Impact of intercropping and low-external input integrated pest management on Spodoptera frugiperda (J. E. Smith) in maize

Context

The Fall armyworm (FAW) or Spodoptera frugiperda, an invasive insect pest, is polyphagous and destructive to maize crop in India. Farmers are resorting to the indiscriminate use of insecticides for its control. Solely resorting on chemical insecticides is uneconomical, and unsustainable. Further, practicing monocropping encourages pest incidence while intercropping creates the crop diversity and provides natural control. Thus, it is imperative to identify environmentally and economically sustainable pest management options.

Objective

Achieving a system with improved entomological, agronomical, and economic efficiencies by accomplishing low-external-input integrated pest management (LEIIPM) and promoting the crop diversity through intercropping for the management of S. frugiperda.

Methods

Efficacy of the pest management treatments based on readily available low external inputs such as application of additional K-nutrition, prophylactic measures, biorationals and their integration as LEIIPM module were evaluated in comparison with chemical control and untreated check. These treatments were imposed across three cropping systems viz., sole crop of maize, maize+cowpea (1:2), and maize+pigeonpea (2:1). Insect pest incidence was monitored at weekly intervals by recording absolute larval population, leaf damage, and the natural enemy (Coccinellids and Spiders) population. The competitive behavior of maize and intercrops was estimated in terms of maize equivalent yields (MEY) land equivalent ratio (LER), and area time equivalent ratio (ATER). The economic efficiency of these systems in terms of marginal rate of returns (MRR) and benefit-cost ratio (BCR) was evaluated.

Results

Intercropping maize with cowpea reduced the absolute larval population in the vegetative (30 %) and reproductive stages (24.54 %) of the crop in LEIIPM. A similar reduction was observed when intercropped with pigeonpea. Natural enemy population (coccinellids and spiders) was higher in maize+cowpea system (1.19 and 0.94) followed by maize+pigeonpea (1.1 and 0.86) with LEIIPM module. Agronomic efficiency measured in terms of MEY (58.10), LER (1.69) and ATER (1.45) and economic efficiency in terms of BCR (1:5.45) and MRR (6.45) were higher in maize+cowpea system with LEIIPM module.

Conclusion

Integration of diversified cropping systems with non-chemical approaches in the form of LEIIPM was agronomically suitable, entomologically efficient, and cost-effective in the management of S. frugiperda in maize crop.

Implications

LEIIPM with diversified intercropping systems in maize offers effective and economical insect pest management. However, in order to achieve the effective management, timeliness, planning, preparation in advance and area-wide adoption are required.