A notodontid novelty: Theroa zethus caterpillars use behavior and anti-predator weaponry to disarm host plants.

Unlike most notodontids, Theroa zethus larvae feed on plants that emit copious latex when damaged. To determine how the larvae overcome this defense, we filmed final instars on poinsettia, Euphorbia pulcherrima, then simulated their behaviors and tested how the behaviors individually and combined affect latex exudation. Larvae initially scraped the stem, petiole, or midrib with their mandibles, then secreted acid from their ventral eversible gland (VEG) onto the abraded surface. Scraping facilitated acid penetration by disrupting the waxy cuticle. As the acid softened tissues, the larvae used their mandibles to compress the plant repeatedly, thereby rupturing the latex canals. Scraping, acid application, and compression created withered furrows that greatly diminished latex exudation distal to the furrows where the larvae invariably fed. The VEG in notodontids ordinarily serves to deter predators; when attacked, larvae spray acid aimed directly at the assailant. Using HPLC, we documented that the VEG secretion of T. zethus contains 30% formic acid (6.53M) with small amounts of butyric acid (0.05M). When applied to poinsettia petioles, the acids caused a similar reduction in latex outflow as VEG secretion milked from larvae. VEG acid could disrupt latex canals in part by stimulating the normal acid-growth mechanism employed by plants to loosen walls for cell elongation. Histological examination of cross sections in poinsettia midribs confirmed that cell walls within furrows were often highly distorted as expected if VEG acids weaken walls. Theroa zethus is the only notodontid caterpillar known to use mandibular scraping and VEG acid to disable plant defenses. However, we document that mandibular constriction of petioles occurs also in other notodontids including species that feed on hardwood trees. This capability may represent a pre-adaptation that facilitated the host shift in the Theroa lineage onto latex-bearing plants by enabling larvae to deactivate laticifers with minimal latex contact.

Three new South American species of genus Aphis (Hemiptera: Aphididae) living on species of Euphorbia (Euphorbiaceae).

Three species of Aphis living on species of Euphorbia in Argentina and Chile are described: Aphis tehuelchis Nieto Nafría & López Ciruelos, sp. n., from viviparous females collected in the Argentinean provinces of Santa Cruz and Neuquén, Aphis maulensis Mier Durante & García-Tejero, sp. n., from viviparous females collected in the Chilean Region VII, and Aphis eucollinae López Ciruelos & Ortego, sp. n., from viviparous females, oviparous females and males collected in the Argentinean province of Mendoza. These new species may be distinguished from each other, besides other features, by the abdominal marginal tubercles: in A. tehuelchis these are present on segments 1 and 7 and on several of segments 2 to 6, in A. maulensis they are on segment 1 and on several segments 2 to 6, but lacking on segment 7, and in A. eucollinae they are only on segments 1 and 7. Differences between the new species and those currently known living on Euphorbia around the world are presented.

Revision of the Genus Physiphora Fallén 1810 (Diptera: Ulidiidae: Ulidiinae).

The genus Physiphora includes at least 29 species, most of them occurring predominantly in the Afrotropical Region and a few species native to the other regions of the Old World. At least P. alceae (Preyssler 1791) and P. clausa (Macquart 1843) are subcosmopolitan species unintentionally introduced into the Australasian, Nearctic, and Neotropical Regions. Twelve new species from the Afrotropical Region are described: P. hendeli sp. n., P. igniceps sp. n., P. kirki sp. n., P. maraisi sp. n., P. meyi sp. n., P. opalizana sp. n., P. orinigra sp. n., P. polita sp. n., P. rugosa sp. n., P. spriggsi sp. n., P. steyskali sp. n., and P. virens sp. n. Detailed illustrated descriptions and a key for identification are provided for all the species of Physiphora. Analysis of the new and previously known biological data shows that larvae of most Physiphora species are saprophagous associated with rotting tissues of palms (apparently infested by the palm weevils), giant Euphorbia, and even baobabs and poplars. Some species are attracted to (and as larvae possibly can develop in) the dung of ungulates. The following synonymy is established: Physiphora clausa (Macquart 1843) = Physiphora hainanensis Chen in Chen & Kameneva 2007: 24, syn. n.; Physiphora flavipes (Karsch 1888) = Chrysomyza africana Hendel 1909, syn. n., = Cliochloria senegalensis Enderlein 1927, syn. n.

