Identifying control strategies for tomato leaf curl virus disease using an epidemiological model

Abstract

Summary1. A number of insect vectors of plant-virus diseases make only transitory visits to the crop in which the economic eects of the disease are important. The incidence of disease in the crop depends primarily on the immigration of vectors from alternative hosts which act as a reservoir of both the virus and vector.2. An epidemiological model was developed to represent this situation and parameters were estimated for the case of tomato leaf curl virus disease (TLCVD) (Geminiviridae, Subgroup III) in India. From an analysis of the model, the following possibilities for the management of TLCVD emerged. 3. It was clear that varietal resistance to infection could be an important component of disease management but whether, once infected, the tomato plants acted as a source of inoculum had little impact on disease incidence in the tomato crop. 4. A very low rate of simulated vector immigration into a tomato crop suced to cause almost total infection. Around Bangalore, vectors may migrate into tomato crops in numbers in excess of those required for disease`saturation', explaining why, using conventional insecticides, very ecient and intensive vector control is currently required to reduce disease incidence. 5. Disease incidence was sensitive to vector mortality only when vector numbers were low. In most cases, the immigration of viruliferous vectors made disease incidence insensitive to the mortality of vectors within the tomato crop. 6. A strategy for disease management which targets more than one of the parameters to which the model proved most sensitive is likely to be necessary. In particular, the use of protective netting combined with the growing of resistant varieties has the potential to reduce both B. tabaci immigration to the crop and to reduce virus inoculation by those insects which do reach the crop.

Variations of Incidence, Types of Virus Diseases and Insect Vector Populations of Tomato (Solanum lycopersicum L.), Grown in Different Agroecological Regions of Sri Lanka under Two Crop Management Systems

“…This could be due to similar effects caused by the application of insecticides and the components present in the IMP system towards increasing vector death rate, decreasing vector immigration rate and increasing vector departure rate (Holt et al, 1999). This possibility agrees with the potential for reducing disease incidence of TYLCVD and TSWVD significantly by integrating multiple management practices as highlighted by Hilje et al (2001) and Culbreath et al (2003), respectively.…”

Development of tomato hybrids resistant to tomato leaf curl virus disease in South India

“…For vector control, farmers readily apply excessive quantities of insecticides, often exceeding 50 applications during a crop cycle (Nagaraju et al 2002), at great risk to themselves and to the environment. However, ToLCVD management measures based on control of the vector population are unlikely to be successful because of the high turnover rate of the vector population in the crop (Holt et al 1999). A more eVective and environmentally acceptable means of control is through breeding cultivars resistant to both ToLCV (Nateshan et al 1996;Lapidot et al 1997;Pico et al 1998) and B. tabaci (Channarayappa et al 1992).…”

Mathematical models are a powerful method to understand and control the spread of Huanglongbing

“…In a later paper, Holt et al (1999) within a citrus grove, or from grove to grove. We review here those models which have been applied to 175 HLB because they demonstrate the major insights models have already provided to this disease system.…”