Spatio-temporal dynamics of mealybug (Hemiptera: Pseudococcidae) populations in plantations of Jatropha curcas L. in Yucatan, Mexico

Mealybug Paracoccus marginatus Williams and Granara de Willink (Hemiptera: Pseudococcidae) is an important pest of physic nut Jatropha curcas L. (Euphorbiaceae), infestations can be severe and dispersion is unknow. The objective was to determine the temporal and spatial dynamics in four experimental areas in 2014 and 2015 in Yucatan, Mexico. Incidence (mealybug-infested or uninfested plants) was assessed from May to July at nearly-regular day intervals. Temporal analysis was carried out using deterministic, growth epidemiological models, whereas spatial analysis was conducted through mapping, randomness tests and spatial autocorrelation. The exponential and logistic models described the incidence of mealybugs in 2014 with a coefficient of determination (R2 = 0.9 and 0.9); mean square error (MSE = 0.66 and 0.70); and P value < 0.05 for both models, respectively. The three spatial analysis methods showed the presence of a random dispersion pattern of mealybug-infested physic nut plants at the beginning of the epidemic followed by a rapid anisotropic aggregation (along rows) by mid-June to end of July in the four experimental areas. Infestations intensify within rows, forming aggregates of up to 41 contiguous plants. The results suggest that practices for control of this pest in the region should be implemented from early to mid-May, before aggregates of infested plants start to form and serve as sources for mealybugs dispersal across rows and over larger distances.