Comparative morphological study of the venom glands of the centipede Cryptops iheringi, Otostigmus pradoi and Scolopendra viridicornis.

Centipedes are widely distributed over all the continents. As they are well adapted to urban areas they can often cause accidents to humans by injecting venom produced in the glands located inside their maxillipeds. The fine morphology of the centipede venom glands is practically unknown. This present study is the first comparative report on the histology, histochemistry and ultrastructure of the venom glands of the centipede species responsible for the majority of accidents to humans in Brazil: Scolopendra viridicornis, Cryptops iheringi and Otostigmus pradoi. In all species the glands are basically composed of columnar secretory cells radially disposed side by side, individually opening through pores in a central chitinous duct. Each secretory cell is covered by striated muscular fibres. The secretion has the form of small PAS positive granules and large hyaline secretory bromophenol blue positive vacuoles, indicating the presence of neutral polysaccharides and protein. The secretion is conducted through the secretory cell necks to the pores, which open into the central chitinous duct. The results indicate a great similarity both in morphology and primary chemical composition of the venom among the studied species, except for the size of the glands, which is proportional to the body dimensions of each species.

Toxic activities of Brazilian centipede venoms.

Centipedes have a venom gland connected to a pair of forceps, which are used to arrest preys. Human victims bitten by centipedes usually manifest burning pain, paresthesia and edema, which may develop into superficial necrosis. The aim of this work was to characterize and compare toxic activities found in venoms of three species of Brazilian centipedes-Otostigmus pradoi, Cryptops iheringi and Scolopendra viridicornis. By SDS-PAGE (4-20%), important differences were noticed among venoms (between 7 and 205kDa). Few bands showed feeble caseinolytic, fibrinogenolytic and gelatinolytic activities by zymography, but strong hyaluronidase activity was observed in S. viridicornis and O. pradoi venoms. In addition, such activities could be inhibited by o-phenanthroline, indicating that these enzymes are metalloproteinases. All venoms induced nociception, edema and myotoxicity in mice, but only S. viridicornis induced mild hemorrhagic activity. No coagulant activity was detected in centipede venoms. Low phospholipase A(2) activity was observed exclusively in S. viridicornis and O. pradoi venoms, but these venoms had intense direct hemolytic activity on human erythrocytes. Cross-reactivity among venoms was observed using species-specific sera raised in rabbits. Differences were noticed among centipede venoms, but S. viridicornis is indeed the most toxic venom and thereby it could induce a more severe envenomation.

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)