds present in both species was 2.34 to 5.66 times higher in T. urticae.

Tetranychus urticae es una importante plaga asociada al cultivo de fresa debido a las altas densidades poblacionales alcanzadas y a los daños ocasionados a las plantas. Los productores utilizan acaricidas en grandes volúmenes sin cumplir los periodos de carencia, ocasionando residuos tóxicos en los frutos, desarrollo de poblaciones resistentes a los productos, destrucción de organismos benéficos, intoxicación de mamíferos y contaminación del medio ambiente. Por lo tanto, es necesario generar otras alternativas de manejo de este ácaro plaga. El objetivo de este trabajo fue evaluar, mediante el análisis conjunto de la concentración letal y subletal, la acción tóxica de productos comerciales a base de nim sobre los ácaros T. urticae y Phytoseiulus macropilis. Fueron controladas poblaciones de T. urticae en plantas de fresa cuando se emplearon concentraciones correspondientes a CL95 de los productos alternativos a base de nim, y también cuando se utilizaron concentraciones inferiores. La aplicación de los productos a base de nim, Neem Pro, Organic Neem y Natuneem en la CL95 y cuando la tasa instantánea de crecimiento poblacional ri=0,1 para el predador representan una alternativa viable para el control del ácaro fitófago T. urticae.

Tetranychus urticae is an important pest associated with strawberry, due to its high densities and plant damage. Farmers use acaricides in large volumes without complying with the window between the last application and harvest, resulting on toxic residues in fruits, as well as pest populations resistant to pesticides, decrement of beneficial organisms, mammalian toxicity and environmental pollution. Therefore, it is necessary to generate new alternatives for the control of this mite. The aim of this work was to evaluate the toxic effect of commercial neem-based products on the mites T. urticae and Phytoseiulus macropilis, through a combined analysis using both, lethal and sublethal concentrations. Tetranychus urticae populations were controlled in strawberry plants when neem was used at or below LC95 concentrations. The application of the neem-based products, Neem Pro, Organic Neem and Natuneem at CL95, and when the instantaneous predator’s rate of population increase ri = 0.1, represents a viable alternative to be considered for the control of the phytophagous mite T. urticae.

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.

Plants have a type of defense that interferes with the digestive system of insects through the expression of different protease inhibitors (PIs). PIs act by inhibiting proteolytic enzymes in the gut of insects, and may even lead them to death. Therefore, studies have been conducted in order to use these compounds as an alternative method in control of phytophagous insects. The Thyrinteina leucoceraea is prague on eucalypts, but does not cause severe damage in leaves of guava, so it is interesting that the defense of this plant is investigated. Thus, this work studied the enzymatic response of the caterpillar T. leucoceraea further concentration of benzamidine PI (PI synthetic of serine proteases) applied to the leaves of guava in order to evaluate the effects of synthetic inhibitor in conjunction with the natural inhibitor produced by these plants. For this investigation, we used three different concentrations of benzamidine, 0.12, 0.25 and 0.5%. It was found that the guava produce IPs in response to defense and that the benzamidine applied on leaves of guava interfere in the activity of serine proteases in the gut of larvae of T. leucoceraea. However, it can also be observed that the caterpillars were adapted to the ingestion of PIs by increasing the activity of cysteine proteases in almost all treatments.

As plantas têm um tipo de defesa que interfere no sistema digestivo dos insetos através da expressão de diferentes inibidores de proteases (IPs). Os IPs agem inibindo enzimas proteolíticas no intestino dos insetos, podendo até levá-los à morte. Por isso, estudos têm sido realizados visando à utilização desses compostos como método alternativo no controle de insetos fitófagos. As lagartas de Thyrinteina leucoceraea causam muitos danos em eucaliptais, mas não conseguem se desenvolver bem em folhas de goiabeira, portanto é interessante que a defesa desta planta seja investigada. Sendo assim, este trabalho estudou a resposta enzimática da lagarta T. leucoceraea ao aumento da concentração do IP benzamidina (IP sintético de serino-proteases) aplicado sobre as folhas de goiabeira, a fim de estudar a ação do inibidor sintético em conjunto com o inibidor natural produzido por essas plantas. Para tal investigação, foram utilizadas três diferentes concentrações de benzamidina: 0, 12, 0,25 e 0,5%. Verificou-se que as goiabeiras produzem IPs como resposta de defesa e que a benzamidina aplicada nas plantas de goiaba interferiu na atividade das serino-proteases no intestino de lagartas de T. leucoceraea, entretanto, pode-se observar também que as lagartas apresentaram adaptação à ingestão dos IPs através do aumento da atividade de cisteíno-proteases em quase todos os tratamentos.

