Uemerson Silva da Cunha

Effects of azadirachtin on Tetranychus urticae (Acari: Tetranychidae) and its compatibility with predatory mites (Acari: Phytoseiidae) on strawberry

BACKGROUND The spider mite, Tetranychus urticae, is the major strawberry pest in Brazil. The main strategies for its control comprise synthetic acaricides and predatory mites. The recent register of a commercial formula of azadirachtin (Azamax(®) 12 g L(-1) ) can be viable for control of T. urticae. In this work, the effects of azadirachtin on T. urticae and its compatibility with predatory mites Neoseiulus californicus and Phytoseiulus macropilis in the strawberry crop were evaluated. RESULTS Azadirachtin was efficient against T. urticae, with a mortality rate similar to that of abamectin. In addition, the azadirachtin showed lower biological persistence (7 days) than abamectin (21 days). Azadirachtin did not cause significant mortality of adult predatory mites (N. californicus and P. macropilis), but it did reduce fecundity by 50%. However, egg viability of the azadirachtin treatments was similar to that of the control (>80% viability). The use of azadirachtin and predatory mites is a valuable tool for controlling T. urticae in strawberry crop. CONCLUSIONS Azadirachtin provided effective control of T. urticae and is compatible with the predatory mites N. californicus and P. macropilis. It is an excellent tool to be incorporated into integrated pest management for strawberry crop in Brazil.

Frações de Trichilia pallens com atividade inseticida sobre Tuta absoluta

This work aimed at identifying fractions of aqueous and organic extracts of the meliaceous Trichilia pallens with insecticidal activity against the tomato leafminer Tuta absoluta (Meyrick). Leaf and twig freeze-dried aqueous extracts (FDA) of T. pallens were resuspended in water at a concentration of 3% and sprayed over tomato leaflets, which were infested with newly-hatched larvae. Larval mortality at 5 and 10 days after infestation (dai) were higher for leaf extracts. In a second set of experiments, 1% leaf extracts were produced by maceration in hexane (HEX), dichloromethane (DIC) and methanol (MET), and tested as described before, using acetone and water as controls. DIC extracts were the most promising as a source of substances with insecticidal activity against T. absoluta larvae, and were further processed and subjected to partition assays, producing fractions in HEX, MET, ethyl acetate (ETA), n-butanol (NBU) and water (WA). After testing, 0.1% WA fraction, obtained from the partition assay of DIC extracts showed the highest insecticidal activity against T. absoluta.

Bioatividade de moléculas isoladas de Trichilia pallida Swartz (Meliaceae) sobre Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae)

Dichloromethane (DIC) leaf and fruit extracts of Trichiliapallida Swartz were obtained for the isolation and identification of molecules with insecticidal activity against the tomato leafminer, Tuta absoluta (Meyrick). DIC leaf extracts of T. pallida yielded six compounds, the triterpenes 24-methylenecycloarta-3beta-ol (TRIT-1), 24-methylenecycloarta-3beta-26-diol (TRIT-2) and cycloarta-23-eno-3beta,25-diol (TRIT-3), the sterols 24-methylene-3,22-dihydroxycholesterol (EST-1), 24-methylenecholesterol (EST-2) and 24-methylene-3beta,4beta,22-trihydroxycholesterol (EST-3), while the fruit extract yielded the limonoid gedunine (LIM). These molecules were dissolved in acetone and sprayed at 0.1% on tomato leaflets infested with newly-hatched larvae. Larval mortality at day 5 and 9 after infestation, larval and pupal developmental time and survival, pupal weight and adult malformation were evaluated. TRIT-1, EST-1 and LIM were the most effective against T. absoluta due to larval development arrestment and reduced larval survivorship.

Efeitos do nim sobre tetranychus urticae Koch (Acari: Tetranychidae) e os predadores Phytoseiulus macropilis (Banks) e Neoseiulus californicus (Mcgregor) (Acari: Phytoseiidae)

The aim of the present study was to evaluate the efficiency of control and adverse effects of two neem based products: Azamax TM (Azadirachtin A/B 12g/L) and Neemseto TM (Azadirachtin A/B, Nimbin and Salanin 2,389 g/L) over two-spotted spider mite Tetranychus urticae and the predators Phytoseiulus macropilis and Neoseiulus californicus in laboratory. Effects over the mortality, fecundity, eggs and biological persistence of the two-spotted spider mite when treated with neem based products were evaluated. For the phytoseiids the effects on mortality and fecundity were evaluated. The maximum mortality of two-spotted spider mites rates observed were 89.7% and 91.5% for Azamax TM and Neemseto TM respectively, on the 0.5% concentration after reapplying the product on the seventh day. Adverse effects were also observed over the fecundity and viability of the eggs when treated with commercial products (c.p.). The biological persistence of the products was of approximately three days after being pulverized. The formulations present selectivity in relation to the phytoseiids, however they caused fecundity reduction.

