Eco-friendly Approach for the Management of Rust Red Flour Beetle, Tribolium castaneum (Herbst) on Wheat Grains

Wheat (Triticum aestivum Linn.) is known as the “KING OF CEREALS”. It is mostly consumed in the north and north - west parts of the country. Wheat is the major cereal crop occupying an eminent place in economy of our country. Production of wheat during 2019-20 is estimated with a record of 107.18 million tonnes. In India, majority of small and marginal farmers store small quantities of wheat grains in their house for consumption and seed purpose. About 10-15% wheat is lost annually due to ravages of stored grains pests during storage.

T. castaneum (Herbst) is considered as a major pest of stored grain (Howe, 1965). This beetle is found in granaries of wheat, cereals, mixed cake, dried flowers and pet food, seeds, chocolate, meal, spices, nuts etc., In some tropical countries these losses are as high as 30% (Lohar, 2001). The red flour beetle may be present in large numbers in infested grains.

Control of these relies heavily on the use of synthetic insecticides and fumigants. But their widespread use has led to some serious problem including development of insect strains resistant to insecticides (Zettler and Cuperus, 1990) toxic residues on stored grains, toxicity to consumers and increasing costs of claim, environmental contamination, harmfulness to non-target organisms etc. In view of all these problems, several insecticides have either been banned or restricted in their use. For example, the use of organophosphate was decreased, because of increasing resistance incidence in stored-product insects against these chemicals (Fang et al., 2002).

Therefore, Environmentally Friendly Management is the good option for stored pest. We need to go for safe alternatives like inert materials, which are chemically inactive, no toxicity and local availability. Inert dusts absorb the waxy layer of insects, leading to dehydration and death. So, in view of above information the objective was to identify an eco-friendly management of rust red flour beetle, T. castaneum on wheat grains.

Some inert materials were evaluated for their efficacy against T. castaneum on wheat grains during the period of December 2020 to April 2021 in research lab of Entomology Department, Central Agricultural University, Imphal, Manipur. With the ambient conditions used as maximum and minimum temperature was 35°C and 30°C, respectively. The maximum and minimum relative humidity were 70 and 65 per cent, respectively during the course of inquiries. There were 8 treatments viz., paddy straw, paddy husk ash, cow dung ash, coal ash, saw dust, sand dust, boric acid and untreated control with three replications.
 
Sources of inert materials
 
Paddy straw was collected from our college field and Paddy husk ash was obtained from nearby rice mill. Cow dung pallets were collected from the college farm and it was burnt to get the ash. Coal ash was obtained from kitchen. Saw dust was also collected from the carpentry workshop. Sand dust was available in campus. Boric acid was obtained from the Department of Soil Science, CAU, Imphal.
 
Details of the experiment
 
100 gm of healthy and disinfest broken grains of local wheat variety was kept in plastic bottles. Each bottle was mixed with inert materials at the rate of 1.5 gm/100 gm seed. Treatments were replicated for three times and design used to be CRD (completely randomized design). One untreated control was maintained without mixing the inert material. Freshly emerged 10 pairs of adult beetles was released in each plastic bottle. Bottle was covered with muslin cloth and tied with rubber bands.
 
Per cent adult mortality
 
The adult mortality of T. castaneum was recorded for each treatment after 5, 10 and 15 days of exposure by using the following formula:

  

Per cent weight loss of grains
 
The weight losses were calculated after 30 and 60 DAT by subtracting the value of infested grain weight from the original weight. The per cent weight loss was calculated by using the following formula:
 

 
Where,
Initial weight = Weight of original wheat grains
Final weight = Weight of infested wheat grains
 
Per cent adult emergence
 
After weight loss were calculated in the containers removing the insect decease ones and frass were kept separately for (adult emergence) population build up. The adult emergence was calculated after 15, 45 and 90 DAT by using the following formula:
 

Per cent adult mortality
 
After evaluation of some inert materials the results depicted in the Table 1 shows that the 100 per cent adult mortality of T. castaneum was recorded at 5 DAT in case of grains treated with boric acid (100%). Thakur et al., (2014) reported that among different inert materials evaluated for their efficacy against the T. castaneum, after 7 days of storage cent per cent mortality of adult was recorded in boric acid was highest. The next best alternatives are cow dung ash, coal ash with adult mortality of 91.67% and 86.67% after 15 days of storage. Pawar (1980) evaluated that 1.25 cm layer of cow dung ash at the top was effective in protecting seeds from C. chinensis in tanks and barrel. Further, mixing with 30 per cent wood ash was also effective against S. oryzae and S. cerealella in maize. Paddy husk ash resulted as intermediate effect at 5 DAT (55%), 10 DAT (73.33%) and 15 DAT (78.33%). Krishnamurthy and Rao (1950) reported that rice husk ash has been tested as an insecticide, mixed with stored grains and have been used by farmers in Japan and India. Paddy straw (48.33%) and sand dust (53.33%) was the next shows the similar kind of adult mortality at 10 days after treatment. Saw dust was the least effective treatment, with an adult mortality rate of 38.33 per cent. Kumar (2012) recorded the adult mortality of T. castaneum through inert materials, after 30 days of storage cow dung ash was found best treatment. While saw dust was least effective treatment Although, there was 5 per cent adult mortality was recorded in uncontrol. In the case of boric acid, the rest of the periods show zero per cent adult mortality because its already showing 100 per cent in the first 5 days. Over all pooled mean were also calculated.


