Screening of Mungbean [Vigna radiata (L.) Wilczek] Genotypes against Bruchid (Callosobruchus maculatus) Attack to Reduce Postharvest Losses

Mungbean [Vigna radiata (L.) Wilczek] is the vital protein rich pulse crop of Indian origin referred to as poor man’s meat. It is a traditional short duration crop substantially grown in tropical and sub-tropical part of the world particularly in South-East Asia. The mungbean production is hampering through the post-harvest losses due to bruchid attack. Bruchids (Callosobruchus maculatus) (Coleoptera: Bruchidae) are the major polyphagous storage pest of mungbean which causes the substantial post-harvest quantitative loss. At the same time, it causes the deterioration of the quality of mungbean seeds (Sarwar et al., 2009). The loss has a profound impact on both the farmers as well as on the consumers. Bruchid infestation primarily starts in the field condition and continues to carry this into the storage condition (Srinives et al., 2007). The end result is that the seeds are entirely damaged by perforation within two to three months. Therefore, the post-harvest losses are the major obstacle to reach food security in developing nations (Somta et al., 2007) and also, the storage problem due to bruchid infestation is one of the major constraints for mungbean production. The conventional farmers are trying to keep a small percentage of seeds for their family to use as staple food and rest of the maximum harvested seed materials store into their storehouse where the cross infestation is found in most of the cases (George and Deus, 2009; Stathers et al., 2002). The farmers have no choices but to use costly pesticides for seed preservation during storage (Sarwar et al., 2009). Although the pesticides are effective to control the storage pest but it gives an adverse effect on the environment as well as on human health (Duan et al., 2014). So, the use of resistant genotype is an eco-friendly management strategy for pest control. Therefore, the identification of resistant genotype is an appropriate and promising approach to prevent the bruchid attack. Keeping in mind the importance of mungbean in current day sustenance, we have initiated the study to screen mungbean genotypes against the parameters of bruchid attack and also identify the less postharvest losses in mungbean genotype.

Experimental materials
 
Fifty-two mungbean genotypes were collected from different part in India. For example, some genotypes (fourteen) were collected from the National Bureau of Plant Genomics Resources (NBPGR), New Delhi, some (twenty four) from Pulse and Oilseed Research Station, Baharampur (West Bengal), some (four) from the local district of West Bengal and some (ten) from the Department of Genetics and Plant Breeding, Institute of Agricultural Science, University of Calcutta.
 
Experimental site and design
 
The present experiment was carried out at the Laboratory of the Department of Genetics and Plant Breeding, Institute of Agricultural Science, University of Calcutta. The seeds of fifty-two mungbean genotypes were evaluated during the season of June to August for three consecutive years (2015 -2017) in completely randomized design (CRD) with three replications.
 
Insect culture
 
The male and female bruchids were identified phenotypically according to Raina (1970) and Beck and Blumer (2014). For insect culture, forty (20 males and 20 females) newly emerged (5-7 days old) bruchid were taken from the State Seed Testing Laboratory, Department of Agriculture, Tollygunge, West Bengal, India and introduced into the setup culture jar for oviposition and then the jar was placed into B.O.D condition for maintaining the constant temperature (28±2°C) and humidity (65±5%). After a week, forty bruchids, alive or dead, were removed (Kananji, 2007). After the culture, newly emerged bruchids were used for this experiment.
 
Evaluation of bruchid bioassay through no choice test
 
The method of no choice test or force choice test as per Somta et al., (2008) was applied for the bruchid bioassay evaluation. Newly harvested fifty fresh seeds were taken from each genotype and dried them at 45°C for next 24 hours to destroy if any bruchid’s egg or larvae could have been present in the seed. The dry seeds of each genotype were weighed before forced infestation. The seeds of each genotype were put into the plastic container (12 nt lines during 2009.  These three lines viz.,  DSb 21 (JS 335 × 4 cm) along with two pairs of male and female bruchids (newly cultured bruchid) for oviposition and infestation purposes. These plastic containers were placed into a tray and put into the B.O.D for maintenance of the temperature and humidity.
 
