Comparative demography of the exotic Harmonia axyridis with other aphidophagous coccinellids reared on artificial diet

The objective of this work was to compare biological aspects and life table parameters of the coccinellids Harmonia axyridis, Cycloneda sanguineaand Hippodamia convergens. Insects were fed eggs of Anagasta kuehniella, and reared at 24.5±1ºC, 70±10% relative humidity, with a 12 hour photophase. Hippodamia convergenstook about 1.6 day to complete development, longer than H. axyridis, and 2.4 day longer than C. sanguinea.At immature stages, H. axyridisexhibited the highest survival percentage (49.2%), in comparison to the other coccinellids. For mean adult longevity, H. convergenswas deficient, in comparison with the other species. Mean period of pre oviposition was the longest in C. sanguinea; the longest oviposition time occurred for H. axyridis; and the post oviposition period was similar between the coccinellids. Considering the reproductive parameters, H. axyridisshowed the best performance in all aspects. For life table, the values of H. convergenswere higher than, although close, to those of H. axyridis. Nevertheless, the high net reproductive rate of H. axyridis showed this species potential to increase population size. The biological characteristics of the exotic H. axyridis favors its invasion and establishment in Brazil, corroborating results noticed in other countries.

The avocado fruit borer, Stenoma catenifer (wals.) (Lepidoptera: elachistidae): egg and damage distribution and parasitism

The avocado fruit borer, Stenoma catenifer (Wals.) has been a limiting factor in growing avocados over the last years in many Brazilian states. This is a result of the lack of safe and feasible management practices to minimize the fruit borer damage. The aim of this study was to obtain information on the pest biology and ecology as well as on the role of natural enemies to define strategies to control the pest. Samples were taken biweekly and consisted of 20 fruits collected randomly (10 from the upper half and 10 from the lower half of the plant) in ten plants, cv. Margarida, in a commercial avocado grove in Arapongas and Cambé regions, PR, from October/2001 to September/2002. Laboratory determinations of the percentage of damaged fruit per plant region, location and number of bored fruit sites, and the number and location of the fruit borer eggs, including parasitized ones, were performed. The results showed that S. catenifer preferred to oviposit and attack fruits located on the upper half of the trees. The majority of the eggs were laid on the fruit pedicel whereas the damage was mainly located on the lower half of the fruits. Trichogrammatids were the most constant and abundant parasitoids found in both localities throughout the study period.

Parasitism on Eriosoma lanigerum (Homoptera: Aphididae) by Aphelinus mali (Hymenoptera: Encyrtidae) on apple orchards, in Fraiburgo county, state of Santa Catarina, Brazil

The parasitism of the woolly apple aphid (Eriosoma lanigerum Hausmann) by Aphelinus mali (Hald.) was evaluated in apple orchards cultivated with the varieties Gala and Fuji in Fraiburgo County, State of Santa Catarina, Southern Brazil. Colonies of the woolly apple aphid were evaluated during one year on 16 apple trees of each variety, starting in August 1999. The number of aphids at the mummy stage or presenting the orifice of the parasitoid emergence was recorded. Results have shown that A. mali parasitized more than 50% of the woolly apple aphids and occurred during the four seasons. It was concluded that that under these conditions no chemical control against the aphid is necessary for the apple varieties Gala and Fuji.

Seletividade de agrotóxicos utilizados em pomares de pêssego a adultos do predador Chrysoperla externa (Hagen, 1861) (Neuroptera: Chrysopidae)

A seletividade de dezesseis agrotóxicos utilizados na produção integrada e convencional de pêssego foi avaliada sobre a fase adulta de Chrysoperla externa através de bioensaios de exposição residual conduzidos em laboratório (temperatura de 25±1ºC, umidade relativa 70±10% e fotofase 14 horas), utilizando-se de metodologia prescrita pela "International Organization for Biological Control" (IOBC). Os agrotóxicos (% de ingrediente ativo na calda) azoxystrobina (0,016), captana (0,192), dodina (0,126), folpete (0,200), mancozebe (0,256), mancozebe + oxicloreto de cobre (0,140 + 0,096), tebuconazole (0,320), abamectina (0,002), óleo mineral 1 (2,420), óleo mineral 2 (1,920), dicloreto de paraquate (0,300) e glifosato (1,440) foram inócuos; deltametrina (0,002) foi levemente nocivo e dimetoato (0,160), fosmete (0,160) e malationa (0,240) foram nocivos a adultos de C. externa.

