Studies on major insect pests of French bean (Phaseolus vulgaris L.) and bio-efficacy evaluation of newer insecticides

Introduction

The French bean (Phaseolus vulgaris L.) is an annual, diploid (2n=2x=22), herbaceous plant belonging to the Fabaceae family and the Phaseolus genus. Common bean (Phaseolus vulgaris L.; Fabaceae) is a legume of importance, and it is also known as French bean, kidney bean, snap bean, runner bean and string bean (Onder et al., 2006) [6] . Today, the common bean is considered one of the most important legumes globally. In India, dry seed varieties are commonly referred to as "French beans." The yield losses due to insect pests alone have been estimated to the tune of 35 to 100%. Both biotic and abiotic factors impact crop production. French beans are affected by around 30 insect pests, including common sucking pests such as aphids (Aphis craccivora), leafhoppers (Empoasca dolichi), thrips (Megalurothrips sjostedti), whiteflies (Bemisia tabaci), and mites (Tetranychus urticae) (Srivastava and Butani, 1998) [8] . Leguminous plant species are susceptible to many biotic stresses, including attacks by many different insect pests and diseases. Pest and disease problems are the major constraints to agricultural productivity of the common bean, particularly in the tropics (Graham and Vance, 2003) [2] . Worldwide, yield losses due to insect pests alone have been estimated to the tune of 35% to 100% annually (Singh and Schwartz, 2011) [7] . The pods are also rich in minerals and vitamins. Additionally, French beans have medicinal benefits, such as helping control diabetes, heart problems, and bladder issues. They also have properties that can help with constipation and diarrhea.

Materials and Methods

Efficacy of botanical and chemical insecticides

Preparation of pesticide solution

The insecticides and biopesticides of the required concentration were prepared in water and sprayed after the proper stirring of the solution. The knapsack sprayer fitted with a flat cone nozzle was used to spray the material. The insecticidal solution was prepared using the following formula:

Where, C1 = Concentration of given formulation (%) V1 = Volume/amount of formulation required (ml or g) C2 = Concentration of spray fluid required (%) V2 = Volume/amount of spray fluid required.

Method of application of insecticides

Treatment wise applications of insecticides were given after the appearance of the pests by using high volume sprayer with required concentration. The subsequent second spray was made after 15 days of first spray.

Spray schedule of insecticidal solution

All the insecticides were applied as foliar spray in morning or evening hours on the crop using pre-calibrated knapsack sprayer when the pest population built up sufficiently on 13th January, 2023 and second was repeated after 15th days of the first spray when pest populations again built up. An untreated check was maintained for comparison.

Observation methods

The data on population of french bean aphid A. craccivora three shoots were observed on each selected plant and the population of aphids was counted from 10 cm length of each shoot. The pre-treatment observation was recorded at one day before 1st spray and post treatment observations were recorded at 1, 3, 7, 10 and 14th days after each spray.

Interpretation of data

The data obtained just before treatment and one, three, seven, ten and fourteen days after the spray were taken into consideration to find out the percent reduction in the population which was determined using the Henderson and Tilton (1955) [5] equation:

Percent reduction in pest populatio = 1 -Ta x Cb Tb x Ca 𝑋100

Where, Ta = Population in treated plots after treatment Tb = Population in treated plots before treatment Ca = Population in untreated plots after treatment Cb = Population in untreated plots before treatment.

Statistical analysis

The data obtained were analysed statistically after using appropriate transformation. Square-root transformation is appropriate for data consisting of small whole numbers, for example, data obtained in counting rare events, such as the number of infested plants in a plot, the number of insects caught in traps, or the number of weeds per plot. The square-root transformation is also appropriate for percentage data where the range is between 0 and 30% or between 70 and 100%. For other ranges of percentage data use the arc sine transformation. If most of the values in the data set are small (e.g., less than 10), especially with zeroes present, √(X + 0.5)/1/2 should be used instead of X1/2, where X is the original data. All percentage data of experiments were processed under square-root transformation before statistical analysis. This transformed data was then analyzed by the method of analysis of variance. The "F" test was used at 5 percent level of significance. Critical difference (CD) values were analysed at 5 percent level of significance (Gomez and Gomez, 1984; Draper and Smith, 1998) [4,1] . CD = SEd (Standard error of deviation) x Table t-value at 5% of significance.

