Biology and seasonal incidence of Mexican beetle Zygogramma bicolorata pallister on parthenium in New Alluvial Zone of West Bengal.
This paper presents the results of an experiment conducted in Murshidabad, West Bengal, India, during 2014-15 to study the biology and seasonal incidence of the Mexican beetle, Zygogramma bicolorata, on parthenium weed, Parthenium hysterophorus. Data were recorded on colour, shape, size and developmental periods of eggs, larvae, pupae and adults. The pre-mating, pre-ovipoition period and fecundity of the adults were also observed. The feeding behaviours of larvae and adults of the beetle were also investigated both in the laboratory and field. For studying seasonal incidence, natural population was recorded at weekly intervals from the randomly selected 50 parthenium plants. Simple correlation and multiple regression equations were worked out between the beetle populations per plant versus weather parameters (rain, maximum and minimum temperature, maximum and minimum relative humidity) during the summer, rainy and winter seasons of 2014-15.