Mites fluctuation population on peach tree (Prunus persica (L.) Batsch) and in associated plants

Despite the importance of peach (Prunus persica (L.) Batsch) in Rio Grande do Sul, little is known about mites fluctuation population considered important to this crop. The objective of this study was to know the population diversity and fluctuation of mite species associated with Premier and Eldorado varieties in Roca Sales and Venâncio Aires counties, Rio Grande do Sul. The study was conducted from July 2008 to June 2009 when 15 plants were randomly chosen in each area. The plants were divided in quadrants and from each one a branch was chosen from which three leaves were removed: one collected in the apical region, another in the medium and the other in the basal region, totalizing 180 leaves/area. Five of the most abundant associated plants were collected monthly in enough amounts for the screening under the stereoscopic microscope during an hour. A total of 1,124 mites were found belonging to 14 families and 28 species. Tetranychus ludeni Zacher, 1913, Panonychus ulmi (Koch, 1836) and Mononychellus planki (McGregor, 1950) were the most abundant phytophagous mites, whereas Typhlodromalus aripo Deleon, 1967 and Phytoseiulus macropilis (Banks, 1904) the most common predatory mites. The period of one hour under stereoscopic microscope was enough to get a representative sample. In both places evaluated the ecologic indices were low, but little higherin Premier (H' 0.56; EqJ: 0.43) when compared to Eldorado (H' 0.53; EqJ 0.40). In Premier constant species were not observed and accessory only Brevipalpus phoenicis (Geijskes, 1939), T. ludeni and T. aripo. Higher abundance was observed in December and January and bigger amount in April. Already in Eldorado, T. ludeni and P. ulmi were constants. Greater abundance was observed in November and December, whereas grater richness in December and January. In both orchards were not found mites in buds. Tetranychus ludeni is the most abundant phytophagous mites with outbreak population in November, December and January and high predator diversity was observed on associated plants and on peach plants, indicating the existence of species mobility in peach orchard.

Estudo termogravimétrico e calorimétrico da algaroba

Humidity and ash content of powder and bran of algaroba pods are important quality parameters for biological control during storage. The studies of humidity and ash content were carried out conventional and thermogravimetric methods. Different values were obtained by the various methods. The thermogravimetric method was faster and required less sample for the humidity and ash analyses of the powder and bran of algaroba pods. The differential scanning calorimetry curves of the powder and bran of algaroba pods, dryed at 55 ºC, showed two peaks, one corresponding to the gelatinization of starch and the other to the vaporization of water. The samples dryed at 65, 75, 85, 95 and 105 ºC showed one peak, corresponding to the vaporization of water.

Molecular characterization of Brazilian Dicyma pulvinata isolates

Forty-nine Brazilian Dicyma pulvinata isolates were examined by morphological traits and RFLP, RAPD and AFLP analyses. This fungus is a mycoparasite of Microcyclus ulei, the causal agent of the most devastating rubber (Hevea brasiliensis) disease, known as "South American Leaf Blight" (SALB). These isolates were compared with an Indian isolate from Cercosporidium sp., and a French isolate from Cladosporium fulvum. They were also compared with Dicyma ampullifera from Papua New Guinea. The morphological parameters analyzed confirmed the identification of the Brazilian isolates. The graphic representations of the distance matrices of each molecular marker showed similar results. Dicyma pulvinata isolates from M. ulei were closely related, whereas the reference isolates examined were dispersed. Among the D. pulvinata isolates obtained from M. ulei, a significant pairwise distance was obtained, for all the molecular markers, between the isolates from the areas favorable to the occurrence of SALB (North and Northeast of Brazil) and the region of escape for the disease (Mato Grosso State).

