INHERITANCE OF WEIGHT IN RHIPICEPHALUS-APPENDICULATUS TICKS (ACARI, IXODIDAE) IN THE LABORATORY

A selection of the 10% lightest and 10% heaviest males and females of a population of individually weighed Rhipicephalus appendiculatus Neum ann adults was made in two experiments. The offspring of homologous pa irs were followed until the next adult stage (light x light, control x control and heavy x heavy). The engorged nymphal weights, unfed adult weights, engorged female weights of the parents, egg mass weights, eg g weights, larval scutal lengths, engorged larval weights, unfed nymph al weights, engorged nymphal weights and adult weights of the progeny were determined. No significant differences could be demonstrated betw een the two lines for egg weight, larval scutal length, engorged larva l weight and unfed nymphal weight. Significant differences were found between the egg masses, engorged nymphal weights and adult weights of the two lines. The heritability coefficients of body weight determined from adult to adult were 0.14 and 0.10, respectively, during the firs t and second experiments. Considering females and males separately, th e coefficients were 0.10 and 0.18 during the first experiment and 0.12 and 0.09 during the repeat experiment respectively.