Modelling of tea mosquito bug (Helopeltis theivora) incidence on neem tree: A zero inflated count data analysis

Abstract

Neem (Azadirachta indica) is an evergreen tree belonging to the Meliaceae family and is highly infected by the seasonal pest called Helopeltis theivora, the tea mosquito bug. The study monitors the pest infection between May 2019 and April 2021 by the direct counting method. Weekly counts of insect pest population were found to be correlated with weather parameters viz., maximum temperature (Tmax.), minimum temperature (Tmin), relative humidity [morning (07.22hrs) and afternoon (14.22hrs) (RH)], rainfall (mm/day) and wind speed (km/h). Zero inflated count data techniques were opted for modelling the pest dynamics of tea mosquito bug as the data was featured by excess zeroes and heteroscedasticity nature. Poisson, Negative Binomial (NB), zero-inflated Negative Binomial (ZINB) and Negative Binomial Hurdle (NBH) models were fitted for the collected data and compared. The results of different count data models show that the negative binomial hurdle model is a good fit for given data, followed by the zero-inflated negative model. The fitted models show the weather covariates, which highly influencing the pest infestation on neem tree.

Keywords

• Count data models
• Helopeltis theivora
• Statistical models
• Weather parameters