Yield of
Abstract
Green gram is most important legume crop and richest source of 24% easily digestible protein. The green gram is attacked by number of insect pests but Spodoptera litura is more serious pest. The uses of entomopathogenic nematodes (EPN) as a biological control agent of insect pests are more effective. EPNs have been found effective for the management of tobacco caterpillar and are used as bio insecticides against a number of lepidopteran pests. The mass multiplication of Steinernema carpocapsae can be done on rice moth (Corcyra cephalonica), greater wax moth (Galleria mellonella), gram pod borer (Helicoverpa armigera) and tobacco caterpillar (Spodoptera litura). Infectivity of entomopathogenic nematode, S. carpocapsae against tobacco caterpillar was studied and observation was recorded after every day up to 10 days with different inoculum levels viz., 10,000, 15,000 and 20,000 IJs/plant of S. carpocapsae. The experimental results revealed that maximum 82.50% mortality of S. litura was observed at inoculum level 20,000 IJs/plant of S. carpocapsae after 9th day of inoculation followed by 75.00% mortality at inoculum level 15,000 IJs/plant. While, minimum 67.50% mortality was recorded at inoculum level 10,000 IJs/plant. Therefore, it was concluded that the mortality of insect larvae increased with an increase in the inoculum levels and period of exposure.
Keywords
- green gram
- infectivity
- mass multiplication
- Spodoptera litura
- Steinernema carpocapsae
1. Introduction
Green gram (
Green gram is an important source of easily digestible high quality protein for vegetarians. It contains 24% protein, 0.326% phosphorus, 0.0073% iron, 0.00039% carotene, 0.0021% of niacin [2]. Researchers has pointed out that plant protection remains a most neglected aspect in pulse cultivation; further stating that only 5–6% of the growers adopt plant protection measures in only 1.5% of the total area under this crop. The green gram is attacked by number of insect pests
Realizing the role of these pests as limiting factor in agricultural productivity, several methods were developed and incorporated in to management program of the economically important pest. Out of these, use of insecticides could initially catch up to the growers because of their ready availability, ability to suppress pest’s populations quickly and increasing productivity. Widespread development of resistance to chemical insecticides including the widely used pyrethroids has been reported in
Use of insecticides although found effective however, looking into the adverse effect of chemical insecticides, several bioagents have been tried time to time to manage this pest but none of them could give desirable results.
Biological control of pests using entomopathogenic nematodes (EPNs) may prove to be an ideal alternative to other bioagent earlier used they have long term effect, without any harmful effect on non-target organisms. EPNs are potential agents as they serve as vectors of bacteria, achieve a quick kill of target insect pests, have broader host range, highly virulent, possess chemoreceptor’s and can be cultured easily
2. Mass multiplication of Steinernema carpocapsae on different hosts
Mass multiplication of
Results have indicated that, on the basis of per mg. body weight of cadaver maximum 572.00 IJs of