Novel ophiostomatalean fungi from galleries of Cyrtogenius africus (Scolytinae) infesting dying Euphorbia ingens.

Euphorbia ingens trees have been dying in large numbers in the Limpopo Province of South Africa for approximately 15 years. The ambrosia beetle Cyrtogenius africus is often found infesting diseased and dying trees. The aim of this study was to identify the ophiostomatoid fungi occurring in the galleries of C. africus. Logs infested with this beetle were collected from the KwaZulu-Natal, Limpopo, Mpumalanga, and North West Provinces of South Africa. Fungi belonging to the Ophiostomatales were identified based on morphology and comparison of sequence data for the ß-tubulin, ITS1-5.8S-ITS2 and LSU gene regions. A novel species of Ophiostoma and a novel genus in the Ophiostomatales were identified. Inoculation studies with these fungi produced lesions in the branches of healthy E. ingens trees.

In situ chlorophyll fluorescence kinetics as a tool to quantify effects on photosynthesis in Euphorbia cyparissias by a parasitic infection of the rust fungus Uromyces pisi.

BACKGROUND: Photosynthesis is the key process for plant growth and development. The determination of chlorophyll fluorescence kinetics allows the quantification of effects on photosynthetic processes triggered by environmental stress factors such as, e.g., the infection by fungal phytopathogens. The technique is non-invasive, rapid and well suited for experimental field work. RESULTS: Healthy and Uromyces-infected plants of Euphorbia cyparissias were monitored directly in situ in the field using rapid fluorescence kinetics. Non-infected healthy plants show a typical maximum value for the relative variable fluorescence Fv/Fm of around 0.8 with occasional variation between the leaves from the plant top towards the base, while infected plants exhibited a strong gradient to low values at the base. The photosynthetic performance index (PI) showed a higher heterogeneity within the leaves in both plant types. CONCLUSIONS: The non-invasive and rapid measurement of chlorophyll fluorescence induction allows characterizing the photosynthetic capacity of healthy and infected plants and of parts of them directly in the field. The PI, is highly sensitive not only concerning infection, but also towards other local environmental influences.

Phytomonas: trypanosomatids adapted to plant environments.

Over 100 years after trypanosomatids were first discovered in plant tissues, Phytomonas parasites have now been isolated across the globe from members of 24 different plant families. Most identified species have not been associated with any plant pathology and to date only two species are definitively known to cause plant disease. These diseases (wilt of palm and coffee phloem necrosis) are problematic in areas of South America where they threaten the economies of developing countries. In contrast to their mammalian infective relatives, our knowledge of the biology of Phytomonas parasites and how they interact with their plant hosts is limited. This review draws together a century of research into plant trypanosomatids, from the first isolations and experimental infections to the recent publication of the first Phytomonas genomes. The availability of genomic data for these plant parasites opens a new avenue for comparative investigations into trypanosomatid biology and provides fresh insight into how this important group of parasites have adapted to survive in a spectrum of hosts from crocodiles to coconuts.

A new species of Anastrepha (Diptera: Tephritidae) from Euphorbia tehuacana (Euphorbiaceae) in Mexico.

Anastrepha tehuacana, a new species of Tephritidae (Diptera) from Tehuacán, Puebla, Mexico reared from seeds of Euphorbia tehuacana (Brandegee) V.W. Steinm. (Euphorbiaceae), is described and illustrated. Its probable relationship to A. relicta Hernández-Ortiz is discussed.

Chemical class rotations for control of Bemisia tabaci (Hemiptera: Aleyrodidae) on poinsettia and their effect on cryptic species population composition.

BACKGROUND: Bemisia tabaci, a polyphagous insect with over 900 host plants, is an effective vector of more than 100 plant viruses. Being highly fecund, B. tabaci has the potential to develop insecticide resistance rapidly, as demonstrated by reports of use failures with MEAM1 and MED cryptic species (commonly known as biotypes B and Q respectively). Insecticide resistance management is a key component of pest management practices. The research herein studied season-long rotational management programs on poinsettia and their impact on the ratio of MEAM1:MED cryptic species in the surviving treated populations. RESULTS: In all four experiments, only three of the treatments completely eliminated the adult or immature whiteflies, but all significantly reduced the populations. Out of 18 active ingredients tested, dinotefuran (applied as a soil drench) was the most efficacious against both MEAM1 and MED cryptic species compared with the other chemical or biorational insecticides evaluated. Reduced susceptibility of MED was reported against a variety of treatment regimes. CONCLUSION: Rotations can be used to manage MEAM1 and MED cryptic species and maintain a very low population level or completely eliminate Bemisia on poinsettia. It is imperative to continue to emphasize the importance of rotating among different modes of action in pest management programs in order to retain effective chemistries for as long as possible in the market place.