Data collection
 
The data were recorded from each replication on different parameters of bruchid attack as follows:
 
a.  Initial seed weight (ISW): Seed weight was taken before bruchids were introduced into the plastic container.
b.  Number of eggs laid (NOEL): Number of eggs counted in each seed after infestation.
c.  Number of adult bruchid emerge (NOAE): Number of adult bruchid counted after the egg hatching.
d. 
e.  Number of seed damage (NOSD): Number of damaged seed recorded if the seed had any perforation after the emergence of the adult bruchid.
f.  
g. 
     Where
     Residual weight is the seed weight taken after infestation.
 
h.  Mean development days (MDD): (X1+X2+X3)/3,

    Where, X was the development period from egg to adult bruchidin each replication.
 
i.  
j.   Bruchid susceptibility index (BSI): The susceptibility index was calculated by the formula of Dobie (1974): BSI= log F/D) ×100
     Where
     F= Total number of emerged F1 (Adult) bruchid.
    D= Mean development days.
        
According to Dobie (1974), the susceptible index can be classified into five groups with minor modification such as BSI 0 to 3 - resistant; 3.1 to 6 - moderately resistant; 6.1 to 8 - moderately susceptible; 8.1 to 10 - susceptible and > 10 - highly susceptible.
 
Statistical analysis
 
The analysis of variance (ANOVA) and mean performance analysis of ten (a-j) different parameters of bruchid attack was done through IBM SPSS 20.0 software.

The present investigation was performed to study fifty-two mungbean genotypes against bruchid attack during storage condition for reducing postharvest losses. The laboratory bruchid screening was performed through the method of no choice test and displayed in Fig 1 to Fig 9. The analysis of variance (ANOVA) is shown in Table 1. Significant differences are observed among the parameters of bruchid screening in relation to bruchid attack. Higher significant difference at P>0.01 level is recorded on percentage of seed damage as well as percentage of bruchid resistance (1218.57) and also percentage of seed weight loss (1090.97) followed by number of eggs laid (608.96), number of adult emergence (516.19), percentage of egg hatched (432.99), number of seed damage (304.64) and mean development days (101.57). Least significant difference is recorded on initial seed weight (0.524) followed by bruchid susceptibility index (9.93). Shafique and Ahmad, (2002) reported that the significant difference showed to the oviposition, seed weight loss and adult emergence in different pulses such fifteen mungbean, two black gram, nine lentil, one cowpea and seven chickpea cultivars. The mean values of parameters of bruchid screening is shown in Table 2.
  

 

 


Number of eggs laid (NOEL)
 
The oviposition ranges from 20.85-73.89. In terms of oviposition, genotype KM-139 (76.51) shows highest number of eggs laid followed by Howrah local (73.89), IPM-99-125 (73.48), CUM4 (73.46), TM-98-20 (72.69). The lowest number of eggs laid is found in VC -639 (20.85) followed by HUM-8 (22.08), PM-11-51 (25.13), APDM-84 (28.43), CUM2 (30.27). Rest of the mungbean genotypes show the average number of eggs laid. Nongnut et al., (1999) reported in their study that bruchid, particularly C. chinensis, deposited 311 and 365.1 eggs on 5 gm seed of wild mungbean cultivars TC1966 and KPS1 respectively.
 
Number of adult bruchid emergence (NOAE)
 
The emergence of adult bruchid is one of the most important traits because it ultimately affects seed quality and quantity. The adult bruchid emergence ranges from 8.40-62.60. The low number of adult bruchid emergence are found in genotypes HUM-8 (8.40), APDM-84 (9.79), PM-11-51 (11.37), VC -639 (11.52). The highest number of bruchid is found to emerge from genotype CUM4 (62.63) followed by Howrah local (55.66), KM-139 (53.19), TM-98-20 (52.48), IPM-99-125 (51.03). The remaining genotypes show a medium number of adult bruchid emergence.
 
Percentage of egg hatch (POEH)
 
Our result exhibits over 80% of eggs are actually hatched. The highest percentage of eggs hatched is in genotype CUM4 (86.31) followed by CUS2 (81.31), K-851 (77.83), IPM-5-17 (76.92), SML-115 (76.68), Pusa-1432 (75.46),  Howrah local (75.33), Sonali (75.24), Pusa-1431 (74.12), CUM5 (73.28). Somta et al., (2007) reported that the less percentage of eggs hatched is an indication of the presence of the antinutritional factors in seeds which may create the situation of a long developmental period. The lowest number of eggs are hatched in genotype APDM-84 (34.55) followed  by HUM-8 (38.03), Panna (41.35), A-82 (44.33), PDM-54 (44.89). Remaining twenty-seven genotypes exhibit an average percentage of eggs hatched.
 
