Adenir Vieira Teodoro

Life history of Amblyseius herbicolus (Chant) (Acari: Phytoseiidae) on coffee plants

The predaceous mite Amblyseius herbicolus (Chant) is the second most abundant phytoseiid on coffee plants (Coffea arabica L), after Euseius alatus DeLeon, in Lavras, MG, Brazil, associated to the vector of the coffee ring spot virus, Brevipalpus phoenicis (Geijskes) (Acari: Tenuipalpidae). Its life history was studied taking into account biological aspects, life table, predatory activity and functional and numerical responses in relation to the density of the prey. The adult female has longevity of 38 days when supplied with B. phoenicis. The intrinsic rate of population increase (r m) was 0.150 and the mean generation time (T) 25.3 days. The population doubles every 4.6 days. Thirty mites B. phoenicis /3-cm diameter coffee leaf arenas were separately offered to one specimen of each predator phase. Adult females were more efficient in killing all developmental phases of B. phoenicis, followed by the nymph stages. For the functional and numerical responses studies, from 0.14 to 42.3 immature specimens of the prey /cm(2) of arena were submitted to the predator, the preferred phase for predation. Predation and the oviposition of A. herbicolus increased with increasing prey density, with a positive and highly significant correlation. Regression analysis suggests a functional type II response, with a maximum daily predation near 35 B. phoenicis /cm(2) /one adult female.

Driving factors of the communities of phytophagous and predatory mites in a physic nut plantation and spontaneous plants associated

Seasonal changes in climate and plant diversity are known to affect the population dynamics of both pests and natural enemies within agroecosystems. In Brazil, spontaneous plants are usually tolerated in small-scale physic nut plantations over the year, which in turn may mediate interactions between pests and natural enemies within this agroecosystem. Here, we aimed to access the influence of seasonal variation of abiotic (temperature, relative humidity and rainfall) and biotic (diversity of spontaneous plants, overall richness and density of mites) factors on the communities of phytophagous and predatory mites found in a physic nut plantation and its associated spontaneous plants. Mite sampling was monthly conducted in dicotyledonous and monocotyledonous leaves of spontaneous plants as well as in physic nut shrubs over an entire year. In the dry season there was a higher abundance of phytophagous mites (Tenuipalpidae, Tarsonemidae and Tetranychidae) on spontaneous plants than on physic nut shrubs, while predatory mites (Phytoseiidae) showed the opposite pattern. The overall density of mites on spontaneous plants increased with relative humidity and diversity of spontaneous plants. Rainfall was the variable that most influenced the density of mites inhabiting physic nut shrubs. Agroecosystems comprising spontaneous plants associated with crops harbour a rich mite community including species of different trophic levels which potentially benefit natural pest control due to increased diversity and abundance of natural enemies.

Distribuição espacial do ácaro Brevipalpus phoenicis (Geijskes) (Acari: Tenuipalpidae) em cafeeiro (Coffea arabica L.)

The spatial distribution of the false spider mite Brevipalpus phoenicis (Geijskes) (Acari: Tenuipalpidae), vector of the ringspot virus, was studied in coffee plants (Coffea arabica L.), in order to assess the mite preferred sites. Samples were taken throughout leaves, branches and berries, from lower, medium and superior parts of the plants. The inner and the outer side of the plants were compared. All development stages of the mites were recorded. B. phoenicis was mostly found on the internal leaves, branches and berries, in the lower and medium parts of the plants. On the leaves, mites were localized mostly at the lower leaf surface, mainly next to the midrib. On the berries, eggs and mites were found mainly at the crown and peduncle. On the branches, they were found in the nodes and coat gap.

Predatory activity of Phytoseiid mites on the developmental stages of coffee ringspot mite (Acari: Phytoseiidae: Tenuipalpidae)

Atraves de bioensaios realizados em arenas com 3 cm de diâmetro, confeccionadas com folhas de cafeeiro flutuando em agua, foram estudadas as fases do acaro da mancha-anular do cafeeiro Brevipalpus phoenicis (Geijskes) quanto a preferencia pelos diversos estadios do desenvolvimento dos acaros predadores Euseius alatus DeLeon e Iphiseiodes zuluagai Denmark & Muma. Os experimentos foram conduzidos em laboratorio a 25 ± 2oC, 70 ± 10% de UR e 14 horas de fotofase. O estadio do acaro vetor mais predado foi o de larva, seguido pelo de ninfa e ovo. A fase adulta teve muito pouca predacao. De modo geral, a fase mais agressiva dos predadores foi a de femea adulta, seguida pela de ninfa. A fase de larva foi a menos eficiente na predacao. As medias de predacao de E. alatus e I. zuluagai para as diferentes fases do B. phoenicis foram respectivamente: larva (79% e 90%) > ovo (47% e 83%) > ninfa (40% e 77%) > adulto (1% e 18%), o que demonstra que I. zuluagai mostrou maior atividade predatoria que E. alatus.