New species of Gondwanamyces from dying Euphorbia trees in South Africa.

Gondwanamyces and its Custingophora anamorphs were first described from Protea infructescences in South Africa. Subsequently these unusual fungi were also found on Cecropia in Central America. During an investigation into the decline and death of native Euphorbia trees in South Africa, several fungal isolates resembling the anamorph state of Gondwanamyces were obtained from diseased tissues. In this study these isolates are identified based on morphology and comparisons of DNA sequences. Two previously unknown Gondwanamyces species were identified, both were associated with damage caused by beetles (Cossonus sp.). Inoculation studies showed that the new species of Gondwanamyces are pathogenic on Euphorbia ingens and may contribute to the decline of these trees.

Effects of selected fertilizers on the life history of Bemisia tabaci (Hemiptera: Aleyrodidae) biotype B.

We tested the effects among a purportedly sustainable water-soluble fertilizer, a conventional water-soluble fertilizer, an alternation of these, a controlled-release fertilizer, and a clear water control on the life-history traits of sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae; =Bemisia argentifolii Bellows & Perring) biotype B reared on poinsettia (Euphorbia pulcherrima Willdenow ex Klotzch). Free amino acids in petioles were measured to estimate plant nutrient assimilation and phloem nutritional quality for B. tabaci biotype B. The sustainable fertilizer produced plants with the highest concentration of amino acids. In contrast, fecundity of whiteflies was lowest in plants treated with the sustainable fertilizer and the water control. The relationship between total amino acids in phloem and survival was significantly quadratic, with the highest survival at intermediate levels. Fecundity, however, was negatively correlated with total amino acid content of the maternal host plant. Variation in total amino acid concentration in petioles of plants treated within fertilizer treatments makes it difficult to predict whether a particular fertilizer will produce plants with enough amino acids to deleteriously affect both survivorship and fecundity and yet yield a plant of good quality. Despite this limitation, we can conclude that the use of this sustainable fertilizer will not cause increases in whitefly populations relative to plants fertilized with water-soluble and slow-release fertilizers that deliver the same level of nitrogen to the plant.

Applying DNA barcoding for the study of geographical variation in host-parasitoid interactions.

Studies on the biogeography of host-parasitoid interactions are scarce, mainly because of technical difficulties associated with rearing and species identification. DNA barcoding is increasingly recognized as a valuable tool for taxon identification, allowing to link different life history stages of a species. We evaluate the usefulness of a protocol based on cytochrome oxidase I (COI) sequencing for the study of geographical variation of host-parasitoid interactions. Larvae of Acroclita subsequana (Lepidoptera: Tortricidae) were collected in Macaronesia and dissected to search for parasitoid larvae. Both hosts and parasitoids were sequenced and assigned to molecular operational taxonomic units (MOTUs) based on pairwise genetic distances, tree-based and similarity-based methods. Hosts were grouped into six MOTUs, usually with an allopatric distribution, while parasitoids clustered into 12 MOTUs, each of which was mostly found attacking a single host MOTU. Available COI sequence databases failed to provide identification to species level for these MOTUs. Three challenges related to the applicability of DNA barcoding in this type of studies are identified and discussed: (i) more suitable primers need to be developed for both parasitoids and hosts; (ii) the most commonly used approaches for inferring MOTUs have different limitations (e.g. arbitrary nature of defining a threshold to separate MOTUs) and need to be improved or replaced by other techniques; and (iii) for the identification of MOTUs, it is imperative to increase the range of sequenced taxa in the currently available reference databases. Finally, in spite of these difficulties, we discuss how DNA barcoding will help ecological and biogeographical studies of host-parasitoid interactions.

Feeding deterrents against two grain storage insects from Euphorbia fischeriana.

