Investigating on control of tomato fruitworm Helicoverpa armigera (Hbn.) by integrating chemical insecticides and the parasitoid wasp Habrobracon hebetor (Say) in field conditions

Document Type : Research Paper

Authors

• Ardavan Mardani ¹
• Qodratollah Sabahi ²
• AZIZ Sheikhigarjan ³

¹ Department of Plant Protection, Campus of Agriculture and Natural Resources, University of Tehran, Karaj, Iran.

² Department of Plant Protection, Campus of Agriculture and Natural Resources, University of Tehran, Karaj, Iran

³ Iranian Institute of Plant Protection, Tehran, Iran

Abstract

Keywords

• tomato fruit worm
• Habrobracon wasp
• integrated pest management
• yield rate

Extended Abstract

Introduction

Extensive application of insecticides has caused the phenomenon of insecticide resistance in tomato fruit worm, Helicoverpa armigera (Hbn.). To prevent the development of this process, scientists believe the frequency of insecticide application against this pest should be reduced. One of the methods to reduce the use of insecticides is to integrate them with biological control agents. In this study, the feasibility of controlling the tomato fruit worm in field conditions using an integrated pest management method with the use of two selective insecticides, pyridalyl, and chromafenozide, along with the most important and widely used biological control agent, Habrobracon hebetor (Say) has been studied.

Materials and Methods

To evaluate the effectiveness of the mentioned insecticides and parasitoids on the pest in field conditions, an experiment was designed in the form of a randomized complete block design in six treatments with three replications. This experiment was carried out in two tomato farms in the Kooshk area of ​​Marvdasht City in Fars province in 2019. To conduct field experiments, two fields were selected at a distance of more than 1200 meters in the Kooshk area to minimize the possibility of movement through its flight. The tested treatments include H. hebetor parasitoid, pyridalyl + parasitoid, chromafenozide + parasitoid, pyridalyl, chromafenozide, and control. The first three treatments were done in the separated farm and the next three treatments were done in the other farm. The number of the released parasitoid was 2500 per hectare (2000 female insects and 500 male insects) and the application of pyridalyl and chromafenozide insecticides was done as recommended field concentration, 150 ml. and 1.5 l. per hectare respectively.

Results and Discussion

The highest efficiency percentage was observed in the treatments of chromafenozide + parasitoid and pyridalyl + parasitoid and the lowest of this parameter was observed in the treatment of parasitoid. The highest amount of damaged tomato fruit was observed in the control treatment, and among the tested treatments, chromafenozide + parasitoid and pyridalyl + parasitoid treatments caused the greatest decrease in this parameter, and parasitoid treatment caused the least decrease in this parameter. The highest healthy green fruit yield was observed in the pyridalyl treatment, the highest healthy red fruit yield and the highest total yield were observed in the chromafenozide + parasitoid and pyridalyl + parasitoid treatments, and the lowest of these parameters was observed in the control treatment. Also, the lowest yield of damaged green fruit, red damaged fruit, and red shriveled fruit was observed in the treatments of chromafenozide + parasitoid and pyridalyl + parasitoid, and the highest of these parameters was observed in the control treatment. In addition, the highest increase in total yield was observed in the treatments of chromafenozide + parasitoid and pyridalyl + parasitoid, and the lowest of this parameter was observed in the treatment of parasitoid.

Conclusion

This study showed that combined treatments (pyridalyl + parasitoid, and chromafenozide + parasitoid) compared to single treatments (insecticides or parasitoid) had more effects on tomato fruitworm larvae so that by killing most of the larvae, the population of the pest has been reduced and, in this way, the tomato fruits have been protected from the damage of the larvae so that it has increased the yield. This study proved that the combination of pyridalyl insecticide or chromafenozide with the parasitoid wasp H. hebetor will be more successful in controlling the tomato fruit worm than the use of the insecticide or the parasitoid alone, and as a result, the use of pyridalyl or chromafenozide insecticides along with the parasitoid H. hebetor in the integrated management program of H. armigera is feasible.