Call number: LD2668 .T4 1984 K78 / Master of Science

Field studies of population of Geocoris and Nabis indicated that the density of adult Nabis was higher than Geocoris before April, but the reverse was true after April. In general, the abundance of adults and nymphs of each species was caused by alfalfa harvesting, dispersal of adults, discrepancies of sweep-net sampling, differences in mortality of eggs and the differences in the diapause termination of adults. The field cuttings of alfalfa reduced populations of both species, but adults were reduced more than the nymphs. In laboratory studies adults and nymphs of each species fed on each other on alfalfa in small cages, but in larger cages when only adults were caged, interspecific predation of adults did not occur. This suggests that, in the field, interspecific predation of nymphs can be more prevalent than adults of each species since nymphs which are more sedentary than adults are less affected by alfalfa cuttings. A number of predatory insects other than Nabis that were common in the alfalfa, such as Chrysopa carnea Stephens, Orius tristicolor (White), Hippodamia convergens Guerin, and Sinea confusa Caudell, were also found to prey upon Geocoris in the laboratory. Hyalomya aldrichii Townsend was the only parasite reared from Geocoris adults and nymphs from the field. The parasite did not numerically respond to the density of Geocoris and had minor impact on the population of the predator. The host preference of this parasite among the Geocoris spp. and between Geocoris and Nabis was not determined since rearing the parasite in the laboratory failed. Telenomus sp. parasitized groups of Geocoris eggs exposed in alfalfa fields. In the laboratory, it parasitized both G. pallens and G. punctipes eggs. Rearing the parasite at 30(DEGREES)C resulted in poorer emergence of adults than at 20(DEGREES)C and 25(DEGREES)C. Predaceous insects that synchronize with populations of Geocoris, larger in size then Geocoris, especially Nabis and Sinea spp. may be more important than parasites in regulating population of Geocoris in the field.

No description available.

Thesis (PhD)--Montana State University--Bozeman, 2008. / Typescript. Chairperson, Graduate Committee: David K. Weaver. Includes bibliographical references.

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Study object. The research was made in two forest stands: one was affected by fire and another without fire damage. A sample plot was in a pine stand damaged by fire a year ago, which is is in Kaunas forest enterprise, in Kulautuva forest department. The stand is in square No. 169 and the plots numbers are 14 and 15. The damaged area takes 0,4 hectare. It is 100% pine stand with a site index Nbl. Study aim. To investigate the low fire influence on pine stand litter entomocomplex fluctuation: on their number and seasonal dynamic, on their distrubution by trophical groups, on species abundance and variety in a fire damaged stands. Methods. The research was made in 2004 since april till october. The Barberis ground trap was used in a research. The trap is made from a 150 ml volume and 6,5 cm diameter plastic cruet. The traps were digged into ground to the top of the trap. 1/3 of the trap was filled with a 10% formalin soak. In that case the insects were saved of decomposing and birds. The traps were placed in three zones: in burned area, chequerwise in the place between damaged and undamaged area, and in undamaged area. There were 6 satelites in each area holding 4 traps in each. All together it was 72 traps placed. The distance between the areas was 20 m and the distance between satelites – 10 m. The collected insects were dried and recognized in the labs of Lithuanian University of Agriculture and Forest Research Institute. Results. The total amount of collected insects in 6... [to full text]

The research object. The research was made in the territory of Neris regional park (Kaisiadoriu forest enterprise, Vievis forest district) in order to evaluate the impact of recreational activities on the forest litter arthropods. The aim of the study – to evaluate different recreational digression stage impact on pinery litter arthropods: their amount and seasonal dynamics, distribution trophic groups, the abundance and variety of species in stands affected by recreation. Methods. Arthropods were collected in Barber ground traps from April through October 2005, which are plastic, 150 ml. volume, with 6.5 cm diameter receptacle. They were dug in the ground and 1/3 of trap was filled with 10 % formalin liquor, which protected insects from decaying and insectivorous birds. Ground traps in each sample plot were spread in groups by 4 (square), the distance between them was 2 m. The distance between sample plots was 20-50 meters. The results. 157 species were identified in trap catches: 96 in the control plot, 97 in the plot with low recreational damage and 110 in the plot wit high recreational damage. Entomophagous predominated and made 60-73 %, kaprophagous 8-25%, saprophagous 10% of catch. 2 extremely rare species and 7 rare species in Lithuania were found, the biggest number of rare species was found in the plot with high recreational damage. Shannon diversity index H’ was 2.5-3.31, evenness E – 0.55-0.66, Berger-Parker dominance d – 0.170-0.367. Sorensen similarity index Cs... [to full text]