2.1 Rice moth (Corcyra cephalonica )
The data on yield of IJs presented in Table 2 showed that maximum 60212.0 IJs of
S. no. | Size of larvae (mm) | Mean weight (mg/larvae) | IJs harvested/larvae | IJs/mg body weight of cadaver |
---|---|---|---|---|
1. | Small (10–12) | 86 | 49252.00 | 572.75 |
2. | Medium (13–15) | 131 | 66036.00 | 504.25 |
3. | Large (18–20) | 202 | 100240.00 | 496.25 |
SEm± | 3.543 | 662.457 | 8.504 | |
CD (5%) | 11.334 | 2119.316 | 27.205 | |
CV (%) | 5.07 | 1.84 | 3.24 |
S. no. | Size of larvae (mm) | Mean weight (mg/larvae) | IJs harvested/larvae | IJs/mg body weight of cadaver |
---|---|---|---|---|
1. | Small (6–8) | 73 | 39635.00 | 542.94 |
2. | Medium (10–12) | 90 | 48320.00 | 538.50 |
3. | Large (14–16) | 134 | 60212.00 | 449.50 |
SEm± | 2.465 | 1163.214 | 4.976 | |
CD (5%) | 7.886 | 3721.324 | 15.919 | |
CV (%) | 4.98 | 4.72 | 1.95 |
2.2 Greater wax moth (Galleria mellonella )
The data on yield of IJs presented in Table 1 showed that maximum 100240.0 IJs of
2.3 Gram pod borer (Helicoverpa armigera )
The data on yield of IJs presented in Table 3 showed that maximum 115362.0 IJs of
S. no. | Size of larvae (mm) | Mean weight (mg/larvae) | IJs harvested/larvae | IJs/mg body weight of cadaver |
---|---|---|---|---|
1. | Small (20–22) | 205 | 113590.00 | 554.25 |
2. | Medium (25–27) | 236 | 106070.00 | 449.25 |
3. | Large (30–32) | 274 | 115362.00 | 421.00 |
SEm± | 3.976 | 1795.069 | 7.535 | |
CD (5%) | 12.719 | 5742.737 | 24.105 | |
CV (%) | 3.34 | 3.21 | 3.17 |
2.4 Tobacco caterpillar (Spodoptera litura )
The data on yield of IJs presented in Table 4 showed that maximum 201280.0 IJs of
S. no. | Size of larvae (mm) | Mean weight (mg/larvae) | IJs harvested/larvae | IJs/mg body weight of cadaver |
---|---|---|---|---|
1. | Small (18–20) | 340 | 193140.00 | 568.00 |
2. | Medium (22–24) | 400 | 200900.00 | 502.00 |
3. | Large (26–28) | 430 | 201280.00 | 468.25 |
SEm± | 8.808 | 4406.542 | 11.159 | |
CD (5%) | 28.179 | 14097.29 | 35.698 | |
CV (%) | 4.52 | 4.44 | 4.35 |
3. Infectivity of Steinernema carpocapsae recovered from different hosts against Spodoptera litura infecting green gram
Experiment was conducted to find out the infectivity of
3.1 After 1st day
The experimental results presented in Table 5 revealed that there was no mortality of insect larvae, by inoculating IJs recovered from natural hosts
S. no. | Treatments | Mean percent mortality at different intervals | |||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
1 day | 2 day | 3 day | 4 day | 5 day | 6 day | 7 day | 8 day | 9 day | 10 day | ||
1. | S1 D1 | 0.00 | 10.00 (18.43) | 17.50 (24.16) | 25.00 (29.89) | 35.00 (36.22) | 45.00 (42.12) | 55.00 (47.88) | 65.00 (53.78) | 75.00 (60.11) | 75.00 (60.11) |
2. | S1 D2 | 0.00 | 12.50 (20.47) | 25.00 (29.89) | 35.00 (36.22) | 45.00 (42.12) | 55.00 (47.88) | 67.50 (55.28) | 77.50 (61.77) | 77.50 (61.77) | 77.50 (61.77) |
3. | S1 D3 | 0.00 | 15.00 (22.50) | 40.00 (39.17) | 50.00 (45.00) | 60.00 (50.83) | 70.00 (56.95) | 77.50 (61.77) | 77.50 (61.77) | 80.00 (63.43) | 80.00 (63.43) |
4. | S2 D1 | 0.00 | 10.00 (18.43) | 15.00 (22.50) | 25.00 (29.89) | 35.00 (36.12) | 47.50 (43.56) | 57.50 (49.33) | 67.50 (55.28) | 77.50 (61.77) | 77.50 (61.77) |
