Parasitism and hyper parasitism on Pyrilla Perpusilla Walker in sugarcane ecosystem

Abstract

The seasonal variation in parasitism on Pyrilla perpusilla Walker (Lophopidae: Homoptera) in situ by parasitoids were examined at fortnightly interval, from April to December 2004 (Plant crop) and 2005 (Ratoon crop) in sugarcane ecosystem. These fields were kept free from insecticidal applications. During, 2004 there was no parasitization in the month of April while 3.7± 0.2 per cent nymphs were parasitized in May first fortnight. With the increase in Pyrilla population, rise in parasitization by Epiricania melanoleuca (Epipyropidae: Lepidoptera) started and reached its peak 80.5± 4.9 per cent on nymphs in November second fortnight. Adult parasitization (6.2± 0.5%) was noticed in May first fortnight and touched its peak at 77.0± 5.1 per cent in November second fortnight. While during 2005 parasitization were observed at 82.3± 4.8 per cent on nymphs and 75.0± 3.9 per cent on adults in November second fortnight. The range of parasitization by E. melanoleuca on nymphs+ adults was 5.0± 0.4 to 78.8± 5.0 per cent and 4.8± 0.7 to 78.7± 4.4 per cent during 2004 and 2005, respectively. Significant negative correlation with maximum (r=−0.825) and minimum (r=−0.800) temperature and non significant positive correlation with Relative humidity (r=0.352) and Rain fall (r=0.242). Per cent parasitism by egg parasitoids (combined) viz., Parachrysocharis javensis, Cheiloneurus pyrillae and Ooencyrtus pyrillae varies from 23.8± 2.9 to 83.0± 5.8 per cent from the month of July to December based on egg mass but based on individual eggs it was 9.6±2.1 to 78.2±5.2 per cent. Highest parasitization was in the month of December. No hyper parasitoid recorded on egg of E. melanoleuca. The hyper parasitoid Ecthrodryinus sp. (0.7±0.2 to 2.3± 0.2 per cent) and Fusarium sp. (0.4± 0.1 to 6.8± 2.3 per cent) recorded on pupae of E. melanoleuca from September to November.