Joelma Melissa Malherbe Camargo

Seleção de isolados de Verticillium lecanii para o controle de Cinara atlantica

The aim of this study was to evaluate the pathogenicity of Verticillium lecanii isolates against Cinara atlantica, and the LC50 of the best strain. For selection tests, nymphs of C. atlantica were placed on individual pine seedling with 20 isolates and one control, in a total of 21 treatments and ten replicates. For the LC50 estimation it was used the CG 904 strain with six concentrations and ten replicates. VL 6, CG 902 and VL 2 produced the highest mortality, of 72.22%, 67.34% and 67.31%, respectively. The control plot showed mortality of 15.6%. The LC50 of the CG 904 strain indicated mortality of 100% at the concentration of 108 conidia mL-1; LC50, 2x105 conidia mL-1; and LT50, 4.4 days.

Resistência induzida ao pulgão-gigante-do-pinus (Hemiptera: Aphididae) em plantas de Pinus taeda adubadas com silício

INDUCED RESISTANCE EFFECT TO THE GIANT CONIFER APHID (HEMIPTERA:APHIDIDAE) IN SILICON FERTILIZED PLANTS OF PINUS TAEDA This research aimed to study the effect of silicon as a resistance inducer in P. taeda L. to C. atlantica (Wilson). Preference and reproductive rate tests were performed in plants of P. taeda with and without silicon application. The experiment was carried out in controlled environmental chamber (T: 20oC; UR: 70%; fotofase: 12h), in a completely random design, and consisted of three treatments and ten replications. The treatments were: T1- substratum standard (without silicon application), T2 – substratum standard + one dose of 0,01g de silicon, T3 – substratum standard + four doses of 0,01g de silicon, with intervals of five days between the applications. Twenty days after the application, a free choice preference test was performed in two different arenas: Petri dishes with pine branches and PVC cages with pine seedlings. Twenty adult aphids were released in each arena. Petri dishes were observed at 40 and 90 minutes, then 4, 12, 18, 24, 36 and 72 hours after release. Pine seedlings in PVC cages were examined in the first, second, third, fourth and seventh days, followed by a weekly record on the next three weeks. Silicon application showed a negative response to preference and reproductive capacity in adults of C. atlantica.

Efeito da aplicação do silício em plantas de Pinus taeda L., sobre a biologia e morfologia de Cinara atlantica (Wilson) (Hemiptera: Aphididae)

Objetivou-se avaliar o efeito da aplicacao de silicio em parâmetros biologicos e na morfometria de C. atlantica. O bioensaio foi conduzido em sala climatizada com temperatura de 20oC, 70% UR e fotofase de 12 horas, com delineamento experimental inteiramente casualizado. Femeas adultas obtidas apos a ultima ecdise ninfal foram transferidas para as unidades experimentais (gaiolas de PVC) e, entre o 4o e 5o dia reprodutivo, a femea foi retirada e dentre os descendentes produzidos nesse periodo, um foi escolhido aleatoriamente para a conducao do ensaio. Nos tratamentos com a aplicacao de diferentes doses do acido silicico, ocorreram prolongamento da fase ninfal e reducao na performance biologica, afetando assim o ciclo biologico do pulgao. Em relacao a capacidade reprodutiva do inseto, obtiveram-se, para os tratamentos com aplicacao do acido silicico, valores distintos da testemunha que apresentou numero elevado de ninfas/femea. Em relacao a morfometria, dentre os quinze caracteres avaliados, apenas a largura da cabeca e o comprimento total da antena de C. atlantica, que foram mantidos em plantas com aplicacao de silicio, diferiram estatisticamente da testemunha.

ABSORÇÃO E TRANSLOCAÇÃO DE SILÍCIO EM MUDAS DE Eucalyptus camaldulensis

The search for high productivity of Eucalyptus plants and seedlings with good nutritional and genetic quality, that are more resistant to the insect-pest attack are being more and more studied. On this context, this study was realized to understand the absorption and the translocation of silicon in Eucalyptus camaldulensis seedlings. The experiment was carried through in a nursery belonging to ‘Votorantim Siderurgia’ company, in Joao Pinheiro –MG state, where the application in substrate(calcium silicate) of the micronutrient was evaluated as well as its application on plant leaves (potassium silicate), at three different doses. The experimental design was entirely randomized, with eight treatments, 20 replicates, totalizing 160 plants. The evaluation of the experiment was carried through on the basis of the values of silicon present on the analysis of the dry matter of roots and aerial parts of plants (mg plant -1 ) and in substrate (%). Three evaluations had been carried through at 30, 60 and 90 days after application of the doses of silicon in leaves and roots and four evaluations for the substrate samples, being the first evaluation at the beginning of the experiment (before the silicon fertilization) and the others at 30, 60 and 90 days after the eucalyptus sowing. Considering the leaf analyses, greater silicon content was observed on the treatment with application of potassium silicate (10 ml/plant) T8, that was on average 3 times more when compared to treatments without silicon (standard fertilization + 110 grams of CaO) - T1 and without application of silicon (standard fertilization + 1.71 grams of KCl) -– T2. There were no differences among treatments in relation to silicon content in the E. camaldulensis roots. In the substrate samples, a significant increase in the micronutrient content was observed at 30, 60 and 90 days, due to the increasing doses of silicate, in the two forms of application, especially on T8. Thus, it was possible to conclude that E. camaldulensis is able to absorb and to translocate the micronutrient.