Insect emergence from a shallow southern West German lake, with special reference to the parasitic host-associated water mite larvae
- 1) Limnologisches Institut, Universität Konstanz, Postfach 5560, 7750, Konstanz, Federal Republic of Germany
Insect emergence was studied with floating box traps in the littoral of Lake Mindelsee from July 1st until September 30th, 1984. The material was collected every 48 h. Out of the total catch of 6897 specimens per m2, 75.1 % belonged to the Chironomidae, 4,9% to the Chaoboridae, 15,4% to the Ephemeroptera and 3,2% to the Trichoptera. Endochironomus sp., Lauterborniella agrayloides, Polypedilum pullum (Chironomidae) and Oocetis testacea (Trichoptera) are reported for the first time from Lake Mindelsee. The seasonal course of the total emergence showed two distinct peaks: one at the end of July, the other at the beginning of September. Diurnal emergence was studied on two occasions, in July and in August. Most of the insects emerged during dusk and dawn. Species composition and degree of water mite infection of the collected nematocerans were studied. Host range and specific attachment sites of the different water mite taxa could only be established on the genus or family-level, with the exception of the most common water mite species Hydrodroma despiciens. In addition to its main host Chaoborus flavicans, this mite species infested 16 chironomid species with Corynoneura sp., Cryptocladopelma viridula, Pseudochironomus prasinatus and Tanytarsus lactescens as new records. The larvae of Hydrodroma despiciens were attached almost exclusively to the thorax of the imagines. Chaoborus flavicans, and within the Chironomidae Procladius sp. of the subfamily Tanypodinae, showed the highest average mite load. Species of the subfamily Chironominae were also heavily infested (e.g. Microtendipes sp., infestation rate 76 % with a maximum mite load of 18). Within the representatives of the subfamily Orthocladiinae however, only low infestation rates occurred with maximum one larva per host. Finally, problems like the synchronization of the life-cycles of hosts and parasites and strategies of coexistence between the different water mite taxa parasitizing one host are discussed.
- 1 - sciences appliquees, technologies et medecines
- 2 - sciences biologiques et medicales
- 3 - sciences biologiques fondamentales et appliquees. psychologie
- 4 - invertebres