​Effect of Various Plant Powders on Pulse Beetle, Callosobruchus maculatus (F.) (Coleoptera: Bruchidae) and Seed Weight Loss in Stored Black Gram

Pulses are an important part of the vegetarian diet of Indian subcontinent, being a rich source of protein (20-30%) and high nutritional value, offer the most practical means of solving malnutrition in our country (Vasanthakumar, 2016). India stands first in terms of area and production of Pulses. Black gram is (4.05 lakh ha), Production (3.10 lakh tonnes) and Productivity (851 kg/ha) and among the pulses black gram and green gram account for about 71 per cent of the area in Tamil Nadu (Vasanthakumar, 2016). Black gram Vigna munga (L.), an important legume crop suffers losses both qualitatively and quantitatively due to the attack by bruchids in the post harvest stages (Raghu et al., 2016). Infestation begins in the field but causes serious damage to the seeds during storage and cause quantitative and qualitative losses to stored pulses (Dongre et al., 1996). Callosobruchus spp. can cause damage of legume seeds up to 100 per cent during storage (Gbaye et al., 2011).

Many synthetic insecticides have been found effective against stored product pests but proved to be hazardous to men and domestic animals. The over reliance on and non judicious use of synthetic pesticides especially insecticides since last four decades led to wide spectrum of pests problem like pests resistance to chemicals, resurgence of pests, residues in food and soil and risks to human and animal health, besides environmental pollution (Mohapatra and Gupta, 1998). Musa and Uddin (2016) reported that many plants possess activities against stored grain pests. To solve this problem, many researchers have discovered alterna­tive pest management products derived from plants (Isman, 2013). Plant products are cheap and are easily accessed by farmers and small-scale industries in the form of crude or partially purified extracts. It was indicat­ed that mixing storage pulses and plant products such as leaf, bark, powder or extracted oils reduced the oviposition rate, inhibited the adult emergence of bruchids and decreased the seed damage rate (Soe et al., 2020). Therefore, in present study seven plant powders were tested for the mortality, adult emergence and seed weight loss against caused by C. maculatus infesting stored black gram seeds.

Laboratory experiments were carried out at of Crop Protection, Agricultural College and Research Institute, Vazahavacnur during 2018-2019 study the effect of seven plant powders on C.maculatus.
 
Rearing of test insect
 
Adults of Callosobruchus maculatus were initially collected from three villages of Vanapuram, Perunduraipattu and Vazhavachanur infested stored black gram seeds from the farmers granaries and brought to the laboratory. The pulse beetle, Callosobruchus maculatus was reared on black gram seeds in glass jars covered with muslin cloth by following the method developed by Credland and Wright (1989). C. maculatus were maintained at ambient laboratory temperature (28±2^oC) and relative humidity (70±5%) conditions.
 
Preparation of plant powders
 
Seven insecticidal plants are indicated below in (Table 1) collected, washed with distilled water and shade dried at room temperature for seven days and crushed a pulverizer model of fritsch rotor speed mill pulverisette 14 with motor load is normal and rotational speed 14, 000 rpm using in to fine powder using a pulveriser (0.05 mm mesh sieve) (Govindan and Nelson 2007). All the powders were kept in plastic containers at room temperature and properly sealed to prevent quality loss and used for conducting experiments.


 
Effect of insecticidal plant powders on the adult mortality of pulse beetle, Callosobruchus maculatus (F.)
 
Twenty grams of black gram seeds were taken in petridishes. The powder of various plant parts at the rate of 2: 100 (w/w) were added to black gram seeds and shaken thoroughly. Thirty newly emerged adults were released in to each petridish and kept in laboratory. Mortality (lack of locomotion and or response to repeated probing) was recorded at one day intervals up to seven days (Govindan and Nelson 2007).

