E. T. Iede

Densidade e tamanho de formigueiros de Acromyrmex crassispinus em plantios de Pinus taeda

The objective of this work was to evaluate the density and size of Acromyrmex crassispinus nests in Pinus taeda plantations along the year. The experiments were carried out in Rio Negrinho and Tres Barras, SC, Brazil, in P. taeda plantations of different ages (recently planted and three and six years old). Three plots of one hectare were delimited in each treatment. The nests were classified according to three size classes: class I, up to 30 cm diameter; class II, 31 up to 60 cm; class III, above 61 cm. The density of A. crassispinus nests was low in recently planted areas, nearly twofold in three year-old plantations, and it reduced when the forest was six years old. The greatest nest density occurred in the period from December to April. The nests size increased along with the age of the P. taeda plantations.

The Woodwasp Sirex noctilio in Brazil: Monitoring and Control

Until 1988, a small number of outbreaks of native pests had been recorded in the 1.84 million ha of pine plantations in Brazil. Most of these stands were planted with little species diversity, and at high density and received inadequate management. In 1988, an outbreak of Sirex noctilio was first recorded in southern Brazil and the insect currently infests 450,000 ha in the southern and southeast regions. The presence of Sirex has the potential to cause losses of up to

Ocorrência e flutuação populacional de Chrysopidae (Neuroptera) em áreas de plantio de Pinus taeda (L.) (Pinaceae) no sul do Paraná

US30 million annually. The discovery of this insect resulted in an immediate change in silvicultural practices used in forest plantations, with the introduction of Integrated Pest Management (IPM) as a part of the Forest Management Programs. In 1989, the National Programme of Woodwasp Control (PNCVM) was established. This programme has a broad scope and includes the early detection and monitoring of the spread of Sirex through the use of trap trees (trees artificially stressed with herbicides) and ground inspections. Appropriate silvicultural practices, especially stand thinning, preventing competition and providing healthy growing conditions are also an important aspect of control programs. Curative measures used are based on biological control using the nematode parasite Deladenus (=Beddingia) siricidicola, introduced from Australia, which sterilizes the females and reaches up to 100% parasitism. The egg parasitoid Ibalia leucospoides has also been introduced and can reach about 25% parasitism. Two other parasites, Rhyssa persuasoria and Megarhyssa nortoni were introduced into Brazil between 1996 and 1998, and in 2003, from Australia. Establishment of these two parasites has not been confirmed. This combination of biological control and appropriate silvicultural practices are essential to keep the Sirex population under control in Brazil.

Ocorrência e recomendações para o manejo de Sirex noctilio Fabricius (Hymenoptera, Siricidae) em plantios de Pinus patula (Pinaceae) em Minas Gerais, Brasil

The lacewings are very voracious predators of aphids. The objective of this research was to evaluate the occurrence of adult chrysopids in areas of Pinus reforestation where the giant conifer aphid Cinara spp. (Hemiptera: Aphididae) is causing severe damages. A total of 47 specimens were collected during one year and identified as: Chrysoperla externa (Hagen, 1861), Leucochrysa (Nodita) intermedia (Scheneir, 1851) and Leucochrysa (Nodita) vieirana (Navas, 1913). The captures in the area where the plants were one year old represented about 75% of the adults probably due to the high Cinara infestation on the trees in this area. The chrysopids were recorded mostly during the summer, possibly influenced by temperature.

Leaf-cutting ant attack in initial pine plantations and growth of defoliated plants

The woodwasp Sirex noctilio Fabricius, 1793 (Hymenoptera, Siricidae) is the most important pest on Pinus spp. in Brazil. It was introduced in the state of Rio Grande do Sul in 1988 and dispersed through the southern states. In 2004 it was detected in Sao Paulo state. In this work, it is reported the occurrence of S. noctilio in the state of Minas Gerais, in January 2005, on commercial areas of Pinus patula. It is discussed some measures that can be adopted to restrict its spread in the southeastern region.