Result and Discussion

A) Efficacy of insecticide and biopesticides against Aphid: first spray On evaluation of the bio-efficacy of different modern insecticide and biopesticides against aphids on french bean revealed that the pre-treatments observations were nonsignificant to each other with incidence ranged from 12.11 to 19.82 percent during Rabi 2022-23. After first spray, at 1 days the lowest infestation (2.95%) of Aphid was recorded in T5-Chlorpyrifos 20 EC @ 200 g a.i./ha (2.95%). followed by T4-Sulfoxaflor 12% SC @ 33.75 g a.i./ha (2.98%)., T3-Sulfoxaflor 12% SC @ 27 g a.i/ha (3.04%), T2-Sulfoxaflor 12% SC @ 24 g a.i./ha (3.10%). T1-Sulfoxaflor 12% SC @ 21 g a.i./ha (3.17%), and T6 Imidacloprid @ 25.00 g a.i./ha (5.40%) The least effective treatment was T7-Lecanicillium lecanii @ 10% (1x108) CFU/ml (10.55%) percent infestation of aphids but it was significantly superior over untreated control recorded 18.30 percent Aphids/plant. After 3 days of first spray, different chemical insecticides and biopesticides were significantly superior to untreated control. Among the different treatments, lowest (3.08%) aphids were found in T3-Sulfoxaflor 12% SC @ 27 g a.i./ha which was significantly superior over untreated control with 24.70 percent infestation followed by T4-Sulfoxaflor 12% SC @ 33.75 g a.i./ha (3.22%), T2-Sulfoxaflor 12% SC @ 24 g a.i./ha (3.26%), T1-Sulfoxaflor 12% SC @ 21 g a.i./ha (3.37%), T5-Chlorpyrifos 20 EC @ 200 g a.i./ha. (3.40%), T6 Imidacloprid @ 25.00 g a.i./ha (5.88%) and the least effective treatment was T7-Lecanicillium lecanii @ 10% (1x108) CFU/ml (8.08%) which was significantly superior over untreated control with 20.84 percent infestation. After 7 days of first spray, different chemical insecticides and biopesticides were significantly superior to untreated control. Among the treatments, lowest (3.02%%) aphids were found in T4-Sulfoxaflor 12% SC @ 33.75 g a.i./ha (3.02%), which was significantly superior over untreated control with 23.79 percent infestation followed by T3-Sulfoxaflor 12% SC @ 27 g a.i./ha (3.18%), T2-Sulfoxaflor 12% SC @ 24 g a.i./ha (3.39%), T1-Sulfoxaflor 12% SC @ 21 g a.i./ha (3.54%), T5-Chlorpyrifos 20 EC @ 200 g a.i./ha. (4.78%), T6 Imidacloprid @ 25.00 g a.i./ha (6.50%) and the least effective treatment was T7-Lecanicillium lecanii @ 10% (1x108) CFU/ml (6.68%).

After 10 days of first spray, different chemical insecticides and biopesticides were significantly superior to untreated control. Among the treatments, lowest (3.66%) aphids were found in T4-Sulfoxaflor 12% SC @ 33.75 g a.i./ha (3.66%), which was significantly superior over untreated control with 24.15 percent infestation followed by T3-Sulfoxaflor 12% SC @ 27 g a.i./ha (4.19%), T2-Sulfoxaflor 12% SC @ 24 g a.i./ha (4.41%), T1-Sulfoxaflor 12% SC @ 21 g a.i./ha (4.74%), T5-Chlorpyrifos 20 EC @ 200 g a.i./ha. (5.72%), T6 Imidacloprid @ 25.00 g a.i./ha (6.96%) and the least effective treatment was T7-Lecanicillium lecanii @ 10% (1x108) CFU/ml (8.35%). After 14 days of first spray, different chemical insecticides and biopesticides were significantly superior to untreated control. Among the treatments, lowest (4.02%) aphids were found in T4-Sulfoxaflor 12% SC @ 33.75 g a.i./ha (4.02%), which was significantly superior over untreated control with 26.73 percent infestation followed by T3-Sulfoxaflor 12% SC @ 27 g a.i./ha (4.91%), T2-Sulfoxaflor 12% SC @ 24 g a.i./ha (5.52%), T5-Chlorpyrifos 20 EC @ 200 g a.i./ha. (6.06%), T1-Sulfoxaflor 12% SC @ 21 g a.i./ha (6.73%), T6 Imidacloprid @ 25.00 g a.i./ha (7.70%) and the least effective treatment was T7-Lecanicillium lecanii @ 10% (1x108) CFU/ml (9.01%).