Tetranychus evansi Baker & Pritchard is an important pest of solanaceous plants, including tomatoes. This mite is characterized by a high reproductive rate, which leads to high population growth in a short period of time causing important economic damage. Control of T. evansi is mainly through synthetic acaricides. In searching for environmentally friendly control measures, we evaluated the efficiency of alternative products to control T. evansi on tomato plants under greenhouse conditions. The products tested were lime sulphur and neem based products. We first estimated the lethal concentration (LC) and instantaneous rate of increase (r i) of T. evansi exposed to different product concentrations in laboratory conditions, and later tested the efficacy of LC95 and the concentrations that restrained mite population growth (r i = 0) in greenhouse conditions. The following treatments were repeated three times: NeemPro (81.0 and 71.6 mg a.i./l), Natuneem (31.1 and 20.4 mg ai/l), Organic Neem (39.1 and 30.4 mg a.i./l), lime sulphur (1.0 and 0.6%) and water (control). For all products, control provided by LC95 was higher than provided for lower concentrations (r i = 0) one day after spraying. However, after five days, for both concentrations, the percentage of T. evansi population reduction was superior to 95% and increased over time. Only plants sprayed with Natuneem (31.1 mg a.i./l) showed symptoms of phytotoxicity. Lime sulphur and neem based products, applied in appropriate concentrations and formulations, bear out as a viable alternative to control T. evansi on tomato plants.

The effects of increasing plant diversity on the population of the coffee leaf-miner Leucoptera coffeella (Guérin-Mèneville) were investigated in two organic coffee production systems. One system consisted of coffee intercropped with banana trees (shaded system) and the other one of coffee intercropped with pigeon pea (unshaded system). The increase in plant diversity on both systems was achieved via introduction of green manures such a perennial pea nut, sunn hemp and Brazilian lucerne. The population of L. coffeella, predation and parasitism of L. coffeella mines were biweekly evaluated during eight months. The increase in plant diversity on both systems did not affect the attack of L. coffeella on coffee leaves and the mine parasitism rate. However, there was a positive and significant relationship between increasing plant diversity and coffee leaf mine predation by wasps on unshaded coffee system and a negative relationship on shaded coffee system.

O objetivo deste trabalho foi avaliar a capacidade de parasitismo do parasitoide larval-pupal Oomyzus sokolowskii, submetido a diferentes densidades do hospedeiro traça-das-crucíferas (Plutella xylostella), em laboratório, casa telada e campo. Em laboratório e campo, O. sokolowskii foi exposto às densidades de 2, 4, 8 e 16 lagartas. Em laboratório, empregaram-se recipientes de 300 mL e, em campo, plantas de couve foram confinadas em gaiolas de organza (30x50 cm). Em casa telada, foram utilizadas microparcelas compostas por seis plantas de repolho infestadas com 25, 50, 85 ou 100 lagartas. O número de lagartas parasitadas aumentou de acordo com a densidade do hospedeiro e variou de 1,7 a 10,4, em laboratório, e de 0,61 a 7,0, em campo. Em casa telada, a maior taxa de parasitismo foi observada nas microparcelas com densidades mais elevadas do hospedeiro. O tempo de exposição aos parasitoides proporcionou maior taxa de parasitismo após 72 horas (24 horas, 52,4% e 72 horas, 80,7%) independentemente da densidade. Oomyzus sokolowskii responde positivamente ao incremento na densidade de P. xylostella, embora a taxa de parasitismo permaneça constante independentemente da disponibilidade do hospedeiro.

