Field evaluation of alternative plants for the management of Nesidiocoris tenuis


Abstract: Nesidiocoris tenuis (Hemiptera: Miridae) is a generalist predator able to feed on a
wide range of arthropod pests and it is largely applied on tomato protected crops through
augmentative releases and conservative strategies. However, the predatory mirid may cause
damage to tomato plants due to its zoophytophagy. Nevertheless, habitat management strategies through the use of alternative plants can mitigate this adverse impact. We evaluated the suitability of sesame (Sesamum indicum) and/or verbena (Verbena x hybrida) when intercropped on greenhouse tomatoes for N. tenuis management. Four plots of 1.000 m2 with 1.100 tomato plants each were compared as follows: (i) tomato + sesame, (ii) tomato + verbena, (iii) tomato + verbena and sesame, and (iv) tomato only as a control plot. Rows of sesame and/or verbena were placed in the central part of the plots and N. tenuis naturally occurred with uniform density at the beginning of the trial. Nesidiocoris tenuis adults and nymphs, and the “”necrotic rings”” caused on tomato stems and leaf petioles were counted for three months in 2021 and repeated for two subsequent crop cycles. We also recorded the number of N. tenuis adults, other arthropod pests and natural enemies on alternative plant rows and chromotropic trap bands. Both alternative plants showed good adaptability, but sesame development was strongly impaired by low temperatures during the first crop cycle. By contrast, verbena plants developed regularly and flowered constantly and abundantly in both crop cycles. Sesame and verbena plants resulted both attractive for N. tenuis adults, but they did not differ in comparison with tomato plants. Interestingly, the number of rings recorded in the tomato plants intercropped with sesame was significantly lower than in the control plot. Although preliminary results are promising, further field trials are required to optimize this strategy in different seasonal and cultural conditions. The potential of verbena intercropping on other horticultural crops is also discussed.

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