Effect of abiotic factors on the incidence of hadda beetle, (Henosepilachna vigintioctopunctata) in arid region of Rajasthan

The muskmelon and watermelon are gaining popularity among the farmers of arid and semi arid areas for economic cultivation. However, the quality of fruits and productivity is not obtained up to the standard. One of the reasons is infestation of insect pests on the vegetative as well as developing fruits which ultimately leads to significant yield loss and quality attributes of the fruits. It revealed from the study that the damaging effect of hadda beetle, Henosepilachna vigintioctopunctata was recorded on muskmelon and watermelon from March to June. The damaging intensity of this hadda beetle was recorded 20 to 29 percent leaves damage.  The minimum population (0.27 in muskmelon & 0.47 in watermelon per plant) of hadda beetle was recorded in the month of March (first fortnight). The mean population of hadda beetle 2.88 per plant in muskmelon and 2.39 per plant in watermelon were recorded. Maximum population of hadda beetle (6.67 & 5.47 per plant in muskmelon & watermelon, respectively) was recorded in the month of June (first fortnight). The relationship between hadda beetle population in muskmelon (0.83) and watermelon (0.79) with maximum temperature was positively correlated whereas, the maximum relative humidity was (-0.35 & -0.39) negatively correlated. The rainfall was also positively correlated (0.58 & 0.66) with beetle population of muskmelon and watermelon in arid region. It is concluded that the beetle population gradually increased and reached to its peak, when the temperature increased and humidity decreased.