Efficiency of phylloplane bacteria in controlling aerial tomato diseases under field conditions

The capacity of two bacteria isolated from the tomato phylloplane to control late blight (Phytophthora infestans) was investigated in the field, and compared against the effectiveness of spraying with the fungicide chlorothalonil (1.5 g a.i. L-1) or water (control). A 55% reduction in late blight intensity was observed in the leaves of the middle of the plant and 62% in those of the upper leaves when using the antagonist UFV-STB 6 (Novosphingobium capsulatum) as compared to the control. Isolate UFV-IEA 6 (Bacillus cereus) was able to reduce disease intensity by 55%, but only in the upper leaves of the tomato plants. Treatment with isolate UFV-STB 6 also led to a significant reduction in the percentage of fruits with late blight symptoms. The results demonstrate the potential of these two bacteria in controlling this disease.

Trichoderma spp. decrease Fusarium root rot in common bean

The effectiveness of six Trichoderma-based commercial products (TCP) in controlling Fusarium root rot (FRR) in common bean was assessed under field conditions. Three TCP, used for seed treatment or applied in the furrow, increased seedling emergence as much as the fungicide fludioxonil. FRR incidence was not affected, but all TCP and fludioxonil reduced the disease severity, compared to control. Application of Trichoderma-based products was as effective as that of fludioxonil in FRR management.

Limitations in controlling white mold on common beans with Trichoderma spp. at the fall-winter season

We studied the effectiveness of application of Trichoderma spp. in controlling white mold on common beans at the fall-winter crop in the Zona da Mata region of the State of Minas Gerais, Brazil. There was no effect of the antagonist in reducing the disease severity, which could be explained by the low temperatures and the high inoculum pressure in the field. We concluded that Trichoderma applications are not recommended for control of white mold on common beans at the fall-winter season in regions with average temperature bellow 20 °C, since this condition favor more the pathogen than the antagonist.

Efficiency of a yeast-based formulation for the biocontrol of postharvest anthracnose of papayas

To identify formulations of biological agents that enable survival, stability and a good surface distribution of the antagonistic agent, studies that test different application vehicles are necessary. The efficiency of two killer yeasts, Wickerhamomyces anomalus (strain 422) and Meyerozyma guilliermondii (strain 443), associated with five different application vehicles, was assessed for the protection of postharvest papayas. In this study, after 90 days of incubation at 4ºC, W. anomalus (strain 422) and M. guilliermondii (strain 443) were viable with all application vehicles tested. Fruits treated with different formulations (yeasts + application vehicles) had a decreased severity of disease (by at least 30%) compared with untreated fruits. The treatment with W. anomalus (strain 422) + 2% starch lowered disease occurrence by 48.3%. The most efficient treatments using M. guilliermondii (strain 443) were those with 2% gelatin or 2% liquid carnauba wax, both of which reduced anthracnose by 50% in postharvest papayas. Electron micrographs of the surface tissues of the treated fruits showed that all application vehicles provided excellent adhesion of the yeast to the surface. Formulations based on starch (2%), gelatin (2%) and carnauba wax (2%) were the most efficient at controlling fungal diseases in postharvest papayas.

Antimicrobial activity of extracellular metabolites from antagonistic bacteria isolated from potato (Solanum phureja) crops

Microorganisms for biological control are capable of producing active compounds that inhibit the development of phytopathogens, constituting a promising tool toob tain active principles that could replace synthetic pesticides. This study evaluatedtheability of severalpotentialbiocontrol microorganismsto produce active extracellular metabolites. In vitro antagonistic capability of 50 bacterial isolates from rhizospheric soils of "criolla" potato (Solanum phureja) was tested through dual culture in this plant with different plant pathogenic fungi and bacteria. Isolates that showed significantly higher antagonistic activity were fermented in liquid media and crude extracts from the supernatants had their biological activities assessed by optical density techniques. Inhibitory effecton tested pathogens was observed for concentrations between 0.5% and 1% of crude extracts. There was a correlation between the antimicrobial activity of extracts and the use of nutrient-rich media in bacteria fermentation. Using a bioguided method, a peptidic compound, active against Fusarium oxysporum, was obtained from the 7ANT04 strain (Pyrobaculum sp.). Analysis by nuclear magnetic resonance and liquid chromatography coupled to mass detector evidenced an 11-amino acid compound. Bioinformatic software using raw mass data confirmed the presence of a cyclic peptide conformed by 11 mostly non-standard amino acids.