Number of seed damage (NOSD) and percentage of seed Damage (POSD)
 
The perforated seed is considered as a damaged seed. The seed damage ranges from 5.71-45.11. Genotype KM-139 (NOSD-45.11, POSD-90.21) displays the highest number of seed damage followed by CUM4 (NOSD-40.17, POSD-80.34), CUM5 (NOSD-37.99, POSD-75.98), Pusa-1431 (NOSD-37.26, POSD-74.52), CUS3 (NOSD-36.98, POSD-73.97). Genotype HUM-8 (NOSD-5.71, POSD-11.41) exhibited least number of seed damage followed by PM-11-51 (NOSD-6.34, POSD-12.68), APDM-84 (NOSD-7.44, POSD-14.89), VC-639 (NOSD-9.42, POSD-18.85). The remaining mungbean genotypes show medium number of seed damage.
 
Initial seed weight (ISW-g)
 
Initial seed weight ranges from 0.30-2.03. The seed weight is highest for genotype VC-639 (2.03) followed by APDM-84 (1.94), SML-302 (1.82), HUM-8 (1.73), Pant Mung-5 (1.68). The lowest seed weight is found for genotype KM-139 (0.30) followed by CUM5 (0.35), CUM4 (0.42), CUS3 (0.50), CUM1 (0.54). Rest of the genotypes recorded medium seed weight.
 
Percentage of seed weight loss (POSWL)
 
Seed weight loss is an indicator of economic loss. The percentage of seed weight loss indicates that genotype KM-139 (86.96) underwent maximum percentage of seed weight loss followed by TM-98-20 (74.22), CUM4 (71.56), CUS3 (71.27), IPM-99-125 (69.16). The lowest percentage of seed weight loss recorded for HUM-8 (5.68) followed by APDM-84 (6.22), VC-639 (7.42), PM-11-51 (8.94). The remaining genotypes show average percentage of seed damage. Cowpea cultivar CP-17 showed similar result as reported by Shivanna et al., (2011).
 
Mean development days (MDD)
 
The mean development days also plays a major role in the bruchid infestation. The longest development period is recorded in genotype HUM-8 (43.09) followed by PM-11-51 (41.48), APDM-84 (39.13), VC-639 (36.35), Panna (34.61). The shortest bruchid development period is recorded in genotype KM-139 (17.84) followed by IPM-5-17 (18.74), Pusa-1431 (19.15), CUS3 (19.25) and Pusa-1432 (19.30). The remaining genotypes recorded development periods that fall between the highest and lowest values. Amusa et al., (2014) reported the longest (47 days) development period in cowpea cultivar IT97K-1042 and shortest development period in cultivars TVu 11952 and IT81D-994.
 
Percentage of bruchid resistance (POBR)
 
The present study exhibited that no mungbean genotypes are completely immune to bruchid attack, but they resist almost 90% attack. The range of the percentage of bruchid resistance is wide (9.79-88.59). Genotype HUM-8 (88.59) shows maximum bruchid resistance percentage followed by PM-11-51 (87.32), APDM-84 (85.11), VC-639 (81.15), Panna (77.27), SML-302 (75.34). The least percentage of bruchid resistance is found in genotype KM-139 (9.79) followed by CUM4 (19.66), CUM5 (24.02), Pusa-1431 (25.48), CUS3 (26.03). Remaining genotypes are shown a moderate percentage of bruchid resistance.
 
Bruchid susceptibility index (BSI)
 
The bruchid susceptibility index ranges from 2.14-9.68. The variations of bruchid susceptibility index among genotypes are based on particularly adult emergence number and seed damage and seed damage. The highest bruchid susceptibility index is shown in genotype KM-139 (9.68) followed by CUM4 (8.83), Pusa-1431 (8.56), Pusa-1432 (8.53), IPM-99-125 (8.52). The lowest bruchid susceptibility index is shown in genotype HUM-8 (2.14) followed by APDM-84 (2.53), PM-11-51 (2.54) and VC-639 (2.92). Rest of mungbean genotypes show moderate bruchid susceptibility index. Evaluation of six chickpea genotypes against bruchid attack showed less susceptible local genotype Grumo Appula (Panzarino et al., 2011). Duraimurugan et al., (2014) reported that four mungbean cultivars observe moderate resistance out of 335 cultivars with low growth index ranging from 0.051 to 0.055. 
        