5. | S2 D2 | 0.00 | 12.50 (20.47) | 25.00 (29.89) | 35.00 (36.22) | 45.00 (42.12) | 55.00 (47.88) | 67.50 (55.28) | 77.50 (61.77) | 77.50 (61.77) | 77.50 (61.77) |
6. | S2 D3 | 0.00 | 15.00 (22.50) | 47.50 (43.56) | 57.50 (49.33) | 67.50 (55.28) | 72.50 (58.45) | 75.00 (60.11) | 77.50 (61.77) | 80.00 (63.43) | 80.00 (63.43) |
7. | S3 D1 | 0.00 | 10.00 (18.43) | 15.00 (22.50) | 22.50 (28.23) | 32.50 (34.72) | 42.50 (40.67) | 52.50 (46.44) | 62.50 (52.27) | 72.50 (58.45) | 72.50 (58.45) |
8. | S3 D2 | 0.00 | 12.50 (20.47) | 27.50 (31.39) | 37.50 (37.66) | 47.50 (43.56) | 57.50 (49.39) | 67.50 (55.28) | 75.00 (60.11) | 75.00 (60.11) | 75.00 (60.11) |
9. | S3 D3 | 0.00 | 15.00 (22.50) | 42.50 (40.61) | 52.50 (46.44) | 62.50 (52.34) | 72.50 (58.61) | 77.50 (61.77) | 77.50 (61.77) | 80.00 (63.43) | 80.00 (63.43) |
10. | S4 D1 | 0.00 | 10.00 (18.43) | 20.00 (26.19) | 30.00 (33.05) | 37.50 (37.73) | 47.50 (43.56) | 57.50 (49.33) | 67.50 (55.28) | 67.50 (55.28) | 67.50 (55.28) |
11. | S4 D2 | 0.00 | 12.50 (20.47) | 32.50 (37.42) | 42.50 (40.67) | 52.50 (46.44) | 62.50 (52.27) | 75.00 (60.11) | 75.00 (60.11) | 75.00 (60.11) | 75.00 (60.11) |
12. | S4 D3 | 0.00 | 15.00 (22.50) | 50.00 (45.00) | 60.00 (50.77) | 70.00 (56.79) | 75.00 (60.11) | 80.00 (63.43) | 80.00 (63.43) | 82.50 (65.47) | 82.50 (65.47) |
13. | Control | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 |
SEm ± | 0.00 | 1.703 | 2.217 | 1.817 | 1.707 | 1.860 | 1.443 | 1.486 | 1.445 | 1.445 | |
CD (5%) | 0.00 | 4.872 | 6.342 | 5.197 | 4.882 | 5.322 | 4.128 | 4.251 | 4.134 | 4.134 | |
CV (%) | 0.00 | 18.03 | 14.80 | 10.19 | 8.30 | 8.04 | 5.63 | 5.45 | 5.11 | 5.11 |
3.2 After 2nd day
Results showed that 15.00, 12.50 and 10.00% mortality of
3.3 After 3rd day
Data pertaining to mean percent mortality of
3.4 After 4th day
Results showed in Table 5 revealed that maximum 60.00% mortality of
3.5 After 5th day
Maximum 70.00% mortality of
3.6 After 6th day
Data pertaining to mean percent mortality of
3.7 After 7th day
Maximum 80.00% mortality of
3.8 After 8th day
Results showed in Table 5 revealed that maximum 80.00% mortality of
3.9 After 9th day
Data pertaining to mean percent mortality of
3.10 After 10th day
Maximum 82.50% mortality of
4. Conclusion
EPNs are excellent biocontrol agents for insect pests. When an EPN is used against a pest insect, it is critical to match the right nematode species against the target pest. Biotic agents including nematode pathogens, predators and other soil organisms, as well as abiotic factors such as ultraviolet radiation, soil moisture/relative humidity, temperature, etc., can affect EPN application efficacy. Recently, improvement of nematode formulation, application equipment or approaches, and strain improvement have been made to enhance EPN application efficacy. Additional research toward lowering product costs, increasing product availability, enhancing ease-of-use, and improving efficacy and carryover effect will stimulate the extensive use of EPNs in biocontrol. With these advances EPNs will serve to reduce chemical insecticide inputs and contribute to the stabilization of crop yields and the environment.
In this chapter, we studied about the effect of host on multiplication and temperature on infectivity of
When we studied about infectivity of
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