This study aimed to identify and quantify the compounds present in the abdominal glands of Alphitobius diaperinus Panzer, 1797 (Coleoptera: Tenebrionidae) and to evaluate the influence of these compounds on its behavior. The extraction of volatiles present in the abdominal glands was made by dissection (10 individuals per sex) and by air entrainment (200 insects per sex), and they were analyzed by gas chromatography-flame ionization detector, gas chromatograph-mass spectrometer, and gas chromatograph-electroantennography detector (GC-EAD). The influence of these volatiles on the behavior of conspecifics was evaluated in a four-arm olfactometer. Twenty-three compounds were identified from male and female abdominal gland extracts, of which six were quinones: the 2-methyl-1,4-benzoquinone and the 2-ethyl-1,4-benzoquinone were the major components, and 1,4 benzoquinone and three hydroquinones were registered for the first time for this species. The GC-EAD analysis using the crude extracts from abdominal glands showed that male and female antennae responded to the three major benzoquinones. For the olfactometer bioassays, both genders were repelled either by the abdominal gland extracts or by synthetic solutions containing the three benzoquinones. The results suggest that the 1,4-benzoquinones play a role as a repellent to A. diaperinus.

The Brazilian Pampa presents a high diversity of fauna and flora within a mosaic of environments. The aim of this study was to evaluate the assemblages of predatory mites (Phytoseiidae and Stigmaeidae) in three different Pampa environments: Grassland shrub vegetation, Grazing Exclusions fenced for six years and Riparian Forest with tree vegetation. Phytoseiidae and Stigmaeidae were evaluated with a total of 324 plant sampled from nine sites in three environments. Twenty-two Phytoseiidae species and six Stigmaeidae species were found. Riparian Forest presented the highest abundance of predatory mites (243) and the greatest species diversity. Mites were more abundant in Grazing Exclusions (64) than in Grassland (25) environments, but species diversity was similar. In Riparian Forest, the most abundant species were Amblyseius tamatavensis Blommers, Amblyseius herbicolus (Chant) and Agistemus floridanus González-Rodríguez. Arrenoseius gaucho Ferla, Silva and Moraes and Zetzellia malvinae Matioli, Ueckermann and Oliveira were the most abundant in Grassland environment. Our results demonstrate that the Brazilian Pampa has a high diversity of predatory mites and mite communities seem to be affected by the type of environment, showing the importance of this ecosystem as a reservoir of natural enemies.

Myrceugenia myrtoides (Myrtaceae) is a species of tree size, occurring restricted to the state of Rio Grande do Sul state in Brazil, and Uruguay, presenting ornamental potential. The interest in native species for diverse uses is increasing, but their insertion is limited due to the lack of information on its propagation and cultivation. Thus, the objective of this study was to evaluate the effects of temperature and light on the germination of M. myrtoides seeds, in order to generate information that could aid in the propagation of the species and the exploration of its potential. The effects of constant temperatures of 20, 25 and 30 °C under a 16-hour photoperiod were evaluated. To evaluate the effect of light, the germination was tested in continuous darkness and under photoperiod of 16 hours, at a temperature of 25 °C and light intensity of 27 and 33.75 μmol m-2s-1 under white light quality and diffuse green light. The results showed a lower average germination time at temperatures of 25 and 30 ºC and a higher accumulation of dry mass under 30 ºC. There was superiority in the variables of seedling formation, shoot and root length and seedling formation under the number of seeds germinated at 25 ºC. However, the different light conditions tested did not affect the percentage of ermination. It is concluded that the temperature of 25 °C was the most adequate for seed germination and development of M.myrtoides seedlings and their seeds are classified as neutral photoblasts.

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Bromelia antiacantha Bertol. is a native species of Brazil with food, medicinal, industrial and forest restoration potential. The objective of this study was to test different substrates and temperatures in the germination and seedling formation of B. antiacantha. Seeds obtained from fruits collected in situ from three localities, one in Paverama/RS and two in Taquari/RS, were washed in running water and homogenized in a single batch. After drying, the seeds were disinfested and seeded in medium sand and germibox paper, and exposed to constant temperatures of 25 and 30ºC. Firstly, the water content of the seeds were determined and, after installation of the experiment, the percentage of germination (G) and seedlings formed (SF), germination mean time (MTG) and seedling formation mean time (MTS), germination rate index (GRI) and seedling formation rate index (SRI) were calculated. The experimental design was completely randomized, in a 2 x 2 factorial arrangement with 4 replicates of 50 seeds. The water content and the weight of one thousand seeds corresponded to 17.02% and 27.09 g, respectively. The paper was superior to sand, with an average of 87% of germinated seeds, as well as a percentage of 86.25% of normal seedlings formed. Regarding the temperature, at 25 ºC, the seeds showed lower MTG and MTS and higher GRI and SRI. B. antiacantha seeds showed superior germination and initial seedling formation when sown on paper substrates and at 25 °C.