In the present work, four mungbean genotypes are identified as bruchid resistant based on their bruchid susceptibility index values. Resistant mungbean genotypes display significantly low number of eggs laid, inhibited less number of adult emergence, less reduced seed weight and also longer mean development days which indicate noticeable resistance against bruchid attack. Sarwar et al., (2009) reported a similar trend in lentil cultivars. The present study shows that no mungbean genotypes are excluded completely for the bruchid oviposition and the susceptible genotypes recorded a greater number of eggs laid compare to resistant genotypes. George and Dues, (2009) observed higher number of eggs (58.4) laid in cowpea seeds whereas less number of eggs (6.0) laid in soybean seeds. Shivanna et al., (2011); Shafique and Ahmad, (2002); Badii et al., (2013) and Sarwar et al., (2009) support finding of the present study. The high percentage of adult emergence was recorded in CUS2, CUM5, B1, SML-115, IPM-5-17, etc. among all the mungbean genotypes, despite medium number of eggs laid. George and Dues, (2009) noticed that larger number of bruchid hatched in seeds of garden pea and cowpea are comparable with chickpea, pigeon pea, mungbean and Bambara nut whereas the smaller number of bruchids are hatched in seeds of common beans. Here, the number of eggs laid may be less important compared to the number of adult emergence due to the fact that number of adult emergence has more effects on the percentage multiplication of bruchid. Bhalla et al., (2002) reported that sex ratio is an important factor which directly involves in population growth where males and females are generally formed in numbers to balance an equilibrium.
        
The number of adult emergence demonstrated that early and quick developmental period for susceptible mungbean genotypes whereas resistant genotypes showed slow and delayed developmental period. Offor, (2010) reported that adult emergence number displays the level of damage as well as the loss of market value. The present experiment indicates seeds of genotype CUM4 has the higher number of eggs laid (73.46), higher per cent of eggs hatched (85.28), shortest mean development days (19.66) and the high bruchid susceptibility index (8.83) and thereby identified as bruchid susceptible mungbean genotype. Long mean development day demonstrates that either the quality of seeds is not good enough for larval growth development or that the larvae are not able to utilize the quality of food material. Beck and Blumer, (2014) reported that the average life cycle on a bruchid susceptible cultivar ranges from 21-25 days. Genotype CUM4 shows minimum mean development days (19.66) to be considered as bruchid susceptible whereas prolonged days of growth and development (43.09) is found in resistant genotype HUM-8. George and Deus, (2009) reported that comparing with pigeon pea (27.5), maximum developmental period was exhibited for seeds of common bean (38.2 days) followed by soybean (34.6 days) and chickpea (34 days) whereas the minimum was found in cowpea (25.2). The seed weight loss percentage depends on the bruchid infestation and the genotypes with higher seed weight loss percentage are correlated with higher bruchid susceptibility. Genotype TM-98-20 and KM-139 show higher percentage of seed loss (74.22% and 82.96% respectively). Sazodai et al., (2003) reported that adult emergence days (28.60), developmental growth period (longest 32 days and shortest 19.20 days), percent weight loss (36.64) and seed damage percentage (79.55) are found in mungbean. However, although some mungbean genotypes (MH-909 and CUM5) show more than sixty per cent (62.84% and 68.74% respectively) seed damage, the susceptibility index indicates that these genotypes are moderately susceptible (7.21, 7.29) to bruchid attack. Singh et al., (2002) reported that some cowpea cultivars show combined bruchid resistance ability as well as other pest resistance ability. Higher percentage seed weight loss with higher susceptibility index found in susceptible mungbean genotypes rather than resistant genotypes. The seed weight loss due to bruchid attack varies from variety to variety (Gevina et al., 2016; Sharma and Thakur, 2014a) and crop to crop (Ebinu et al., 2016; Sharma and Thakur, 2014b). Higher percentage of seed weight loss (78%) has been recorded in common bean during six months of storage condition (Kananji, 2007).
        