The screening of several Chinese medicinal herbs for insecticidal principles showed that Euphorbia fischeriana roots possessed significant feeding deterrent activity against two stored-product insects (Tribolium castaneum and Sitophilus zeamais). From ethanol extract, four feeding deterrents were isolated by bioassay-guided fractionation. The compounds were identified as jolkinolide B, 12-deoxyphorbol 13-(9Z)-octadecenoate 20-acetate, 17-hydroxyjolkinolide A and B on the basis of their phytochemical and spectral data. Jolkinolide B and 17-hydroxyjolkinolide B possessed strong feeding deterrent activities against S. zeamais (EC50 = 342.1 and 543.9 ppm, respectively) and T. castaneum adults (E50 = 361.4 and 551.5 ppm, respectively). 17-Hydroxyjolkinolide A and 12-deoxyphorbol 13-(9Z)-octadecenoate 20-acetate A also exhibited feeding deterrent activity against the two grain storage insects with EC50 values of 631.9 and 884.3 ppm for S. zeamais and 656.5 and 1058.4 ppm for T. castaneum adults.

Inundative release of Aphthona spp. flea beetles (Coleoptera: Chrysomelidae) as a biological "herbicide" on leafy spurge in riparian areas.

Inundative releases of beneficial insects are frequently used to suppress pest insects but not commonly attempted as a method of weed biological control because of the difficulty in obtaining the required large numbers of insects. The successful establishment of a flea beetle complex, mixed Aphthona lacertosa (Rosenhauer) and Aphthona nigriscutus Foundras (87 and 13%, respectively), for the control of leafy spurge, Euphorbia esula L., provided an easily collectable source of these natural enemies that enabled us to attempt inundative release as a possible leafy spurge control method in a sensitive riparian ecological zone where chemical control is restricted. Our target weed populations were small isolated patches of leafy spurge along three streams in southwestern, central, and northeastern Idaho. This study assessed leafy spurge and associated vegetation responses to inundative releases of 10 and 50 beetles per spurge flowering stem over two consecutive years. Releasing 10 beetles per flowering stem had inconclusive effects on spurge biomass, crown, stem, and seedling density. Alternatively, releasing 50 beetles per flowering stem resulted in a reduction of biomass, crown and stem density in the range of 60-80% at all three study sites, and about an approximately 60% reduction of seedling density at one site, compared with untreated plots. In contrast to leafy spurge, associated vegetation did not conclusively respond to beetle release, indicating that it may take more than two years for desired riparian vegetation to respond to reductions in leafy spurge competition.

Overwintering survival of Aphthona beetles (Coleoptera: Chrysomelidae): a biological control agent of leafy spurge released in North Dakota.

We evaluated the effects of snow cover and debris cover on overwintering success of Aphthona from 2001 to 2004 in southeast North Dakota. Chill degree-days, soil temperature, and duration of soil temperatures were monitored in field plots. Emergence of Aphthona from soil cores collected in October and held in the laboratory under simulated winter conditions did not differ across treatments. Field emergence of Aphthona was significantly reduced compared with emergence of Aphthona in the laboratory under simulated winter. Snow cover protected overwintering of Aphthona during 3 yr. Overwintering success was 77-94% lower in no-snow plots than in snow plots except in 2002. In 2001, when the soil temperature was as low as -4.4 degrees C, 90% of the Aphthona beetles emerged from snow-covered plots. The ranges of winter temperature and winter period for overwintering Aphthona were determined as -5.0-4.5 degrees C and 56-132 d, respectively, by using linear regression. A negative linear relationship between soil temperature and winter period may help predict the minimum needed overwintering period at a given winter temperature. Warmer temperatures during the winter of 2002 caused snow to melt in the snow plots, which led to excessive moisture that seemed to reduce overwintering success of Aphthona in those plots. Overall emergence was too low to conduct statistical procedures in 2003 and 2004 because of temperature extremes and warm periods during the winters that may have caused Aphthona to break diapause prematurely.

[Mites (Acari) from rubber trees (Hevea brasiliensis Muell. Arg., Euphorbiaceae) and spontaneous euphorbiaceous in rubber trees cultivation]. / Acaros (Acari) de seringueira (Hevea brasiliensis Muell. Arg., Euphorbiaceae) e de euforbiáceas espontâneas no interior dos cultivos.

