Wilson Reis Filho

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

Emigration of a colony of the leaf-cutting ant Acromyrmex heyeri Forel (Hymenoptera, Formicidae)

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.

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

Emigration of a colony of the leaf-cutting ant Acromyrmex heyeri Forel (Hymenoptera, Formicidae). Colony migration is a poorly studied phenomenon in leaf-cutting ants. Here we report on the emigration of a colony of the leaf-cutting ant A. heyeri in Brazil. The colony emigrated to a new location 47.4 m away from the original nest site, possibly because it had undergone considerable stress due to competitive interactions with a colony of Acromyrmex crassispinus.

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

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.

Evaluation of the Pinus taeda quality using ultrasound

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.

Pulgão do Pinus: nova praga florestal

The pinus is a type of wood that is widely used as feedstock for the production of softwood pulp and higher quality paper, boards, MDF (Medium Density Fiberboard), OSB (Oriented Standard Board), plywood, furniture and others. The main problem for the pinus is the attack by the wood wasps (Sirex noctilio F., 1793) (Hymenoptera; Siricidae) that damages the wood due to galleries built by the wasps larvae. The use of nondestructive techniques to assess the quality and to evaluate mechanically the wood has been the focus of many studies and is certainly an essential tool to decrease the production costs. This work aimed to evaluate the damage due to the infestation of S. noctilio in Pinus taeda L. using ultrasound. The tests have been carried out in the through transmission mode, using a pulser-receiver, two pairs of ultrasound transducers (50 kHz and 100 kHz of central frequencies for each), a digital oscilloscope and a portable microcomputer for data storage. The initial tests have been done using seven logs of pinus samples (lengths in the range 0.70 - 0.94 m and diameters 0.09 - 0.18 m). The transducers were positioned in the samples to measure the ultrasound propagation velocity and the attenuation in the axial, radial (lower, middle and upper parts of the logs), longitudinal (middle and upper parts), inclined at approximately 45 degrees (middle and upper parts), longitudinal/transversal (middle and upper parts) and inclined/transversal (middle and upper parts) modes. The initial results of the 960 tests (430 with each pair of transducers) that have been done with the pinus samples have shown that the infested samples presented a decrease in the propagation velocity and an increase in the attenuation when compared to the control sample results. The initial results showed that the ultrasound technique can help the quality evaluation of P. taeda and to detect the infestation of wood wasps. Further tests should be made with a larger number of samples to evaluate the elastic modulus and other ultrasound parameters. The results will be used to define a novel test protocol to be used for material characterization in the agronomical area.