A contribution to the functional morphology of the femoral chordotonal organ in the green lacewing Chrysoperla carnea (Neuroptera).

The femoral chordotonal organ (FCO) and the subgenual organ (SGO) of the green lacewing Chrysoperla carnea were examined by conventional light and confocal laser scanning microscopy in order to search for neuroactive substances which are used for neurotransmission in sensory cells of these organs. Antibodies against serotonin, histamine and choline acetyltransferase were tested immunohistochemically. In the FCO, antiserum against serotonin strongly labelled cell bodies and axons of about 16 sensory cells. In the proximal scoloparium all 12 sensory cells showed immunoreaction with antiserotonin. In the distal scoloparium only four of 40 sensory cells were immunoreactive. These results suggest that different neuroactive substances are employed as neurotransmitters in the FCO of the green lacewing and that the proximal scoloparium and the distal scoloparium are functionally differentiated. Contrary to the FCO in the locust, acetylcholine was not found as a neurotransmitter in the FCO of the green lacewing. Additionally, histamine showed a negative result in the sensory cells of the FCO. Other neuroactive substances seem to be used as transmitters in the SGO because none of the tested antibodies showed positive reaction.

The visually controlled prey-capture behaviour of the European mantispid Mantispa styriaca.

Mantispids (Mantispa styriaca) are predatory insects; on bright sunny days, they wait in ambush for insect prey. The prey is captured as soon as it is within reach by means of lightning-speed strikes with the powerful forelegs. The strikes can take less than 60 ms. The mantispid accomplishes this almost as effectively as the larger praying mantis, which occupies a similar habitat, even though the praying mantis has apposition eyes with a high-resolution fovea, whereas the mantispid has unspecialized optical superposition eyes. Mantispa styriaca reacts to an item of prey when the latter covers a critical visual angle. The detection of prey immediately triggers adjustment reactions in the mantispid, which attempts to position the prey item in the visual field of both eyes and in the capture zone. Irrespective of the size of the prey, the capture reaction of the mantispid is always triggered if the distance to the prey falls below a certain critical value. As indicated by the analysis of individual video frames, immediately before an aimed strike, the item of prey is always positioned exactly in the centre of the binocular field of vision in the extended midsagittal plane of the mantispid's head. The strike may be triggered by the ommatidia of the left and right eyes, the lines of sight of which converge precisely on this region. The principal conclusion to be drawn is that the prey-capture behaviour of the mantispid appears to be based on a triangulation mechanism.

Femoral chordotonal organ in the legs of an insect,Chrysoperla carnea(Neuroptera).

The femoral chordotonal organ (FCO) inChrysoperla carneais situated in the distal part of the femur and consists of two scoloparia, which are fused at their distal end. The distal scoloparium contains 17-20 scolopidia, and the proximal one six scolopidia. Each scolopidium consists of two sensory cells and three types of enveloping cells (glial, scolopale and attachment cell). The sensory cells of different scolopidia do not lie at the same level in the FCO. Therefore the attachment cells of different scolopidia have different lengths. In the FCO, three types of ciliary roots are found in different sensory cells. The dendrite of the sensory cell terminates in a distal process, which has the structure of a modified cilium (9x2+0). The very distal part of the cilium is surrounded by an extracellular electron dense material, the cap, and ends in a terminal dilation. The scolopale cell contains the electron dense scolopale rods, consisting of plentiful microtubules. In their middle third the scolopale rods are fused and form the scolopale. In the FCO septate junctions, desmosomes and hemidesmosomes are found.

Structure of the subgenual organ in the green lacewing, Chrysoperla carnea.

REM and TEM studies of the subgenual organ in Chrysoperla carnea (Neuroptera: Chrysopidae) show that it is composed of three scolopidia, each with one sensory, one scolopale and one cap cell. The distal part of the dendrite shows a cilium with a '9 + 0' structure. The cross-handing pattern of the ciliary root has a periodicity of bands of about 61 nm. The scolopale material in a certain part of the scolopale cell is organized into five rods. The cell bodies of all three cap cells form a lens-like structure. the velum, which is fixed to the leg wall and the trachea with an extracellular material. The importance of the velum is discussed. Four types of intercellular junction are found; spot desmosomes. belt desmosomes, septate junctions and gap junctions.