Identification of plant families associated with the predators Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae) and Hippodamia convergens Guérin-Menéville (Coleoptera: Coccinelidae) using pollen grain as a natural marker Identificação de famílias de plantas associadas aos predadores Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae) e Hippodamia convergens Guérin-Menéville (Coleoptera: Coccinelidae) usando o pólen como marcador natural

The predators Hippodamia convergens Guérin-Menéville (Coleoptera: Coccinelidae) and Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae), are frequently observed on vegetable crops, especially on tomato plants, as well as on flowers of several plants around crop fields. It is well known that when predators feed on pollen and nectar they can increase their longevity and reproductive capacity. The objective of this work was to identify plants that could be a pollen source for H. convergens and C. externa in order to develop strategies to attract and keep these predators in vegetable fields like the tomato crop. Adults of C. externa (53 individuals) and H. convergens (43 individuals) were collected in fields from 2004-2005 at Embrapa Hortaliças, Brasília, Federal District. The insects were processed by the acetolysis method and pollen from them was extracted and identified. A total of 11335 grains of pollen belonging to 21 families were extracted from C. externa. A total of 46 pollen grains belonging to ten families were extracted from H. convergens. The Poaceae family was the most abundant one for C. externa while Asteraceae was the commonest pollen for H. convergens. The importance of pollen from different plant species as a food resource for each predator species gives an indication of the importance of plant community structure inside and around crop fields for the establishment of these predator populations and to enhance conservation biological control.Os predadores Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae) e Hippodamia convergens Guérin-Menéville (Coleoptera: Coccinelidae) são frequentemente observados em cultivos de hortaliças, especialmente tomateiros, bem como sobre flores de diversas plantas próximas aos cultivos. Sabe-se que os predadores, quando se alimentam de pólen e néctar, aumentam a sua longevidade e a sua capacidade reprodutiva. O objetivo deste trabalho foi identificar as plantas que poderiam servir de fonte de pólen para as espécies selecionadas, com vistas a desenvolver estratégias para atrair e manter estas espécies em cultivos de hortaliças, especialmente de tomateiro. Adultos de C. externa (53 indivíduos) e H. convergens (43 indivíduos) foram coletados em 2005 no campo experimental da Embrapa Hortaliças, Brasília, Distrito Federal. Os insetos foram processados pelo método de acetólise e os grãos de pólen, extraídos e identificados. Um total de 11335 grãos de pólen, pertencentes a 21 famílias foi identificado para C. externa, enquanto que 46 grãos de pólen, pertencentes a dez famílias botânicas, foram identificados para H. convergens. O pólen da família Poaceae foi o mais abundante para C. externa, e o pólen da família Asteraceae foi o mais comum para H. convergens. A importância relativa do pólen de diferentes espécies de plantas como recursos alimentares para cada espécie predadora dá indicações da importância da flora dentro e no entorno da cultura para o estabelecimento das populações desses predadores e incremento do controle biológico conservativo

Identification of plant families associated with the predators Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae) and Hippodamia convergens Guérin-Menéville (Coleoptera: Coccinelidae) using pollen grain as a natural marker

The predators Hippodamia convergens Guérin-Menéville (Coleoptera: Coccinelidae) and Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae), are frequently observed on vegetable crops, especially on tomato plants, as well as on flowers of several plants around crop fields. It is well known that when predators feed on pollen and nectar they can increase their longevity and reproductive capacity. The objective of this work was to identify plants that could be a pollen source for H. convergens and C. externa in order to develop strategies to attract and keep these predators in vegetable fields like the tomato crop. Adults of C. externa (53 individuals) and H. convergens (43 individuals) were collected in fields from 2004-2005 at Embrapa Hortaliças, Brasília, Federal District. The insects were processed by the acetolysis method and pollen from them was extracted and identified. A total of 11335 grains of pollen belonging to 21 families were extracted from C. externa. A total of 46 pollen grains belonging to ten families were extracted from H. convergens. The Poaceae family was the most abundant one for C. externa while Asteraceae was the commonest pollen for H. convergens. The importance of pollen from different plant species as a food resource for each predator species gives an indication of the importance of plant community structure inside and around crop fields for the establishment of these predator populations and to enhance conservation biological control

Biological activity in Cerrado soils: evaluation of vegetation, fire and seasonality effects using the “bait-lamina test”

Aims The Cerrado, a South American savanna, is con- sidered a priority for conservation. In this case study, we assessed soil feeding activity as a way to improve un- derstanding of the ecosystem functioning, in order to support and refine conservation strategies. Methods Soil feeding activity was assessed using the bait-lamina method under different environmental con- ditions: in the dry and rainy seasons, in burned and unburned areas, and under native and invasive grasses. Results Feeding activity was significantly reduced after fire, but recovered to pre-fire levels with the rains. Activity increased significantly during the rainy season in both areas, being more pronounced in the unburned area. The highest feeding activity was observed under the invasive grass (Melinis minutiflora). Feeding activ- ity declined with soil depth and was affected by season and fire. Conclusions Seasonality was the most important factor affecting the feeding activity of soil organisms, followed by the fire history and the extant vegetation. Although this method does not allowdistinguishing between feed- ing activity of different organisms, it can provide valu- able insights into differences in soil functioning due to changes in environmental conditions