Natural Control of Sugarcane Top Borer Scirpophaga excerptalis Walker (Crambidae: Lepidoptera) by Its Egg Parasitoids

Abstract

The sugarcane shoot borer (Scirpophaga excerptalis) is an herbivorous insect that primarily infests sugarcane plants, leading to the development of dead heart symptoms. This study aimed to investigate the contribution of egg parasitoids in mitigating the occurrence of dead heart caused by S. excerptalis infestation. The research was conducted in Asembagus and Malang, East Java, Indonesia. The samples collection of shoot borer eggs were done twice in Asembagus, and three times in Malang. The collected eggs were examined to determine the percentage of parasitism, and the emerged parasitoids were identified. The infestation level of shoot borers was evaluated by counting the dead heart symptoms within 5 m2 observation units, comprising 18 and 15 units in Asembagus and Karangploso, respectively. Three species of parasitoids, namely Telenomus sp., Trichogramma chilonis, and Tetrastichus sp., were found to parasitize S. excerptalis eggs. The average parasitism levels by Telenomus sp., T. chilonis, and Tetrastichus sp. were 74% (ranged: 50-100%), 0.6% (ranged: 0-4.4%), and 14.3% (ranged: 0-100%), respectively. Telenomus sp. was the predominant egg parasitoid observed in all observations at both sites. There was an inverse relationship between the mortality of shoot borer eggs by parasitoids and the occurrence of dead heart symptoms. Higher levels of parasitism were associated with reduced dead shoot symptoms. The natural control of S. excerptalis through the complex of egg parasitoids holds a promise for effective management of sugarcane shoot borers and promoting sustainable agriculture.