Leaf curl epidemic risk in chilli as a consequence of vector migration rate and contact rate dynamics: A critical guide to management

Authors: ROY, BUDDHADEB - Indian Council Of Agricultural Research (ICAR); VENU, E - Indian Council Of Agricultural Research (ICAR); SATHLYASEELAN, K - Indian Council Of Agricultural Research (ICAR); DUBEY, SHAILJA - Indian Council Of Agricultural Research (ICAR); Lakshman, Dilip; MANDAL, BIKASH - Indian Council Of Agricultural Research (ICAR); SINHA, PARIMAL - Indian Council Of Agricultural Research (ICAR)

Submitted to: Viruses
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/15/2023
Publication Date: 3/27/2023
Citation: Roy, B., Venu, E., Sathlyaseelan, K., Dubey, S., Lakshman, D.K., Mandal, B., Sinha, P. 2023. Leaf curl epidemic risk in chilli as a consequence of vector migration rate and contact rate dynamics: A critical guide to management. Viruses. https://doi.org/10.3390/v15040854.
DOI: https://doi.org/10.3390/v15040854

Interpretive Summary: Chili is an economically important spice crop grown in tropical and subtropical climates. A virus disease known as Chili Leaf Curl (ChiLCV) causes significant losses in the yield and quality of chili. The virus is transmitted by whitefly insects. Management of the virus utilizes barrier methods like transparent plant covers to prevent the virus-carrying whiteflies to land on the chili plants during the most susceptible and succulent growth period. In this investigation, several temporal and biological parameters of vector immigration, emigration, contact and virus transmission, and plant growth stages were factored into the equation to derive the most important factors driving the epidemics of ChiLCV. Subsequently, such factors were translated into rules for developing improved management strategies. The inferences made from those experiments will be highly useful for the better management of whitefly-transmitted plant virus diseases. The information gathered will also be helpful to plant pathologists, epidemiologists, extension workers, and farmers.

Technical Abstract: Chili is an important commercial crop grown in tropical and subtropical climates. The whitefly transmitted Chili leaf curl virus (ChiLCV) is a serious threat to chili cultivation. Migration rate and host-vector contact rate as the major drivers involved in the epidemic process have been identified. Complete interception of migrant vectors immediately after transplantation effectively prevented the epidemic. Interception has been noted to increase the survival time (to remain infection free) of the plants. The plant survival time under interception (30 days) has been noted to be 9 weeks (P<0.05) higher than in plants that received less period of interception (14-21 days). Non-significant differences in hazard ratios between 21- and 30-day interceptions helped optimize the cover period to 26 days. Feeding rate estimate as a component of contact rate is noted to increase with host density and peaks at 6 weeks, and declines subsequently. Correspondence between the peak time of virus transmission or transfer rate (at 8 weeks) and peak contact rate suggests that host succulence is of critical importance in host-vector interaction. Infection proportion estimates in inoculated plants at different leaf stages have supported the view that virus transmission potential with plant age decreases presumably due to modification in contact rate. The hypothesis migrant vectors and contact rate dynamics are the major drivers of the epidemic has been proved and translated into rules for evolving rational management strategies.