Predatory behavior of three centipede species of the order Scolopendromorpha (Arthropoda: Myriapoda: Chilopoda)

Studies related to centipede feeding and predatory behavior are rare in the literature, and are limited to observations made during fieldwork. Furthermore, they lack descriptions of prey capture. We conducted a laboratory experiment using South American specimens of Scolopendra viridicornis Newport, 1844 (n = 5), Otostigmus tibialis Brõlemann, 1902 (n = 5), and Cryptops iheringi Brõlemann, 1902 (n = 5), as well as 13 different kinds of prey, to map and describe their predatory behavior. The analysis of video images (65 hours of recordings) resulted in 15 behavioral categories that describe foraging, prey capture, feeding, and cleaning habits. Almost all observations (95%) concluded with the centipede killing the prey. Although we witnessed that a stimulus triggered the movement of the centipede toward the prey in all observation events (suggesting a sit-and-wait strategy), our experiments also showed that these arthropods actively forage to seek food. Field observations during the experiment allowed us to document that scolopendromorphs feed on plants when animal prey items are not available. Moreover, we observed that the size and aggressiveness of the prey determined the centipede capture process. Our results revealed that two behavioral categories were performed only by S. viridicornis , and thus might be genus or species-specific. These are: raising the first third of the body while the rest of the body remains adjacent to the substrate; and restraining the prey along the ventral region of the first third of the body with the aid of locomotory legs. We also observed some peculiar behaviors performed only by O. tibialis . Our results confirm that S. viridicornis , O. tibialis and C. iheringi hold prey between their ultimate pair of legs.

Predatory behavior of three centipede species of the order Scolopendromorpha (Arthropoda: Myriapoda: Chilopoda)

Studies related to centipede feeding and predatory behavior are rare in the literature, and are limited to observations made during fieldwork. Furthermore, they lack descriptions of prey capture. We conducted a laboratory experiment using South American specimens of Scolopendra viridicornis Newport, 1844 (n = 5), Otostigmus tibialis Brõlemann, 1902 (n = 5), and Cryptops iheringi Brõlemann, 1902 (n = 5), as well as 13 different kinds of prey, to map and describe their predatory behavior. The analysis of video images (65 hours of recordings) resulted in 15 behavioral categories that describe foraging, prey capture, feeding, and cleaning habits. Almost all observations (95%) concluded with the centipede killing the prey. Although we witnessed that a stimulus triggered the movement of the centipede toward the prey in all observation events (suggesting a sit-and-wait strategy), our experiments also showed that these arthropods actively forage to seek food. Field observations during the experiment allowed us to document that scolopendromorphs feed on plants when animal prey items are not available. Moreover, we observed that the size and aggressiveness of the prey determined the centipede capture process. Our results revealed that two behavioral categories were performed only by S. viridicornis , and thus might be genus or species-specific. These are: raising the first third of the body while the rest of the body remains adjacent to the substrate; and restraining the prey along the ventral region of the first third of the body with the aid of locomotory legs. We also observed some peculiar behaviors performed only by O. tibialis . Our results confirm that S. viridicornis , O. tibialis and C. iheringi hold prey between their ultimate pair of legs.(AU)

Trap and soil monolith sampled edaphic spiders (arachnida: araneae) in Araucaria angustifolia forest

Forests with Araucaria angustifolia (Bert.) O. Kuntze trees are endangered in Brazil, and information on the diversity of soil spider families associated to these environments is practically inexistent. The present study was set up to evaluate the abundance and diversity of soil spider families in natural and reforested Araucaria forests, impacted or not by fire, and to identify the most efficient method to collect these organisms. The study was conducted in four areas: native forest with predominance of Araucaria (NF); Araucaria reforestation (R); Araucaria reforestation submitted to an accidental fire (RF); and native grass pasture with native Araucaria and submitted to an intense accidental fire (NPF). Considering both sampling methods (Monolith and Pitfall traps), 20 spider families were identified. The pitfall trap method was more effective as it captured 19 out of the 20 recorded families, while the Monolith method extracted only ten spider families. Spider family abundance and Shannon's diversity index (H) were affected by the employed collection method; the values for these attributes were always higher for the NF and lower for the NPF. Correspondence analysis (CA) showed a spatial separation among spider familiy assemblages from the different studied areas. It is suggested that changes in the abundance of soil spider families in Araucaria forests are mainly caused by recurrent human intervention over the last few years.

