Insect‐screened cultivation to reduce the invasion of tomato crops by Bemisia tabaci: modelling the impact on virus disease and vector

Abstract

1 In two experiments carried out in Guadeloupe, barriers were used to reduce the entry of the virus vector Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) to tomato plots. The barriers erected around the crop were of insect-proof cloth fences (<50 mesh), 1.5 m in height, in the first experiment with a deltamethrintreated, insect-attracting strip facing inwards, and, in the second, with the barrier but no insecticide-treated strip. 2 A mathematical model of epidemic development was fitted to the symptom data from the treated and control (unprotected) tomato plots. There were two viruses present, tomato yellow leaf curl and potato yellow mosaic; specific detection confirmed that symptoms gave an accurate indication of infection and that the two virus diseases had similar progress curves. 3 Parameter estimates obtained by model-fitting suggested that the barriers reduced vector immigration by approximately 12-fold but that B. tabaci retention within the plots was also increased slightly despite the mortality caused by the insecticide-treated strips. Disease establishment was delayed by approximately 2 weeks. The results obtained in the second experiment involving barriers deployed without insecticide-treated strips could be explained by a large increase in B. tabaci retention within the barriers resulting in more rapid virus disease progress than in controls. The results of mathematical modelling indicate that partial insect barriers can be worse than none because sufficient whiteflies can enter to establish a population and, at the same time, large numbers are retained in the barrier plot, with the net effect being a more rapid population increase than in the absence of barriers.

Protected cultivation of vegetable crops in sub-Saharan Africa: limits and prospects for smallholders. A review

“…Contradictory results were obtained on cabbage in Benin since similar nets promoted the development of aphids and the finest mesh size did not improve protection against insect pests (Simon et al 2014). Similarly, modeling approaches used by Holt et al (2008) revealed that nets used on tomato crops without insecticide-treated strips can promote the development of whiteflies.…”

“…However, contradictory studies on hot pepper (Capsicum chinense Jacq.) in Uganda (Karungi et al 2013), on cabbage in Benin (Simon et al 2014;Martin et al 2013) and in Kenya (Kiptoo et al 2015), on tomato in Caribbean islands (Holt et al 2008) showed that insect nets provide insufficient protection against insect pests.…”

Sistemas de producción de tomates (Solanum lycopersicum M.) en Nicaragua: una caracterización en el municipio de Tisma, Masaya, Nicaragua

“…Principales plagas y enfermedades que afectan el cultivo en campo. Holt et al (2008), mencionan que la presencia de mosca blanca (Bemisia tabaci) en cantidades y tiempo después del trasplante es directamente proporcional al porcentaje de incidencia de virus en plantas. Se encontró que el 100% de los productores tienen conocimiento de las plagas que afectan el cultivo (Cuadro 3).…”

The Epidemiology of Plant Virus Disease: Towards a New Synthesis

“…The use of insect screening to prevent the entry of virus vectors is practiced in plant nurseries and in field cultivation for some horticultural crops. Experiments were designed to reduce the entry of Bemisia tabaci into tomato crops by insect screens, with or without insecticide-treated strips [ 88 ]. A mathematical model was developed using symptom data of tomato yellow leaf curl disease and potato yellow mosaic disease.…”