Per cent mortality was calculated by the following formula.
Effect of insecticidal plant powders on oviposition, egg hatching and adult emergence of C. maculatus
 
Oviposition
 
Twenty grams of black gram seeds were taken in glass bottles. The powder of various plant parts at the rate of 2:100 (w/w) were added to black gram seeds and shaken thoroughly. Then the glass bottles were covered firmly using muslin cloth. Five pairs of newly emerged adults of male and females C. maculatus were released to each glass bottle, covered firmly and kept in laboratory at ambient conditions. Three replications were maintained for each treatment. Numbers of eggs laid on the seeds were counted on third day after the release of beetles (Govindan and Nelson 2007).
 
Egg hatching
 
On 5^th day after the release of beetles counts on translucent unhatched eggs and opaque hatched eggs were taken and hatchability percentage was worked out (Govindan and Nelson 2007).
 
Adult emergence
 
On 15^th day after the release of beetles all the dead insects were removed from the bottles to prevent them from the mixing with first generation (F₁) offspring. The number of newly emerged adults were counted and removed from the bottle once in three days till the complete emergence of F₁ offspring (up to 30 days after treatment) (Govindan and Nelson 2007).
 
Seed weight loss
 
The weight of the seed was taken on 30, 45 and 60 days after the treatment and seed weight loss percentage was worked out (Govindan and Nelson 2007).  
The experiment was laid out in completely randomized design (CRD) with three replication were maintained for each treatments.
 
Statistical analysis
 
The methods of Gomez and Gomez (1984) were followed in scrutinizing the data from various experiments. Square root and angular transformations were adopted for the data in numbers and percentage respectively (Abbott, 1925). Means in simple CRD analysis were separated by Duncan’s multiple range test (Duncan, 1955).
 

Effect of plant powders on the adult mortality of Callosobruchus maculatus
 
The results of experiments conducted to study the effect of seven insecticidal plants parts against Callosobruchus maculatus and presented. The results clearly indicated that all the treatments revealed a wide variation in mortality compared to untreated control (Table 2). The insecticidal action of first experiment powders of ten plants 2.00 per cent (w/w) were tested for their insecticidal action in comparison with untreated control. Among them results showed that Piper nigrum 2 per cent seed powder was found to be significantly the best compared to other treatments and caused 100 per cent mortality with in 24 hrs after treatment, other plant powders showed least morality range of 3.33 to 10.22 per cent mortality registered one days after treatment (DAT) as compared to untreated control no mortality was observed. This similar study confirmed and documented by Abdullah et al., (2017) observed black pepper caused highest mortalities (98.3% at 24 hr and 100.0% at 48 hr) to C. maculatus. The present finding could be substantiated with the findings of Manju et al. (2019) who stated that P. nigrum one per cent treated green gram seeds resulted in 100 mortality to C. maculatus within 12 hrs. The highest per cent mortality can be arranged in the order of A. indica  (64.66%) > C. indica (62.22%) > S. grandiflora  (49.50 %) > Acalypa indica  (48.88%) > Abutilon indicum (45.99 %) as untreated control (31.11%) for C. maculatus at 5 DAT. Same trend of mortality at 6 DAT. The present findings corroborate the findings of Kaur et al., (2019) who stated that Neem leaf powder 5 g/100 g of pea seed was highly effective and causing 80.00 per cent mortality to pulse beetle at five days after treatment.  At 7 DAT, 87.77 per cent mortality was seen in Coccinia indica 2 per cent followed by A. indica 2 per cent (80.50%) and in untreated control 36.66 per cent mortality was recorded. Similar results reported by Ahmad et al., (2015) through neem leaf powder protection from pulse beetle infestation in mung bean. Among the botanicals, Piper nigrum 2 per cent seed powder was significantly different from all other treatments. Piper nigrum have active compound called Piperine is a major active principle compound found in seeds and it is the responsible for the killing the C. maculatus (Swamy and Raja, 2018).