Quarterly samples were done in 2001 on three rubber tree plantation in the northwest of the state of São Paulo. Three rubber trees of each locality were sampled. Between the rows of rubber tree four species of spontaneous euphorbiaceous were collected: Chamaesyce hirta, C. hyssopifolia, Euphorbia heterophylla and Phyllanthus tenellus. A total of 8.954 mites of 38 species, belonging to 31 genera of 11 families were collected. Tydeidae and Phytoseiidae had the highest diversity of species, 9 and 7, respectively. The most abundant families were Eriophyidae (3.594), Tydeidae (2.825) and Tenuipalpidae (1.027). The most abundant species on the rubber trees were: phytophagous - Calacarus heveae Feres, Tenuipalpus heveae Baker, Lorryia sp.2, Lorryia formosa Cooreman and Lorryia sp.1; predators - Zetzellia quasagistemas Hernandes & Feres, Pronematus sp., Iphiseiodes zuluagai Denmark & Muma and Euseius citrifolius Denmark & Muma. Among the spontaneous euphorbiaceous, predatory mites were abundantly found on C. hirta and E. heterophylla, mainly Pronematus sp. and E. citrifolius, suggesting that these plants could be important in the maintenance of these predators in the rubber tree cultivation areas. However, plants that can shelter predators and at the same time exert strong competition (nutrients, water etc) to rubber trees, can not be recommended for pest management programs. Studies about competition between rubber trees and spontaneous plants need to be conducted for feasible efficient programs of environmental management, aiming at the control of pest mites of rubber tree.

Ácaros (Acari) de seringueira (Hevea brasiliensis Muell. Arg., Euphorbiaceae) e de euforbiáceas espontâneas no interior dos cultivos / Mites (Acari) from rubber trees (Hevea brasiliensis Muell. Arg., Euphorbiaceae) and spontaneous euphorbiaceous in rubber trees cultivation

Foram realizadas coletas trimestrais em 2001 em três cultivos de seringueira no Noroeste do estado de São Paulo. Foram amostradas três seringueiras de cada local. Nas entrelinhas das seringueiras foram coletadas quatro espécies de euforbiáceas espontâneas: Chamaesyce hirta, C. hyssopifolia, Euphorbia heterophylla e Phyllanthus tenellus. Foram coletados 8.954 ácaros de 38 espécies, pertencentes a 31 gêneros de 11 famílias. Tydeidae e Phytoseiidae tiveram maior diversidade de espécies, 9 e 7, respectivamente. As famílias mais abundantes foram Eriophyidae (3.594), Tydeidae (2.825) e Tenuipalpidae (1.027). As espécies mais abundantes nas seringueiras foram: fitófagas - Calacarus heveae Feres, Tenuipalpus heveae Baker, Lorryia sp.2, Lorryia formosa Cooreman e Lorryia sp.1; predadoras - Zetzellia quasagistemas Hernandes & Feres, Pronematus sp., Iphiseiodes zuluagai Denmark & Muma e Euseius citrifolius Denmark & Muma. Entre as euforbiáceas espontâneas, encontrou-se maior abundância de ácaros predadores em C. hirta e E. heterophylla, destacando-se Pronematus sp. e E. citrifolius, sugerindo que estas plantas possam ser importantes na manutenção daqueles predadores nos plantios de seringueira. No entanto, plantas que podem abrigar predadores, mas que também exercem forte competição (nutrientes, água etc.) com a seringueira, não podem ser sugeridas para um programa de manejo de pragas. Estudos sobre competição entre a seringueira e plantas espontâneas precisam ser conduzidos para viabilizar programas eficientes de manejo ambiental, visando o controle dos ácaros-praga da seringueira.