B) Efficacy of insecticide and biopesticides against Aphid: Second spray

On evaluation of the bio-efficacy of different modern insecticide and biopesticides against aphid on french bean revealed that after second spray, at 1 days T5-Chlorpyrifos 20 EC @ 200 g a.i./ha. (2.02%) was most effective with 2.02 percent infestation which was significantly superior over untreated control with 19.42 percent infestation, followed by T3-Sulfoxaflor 12% SC @ 27 g a.i./ha (2.16%), T2-Sulfoxaflor 12% SC @ 24 g a.i./ha (2.22%), T1-Sulfoxaflor 12% SC @ 21 g a.i./ha (2.36%), T4-Sulfoxaflor 12% SC @ 33.75 g a.i./ha (2.75%), T6 Imidacloprid @ 25.00 g a.i./ha (3.40%) and the least effective treatment was T7-Lecanicillium lecanii @ 10% (1x108) CFU/ml (8.42%). After 3 days of second spray, different chemical insecticides and biopesticides were significantly superior to untreated control. Among the treatments, lowest (3.08%) aphids were found in T3-Sulfoxaflor 12% SC @ 27 g a.i./ha which was significantly superior over untreated control with 24.70 percent infestation followed by T4-Sulfoxaflor 12% SC @ 33.75 g a.i./ha (3.22%), T2-Sulfoxaflor 12% SC @ 24 g a.i./ha (3.26%), T1-Sulfoxaflor 12% SC @ 21 g a.i./ha (3.37%), T5-Chlorpyrifos 20 EC @ 200 g a.i./ha. (3.40%), T6 Imidacloprid @ 25.00 g a.i./ha (5.88%) and the least effective treatment was T7-Lecanicillium lecanii @ 10% (1x108) CFU/ml (8.08%) which was significantly superior over untreated control with 20.84 percent infestation. After 7 days of second spray, different chemical insecticides and biopesticides were significantly superior to untreated control. Among the treatments, lowest (2.56%) aphids were found in T4-Sulfoxaflor 12% SC @ 33.75 g a.i./ha (2.56%) which was significantly superior over untreated control with 23.67 percent infestation followed by T3-Sulfoxaflor 12% SC @ 27 g a.i./ha (2.85), T2-Sulfoxaflor 12% SC @ 24 g a.i./ha (3.17%), T1-Sulfoxaflor 12% SC @ 21 g a.i./ha (3.88%), T5-Chlorpyrifos 20 EC @ 200 g a.i./ha. (4.42%), T6 Imidacloprid @ 25.00 g a.i./ha (5.60%) and the least effective treatment was T7-Lecanicillium lecanii @ 10% (1x108) CFU/ml (6.97%) which was significantly superior over untreated control with 23.67 percent infestation.

After 10 days of second spray, different chemical insecticides and biopesticides were significantly superior to untreated control. Among the treatments, lowest (1.85%) aphids were found in T4-Sulfoxaflor 12% SC @ 33.75 g a.i./ha (1.84%) which was significantly superior over untreated control with 24.79 percent infestation followed by T3-Sulfoxaflor 12% SC @ 27 g a.i./ha (3.42%), T2-Sulfoxaflor 12% SC @ 24 g a.i./ha (3.78%), T1-Sulfoxaflor 12% SC @ 21 g a.i./ha (3.89%), T6 Imidacloprid @ 25.00 g a.i./ha (5.70%), T5-Chlorpyrifos 20 EC @ 200 g a.i./ha.

(5.78%), and the least effective treatment was T7-Lecanicillium lecanii @ 10% (1x108) CFU/ml (7.10%) which was significantly superior over untreated control with 24.79 percent infestation. After 14 days of second spray, different chemical insecticides and biopesticides were significantly superior to untreated control. Among the treatments, lowest (2.15%) aphids were found in T4-Sulfoxaflor 12% SC @ 33.75 g a.i./ha (2.15%) which was significantly superior over untreated control with 20.30 percent infestation followed by T3-Sulfoxaflor 12% SC @ 27 g a.i./ha (3.94), T2-Sulfoxaflor12% SC @ 24 g a.i./ha (4.57%), T1-Sulfoxaflor 12% SC @ 21 g a.i./ha (5.43%), T5-Chlorpyrifos 20 EC @ 200 g a.i./ha. (5.95%), T6 Imidacloprid @ 25.00 g a.i./ha (6.28%) and the least effective treatment was T7-Lecanicillium lecanii @ 10% (1x108) CFU/ml (7.32%) which was significantly superior over untreated control with 20.30 percent infestation.

Conclusion

The experimental findings showed that the Sulfoxaflor 12% SC with 33.75 g a.i./ha was found most effective against Aphid as it was recorded lowest pest population (2.84 Aphid/plant) and least damage along with maximum grain yield (34.58 q/ha). The second-best treatment was Sulfoxaflor 12% SC (27 g a.i./ha) with (32.42 q/ha) grain yield followed by Sulfoxaflor 12% SC (24 g a.i./ha) Sulfoxaflor 12% SC (21 g a.i./ha), Chlorpyrifos 20 EC (200 g a.i./ha) Imidacloprid (25.00 g a.i./ha) and Lecanicillium lecanii 10% 1x10 8 CFU declared least effective among all treatments.

References

1. Draper NR. Applied regression analysis. McGraw-Hill Inc.; 1998.
2. Graham PH, Vance CP. Legumes: Importance and Constraints to Greater Use. Plant Physiology. 2003;131:872-877.
3. Nene YL. Indian pulses through the millennia. Asian Agri-History. 2006;10:179-202.
4. Gomez KA, Gomez AA. Statistical procedures for agricultural research. John Wiley & Sons; 1984.
5. Henderson GF, Tilton EW. Test with acaricides against the brown wheat mite. Journal of Economic Entomology. 1955;48:157-161.
6. Onder S, Bozkurt S, Sayilikan G, Onder D, Kara M. Effects of water stress and mulch on green bean yield and yield components in greenhouse condition. Asian Journal of Plant Sciences. 2006;5(1):127-132.
7. Singh SP, Schwartz HF. Review: Breeding common bean for resistance to insect pests and nematodes. Canadian Journal of Plant Science. 2011;91:239-250.
8. Srivastava KP, Butani DK. Pest management in vegetables. Research Periodicals & Book Publishing House; 1998.