The number of adult emergence predicted the level of resistance and showed a significant positive relationship with susceptibility index. This observation is supported by Kananji (2007); Hiruy and Getu, (2018) in beans and maize respectively. The bruchid susceptibility index is linearly correlated with the intrinsic rate of increase of adult bruchid emergence and the logarithmic relation exists between the number of adult bruchid emergence and the mean development period. According to Dobie (1974), the bruchid susceptibility index provides a reliable projection to the resistance level. So, using the susceptibility index formula according to Dobie, (1974), four bruchid resistant, ten bruchid susceptible, seventeen moderately resistant and twenty-one moderately susceptible mungbean genotypes are identified. Out of 52 cultivars, three cowpea cultivars were shown as resistant in both C. chinensis and C. maculatus as reported by Tripathi et al., (2013). Chickpea cultivars BG-267 and BG-256 were observed highest and lowest bruchid attacked, respectively, as recorded by Jha et al., (2011). In the present study, genotypes HUM-8, PM-11-51, VC-639 and APDM-84 exhibit less number of egg laid, number of adult emergence, percentage of egg hatched, number of seed damage, percentage of seed damage, percentage of seed weight loss, longer mean development days, higher percentage of bruchid resistance and are considered as bruchid resistant based on their low bruchid susceptibility index. Mungbean cultivar PLM 89 and PLS 262 recorded low pest survival percentage (26.6%), long growth developmental period (36.6 and 40.7 days, respectively) with low susceptibility index (0.0389 and 0.0351, respectively) against the bruchid (C. maculatus) infestation observed by Srinivasan and Durairaj, (2007).
        
On the other hand, in this study, genotypes KM-139, IPM-99-125, TM-98-20, Howrah local, IPM-5-17, Pusa-1431 and SML-115 show higher number of egg laid, number of adult emergence, percentage of egg hatched, number of seed damage, percentage of seed damage, percentage of seed weight loss, shorter mean development days, low percentage of bruchid resistance and are identified as bruchid susceptible based on their high bruchid susceptibility index. Genotypes Pusa Baishakhi, SML-302, ML-5, MH-98-1, Pusa-9632, Panna, Bankura local, PDML-13-11, HUM-16 and WBM-045 are identified as moderately resistant based on their BSI. PS-10, Pusa Baisakhi and PS-16 are found as bruchid resistant cultivars based on their growth index reported by Jha et al., (2011). However, in the present study, Pusa Baisakhi and PS-16 can be grouped as moderately resistant and moderately susceptible genotypes based on the bruchid susceptibility index. Genotypes B1, PS-16, K-851, PM-2, Sonamung1, Baruipur local, IPM-205-07, Samrat, Sukumar and Pusa-1432 are identified as moderately bruchid susceptible based on their BSI. Chickpea cultivar C-86037 and C-44 were found to be bruchid resistant and susceptible respectively as reported by Ashraf et al., (1991) whereas the cultivars NCS-96002 and NCS-96003 were shown as bruchid susceptible and partially resistant compared to check cultivar Paridar-91 as reported by Riaz et al., (2000). Leach et al., (2001) reported that most of the genotypes are possessing monogenic resistance which rapidly evolved with the pest population. Mungbean genotypes V 2709 and V2802 were found resistant to bruchid particularly in C. chinensis as reported by Talekar and Lin, (1992) whereas genotype V1128 was found susceptible to bruchid in both C. chinensis and C. maculatus as reported by Imrie and Lambrides, (1998). Ponnusamy et al., (2014) identified bruchid resistant mungbean accessions LM 131, V 1123, LM 371 and STY 2633. The present results are in conformity with most of the previous results.

Use of pesticides as a method to control the storage pest is well known but it gives an adverse effect on the environment as well as human health. Alternatively, screening of resistant genotypes is understood to be a better approach to prevent the pest attack during storage condition. The genotypes HUM-8, PM-11-51, APDM-84 and VC-639 are thus identified as promising bruchid resistant mungbean genotypes that could be used for future mungbean improvement program.

Authors are highly acknowledged Dr. Debashree Sengupta, Seed Testing Officer, State Seed Testing Laboratory, Department of Agriculture, Government of West Bengal for providing the pest sample and the University Grant Commission (UGC) for the financial support.