Colonization of Onions by Endophytic Fungi and Their Impacts on the Biology of Thrips tabaci

Endophytic fungi, which live within host plant tissues without causing any visible symptom of infection, are important mutualists that mediate plant-herbivore interactions. Thrips tabaci (Lindeman) is one of the key pests of onion, Allium cepa L., an economically important agricultural crop cultivated worldwide. However, information on endophyte colonization of onions, and their impacts on the biology of thrips feeding on them, is lacking. We tested the colonization of onion plants by selected fungal endophyte isolates using two inoculation methods. The effects of inoculated endophytes on T. tabaci infesting onion were also examined. Seven fungal endophytes used in our study were able to colonize onion plants either by the seed or seedling inoculation methods. Seed inoculation resulted in 1.47 times higher mean percentage post-inoculation recovery of all the endophytes tested as compared to seedling inoculation. Fewer thrips were observed on plants inoculated with Clonostachys rosea ICIPE 707, Trichoderma asperellum M2RT4, Trichoderma atroviride ICIPE 710, Trichoderma harzianum 709, Hypocrea lixii F3ST1 and Fusarium sp. ICIPE 712 isolates as compared to those inoculated with Fusarium sp. ICIPE 717 and the control treatments. Onion plants colonized by C. rosea ICIPE 707, T. asperellum M2RT4, T. atroviride ICIPE 710 and H. lixii F3ST1 had significantly lower feeding punctures as compared to the other treatments. Among the isolates tested, the lowest numbers of eggs were laid by T. tabaci on H. lixii F3ST1 and C. rosea ICIPE 707 inoculated plants. These results extend the knowledge on colonization of onions by fungal endophytes and their effects on Thrips tabaci.

Thrips incidence in green beans and the degree of damage caused

Green bean production accounts for 2.4% of the total value of Australian vegetable production and was Australia's tenth largest vegetable crop in 2008-2009 by value. Australian green bean production is concentrated in Queensland (51%) and Tasmania (34%) where lost productivity as a direct result of insect damage is recognised as a key threat to the industry (AUSVEG, 2011). Green beans attract a wide range of insect pests, with thrips causing the most damage to the harvestable product, the pod. Thrips populations were monitored in green bean crops in the Gatton Research Facility, Lockyer Valley, South-east Queensland, Australia from 2002-2011. Field trials were conducted to identify the thrips species present, to record fluctuation in abundance during the season and assess pod damage as a direct result of thrips. Thirteen species of thrips were recorded during this time on bean plantings, with six dominant species being collected during most of the growing season: Frankliniella occidentalis, F. schultzei, Megalurothrips usitatus, Pseudanaphothrips achaetus, Thrips imaginis and T. tabaci. Thrips numbers ranged from less than one thrips per flower to as high as 5.39 thrips per flower. The highest incidence of thrips presence found in October/November 2008, resulted in 10.74% unmarketable pods due to thrips damage, while the lowest number of thrips recorded in April 2008 caused a productivity loss of 36.65% of pods as a result of thrips damage.

Optimizing Western Flower Thrips Management on French Beans by Combined Use of Beneficials and Imidacloprid

Western flower thrips (WFT), Frankliniella occidentalis (Pergande), is an important pest of vegetable crops worldwide and has developed resistance to many insecticides. The predatory mites Neoseiulus (=Amblyseius) cucumeris (Oudemans), the entomopathogenic fungus Metarhizium anisopliae (Metsch.), and an insecticide (imidacloprid) were tested for their efficacy to reduce WFT population density and damage to French bean (Phaseolus vulgaris L.) pods under field conditions in two planting periods. Metarhizium anisopliae was applied as a foliar spray weekly at a rate of one litre spray volume per plot while imidacloprid was applied as a soil drench every two weeks at a rate of two litres of a mixture of water and imidacloprid per m(2). Neoseiulus cucumeris was released every two weeks on plant foliage at a rate of three mites per plant. Single and combined treatment applications reduced WFT population density by at least three times and WFT damage to French bean pods by at least 1.7 times compared with untreated plots. The benefit-cost ratios in management of WFT were profitable with highest returns realized on imidacloprid treated plots. The results indicate that M. anisopliae, N. cucumeris, and imidacloprid have the potential for use in developing an integrated pest management program against WFT on French beans.

A presença de Pezothrips kellyanus (Bagnall) (Thysanoptera: Thripidae) e outros tripes em parcelas de limoeiro na região de Mafra

Mestrado em Engenharia Agronómica - Instituto Superior de Agronomia - UL

Geographical patterns of the species richness of helminth parasites of moles (Talpa spp.) in Spain: Separating the effects of sampling effort from those of other conditioning factors

We analysed the viscera of 534 moles (Ta l p a spp.) from 30 of the 47 provinces of peninsular Spain, including 255 individuals of T. europaea from eight provinces, 154 individuals of T. occidentalis from 20 provinces, and 125 unidentified Ta l p a individuals from two provinces. We identified their helminth parasites and determined parasite species richness. We related parasite species richness with sampling effort using both a linear and a logarithmic function. We then performed stepwise linear regressions to predict mole parasite species richness from a small set of selected predictor variables that included sampling effort. We applied the resulting models to forecast T. euro p a e a, T. occidentalis, and Ta l p a spp. parasite species richness in all provinces with recorded host presence, assuming different levels of sampling eff o r t . F i n a l l y, we used partial regression analysis to partition the variation explained by each of the selected variables in the models. We found that mole parasite species richness is strongly conditioned by sampling effort, but that other factors such as cropland area and environmental disturbance have significant independent effects.

Potencial alelopático e identificação de compostos secundários em extratos de calopogônio (Calopogonium mucunoides) utilizando eletroforese capilar.

Neste trabalho avaliou-se o potencial alelopático de extratos orgânicos obtidos a partir das folhas de Calopogonium mucunoides sobre a germinação de sementes de algumas plantas daninhas comumente encontradas em áreas de pastagens cultivadas da Amazônia brasileira, as quais causam grandes danos à produtividade: Cassia tora (mata-pasto), Mimosa pudica (malícia) e Cassia occidentalis (fedegoso). Compostos secundários foram identificados e quantificados nos extratos brutos utilizando eletroforese capilar. Após identificar e quantificar os compostos presentes nos extratos realizaram-se novos bioensaios com os padrões dos compostos identificados a fim de verificar se os mesmos poderiam atuar como inibidores na germinação das sementes das plantas daninhas em estudo. Calopogonium mucunoides apresentou potencial alelopático o qual variou com a espécie de planta daninha estudada. Os protocolos desenvolvidos utilizando eletroforese capilar se mostraram eficientes e bastante específicos, sendo possível a separação e identificação de 5 classes de compostos nos extratos brutos sem necessidade de "clean up" ou fracionamento dos mesmos, com análises rápidas (em menos de 20 minutos) e baixas quantidades de solventes utilizadas quando comparadas aos métodos tradicionais de análises. Vários dos compostos identificados apresentaram potencial de inibição de germinação nas sementes estudadas, sendo malícia a mais sensível, os bioensaios também indicaram certo efeito sinérgico ao utilizar a mistura de compostos.