Approaches to conservation of Nesidiocoris tenuis for biological control of pests in field-grown tomato in Senegal

Abstract

Conservation biological control is a promising approach to natural pest control in both open field and protected crops. In sub-Saharan Africa, tomato crops are commonly damaged by several arthropod pests but can also host the predatory mirid bug, Nesidiocoris tenuis. Unfortunately, farmers do not currently take full advantage of this zoophytophagous and generalist biocontrol agent. We conducted field investigations in the Niayes area of Senegal, combined with laboratory experiments, to determine how to enhance natural regulation services provided by this natural enemy. We found that strong full-plant watering and insecticidal sprays, both conventionally applied in the Niayes area, had a detrimental effect on N. tenuis. We identified Sesamum radiatum (false or black sesame) as a promising insectarium plant that could also serve as a leaf vegetable and medicinal plant. This plant supports good N. tenuis development and reproduction, even without alternative food sources. Y-tube olfactometry indicated no attraction to odors of Sesamum radiatum, suggesting that N. tenuis would not abandon tomato plants for this insectarium plants when present in tomato fields. Our results suggest potential approaches to improve conservation of N. tenuis for biological control of Tuta absoluta and other tomato pests in Africa.