We study a family of K3 surfaces which have a big automorphism group. We begin with generalisations of Silverman's results: construction of canonical heights, density of rational points in one orbit,… We continue the study in estimating the density of rational points on the orbiting rational curves; this estimate is compatible with Batyrev–Manin conjecture. Moreover we settle, under more geometric hypothesis, the number of rational points of such surfaces of bounded height.

Field studies on oviposition site, preference and pattern of Busseola fusca on various stages of maize were conducted at Awassa (southern Ethiopia). The positions of egg masses in terms of leaf sheath and height from the ground were described for different ages of the maize plant. Irrespective of the age of maize plants, eggs were laid on the under side of leaf sheaths. Busseola fusca moths showed ovipositional preference to younger maize plants. Significantly fewer egg masses were laid on older plants (r=.0.98, P <0.001). A strong relationship between maize plant age and position of egg masses was found. During the post-tasselling stage the great majority of the egg masses were found below the primary ear.