Weed management practices affect the diversity and relative abundance of physic nut mites

Crop management practices determine weed community, which in turn may influence patterns of diversity and abundance of associated arthropods. This study aimed to evaluate whether local weed management practices influence the diversity and relative abundance of phytophagous and predatory mites, as well as mites with undefined feeding habits—of the families Oribatidae and Acaridae—in a physic nut (Jatropha curcas L.) plantation subjected to (1) within-row herbicide spraying and between-row mowing; (2) within-row herbicide spraying and no between-row mowing; (3) within-row weeding and between-row mowing; (4) within-row weeding and no between-row mowing; and (5) unmanaged (control). The herbicide used was glyphosate. Herbicide treatments resulted in higher diversity and relative abundance of predatory mites and mites with undefined feeding habit on physic nut shrubs. This was probably due to the toxic effects of the herbicide on mites or to removal of weeds. Within-row herbicide spraying combined with between-row mowing was the treatment that most contributed to this effect. Our results show that within-row weeds harbor important species of predatory mites and mites with undefined feeding habit. However, the dynamics of such mites in the system can be changed according to the weed management practice applied. Among the predatory mites of the family Phytoseiidae Amblydromalus sp. was the most abundant, whereas Brevipalpus phoenicis was the most frequent phytophagous mite and an unidentified oribatid species was the most frequent mite with undefined feeding habit.

Functional response of Euseius concordis to densities of different developmental stages of the cassava green mite.

Both prey density and developmental stage of pests and natural enemies are known to influence the effectiveness of biological control. However, little is known about the interaction between prey density and population structure on predation and fecundity of generalist predatory mites. Here, we evaluated the functional response (number of prey eaten by predator in relation to prey density) of adult females and nymphs of the generalist predatory mite Euseius concordis to densities of different developmental stages of the cassava green mite Mononychellus tanajoa, as well as the fecundity of adult females of the predator. We further assessed the instantaneous rate of increase, based on fecundity and mortality, of E. concordis fed on eggs, immatures and adults of M. tanajoa. Overall, nymphs and adults of E. concordis feeding on eggs, immatures and females of M. tanajoa had a type III functional response curve suggesting that the predator increased prey consumption rate as prey density increased. Both nymphs and adult females of the predator consumed more eggs than immatures of M. tanajoa from the density of 20 items per leaf disc onwards, revealing an interaction between prey density and developmental stage in the predatory activity of E. concordis. In addition, population growth rate was higher when the predator fed on eggs and immatures in comparison with females. Altogether our results suggest that E. concordis may be a good candidate for the biological control of M. tanajoa populations. However, the efficiency of E. concordis as a biological control agent of M. tanajoa is contingent on prey density and population structure.

Toxicity of neem oil to the cassava green mite Mononychellus tanajoa (Bondar) (Acari: Tetranychidae)

Neem ( Azadirachta indica A. Juss.)-derived pesticides have been used against a wide range of agricultural pests including tetranychid mites. Approaches combining lethal and sublethal toxicity studies of neem pesticides towards tetranychid mites are necessary to a comprehensive evaluation of such products. Here, we evaluated the lethal and sublethal toxicity of the neem oil Bioneem to the cassava green mite Mononychellus tanajoa (Bondar) by integrating lethal concentration (LC) with population growth and biological parameter studies. According to Probit analyses the concentration of neem oil Bioneem which kills 50% of the population (LC50) of M. tanajoa was 3.28 μL cm-2, which is roughly twice the field concentration recommended of this biopesticide to control pest mites (1.7 μL cm-2). The growth rate of the cassava green mite steadily decreased with dosages of neem oil. Furthermore, sublethal concentrations of the neem oil corresponding to the LC50 reduced the periods of the immature stages of M. tanajoa resulting in a shorter developmental time. Similarly, the number of eggs per day and the number of eggs per female per day, a proxy for fecundity, were drastically reduced in M. tanajoa females exposed to the LC50 of neem oil. Based on our comprehensive approach we conclude that the neem oil showed lethal as well as sublethal toxicity on growth rate and biological parameters such as duration of immature stages and fecundity of the cassava green mite M. tanajoa and it could be used as an ecological alternative for the management of this pest.

