S. Mahunka szerk.: Folia Entomologica Hungarica 48. (Budapest, 1987)

7. ParasitizaUon, abundance of generations The Scelionid parasitoid Telenomus aradi Kozlov was reared in Hungary from the eggs of Ara dus cinnemomeus (VÁSÁRHELYT 1981). This parasitoid together with other possible species were suspected to maintain the high difference between abundance of the major and minor generation (TERHO and HELTÖVAARA 1981, VÁSÁRHELYI 1981, cf. MTKKOLA 1976). The parasitized egg-shells significantly differ from those of the normal eggs. The former is grey, the opening through which the wasp emerged is large and more or less round, practically the whole apex of the egg shell is missing. The first instar larvae of cinnamomeus break up the eggshell with a triangular egg-burster which remains attached to the empty whitish yellow shell. The percentage of parasitized eggs were calculated by counting the empty egg shells in Budapest, where 24.7% of the eggs were parasitized in 1984. Here in 1983 the major generation was that reproducing in even years, however, in 1984 the abundance of the two generations levelled up. Tt might be a consequence of the cutting of lower branches and removing them along with the litter for esthetic reasons in late autumn of 1983, and not of parasitization. From the samples, sufficient in number of individuals, 13 (81 %) showed significantly higher abundance of in iven years reproducing generation, while 3 (19 %) that of uneven years reproducing generation. Ratio of individuals of the two generations ranged from 61-39% to 100-0%. 8. Distribution of individuals ORLOV (1974) investigated the distribution of cinnammomeus individuals along the southern skirts of a pine plantation of unknown age, on the basis of 460 10x10 cm samples, taken at the height of 1.5 m. He found an average abundance of 4.4 individual / sample and the distribution of the number of individuals closely followed the Poisson-distribution. We calculated the distribution on the basis of 3 10x10 cm samples /tree taken from different heights, along the skirts of forest In Vácrátót in 1980-1981; of 8 5x5 cm samples/tree in a linear transsect across the forest in Vácrátót on the 30th April, 1982; and on the basis of 12 5x5 cm samples/tree, vertically one below the other in Budapest in 1983-1984. Samples of such time periods when no significant phenologieal changes occurred were occasionally combined to increase the number of samples. In the first case, the combination of all samples (average 11.8 individual /100 cm) gave a log-normal distribution well reflecting the combination of several factors influencing the abundance and distribution (selection of trees along the skirts, not random distribution of optimal feeding and hidings places, migration in general and on the trees, grouping of individuals characteristic of bugs, etc.). The combination of the selected samples did not lead to any distribution. The selected calculation of samples of the minor generation gave a significant (P > 99%) negative binomial distribution when either the third instar, forth instar larvae, adults or the total population was considered. Here the number of samples and averages were lower, in order 27 - 1.26; 40 - 2.78; 45 - 1.67 and 70 2.11 individual

/100 cm. In the second case (N = 40), the average was lower than along the forest skirts: 4.51 indivlduals/100 cm. The distribution of samples significantly (P > 99%) fitted the negative binomial distribution while at P-60 % the Poisson distribution. In the third case, each combination of samples gave contagious distribution for larvae as well as for adults, k-values being lower than 2 (Southwood, 1984) and the distribution of eggs gave a negative binomial distribution (detailed calculations are accessible at authors). These data do not satisfactorily change our understanding of the distribution pattern of the individuals, however, they reflect the need of further studies in pattern analysis of the species, with regard also to the peculiar population dinamics of Aradus cinnamomeus

. * * * Our studies revealed, that the pine bark bug Aradus cinnamomeu

s is widely distributed in Hungary, that it is highly abundant in young pine plantations and that migrating individuals are present here in higher proportion than in Northern countries. Considering that the planting of pines plays and increasing role in future plans of Hungarian forestry it is time to recognize the harmfulness of this species with all the consequences.