Genetic structure of populations of Pissodes castaneus (De Geer) (Coleoptera, Curculionidae) using amplified fragment length polymorphism

The objective of this work was to evaluate the natural attack by Acromyrmex crassispinus in initial Pinus taeda plantations without control measures against ants, as well as the effect of defoliation in seedlings of P. taeda. Evaluations of the attack of leaf-cutting ants on P. taeda plantations were done monthly in the first six months, then 9 and 12 months after planting. The percentages of plants that were naturally attacked by ants were registered. The effect of defoliation was evaluated by artificial defoliation, simulating the natural patterns of attack by A. crassispinus on P. taeda seedlings. The natural attack of A. crassispinus was greater during the first months after planting, being more intense in the first 30 days. Artificial defoliation indicated that there were no significant losses in diameter and height in plants with less than 75% defoliation. However, there were significant losses in diameter and height in plants with 100% defoliation, independently of the cut of the apical meristem, and also plant death. The control of leaf-cutting ants in P. taeda plantings, in which A. crassispinus is the most frequent leaf-cutting ant, should be intense only at the beginning of planting, since the most severe attacks occur during this time.

Distribuição espacial de formigueiros de Acromyrmex crassispinus (Forel)(Hymenoptera: Formicidae) em plantios de Pinus taeda

Genetic structure of populations of Pissodes castaneus (De Geer) (Coleoptera, Curculionidae) using amplified fragment length polymorphism. The objective of this study was to determine the genetic structure of populations of Pissodes castaneus from different areas and on different species of Pinus using the PCR-AFLP technique. Twenty samples were analyzed, representing 19 populations from Brazil and one from Florence, Italy, which is the region of origin of P. castaneus. The four combinations of primers generated a total of 367 fragments of DNA, and 100% of polymorphic loci, indicating high degree of molecular polymorphism. The dendrogram did not reveal trends for grouping the populations in relation to origin. The low genetic similarity (0.11 between the most distant groups) and genetic distances of 0.13 and 0.44 for 10 out of the 20 samples may indicate several founding events or multiple introductions of heterogeneous strains into Brazil. The allelic fixation index (Fst) was 0.3851, considered high, and the number of migrants (Nm) was 0.3991, indicating low gene flow among populations. The highest genetic distances were between the population from Irani, SC and Cambara do Sul, RS and Bituruna, PR, indicating an independent founding event or a particular allelic fixation in the former location. The high genetic diversity among populations points out that the populations are genetically heterogeneous with a diverse gene pool in the surveyed areas, what makes them to respond differently to control measures.

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

The spatial distribution of insects is essential to perform control strategies, to improve sample techniques and to estimate economic losses. We aimed to determine the spatial distribution of nests of Acromyrmex crassispinus (Forel) in Pinus taeda plantations. The experiments were carried out in P. taeda plantations with different ages (treatments: recently-planted, three and six-year old plants). The study took place in Rio Negrinho and in Tres Barras, SC. Three plots of one hectare were delimited in each treatment, and plots were divided in 64 sample units. The analysis of the dispersion index [variance/mean relationship (I), index of Morisita (Iδ) and k exponent of negative binomial distribution] showed that the majority of the samplings presented random distribution. Among the three distributions of probabilities studied: Poisson, positive binomial and negative binomial, the Poisson distribution was the best model to fit the spatial distribution of A. crassispinus nests in all samplings. The result was a random distribution in the plantings of different ages.

Identification of (1R, 2S)-grandisal and (1R, 2S)-grandisol in Pissodes castaneus male-produced volatiles: evidence of a sex pheromone

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.

Utilização da amostragem seqüencial para avaliar a eficiência do parasitismo de Deladenus (Beddingia) siricidicola (Nematoda: Neotylenchidae) em adultos de Sirex noctilio (Hymenoptera: Siricidae).

The banded pine weevil, Pissodes castaneus (De Geer, 1775) (Coleoptera, Curculionidae) is a forest pest recorded in Brazil since 2001, which is already distributed in the three states of the Southern Region, causing great concern to the forestry sector. Objectives of our study were to isolate, identify, and assess the behavioral activity of male-produced volatiles of P. castaneus. Our results indicate that communication between conspecifics of P. castaneus is mediated by pheromones, as verified by the significant attraction of females to male-produced volatiles. Behavioral tests performed with the insects and the host plant, Pinus taeda, showed that male-produced compounds may act as sex pheromones and that the compounds released by the host plant did not enhance the activity of the male-produced volatiles. The chemical structures of the male specific volatile compounds produced by P. castaneus were determined to be (1R, 2S)-grandisal and (1R, 2S)-grandisol in an enantiomeric excess exceeding 95%.