Bioactivity of cottonseed oil against the coconut mite Aceria guerreronis (Acari: Eriophyidae) and side effects on Typhlodromus ornatus (Acari: Phytoseiidae)

Abstract The coconut mite, Aceria guerreronis Keifer (Acari: Eriophyidae), is a major pest of coconut plantations. In Brazil, the control of A. guerreronis, when accomplished, is heavily dependent on applications of conventional acaricides, which further increases the risks associated with pest resistance, hazards to human health and environmental contamination. Therefore, the development of alternatives to the chemical control concerns outlined above is urgently needed. Here, we assessed the composition, toxicity and repellent activities of cottonseed oil to A. guerreronis and its naturally occurring predator Typhlodromus ornatus Denmark & Muma (Acari: Phytoseiidae). Our results revealed that the major compounds in cottonseed oil were linoleic and oleic acids, which have been shown to be bioactive against pests. Concentration-mortality bioassays revealed that A. guerreronis (LC50 = 0.65 µL/cm2) was more susceptible to cottonseed oil than its predator (LC50= 5.11 µL/cm2). Similarly, as demonstrated for the conventional acaricides (i.e., abamectin, azadirachtin, espirodiclofen, and fenpyroximate), cottonseed oil was shown to repel A. guerreronis and its predator. Overall, our findings support the use of cottonseed oil as a desirable tool to be integrated in management programs aimed at controlling A. guerreronis.

The invasive red palm mite, Raoiella indica Hirst (Acari: Tenuipalpidae), in Brazil: range extension and arrival into the most threatened area, the Northeast Region

ABSTRACT Raoiella indica Hirst (Acari: tenuipalpidae), commonly known as the red palm mite (RPM), is an invasive polyphagous pest, which has emerged as a threat to agriculture in the Americas. In the Americas, the mite has not only spread quickly, but also greatly extended its host range in the new areas where it has been observed. We present here new records of the RPM in Brazilian states, with focus on its arrival into the most threatened area, the Northeast Region. Coconut and banana are important crops in this region of Brazil and represent the main threatened crops by this pest. These new records of RPM reinforce the idea that this species is already widely distributed throughout Brazil eight years after its introduction into the extreme North state of Roraima. Comments on the possible economic, social and environmental impacts are presented.

Rainfall and Coconut Accession Explain the Composition and Abundance of the Community of Potential Auchenorrhyncha Phytoplasma Vectors in Brazil

Abstract Coconut plantations are attacked by the lethal yellowing (LY), which is spreading rapidly with extremely destructive effects in several countries. The disease is caused by phytoplasmas that occur in the plant phloem and are transmitted by Haplaxius crudus (Van Duzee) (Auchenorrhyncha: Cixiidae). Owing to their phloem-sap feeding habit, other planthopper species possibly act as vectors. Here, we aimed at assessing the seasonal variation in the Auchenorrhyncha community in six dwarf coconut accessions. Also, we assessed the relative contribution of biotic (coconut accession) and abiotic (rainfall, temperature) in explaining Auchenorrhyncha composition and abundance. The Auchenorrhyncha community was monthly evaluated for 1 yr using yellow sticky traps. Among the most abundant species, Oecleus sp., Balclutha sp., Deltocephalinae sp.2, Deltocephalinae sp.3, Cenchreini sp., Omolicna nigripennis Caldwell (Derbidae), and Cedusa sp. are potential phytoplasma vectors. The composition of the Auchenorrhyncha community differed between dwarf coconut accessions and periods, namely, in March and April (transition from dry to rainy season) and August (transition from rainy to dry season). In these months, Oecleus sp. was predominantly found in the accessions Cameroon Red Dwarf, Malayan Red Dwarf, and Brazilian Red Dwarf Gramame, while Cenchreini sp. and Bolbonota sp. were dominant in the accessions Brazilian Yellow Dwarf Gramame, Malayan Yellow Dwarf, and Brazilian Green Dwarf Jequi. We conclude that dwarf coconut host several Auchenorrhyncha species potential phytoplasma vectors. Furthermore, coconut accessions could be exploited in breeding programs aiming at prevention of LY. However, rainfall followed by accessions mostly explained the composition and abundance of the Auchenorrhyncha community.