Biodiversity of insect pests and their natural enemies in betelvine ecosystem in Andhra Pradesh.
A fixed plot survey was conducted during 2006-07 and 2007-08 to study population dynamics of betel vine [Piper betle] pests and their natural enemies in Chinthalapudi, Andhra Pradesh, India. The densities of insect pests and natural enemies were recorded at fortnight intervals. Initial infestation was observed on sesbania (Sesbania grandiflora); pests were monitored until the betel vine was lowered. The incidence of leaf-eating larvae on sesbania was highest during the first fortnight of September (113 infested plants/30 m2). These pests persisted until the second fortnight of February, and a second peak was recorded during the second fortnight of October (79 infested plants/30 m2). The leaf-eating larval complex on sesbania included Eurema hecabe, Hyposidra successaria [Hyposidra talaca], Maruca testulalis [Maruca vitrata], Spodoptera litura and Helicoverpa armigera. The incidence of stem borer, Azygophleps scalaris, was observed from the first fortnight of August to the second fortnight of November. Peak activity was evident during the first fortnight of September (8 infected plants/30 m2). The population of leaf-eating larvae and stem borer were positively correlated with minimum temperature and negatively associated with maximum relative humidity. Damage by Spodoptera litura and red spider mites was negatively correlated with maximum temperature and maximum relative humidity. The population of white mite exhibited a negative correlation with rainfall, minimum relative humidity, and minimum temperature. Spiders were the dominant predators in the betel vine ecosystem. Natural epizootics of nuclear polyhedrosis virus (NPV) and Nomuraea rileyi were observed. H. successaria and Spodoptera litura were parasitized by Cotesia species. Brachymeria megaspila, B. tibialis, Coccinella septempunctata and Chilomenes sexmaculata [Cheilomenes sexmaculata] were also present as natural enemies.