 
Effect of plant powder on oviposition, egg hatchability adult emergence of Callosobruchus maculatus and seed weight losses
 
The number of eggs laid by Callosobruchus maculatus  females,  egg hatchability, adult emergence and seed weight loss in the black gram seeds treated with seven plant dry powders (Table 1) @ 2 per cent compared with untreated control in results were furnished in (Table 3). P. nigrum seed powder 2 per cent acted as best oviposition deterrent wherein no egg was laid compared to 107 eggs in control. The present findings also collaborate with the findings of Manju et al., (2019) also stated that P. nigrum 1 per cent seed powder treated green gram seeds sowed highest percentage of oviposition deterrence (71.6%) in C. macultus.  Next effective treatment was neem, Azadirachta indica  treated seeds distinct in reducing the oviposition with only 42.22 eggs on treated black gram seeds followed by Coccinia indica (47.66 Nos) eggs then the next most effective in deterring the bruchids from ovipositing (55.00 Nos) in Abutilon indicum and Acalypa indica (64.44 Nos). Among the different insecticidal plant powders, Sesbania grandiflora least found least effective (72.33 Nos) while 107 eggs laid in untreated control. Regarding the hatchability, insecticidal plant powder reduced the egg hatching significantly. Hatchability in P. nigrum, Acalypa indica, A. indica, Tephrosia purpurea and Abutilon indicum were significantly different from untreated check (90.73%) (Table 3). Regarding the adult emergences, no adult beetle emergence was recorded in P. nigrum and it was significantly different from other treatments. The present findings are in agreement with the reports of Emeasor and Chukwu, (2019) who found that 2 g of P. nigrum powder  admixed with  20 g of mung bean seeds  resulted  complete inhibit the adult  beetle emergences of C. macultus and the result was in line with Manju et al., 2019; Rathod et al., 2019. Next effective treatment is Coccinia indica (26.66 Nos) and A. indica (32 .00 Nos)  among the different insecticidal plant powders highest adult beetles was emerged from S. grandiflora (49.00 Nos), as untreated 90 adult beetles emerged (Table 3). Similarly the results agree with the report of Kaur et al., (2019) who stated that neem leaf powder at 5 g / 100 g of pea seed was highly effective and inhibit the adult beetle emergence.



No seed weight loss (0.00%) was recorded P. nigrum and it was statistically significant with other treatments.  This observation supported by the reports of (Isman, 2013) who reported that the black pepper seed powder has the high insecticidal property and no seed weight loss was recorded at 1.0 per cent powder. Next effective treatment was A. indica  2  per cent leaves  powder   (10.15%),  Abutilon indicum 2 per cent leaf powder (12.45%), Tephrosia purpurea (12.45%) and Acalypa indica  (16. 46%) among the insecticidal plants maximum seed weight was noticed in loss Sesbania grandiflora 2 leaves powder  (26.25%) while 34.26 per cent loss was registered in control at 30 days after treatments. Minimum seed weight loss was (13.88%) observed in seed treated with A. indica followed by A. indicum (14.84%) which was on par effect  with T. purpurea (15.48%) followed by Coccinia indica (20.97%) > Acalypa indica (26.64%) and S. grandiflora (28.26%), respectively compared to untreated (39.22%) at 45 DAT.  These results are in conformity with the findings of earlier researchers with black pepper powder Rathod et al., (2019) who stated that black pepper powder causes less infestation and least weight loss noticed. At 60 DAT, 15.51, 19.50, 22.84 and 22. 50 per cent weight loss in A. indica, T. purpurea, A. indicum and Coccinia indica respectively, as compared with untreated (45.26%) (Table 3). P. nigrum was significantly superior to all other treatments in inhibiting the oviposition, hatchability, adult emergence and seed weight loss.
Effect different concentration of Piper nigrum seed powder on Callosobruchus maculatus
 
Insecticidal action on C. maculatus
 
The screening on insecticidal plant powders tested against  C. maculatus (Table 2) based on screening results  showed  the  Piper nigrum seed powder  have 100 per cent mortality with in 24 hrs. This plant has highly effective in controlling the pulse beetle. Piper nigrum selected for further experiment on different concentrations tested for insecticidal action against C. maculatus and observation taken on 5 hourly interval. Piper nigrum  seed powder  at  0.50, 1.00, 1.50 and 2.00 per cent concentrations. Data on mortality of C. maculatus after 5,10 and 15 hourly interval were recorded. Results (Table 4) revealed that P. nigrum at 2.00 per cent was significantly different from all other treatments with 71.11 per cent mortality after 5 hours after treatment (HAT) next best dose 1.50 per cent (65.55%) and 1.00 per cent (63.33%) among the four concentrations  minimum mortality (36.44%) was  observed in lowest dose at 0.50 per cent. All the beetles were dead in P. nigrum at  2.00 per cent  at 10 HAT, which was followed by 1.50 per cent (94.44%), 1.00 per cent (92.22%) and 0.50 per cent (76.66%) as compared to untreated control no mortality was recorded. All the four doses recorded cent per cent mortality recorded with in 15 hours after treatment. The present finding could be substantiated with the findings of Kaur et al., (2019).


