Restricting lepidopteran herbivory through trap cropping and bird perches in Egyptian clover (Trifolium alexandrinum L.)

Ravinder Kumar,Harpreet Kaur Cheema

doi:10.1186/s41938-020-0210-0

Ravinder Kumar, Harpreet Kaur Cheema

Open Access

https://doi.org/10.1186/s41938-020-0210-0

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Abstract

The Egyptian clover L. is a winter season leguminous forage that supports a great diversity of insect pest populations in the Northern Indian Plains. In the context of evolving non-chemical approach for pest control, different trap crops viz. marigold, Tagetes erecta: chickpea, Cicer arietinum L.; and sunflower, Helianthus annuus, were planted as border rows around the clover plots to trap lepidopteran larvae. The push and pull strategy was further augmented by the help of neem seed kernel extract (NSKE) 3% spray on the main crop. Services of insectivorous birds were utilized through T-shaped bird perches for feeding on lepidopteran larvae. The lowest larval population of Helicoverpa armigera (2.29 individuals/m row length) was recorded in the plots with the trap crops such as marigold and bird perches, and those that received neem insecticidal sprays which indicated the decrease of larval population due to the repellant action of neem gave (75.8%) a reduction in larval population than the sole cropped plots, followed by chickpea (2.58 larvae; 72.8%) reduction in larval population and sunflower (3.53 larvae; 63%). Sunflower recorded the highest number of H. armigera population, at flowering stage of berseem which depicted the suitability of sunflower for the attractiveness of low number of the larvae (2.75 larvae/m row length) on berseem. The plots with berseem as a sole crop without any control measure exhibited significantly high H. armigera larvae (12.95 larvae per meter row length). The fecundity of pod borer on different trap crops revealed the highest fecundity population (7.25 larvae) of Helicoverpa on either chickpea or sunflower as trap crops. During the vegetative phase of berseem and the flowering stage of marigold and sunflower, these were recorded as favorable hosts. The highest green fodder yield (GFY; 1115 q/ha) was recorded in plots sown with marigold as the trap crop and with bird perches and in plots that received NSKE sprays as compared to sole cropped plots (700 q/ha). The data on seed yield also revealed superiority of berseem plots with sunflower, as a trap crop, and also a high parasitization by parasitoids.

Highlights

The Egyptian clover, Trifolium alexandrinum L., a nitrogen-fixing, multi-cut forage crop, is cultivated around 2 million hectares in entire India, spanning the north west zone, the hill zone, and part of the central and eastern zone of the country
H. armigera population As shown in Table 1, larval population recorded during the vegetative stage of berseem started appearing during March (3.22–7.48 larvae/m row length) across all the treatments, and its population tends to decline in April over the two seasons of study (Table 1)
The berseem plots with border row of marigold, chickpea, and sunflower as trap crops with additional neem seed kernel extract (NSKE) sprays harbored larval numbers comparatively lower than the plots with same trap crop without spray of biopesticide

Summary

Introduction

The Egyptian clover (berseem), Trifolium alexandrinum L., a nitrogen-fixing, multi-cut forage crop, is cultivated around 2 million hectares in entire India, spanning the north west zone, the hill zone, and part of the central and eastern zone of the country. A broad spectrum of lepidopteran and other species of insect pests hampers crop establishment, impairs forage quality, and reduces green fodder and seed yield (Saxena et al 2002). Insect pests such as the American bollworm (Helicoverpa armigera Hub.), beet armyworm (Spodoptera exigua Hub.), Bihar hairy caterpillar (Spilosoma oblique Walk.), hairy caterpillars (Euproctis virguncola and E. lunata), green semi-looper (Plusia nigrisigna (Wlk.), Thysanoplusia orichalcea Fab.), cowpea aphid (Aphis craccivora Koch.), and leaf miner (Phytomyza sp.) are reported to cause damage to berseem during their different growth stages (Shah et al 2010).

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