The objective of this work was to evaluate the parasitism capacity of the larval-pupal parasitoid Oomyzus sokolowskii submitted to different densities of the host diamondback moth, Plutella xylostella, in the laboratory, greenhouse and field. In the laboratory and in the field, O. sokolowskii was exposed to densities of 2, 4, 8 or 16 larvae. In the laboratory, 300 mL recipient were used, and in the field kale plants were placed in cages (30x50 cm). In the greenhouse, microparcels consisted of six cabbage plants each infested with 25, 50, 85 or 100 larvae. The number of parasitized larvae increased with host density and varied from 1.7 to 10.4 (laboratory) and from 0.61 to 7.0 (field). In the greenhouse, parasitism rate was higher in microparcels with higher host infestation. The time of exposition was significant, with higher parasitism rate at 72 hours after host exposure (24 hour, 52.4%; and 72 hour, 80.7%), irrespective of host density. Oomyzus sokolowskii responds to increases in host density, but maintains the parasitism rate unchanged irrespective of variations in the host availability.

Mecanismos de defensa en plantas pueden ser activados por estímulos externos como herbivoría. Es bien conocido que la defensa inducida ocurre después de cortos períodos de herbivoría, pero se conoce poco acerca de la inducción de larga duración. En este artículo se estudió los efectos de la defensa inducida en árboles de Eucalyptus sobre Thyrinteina arnobia (Lepidoptera: Geometridae) durante cuatro generaciones Los efectos de la inducción de plantas de Eucalipto parecieron aumentar gradualmente con períodos prolongados de herbivoría. Según nuestro conocimiento es la primera demostración que la defensa inducida cambia de modo gradual con la herbivoría a largo plazo. Eso sugiere que estos árboles, y posiblemente muchas otras plantas, gradualmente invierten más en defensa inducida con ataques prolongados de herbívoros.

Mechanisms of defense in plants can be activated by external stimuli such as herbivory. It is well-known that such induced defense occurs after short periods of herbivory, but little is known about long-term induction. In this paper, we studied the effects of induced defenses of Eucalyptus trees on Thyrinteina arnobia (Lepidoptera: Geometridae) over four generations. The effects of induction of eucalypt plants seemed to increase gradually with prolonged periods of herbivory. To our knowledge it is the first demonstration that induced defense changes in a gradual way with long-term herbivory. This suggests that these trees, and possibly many other plants, gradually invest more in induced defense with prolonged herbivore attacks.

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 objetivo deste trabalho foi avaliar o efeito da teia produzida por Tetranychus evansi (Acari: Tetranychidae) na eficiência de predação por coccinelídeos Cycloneda sanguinea e Eriopis connexa e pelo crisopídeo Chrysoperla externa. A eficiência em predar as fêmeas de T. evansi na presença e na ausência de sua teia em discos de folhas de tomateiro com ácaros foi avaliada para cada instar das diferentes espécies de predadores. Foi observado efeito negativo da teia produzida por T. evansi na eficiência de predação do segundo e do terceiro instar de C. externa. Quanto à E. connexa, somente a predação pelo último instar foi influenciada negativamente pela presença da teia. A predação pelas larvas de primeiro e terceiro instar de C. sanguinea foi significativamente menor na presença da teia; no entanto, o resultado foi contrário para o quarto instar. O efeito da teia de T. evansi como mecanismo de defesa varia conforme a espécie e o estágio de desenvolvimento do predador.

The aim of this work was to evaluate the effect of the webbing produced by Tetranychus evansi (Acari: Tetranychidae) on the predation efficiency of Cycloneda sanguinea and Eriopis connexa coccinellids and of the Chrysoperla externa chrysopid. The predation efficiency on T. evansi females with and without webbing on tomato leaf discs was evaluated for each juvenile stage of the different predator species tested. There was a negative effect of T. evansi webbing on the predation efficiency of the second and third C. externa juvenile stages. Regarding E. connexa, only the predation by the oldest juvenile stage was negatively affected by the webbing. The predation efficiency of the first and the third juvenile stages of C. sanguinea was lower in the presence of webbing, but the opposite was observed for the fourth stage. The defensive role of T. evansi webbing varies according to the predator species and their developmental stage.