Resistência de genótipos de milho para cultivo em várzeas subtropicais à lagarta-do-cartucho Spodoptera frugiperda

Spodoptera frugiperda e uma das pragas com elevado potencial para causar perdas economicas na cultura do milho, no ecossistema de varzeas subtropicais. Com o objetivo de identificar fontes de resistencia, foi avaliado, em laboratorio, o desenvolvimento de S. frugiperda em nove genotipos de milho. Cem lagartas recem-eclodidas foram individualizadas em tubos de vidro, contendo porcoes de folhas de milho, mantidos a temperatura de 25±1°C, umidade relativa de 70±10% e fotofase de 14h. Avaliaram-se a duracao e a viabilidade das fases de larva e pupa, o peso de larvas e de pupas e a mortalidade larval. Dentre os genotipos avaliados, destacaram-se o BRS Missoes-B e o BR 111 VI Sel. Dent C, os quais afetaram, respectivamente, o desenvolvimento da fase de larva e de pupa.

Life cycle of Tydeus californicus (Acari: Tydeidae) on leaves of Inga marginata with and without pollen of Typha angustifolia under laboratory conditions

Knowledge of the behaviour and feeding habits of tydeid mites is fragmentary. To address this lack of knowledge, the biology of Tydeus californicus (Banks) was studied on Inga marginata L. (Fabaceae) leaves with and without pollen of Typha angustifolia L. (Typhaceae) under laboratory conditions. The study started with 32 larvae isolated in experimental units, with 16 having access to pollen and 16 on I. marginata leaves without pollen. The experimental units were maintained at 25 ± 1ºC and 75 ± 5% relative humidity with a 12-h photophase. Immature stages were evaluated three times a day and the subsequent adult stage once a day. The data showed that when Tyd. californicus did not have access to pollen they did not reach adulthood. Additionally, we report thelytoky and larviparity in this mite.

Ocorrência de Euetheola humilis (Burmeister) (Coleoptera: Scarabaeidae) em Eucalyptus saligna Smith (Myrtaceae), no Rio Grande do Sul

Euetheola humilis (Burmeister) is a scarabaeid pest of rice, sugarcane and corn cultures, that attacks the crops during both larval and adult phase. The occurrence of E. humilis was observed in a forest area with Eucalyptus saligna Smith, from Votorantim Celulose & Papel (Fazenda Aroeira), in the Municipality of Candiota, Rio Grande do Sul State. Plants approximately 1m high were damaged by E. humilis adult insects near the stem base, what unraveled its cortex and led some of them to death. The attack was verified in about 10% of the eucalypts plants, in an area of approximately 30 ha.

Ocorrência do ácaro Pyemotes sp. (Acari: Pyemotidae) em criações de insetos em laboratório

Pyemotidae mites have been reported as ectoparasites of a large number of arthropods, especially of insects. These mites are frequently found attacking insects in different habitats, including insect rearing. This paper reports the occurrence of Pyemotes sp., ventricosus group, in colonies of Tuta absoluta (Meyerick) (Lepidoptera: Gelechiidae), Anagasta kuehniella (Zeller) (Lepidoptera: Pyralidae) and Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae), in the insect rearing laboratory of ESALQ-USP, in Piracicaba, State of Sao Paulo, provoking dematitis in those involved with the rearing. This is the first report of a Pyemotes species parasitizing T. absoluta and S. zeamais. Considering the capacity of Pyemotes to cause dermatitis in human beings, demonstrated by other authors, the direct use of the Pyemotes species found in this work for the control of the reported insect species may not be promising.

Associação entre teor de nitrogênio em cultivares de arroz e ataque de Oryzophagus oryzae (Costa Lima) (Coleoptera: Curculionidae)

The rice water weevil Oryzophagus oryzae (Costa Lima) (Coleoptera: Curculionidae) is one of the most important pests in irrigated rice culture due to the damage caused by the larvae in the roots. The association between the nitrogen content and the O. oryzae damage was evaluated on BR IRGA 410, BRS Firmeza, Dawn and BRS Atalanta cultivars differentiated by the phenological development cycle and the insect resistance degree. The experiments were conducted under field conditions, with and without chance of host plant choice, at Embrapa Clima Temperado, Pelotas, RS. The following parameters were evaluated: number of damaged leaves, number and weight of larvae. The nitrogen content in the leaves and roots were evaluated at three different rice growth stages. The adult feeding of O. oryzae were stimulated by the content of nitrogen in the foliage of the plant. The cultivar Dawn was the only one to revover the nitrogen content, due to the presence of the smallest number of larvae and the largest development cycle in compare to other cultivars. The root damage caused by O. oryzae larvae decreased the nitrogen content, and consequently reduced the rice yield.

Efficiency of neem insecticides in the control of Grapholita molesta (Busck, 1916) (Lepidoptera: Tortricidae)

The objective was to evaluate the efficiency of neem insecticides in the control of oriental fruit moth Grapholita molesta at laboratory. The artificial diet was cut in cubes and immersed in the syrups of the respective treatments, soon afterwards, recently-emerged caterpillars were transferred, for glass tubes, containing the diet cubes treated. The tested products were: NeemAzal-T/S®, Dalneem emulsionavel®, Organic Neem® and Natuneem Agricola® in the concentration of 0.5% of the commercial product (p.c.) compared with the chemical insecticide fenitrotion (Sumithion 500 CE®) to 0.15% p.c. and a witness (water). The insecticides NeemAzal-T/S® and Dalneem emulsionavel® presented a mortality of 100% of the caterpillars being efficient in the control of the insect in laboratory conditions. Organic Neem® and Natuneem Agricola® demonstrated lower insecticidal activity, causing mortality of 73.5% and 22.5% respectively, however, significantly affect the larval viability.