 
Effect different concentration of Piper nigrum seed powder on oviposition, egg hatchability and adult emergence of Callosobruchus maculatus and seed weight loss
 
C. maculatus laid significantly variable number of eggs on black gram seeds treated with different concentrations of P.  nigrum viz., 0.50, 1.00, 1.50 and 2.00 per cent (Table 5).  There was no eggs laying observed in P. nigrum at 1.50 and 2.00 per cent. Few eggs were laid by female in P.  nigrum 1.00 per cent (7.66 Nos) which dose statistically on par with  0.50 per cent (7.00 Nos) as compared to untreated (246 Nos) eggs were laid  similar results were reported by  Swamy  and Raja (2018) green gram mixing of black pepper powder even at lower doses of 0.2, 0.3 and 0.4% could control pulse bruchids very effectively.

Regarding the egg hatchability was significantly less in P. nigrum 1.50 and 2.00 per cent. No adult beetle emergence was observed in all the treatments P. nigrum 1.50 and 2.00  per cent  except in  P. nigrum 1.00 per cent (1.00 Nos) and 0.50 per cent (3.32 Nos) as compare with untreated 124 adult beetles were emerged. The present findings also collaborate with the findings of Swamy and Raja, (2018) stated that green gram seeds on mixing of black pepper powder @ 0.1, 0.2 and 0.3 per cent treated seeds of green gram were also found significantly effective as very negligible numbers (0.33, 1.0 and 8.33 adults respectively) emerged. Regarding the seed weight loss, P. nigrum 1.50 and 2.00 per cent showed no weight loss was observed.  Lower dose of P. nigrum 0.50 per cent at 30 DAT (0.43%), 45 DAT (1.33%) and 60 DAT (2.55%) as compare with untreated 30 DAT (29.76%), 45 DAT (34.27%) and 60 DAT (38.22%). The results were in agreement the findings of Swamy and Raja, (2018) stated that green gram seeds on mixing of pepper powder even at lower doses of 0.2, 0.3 and 0.4% could control pulse bruchids effectively and no seed weight losses and protection up to six month of storage period. At 60 DAT, P. nigrum 1.00 per cent caused 0.83, 1.03 and 1.23 per cent mortality at 30, 45 and 60 DAT, respectively. Poornasundari and Daniel (2015) found black pepper powder at doses of 0.5, 1.0, 1.5 and 2.0 g mixed with 40 g of green gram as effective against C. chinensis and protection up to six months of storage period.

Study the effect of seven insecticidal plant dry powders against Callosobruchus maculatus infesting the stored black gram the results revealed that the efficacy of various powders among them, Piper nigrum 2 per cent seed powder caused 100.00 per cent mortality to pulse beetle on two days after treatment. P. nigrum caused complete inhibited egg laying and progeny development and also no weight losses recorded up to 60 days after treatment. Different concentration of P. nigrum experiment results concluded that all the four dose of P. nigrum (0.50, 1.00, 1.50 and 2.00%) highly effective against C. macultus viz., mortality, oviposition, adult emergence and seed weight loss. Therefore, the resource poor farmers can use botanicals namely, black pepper, P. nigrum seed powder in controlling  pulse beetle, C. macultus is stored black gram as they may not afford to buy chemical pesticides due to high cost. Furthermore, the use of botanical pesticides to control pulse beetle is an appropriate strategy to avoid environmental pollution and other hazards, since the chemical pesticides are used by farmers and in agro industries currently.

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