Impact of predatory ants on two lepidopteran insect pests in Indian cauliflower agroecosystems

Abstract

The impact of predatory, agroecosystem-nesting ant species on the larval stages of the two major lepidopteran pests, the diamondback moth (DBM), Plutella xylostella and the black cutworm (BC), Agrotis ipsilon, in cauliflower agroecosystem in Uttar Pradesh, India, was investigated in farmersÕ fields. Field observations revealed that six ant species, the most important being Pheidole sp., preyed on the crop-damaging stages of DBM and BC. Bait experiments with larvae of DBM and BC, placed randomly on the ground, demonstrated significant active retrieval by Pheidole sp. Investigations on larval density of both the insect pests on cauliflower crops, located within 1-5 m distances from nests of Pheidole sp., revealed a significant increase in the level of infestation of the crop plants with increasing distance from the ant nests. While a significant negative correlation was found between infested plants with low larval densities, a positive correlation was found between plants with high larval densities with regard to the distance of crop plant location from the ant nest. Ant-inclusion and -exclusion experiments under field conditions further confirmed the role of predatory ants, with Pheidole sp. having the major impact in the direct retrieval of the lepidopteran larvae from the crop plants. A significant difference was found in the leaf area damaged by BC larvae between the ant-included andexcluded potted plants during the 6-h observation period. Thus, this study provides direct evidence of the role of ants in actively searching and directly preying on the larval stages of DBM and BC, on cauliflower plants. Moreover, we demonstrate that in ephemeral, annual cropping agroecosystems, predatory ants are important natural enemies of lepidopteran pests, playing a significant role in plant protection.

A Survey on Occurrence and Diversity of Insect Pests of Cauliflower in Dindigul and Theni Districts of Tamil Nadu, India

“…1). Variance of these pests from season to season and region to region is comparable with the findings of Sachan and Srivastava, (1972), Sachan and Gangwar (1990) and Chaudhuri et al, (2001), Sarfarazet al, (2005 (Firakeet al, 2012, Jalali et al, 2003, Agarwal et al, 2007, Sood, 2004 Fig. 2).…”

How effective are disturbance – tolerant, agroecosystem – nesting ant species in improving soil fertility and crop yield?

“…The enriched material used as an organic amendment to paddy and tomato plants results in fertilizer responses in these plants and concomitant correlations between performance parameters and soil fertility attributes, in a dose-dependent manner. Since P. latinoda foragers also prey on economically important insect pests such as Plutella xylostella and Agrotis ipsilon (Agarwal et al, 2007), this ant species has the potential to improve crop plant fitness through multiple pathways. Thus, agroecosystem productivity can be enhanced by conserving and/or augmenting the colonies of P. latinoda.…”

“…In an earlier study, we have reported that P. latinoda foragers prey on economically important insect pests such as Plutella xylostella and Agrotis ipsilon, in annual cropping systems (Agarwal et al, 2007). We have also found that the worker ants discard arthropod exoskeletons, seed fragments, leaves etc.…”

“…Many ant species abound in tropical crop fields (Choate and Drummond, 2011), such as sponge gourd (Agarwal and Rastogi, 2008) cauliflower (Agarwal et al, 2007) and even in the earthen banks of rice fields (Way and Heong, 2009) where they play a significant role in insect pest suppression (Way et al, 2002). Many ground-nesting ant species tolerant to the disturbance regimes of annual cropping systems play an important role in suppressing/repelling insect pests of crops (Agarwal et al, 2007;Agarwal and Rastogi, 2008). Their role in the soil fertility management of agroecosystems merits study, particularly in view of the recent recognition (Powell and Eisenhauer, 2015) of the importance of soil ecological health.…”

Ant Community in Neotropical Agrosystems: A Four-Year Study in Conventional and No-Tillage Systems

“…In addition to their role as bioindicators of environmental change, most ant species are efficient predators of other insects, contributing to pest control in crops (Perfecto, 1991;Agarwal et al, 2007;Rico-Gray & Oliveira, 2007;Lange et al, 2008). According to Booij and Noorlander (1992), ants, beetles and spiders are the most effective generalist predators in agrosystems.…”