Kaszab Zoltán (szerk.): A Magyar Természettudományi Múzeum évkönyve 77. (Budapest 1985)

Vásárhelyi, T.: Investigations on the allometric growth of Aradus species (Heteroptera, Aradidae)

ANNALES HISTORICO-NATURALES MUSEI NATIONALIS HUNGARICI Tomus 77. Budapest, 1985 p. 145-151. Investigations on the allometric growth of Aradus species (Heteroptera, Aradidae) by T. VÁSÁRHELYI, Budapest Abstract

—Allometric growth of head length, head width, pronotal width, body length and length of the antennái joints of the Aradus species were investigated with help of bivariate analysis. Of these, relative length of antennái joints 2-4 can be primarily used for distinguishing the developmental stadia and identifying larval specimens. With 10 figures. As insect larvae in general, Aradid larvae have not been much investigated. Morphometric •characters were studied so as to complete the series of attributes used in identification of the developmental stadia as well as of the species of the genus Aradus. Different larval instars have been treated or keyed by JORDAN (1932) and TAMANINI (1956 who

—as in other taxa of Heteroptera e.g. SLATER (1951), SOUTHWOOD & SCUDDER (1956), SOUTHWOOD (1956)—used as primary characters the development of thoracal segments, wing pads, and Tamanini also extended his treatment to the head, apical abdominal segments and relative length of antennái joints 2 and 4. (Antennái joints of his three species grow according to similar patterns, these two joints showing the greatest

—and similar

—changes.) Descriptions of larval development useable for the purposes of this study have been given by HEISS (1979: Aradus lauri NOUALHIER, 1893), TAMANINI (1956: A. betulinus FALLÉN, 1829, A. corticaïis LINNÉ, 1758, A.pictus BAERENSPRUNG, 1859) and VÁSÁRHELYI (1978: A. ribauti WAGNER, 1955; 1979: Oeciacus hirundinis JENYNS, 1839; 1982: Aradus krueperi REUTER, 1882). The larvae of other Aradid subfamilies and especially of apterous species are hardly known. The present paper attempts to investigate allometric growth of body parts, the measurements of which are often given in descriptions but the suitability of which has not been tested, and to give an overall picture of the growth of antennái joints during postembironal development. Material and methods The data, other than published by the authors mentioned above, were taken from dry specimens deposited in the Zoological Museum, Helsinki, in the National Museum in Prague and in the Hungarian Natural History Museum, Budapest. As similar trends of antennái growth were observed in various species of Heteroptera Oeciacus hirundinis (Cimicidae) was also taken into consideration for comparative purposes. As many as possible (but never more than 20) specimens were measured and the significance of the averages were tested with Student's test. Since not the rules of growth, but simply the applicability of certain measurements or ratios were investigated

—though ousted in many studies by multivariate methods

—b ivariate analysis was used. Growth rate and initial growth index were calculated by the regression method from the logarithm of the values. Allometric trends are shown on graphs with linear scale, where data are given in mm. The ratio body length / head width Body length is subject to considerable change during each developmental stadium and it varies according to the state of nourishment (FÖRSTER 1953). In Aradidae the effect of the latter is strengthened by the well sclerotized sclerites and the developed dorsoventral musculature which are partly responsible for their flattened body. Nevertheless, measurements of 10 larvae of the same instar provided averages significant in all cases at a 0.01 probability level. 10 Természettudományi Múzeum Évkönyve 1985