Quarterly samples were done in 2001 on three rubber tree plantation in the northwest of the state of São Paulo. Three rubber trees of each locality were sampled. Between the rows of rubber tree four species of spontaneous euphorbiaceous were collected: Chamaesyce hirta, C. hyssopifolia, Euphorbia heterophylla and Phyllanthus tenellus. A total of 8.954 mites of 38 species, belonging to 31 genera of 11 families were collected. Tydeidae and Phytoseiidae had the highest diversity of species, 9 and 7, respectively. The most abundant families were Eriophyidae (3.594), Tydeidae (2.825) and Tenuipalpidae (1.027). The most abundant species on the rubber trees were: phytophagous - Calacarus heveae Feres, Tenuipalpus heveae Baker, Lorryia sp.2, Lorryia formosa Cooreman and Lorryia sp.1; predators - Zetzellia quasagistemas Hernandes & Feres, Pronematus sp., Iphiseiodes zuluagai Denmark & Muma and Euseius citrifolius Denmark & Muma. Among the spontaneous euphorbiaceous, predatory mites were abundantly found on C. hirta and E. heterophylla, mainly Pronematus sp. and E. citrifolius, suggesting that these plants could be important in the maintenance of these predators in the rubber tree cultivation areas. However, plants that can shelter predators and at the same time exert strong competition (nutrients, water etc) to rubber trees, can not be recommended for pest management programs. Studies about competition between rubber trees and spontaneous plants need to be conducted for feasible efficient programs of environmental management, aiming at the control of pest mites of rubber tree.

Identification of excreted iron superoxide dismutase for the diagnosis of Phtytomonas.

An excreted iron superoxide dismutase (FeSODe) of pI 3.6 with a molecular weight of 28-30 kDa was detected in the in vitro culture of Phytomonas isolated from Euphorbia characias (SODeCHA) and from Lycopersicon esculentum (SODeTOM), in Grace's medium without serum. These FeSODe excreted into the medium had immunogenic capacity: the positivity of the anti-SODeCHA serum persisted to a dilution of 1/30,000, and for the anti-SODeTOM to 1/10,000 by Western blot. In addition, cross reaction was detected between the anti-SODe serum of Phytomonas isolated from E. characias against SODeTOM, and the anti-SODe serum from L. esculentum with SODeCHA. This characteristic offers the possibility of its use to diagnose plant trypanosomatids. The validation of the test was confirmed by experimental inoculation of tomato fruits with Phytomonas isolated from L. esculentum. At 7, 10, 15, and 21 days post infection, it was possible to detect the presence of the parasites with the anti-SODe serum of Phytomonas isolated from L. esculentum at a dilution of 1/250. These serological results were confirmed by visualization of the parasites by optical microscopy. The data of this study confirm that the SOD is sufficient to identify a trypanosomatid isolated from plants as belonging to the genus Phytomonas.

Identification of excreted iron superoxide dismutase for the diagnosis of Phtytomonas

An excreted iron superoxide dismutase (FeSODe) of pI 3.6 with a molecular weight of 28-30 kDa was detected in the in vitro culture of Phytomonas isolated from Euphorbia characias (SODeCHA) and from Lycopersicon esculentum (SODeTOM), in Grace's medium without serum. These FeSODe excreted into the medium had immunogenic capacity: the positivity of the anti-SODeCHA serum persisted to a dilution of 1/30,000, and for the anti-SODeTOM to 1/10,000 by Western blot. In addition, cross reaction was detected between the anti-SODe serum of Phytomonas isolated from E. characias against SODeTOM, and the anti-SODe serum from L. esculentum with SODeCHA. This characteristic offers the possibility of its use to diagnose plant trypanosomatids. The validation of the test was confirmed by experimental inoculation of tomato fruits with Phytomonas isolated from L. esculentum. At 7, 10, 15, and 21 days post infection, it was possible to detect the presence of the parasites with the anti-SODe serum of Phytomonas isolated from L. esculentum at a dilution of 1/250. These serological results were confirmed by visualization of the parasites by optical microscopy. The data of this study confirm that the SOD is sufficient to identify a trypanosomatid isolated from plants as belonging to the genus Phytomonas.

Cytotoxicity of three new triazolo-pyrimidine derivatives against the plant trypanosomatid: Phytomonas sp. isolated from Euphorbia characias.

There is no effective chemotherapy against diseases caused by Phytomonas sp., a plant trypanosomatid responsible for economic losses in major crops. We tested three triazolo-pyrimidine complexes [two with Pt(II), and another with Ru(III)] against promastigotes of Phytomonas sp. isolated from Euphorbia characias. The incorporation of radiolabelled precursors, ultrastructural alterations and changes in the pattern of metabolite excretion were examined. Different degrees of toxicity were found for each complex: the platinum compound showed an inhibition effect on nucleic acid synthesis, provoking alterations on the levels of mitochondria, nucleus and glycosomes. These results, together with others reported previously in our laboratory about the activity of pyrimidine derivatives, reflect the potential of these compounds as agents in the treatment of Phytomonas sp.