Population dynamics of cow bugs and their natural enemies in pigeon pea

Abstract

Background: Cow bugs are seen in groups, mainly in fresh and terminal branches on their host plants. Both nymphs and adults of cow bugs exude a sugary (honey dew) liquid which is consumed by ants which in return may help to protect the cow bugs from natural enemies. The common name of cow bug is derived from this habit of providing 'milk' to the ants. The most potential and abundant natural enemy observed was the aphelinid parasitoid parasitizing the cow bug eggs. Methods: The population of cow bugs and ants were recorded on 10 randomly selected pigeonpea plants from different directions of the experimental plot. Under field condition, the natural enemies like predator and parasitoids were observed on different stages of cow bugs on randomly selected ten plants of pigeonpea. For parasitoids observation, collection of different stages of cow bugs and aphids was made from five randomly selected pigeonpea plants. Statistical analysis: Mean population was calculated for the number of cow bugs per plant and correlation and regression analysis was done by using WASP software. Results: Two predatory spiders belong to genus Argiope were observed throughout the period of observation from October 2020 to March 2021. The most potential and abundant natural enemy observed was the aphelinid parasitoid parasitizing the cow bug eggs. The egg parasitoid Centrodora sp. (Hymenoptera: Aphelinidae). The Centrodora sp. wasp, a solitary endoparasitoid had no species specificity and found parasitizing eggs of Otinotus sp. and O. apicalis. Parasitized eggs were differentiated from unparasitized as they took much longer time to hatch and upon hatching the parasitoid formed a distinct round emerging hole and the egg shape remained intact.