Effect of Infestation Density with Phelipanche aegyptiaca on the Efficiency of Bio-agent, Phytomyza orobanchia and Infestation by Tuta absoluta on Tomato Crop at El-Beheira Governorate, Egypt

Abstract

Tomato is the most susceptible hosts to many insect pests and broomrape, which causes significant yield losses. The present study was carried out with the purpose to know which infestation density of Egyptian broomrape (Phelipanche aegyptiaca Pomel) was affected on efficiency the bio-agent, Phytomyza orobanchia Kaltenbach (Diptera: Agromyzidae) in the area grown with tomato crop, which was affected at the same time by tomato leaf miner, Tuta absoluta (Meyrick) (Gelechiidae: Lepidoptera) under natural conditions during two successive years (2019 and 2020) at El-Beheira governorate, Egypt. Three randomized fields cultivated with tomato crop in summer were selected during 2019 and 2020. Infestation density with Ph. aegyptiaca was divided into three levels, Low (1 -10 shoots / plant), Medium (11 -25 shoots / plant) and High (≥ 25 shoots / plant). Number of pupae in capsules, number of pupae in stems, total number of pupae in shoots and the percentage of pupae in capsules were determined per Ph. aegyptiaca shoot. Highest effectiveness of P. orobanchia (36.0%) was recorded in low infestation density with Ph. aegyptiaca, while with medium and high infestation density with Ph. aegyptiaca only 23.5% and 18.6%, respectively in second year 2020. No significant difference was found between low and medium infestation density with Ph. aegyptiaca in the total number of P. orobanchia pupae per shoot. At the beginning of fruiting stage of tomato crop, leaves and fruits were taken from the randomly selected tomato plants according to infestation density with Ph. aegyptiaca flourishes, to estimate the infestation percent by leaf miner (Tuta absoluta) throughout the two year (2019-2020). In addition to, percentage of parasitism by egg parasitoids of the genus Trichogramma on tomato leaf miner was determined. According to infestation density with Ph. aegyptiaca, tomato yield was calculated. At the end of this study, under the medium infestation density of Egyptian broomrape the infestation percent by T. absoluta was (16.67%) synchronized with high percentage of its parasitoid, Trichogramma spp. (63.2%) with high yield of tomato (820 gm/ plant) compared with control (without infestation with Ph. aegyptiaca).Obtained data may provide information for improving effective of P. orobanchia in biological control program of Ph. aegyptiaca in the frame of integrated pest management (IPM) of T. absoluta in tomato fields. However, combining Egyptian broomrape (Ph. aegyptiaca) and T. absoluta in IPM program will contribute to management efficacy as well as avoid used each control methods separately for each pest. Further research is needed to choose the timing in combining between these pests to use IPM, taking into consideration efficacy, cost and environmental aspects.