Key factors to inoculate Botrytis cinerea in tomato plants

Studies addressing the biological control of Botrytis cinerea have been unsuccessful because of fails in inoculating tomato plants with the pathogen. With the aim of establishing a methodology for inoculation into stems, experiments were designed to assess: i. the aggressiveness of pathogen isolates; ii. the age at which tomato plants should be inoculated; iii. the susceptibility of tissues at different stem heights; iv. the need for a moist chamber after inoculation; and v. the effectiveness of gelatin regarding inoculum adhesion. Infection with an isolate from tomato plants that was previously inoculated into petioles and then re-isolated was successful. An isolate from strawberry plants was also aggressive, although less than that from tomato plants. Tomato plants close to flowering, at 65 days after sowing, and younger, middle and apical stem portions were more susceptible. There was positive correlation between lesion length and sporulation and between lesion length and broken stems. Lesion length and the percentage of sporulation sites were reduced by using a moist chamber and were not affected by adding gelatin to the inoculum suspension. This methodology has been adopted in studies of B. cinerea in tomato plants showing reproducible results. The obtained results may assist researchers who study the gray mold.

Atividade antagônica a microrganismos patogênicos por bactérias endofíticas isoladas de Echinodorus scaber Rataj

Os objetivos desse trabalho foram identificar e avaliar o potencial antagônico in vitro de bactérias endofíticas isoladas de Echinodorus scaber (chapéu de couro) sobre alguns patógenos e verificar sua capacidade de controlar o desenvolvimento de fungos em grãos de soja. Um total de 113 linhagens foi confrontado com cinco fungos patogênicos (método de cultura dupla), e quatro bactérias patogênicas (método de sobrecamada). O controle de crescimento de fungo em grãos de soja foi realizado por microbiolização e avaliado pelo método de papel de filtro. As bactérias antagonistas foram submetidas a teste de antibiose contra quatro bactérias patógenas. Duas linhagens inibiram os fungos Colletotrichum lindemunthianum, C. gloeosporioides, Corynespora cassiicula, Fusarium solani, Microsporum canis. No teste de antibiose contra as bactérias patogênicas somente (BREIII-107) apresentou atividade antagônica. As duas linhagens e foram identificadas como Bacillus sp (BREI-92) e Bacillus subitilis (BREIII-107). Quando inoculadas em grãos de soja, Bacillus sp (BREI-92) e Bacillus subitilis (BREIII-107) inibiram aproximadamente 100% do desenvolvimento de fungos sobre os grãos.

Biocontrol of Sclerotinia sclerotiorum and white mold of soybean using saprobic fungi from semi-arid areas of Northeastern Brazil

ABSTRACTThe incidence and the levels of yield loss caused by the white mold of soybean (caused by the fungus Sclerotinia sclerotiorum) have increased in areas of higher altitude at Cerrado and Southern Brazil, causing yield losses of up to 60%. The aim of this study was to select saprobic fungi with the potential to control the white mold of soybean. First, in vitroantagonism screening was carried out to test eight saprobic fungi against S. sclerotiorum. Assessment of S. sclerotiorum mycelial growth was done at four and seven days after its placement on the culture medium. The isolate showing greatest antagonistic effect in all tests/assessments was Myrothecium sp. An in vivo experiment was conducted in a greenhouse and growth chamber, where plants previously treated with eight saprobic fungi were artificially inoculated with S. sclerotiorum. The fungal culture medium (potato-dextrose) and the commercial resistance inducer acibenzolar-S-methyl were used as controls. In the in vivotests, severity of the white mold was assessed at 8, 14 and 21 days after inoculation. The highest reduction percentage in the lesion length was observed for the treatment with Myrothecium sp. (70%), which has the greater potential to be used as biocontrol agent of soybean under the conditions of this experiment.