Marek Tomalak

The influence of nematodes on the structure of genitalia of Tomicus piniperda (Coleoptera: Scolytidae)

Abstract Larvae and adults of the greater pine shoot beetle, Tomicus piniperda , were collected from geographically distinct areas of Poland and examined for mortality causing agents. Endoparasitic nematodes were found in 1535 (62%) of the adults examined. Primary pathologies caused by the nematodes were reduction in size of fat body and structural damage to the genitalia of male adults. The latter, though not a major cause of mortality, may lead to reduced fertility of the beetle.

Interaction of parasitic nematode Parasitaphelenchus oldhami (Nematoda: Aphelenchoididae) and a bacterium in Dutch elm disease vector, Hylurgopinus rufipes (Coleoptera: Scolytidae)

Abstract The bark beetle, Hylurgopinus rufipes, an important Dutch elm disease vector, was infected with a Gram-negative, rod-shaped bacterium observed in all stages of the hosts development. Large aggregations of this apparently innocuous bacterium were found in the fat body, the cytoplasm of the tropharia of the ovaries, and later in the developing eggs. Bacterial cells were localized in isolated pockets in the tissues. An apparent synergistic effect of a concurrent infection by the bacterium and the nematode, Parasitaphelenchus oldhami, led to the rupture of cell membranes by the nematodes and dispersal of bacteria throughout the hemocoel. Subsequent depletion of the fat body tissue in the host was rapid. Juvenile (L3) P. oldhami invaded teneral adults and developed rapidly during the first 5–6 days. A substantial decrease in the prevalence and intensity of nematode infection in adult H. rufipes was observed prior to and during hibernation.

Parasitism of Parasitorhabditis obtusa and P. autographi (Nematoda: Rhabditidae) in the digestive tract of their bark beetle (Coleoptera: Scolytidae) hosts

Abstract In the survey of nematode parasites of bark beetles in Manitoba, two species of nematodes were abundant in the digestive tract of their hosts. Parasitorhabditis obtusa was found in 76.6% of the Ips perturbatus examined. Juvenile nematodes were present in the mid- and hindgut of adult beetles and caused serious damage to the midgut epithelium. Parasitorhabditis autographi was found in 35.7% of the larvae, pupae, and adults of Dryocoetes autographus examined. Juveniles were present primarily in the midgut lumen and did no apparent damage to midgut epithelium.