 
Evaluation of grain weight loss
 
The Table 2 provide information on grain weight loss after 30 and 60 days of storage. The most effective treatment in inert material was boric acid @1.5 g/100 g grains with zero per cent weight loss. Then it was followed by cow dung ash (0.15%), coal ash (0.25%), paddy husk ash (0.44%) and sand dust (0.65%) of grain weight loss. Tabu et al., (2012) reported that efficacy of some inert materials against Adzuki bean beetle, recorded that low seed weight loss without affecting seed germination in stored chickpea. Sivasrinivasu (2001) assessed the cent per cent mortality of rice weevil at 28 days after storage in sorghum treated with 30 per cent ash and observed no weight loss for 90 days of storage period. The maximum weight loss was seen in the untreated control (0.92%). The least effective treatment was saw dust (0.79%) and then followed by paddy straw with a value of (0.71%). The data collected on grain weight loss after two months of storage were ranged from 2.09 to 0.22 per cent, the minimum weight loss was seen in the treatment of boric acid (0.22%). The remaining treatments viz., saw dust (1.77%), paddy straw (1.57%), sand dust (0.88%) paddy husk ash (0.78%), coal ash (0.75%) and cow dung ash (0.54%). According to Golob et al., (1982) restricted infestation of stored insects in maize grains admixed with wood ash, tobacco dust, saw dust and sand. So far, again the uncontrol of without any treatment to the grains lost maximum weight of (2.09%).  
 
Evaluation of adult emergence
 
The data gathered with respect to adult emergence of T. castaneum in different inert materials at 15, 45 and 90 days after storage are described in Table 2.

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Adult emergence was not noticed in any of the treatments after 15 days of storage, because of the average life cycle of T. castaneum in the laboratory conditions was 22-26 days.  There was no statistically significant difference in the adult emergence of T. castaneum between the inert material treatments after 45 days of storage. The minimum adult emergence was noticed after 45 days of storage in a treatment of boric acid treatment (3.67%) as against 25.34% in untreated control. The remaining treatments are follows saw dust (15.34%), paddy straw (13%), sand dust (12%), paddy husk ash (11.34%), coal ash (9.62%) and cow dung ash (7.34%). Meena et al., (2014) reported the adult emergence of C. cephalonica on wood ash (33.33%) control 90 per cent. Tabu et al., (2012) said that wood ash and sand reduced the F1 progeny emergence. Lakhani and Patel (1985) evaluated that ash at 5 per cent was the most effective and cheapest material in reducing the damage by E. cautella to the bajra by about 9 per cent and in keeping eggs hatching and adult emergence low. Here the inert material treatment of saw dust reported the highest adult emergence of T. castaneum was 40.67 per cent, followed by the next treatments are paddy straw (31.67%) and paddy husk ash (25.33%). Yadav and Tiwari (2017) reported that minimum adult emergence in ash powder, sand and cow dung ash was 2.00, 2.33 and 8.33 per cent. By way of usual the untreated control noticed the maximum number of adult emergences 76 per cent after 90 DAT and the least number of adult emergences was observed in the treatment of boric acid (12.67%). The remaining treatments viz., cow dung ash (17%), coal ash (21.33%) and sand dust 22.33 per cent respectively. Apuli and Villet (1996) verified wood ash against C. maculatus in cowpea. The damage to seeds ranged from 63 per cent in the ash free control to 1.3 per cent in seeds treated with 30 per cent ash. The number of progenies similarly ranged from 148 in the untreated control to 2.5 in 30 per cent ash treatment. In the treatment of coal ash and sand dust there was statistically significant difference between them. After 90 days of storage, the order of adult emergence was: untreated control > saw dust > paddy straw > paddy husk ash > sand dust ³ coal ash > cow dung ash > boric acid.

Present study revealed that boric acid @ 1.5 gm/kg grain was the best to protect the wheat grains from a major storage insect T. castaneum. Other alternatives could be cow dung ash, coal ash and paddy husk ash. These eco-friendly approaches have good potential in future.

I am very thankful to my guide Dr. Kh. Ibohal Singh, Associate Professor and Head of the Entomology Department, College of Agriculture, Central Agricultural University, Imphal for guiding, helping and suggesting treasured information during present investigation is duly acknowledged.