Mikk Heidemaa

Electrophysiological identification of antennal pH receptors in the ground beetle Pterostichus oblongopunctatus

Abstract.  Electrophysiological responses of antennal taste bristles to 100 mm acetate and phosphate buffers were tested at pH 3–11 in the ground beetle Pterostichus oblongopunctatus (F.) (Coleoptera, Carabidae). Additionally, responses of these sensilla to 10 and 100 mm phosphate buffers were compared with each other. Generally, in response to these stimulating solutions, two sensory cells, classified as a salt cell (cation cell) and a pH cell, respectively, showed action potentials distinguished by differences in their amplitudes and polarity of spikes. The firing rate of the cation cell increased with increasing buffer concentration, and was influenced by buffer pH in a complicated way. The best stimulus for the second cell (pH cell) was pH of the stimulating buffer solution. As the pH of the stimulus solution increased, higher rates of firing were produced by the pH cell. For example, the number of action potentials elicited by 100 mm phosphate buffer at pH 11.1 was approximately 16‐fold higher compared with that at pH 8.1, and firing rates during the first second of the response were 27.9 and 1.7 imp/s, respectively. The pH cell did not fire or fired at very low frequency (first second response below 5 imp/s) at pH 3–6. This level of acidity probably represents the pH preferences of this ground beetle in its forest habitat and hibernating sites. By contrast to the cation cell, the pH cell responded to increases in buffer concentration by decreasing its firing rate.

Spike bursts generated by the thermosensitive (cold) neuron from the antennal campaniform sensilla of the ground beetle Platynus assimilis

Responses of the antennal thermosensitive neuron of the ground beetle Platynus assimilis to warming from 20 to 50 degrees C were measured and analysed. During warming, neurons switched from regular spiking to bursting. ISI analysis showed that the number of spikes in the burst and spike frequency within the burst were temperature dependent and may precisely encode unfavourably or dangerously high temperatures in a graded manner. In contrast, regular spikes of the neuron encode moderate temperatures at 20-30 degrees C. The threshold temperature of spike bursting varied in different neurons from 25 to 47 degrees C. As a result, the number of bursting neurons increased with temperature increase. Therefore, in addition to the burst characteristics, the total number of bursting neurons may also contain useful information on external temperature. A relationship between the spike bursts and locomotor activity of the beetles was found which may have importance in behavioural thermoregulation of the species. At 44.4+/-0.6 degrees C, first indications of partial paralysis (of the hind legs) were observed. We emphasize, that in contrast to various sensory systems studied, the thermoreceptor neuron of P. assimilis has a stable and continuous burst train, no temporal information is encoded in the timing of the bursts.

Review of the sawfly genus Empria (Hymenoptera, Tenthredinidae) in Japan

Abstract The following eleven Empria species are reported from Japan: Empria candidata (Fallén, 1808), Empria japonica Heidemaa & Prous, 2011, Empria liturata (Gmelin, 1790), Empria loktini Ermolenko, 1971, Empria plana (Jakowlew, 1891), Empria quadrimaculata Takeuchi, 1952, Empria rubicola Ermolenko, 1971, Empria tridens (Konow, 1896), Empria tridentis Lee & Ryu, 1996, Empria honshuana Prous & Heidemaa, sp. n., and Empria takeuchii Prous & Heidemaa, sp. n. The lectotypes of Poecilosoma pallipes Matsumura, 1912, Empria itelmena Malaise, 1931, Tenthredo candidata Fallén, 1808, and Tenthredo (Poecilostoma) hybrida Erichson, 1851 are designated. Empria itelmena Malaise, 1931, syn. n. is synonymized with Empria plana (Jakowlew, 1891). Poecilosoma pallipes Matsumura, 1912, previously assigned to Empria, is transferred to Monsoma, creating Monsoma pallipes (Matsumura, 1912), comb. n. Results of phylogenetic analyses using mitochondrial (COI) and nuclear (ITS1 and ITS2) sequences are also provided.

Abundanz einiger blattfressender insekten in abhängigkeit von der stickstoffdüngung im iosdv‐versuch in tartu/estland

Im Internationalen Organischen Stickstoffdauerdungungsversuch (IOSDV) in Tartu (Estland) wurde in der Kartoffel‐Sommerweizen‐Sommergerste‐Fruchtfolge die Abundanz der dominierenden Schadlinge—Blattlause, Zikaden, Wiesenwanzen, Blasenfuse, Blattwespen —in zwei Pflanzenentwicklungsstadien wahrend der Sommer 1992–1996 bestimmt. Die Ergebnisse der funfjahrigen Untersuchungen wurden mit der Regressionsanalyse ausgewertet, um die Bedingtheit der Abundanz verschiedener Insektengruppen von der Stickstoffdungung unter verschiedenen Temperaturbedingungen zu erklaren. Die einzelnen Insektengruppen haben auf die Dungung in den verschiedenen Entwicklungsstadien der Wirtspflanze sehr unterschiedlich reagiert. Die N‐Mengensteigerung (von 40 bis 160 kg/ha) hat die Blattlause auf der Kartoffel in beiden Phanophasen gefordert. Beim Getreide hat die Dungung mit der N‐Menge 160 kg/ha die Blattlause gehemmt. Die N‐Dungung hat ganz gering die Zikadenabundanz auf dem Getreide beeinflust. Die Wiesenwanzen haben im allgemeinen im...