As florestas com Araucaria angustifolia (Bert.) O. Kuntze estão ameaçadas de extinção no Brasil, e são praticamente inexistentes as informações sobre a diversidade de famílias de aranhas de solo associadas nestes ambientes. O estudo teve o objetivo de avaliar, em florestas com araucária naturais e reflorestadas, impactadas ou não pela queima acidental, a abundância e diversidade de famílias de aranhas, além de identificar o método mais eficiente para coletar estes organismos. O estudo foi conduzido em quatro áreas: floresta nativa com predominância de araucária (NF); reflorestamento de araucária (R); reflorestamento de araucária submetido a incêndio acidental (RF); e pastagem natural com araucárias nativas e ocorrência de incêndio acidental (NPF). Considerando os dois métodos de amostragem (Monólito e armadilhas de solo), foram identificadas 20 famílias de aranhas associadas às áreas. O método das armadilhas de solo foi mais eficiente, capturando 19 das 20 famílias registradas, enquanto o do Monólito extraiu apenas dez destas famílias de aranhas. A abundância de famílias de aranhas e o índice de diversidade de Shannon (H) foram afetados pelo método de coleta utilizado, sendo os valores destes atributos sempre superiores na NF e inferiores na NPF. A análise de correspondência (AC) demonstrou que existe separação espacial entre as áreas estudadas. Sugere-se que as modificações na abundância de famílias de aranhas de solo sejam provocadas principalmente pelas intervenções antrópicas que as florestas de araucária vêm sofrendo nos últimos anos.

Trap and soil monolith sampled edaphic spiders (arachnida: araneae) in Araucaria angustifolia forest

Forests with Araucaria angustifolia (Bert.) O. Kuntze trees are endangered in Brazil, and information on the diversity of soil spider families associated to these environments is practically inexistent. The present study was set up to evaluate the abundance and diversity of soil spider families in natural and reforested Araucaria forests, impacted or not by fire, and to identify the most efficient method to collect these organisms. The study was conducted in four areas: native forest with predominance of Araucaria (NF); Araucaria reforestation (R); Araucaria reforestation submitted to an accidental fire (RF); and native grass pasture with native Araucaria and submitted to an intense accidental fire (NPF). Considering both sampling methods (Monolith and Pitfall traps), 20 spider families were identified. The pitfall trap method was more effective as it captured 19 out of the 20 recorded families, while the Monolith method extracted only ten spider families. Spider family abundance and Shannon's diversity index (H) were affected by the employed collection method; the values for these attributes were always higher for the NF and lower for the NPF. Correspondence analysis (CA) showed a spatial separation among spider familiy assemblages from the different studied areas. It is suggested that changes in the abundance of soil spider families in Araucaria forests are mainly caused by recurrent human intervention over the last few years.

As florestas com Araucaria angustifolia (Bert.) O. Kuntze estão ameaçadas de extinção no Brasil, e são praticamente inexistentes as informações sobre a diversidade de famílias de aranhas de solo associadas nestes ambientes. O estudo teve o objetivo de avaliar, em florestas com araucária naturais e reflorestadas, impactadas ou não pela queima acidental, a abundância e diversidade de famílias de aranhas, além de identificar o método mais eficiente para coletar estes organismos. O estudo foi conduzido em quatro áreas: floresta nativa com predominância de araucária (NF); reflorestamento de araucária (R); reflorestamento de araucária submetido a incêndio acidental (RF); e pastagem natural com araucárias nativas e ocorrência de incêndio acidental (NPF). Considerando os dois métodos de amostragem (Monólito e armadilhas de solo), foram identificadas 20 famílias de aranhas associadas às áreas. O método das armadilhas de solo foi mais eficiente, capturando 19 das 20 famílias registradas, enquanto o do Monólito extraiu apenas dez destas famílias de aranhas. A abundância de famílias de aranhas e o índice de diversidade de Shannon (H) foram afetados pelo método de coleta utilizado, sendo os valores destes atributos sempre superiores na NF e inferiores na NPF. A análise de correspondência (AC) demonstrou que existe separação espacial entre as áreas estudadas. Sugere-se que as modificações na abundância de famílias de aranhas de solo sejam provocadas principalmente pelas intervenções antrópicas que as florestas de araucária vêm sofrendo nos últimos anos.