Sampling Program and Host Preference of Melon Ladybeetle, Epilachna chrysomelina (F.) on some Hosts of Cucurbit Family in Ahvaz, Southwest Iran

Melon ladybeetle, Epilachna chrysomelina (F.) is one of the most injurious cucurbit attacking pests. Sampling program and host preference of this ladybeetle were studied in Ahvaz, Southwest Iran. Suitable sample size, suitable location for sampling as well as suitable sampling life stage of the insect were obtained to be 12 on, lower leaf surface and egg stage of the ladybeetle, respectively. E. chrysomelina preferred cucumber to other host species under laboratory conditions. Two preference experiments were conducted under field conditions. During the first experiment, the preferences of E. chrysomelina to cucumber and marrow (two most preffered hosts in the laboratory experiment) were evaluated. In the second experiment preference of the ladybeetle to different cucumber cultivars (Prince, Superdominus, R S Fronto as well as Syrana) was arranged in a split plot (in time), employing a completely randomized blocks design of four replications. In the course of the first experiment the mean total population at different developmental stages of E. chrysomelina was found to be higher on cucumber than on marrow from early till late June. As for the second experiment the mean total population at different developmental stages of the ladybeetle was significantly higher on Superdominus cultivar than on the other cultivars tested. So, it is recommended that in the areas suffering from high populations of this pest, cultivation of Superdominus variety be either avoided or it be cultivated as a trap crop along with the other control measures employed to suppress the pest, melon ladybeetle.