Management of groundnut bruchid, Caryedon serratus, with seed protectants and their effect on stored groundnut seed

Introduction

Groundnut (Arachis hypogaea L.), commonly known as peanut, is an important oilseed and food legume crop cultivated extensively in tropical and subtropical regions. Its kernels contain approximately 50 per cent oil and 35 per cent protein, along with essential minerals and vitamins, making groundnut valuable for human nutrition, livestock feed and industrial applications (Dwivedi et al., 2003) [1] . However, insect pests during production and storage adversely affect seed quality, viability and economic returns. More than 100 insect species have been reported to infest stored groundnut, although only a limited number are considered economically important (Redlinger et al., 1982) [2] . Among the major storage pests, the groundnut bruchid, Caryedon serratus (Olivier), is particularly important because of its ability to infest intact groundnut pods. Its larvae penetrate the pod wall and develop within the kernels, causing quantitative and qualitative losses, including reductions in seed weight, germination potential, nutritional quality and market value (Davey, 1958; Wightman et al., 1987) [3,4] . The pest is also associated with several leguminous host plants, including tamarind (Tamarindus indica) and other tree legumes like Indian beech (Pongamia pinnata) (Shivalingaswamy, 1987; Singal et al., 1989) [5,6] . Caryedon serratus undergoes complete metamorphosis, comprising egg, larval, pupal and adult stages. Females lay eggs on the surface of pods or seeds, and newly hatched larvae penetrate the pod wall to feed internally on the kernel. The larval stage is responsible for the major portion of seed damage, whereas adult emergence produces characteristic circular exit holes that indicate infestation (Ranga Rao et al., 2010) [7] . The duration of development varies with temperature, humidity and host substrate. Available studies have reported four larval stages, rather than consistently establishing five to six instars under all conditions. Therefore, developmental duration and the number of larval instars should be reported only with appropriate supporting evidence (Davey, 1958) [3] .

Several researchers, including Nadaf et al. (2010) [8] , Ummer (2012) [9] , Bhogeesh et al. (2014) [10] , Faraz et al. (2015) [11] , Rana et al. (2018) [12] and Sakhare et al. (2018) [13] , have investigated different management aspects of C. serratus. The use of suitable protectants and storage treatments remains important for reducing insect infestation and preserving seed quality. Accordingly, the present study was undertaken to evaluate the efficacy of selected oils used as pod and fabric treatments against C. serratus and to assess their effects on the viability and quality of stored groundnut seed.

Materials and Methods

Laboratary experiment entitled "Management of groundnut bruchid, Caryedon serratus, with seed protectants and their effect on stored groundnut seed" was undertaken during 2025-26 in Seed Entomology laboratory of Seed Technology Research Unit, Mahatma Phule Krishi Vidyapeeth, Rahuri to evaluate the efficacy of various seed protectants against this pest and their influence on the quality of stored groundnut seeds. Freshly harvested and dried 50 kg groundnut pods of variety Phule morna were used for the experiment. Different oils (Sunflower oil, Neem seed oil, Castor seed oil, Musturd seed oil, Soyabean oil) @ 10 ml / kg of seed and insecticides (Spinosad 45 % SC @ 0.3 ml/kg and deltamethrin 2.8 % EC @ 0.4 ml/kg) were used as pod treatments against Caryedon serratus. For each treatment, 2 kg of pods were used. In the treatment, pods were treated with oil and insecticides, shade dried and packed in 2 kg capacity gunny bags After imposing treatments, all the bags were closed and kept on the shelf in the laboratory under room temperature for further observations. The experiment was initiated in August 2025 with eight treatments by adopting Completely Randomized Design (CRD) with three replications. The observations viz. number of eggs laid, number of adults emerged, per cent pod damage, per cent seed weight loss were, per cent seed germination and seed moisture content were recorded at three months interval up to 12 months of storage.

Result and Discussion

To study the effect of different treatments on infestation of groundnut pods by Caryedon serratus in storage

Number of eggs laid

The different seed treatments resulted in significant differences among the treatments with respect to the number of eggs laid by Caryedon serratus on stored groundnut pods. The data presented in the table 1 showed that Neem seed oil, Spinosad 45% SC and Deltamethrin 2.8% EC treatments recorded no egg laying up to 9 months after treatment (MAT). At 12 MAT, the lowest number of eggs was recorded in Deltamethrin 2.8 % EC @ 0.4 ml/kg (5.33 eggs/100 pods), which was at par with Spinosad 45% SC @ 0.3 ml/kg (5.67 eggs/100 pods). Neem seed oil @ 10 ml/kg recorded 9.33 eggs/100 pods. The untreated control recorded the maximum egg laying (54.33 eggs/100 pods) at 12 MAT. The mean data revealed that Deltamethrin 2.8% EC @ 0.4 ml/kg recorded the lowest egg laying (1.33 eggs/100 pods), which was at par with Spinosad 45% SC @ 0.3 ml/kg (1.41 eggs/100 pods), while the neem seed oil @ 10 ml/kg recorded 2.33 eggs/100 pods. Untreated control recorded the maximum mean egg laying (28.16 eggs/100 pods).

Number of adults emerged

The data presented in the table 2 showed that, Neem seed oil @ 10 ml/kg recorded no adult emergence up to 9 months after treatment (MAT), whereas Spinosad 45% SC @ 0.3 ml/kg and Deltamethrin 2.8% EC @ 0.4 ml/kg completely prevented adult emergence throughout the storage period. At 12 MAT, neem seed oil recorded 6.67 adults/100 pods, while the untreated control recorded the maxi-mum adult emergence (49.67 adults/100 pods). The mean data revealed that Spinosad 45% SC @ 0.3 ml/kg and Deltamethrin 2.8% EC @ 0.4 ml/kg recorded zero adult emergence, neem seed oil recorded 1.66 adults/100 pods whereas the untreated control recorded the maximum mean adult emergence (25.08 adults/100 pods).

The data presented in the table 3 showed that Spinosad 45% SC @ 0.3 ml/kg and Deltamethrin 2.8% EC @ 0.4 ml/kg protected the seeds from insect damage throughout the storage period. Neem seed oil @ 10 ml/kg recorded no seed damage up to 9 months after treatment (MAT), whereas the untreated control recorded continuous seed damage throughout the storage period. At 12 MAT, Spinosad 45% SC and Deltamethrin 2.8% EC recorded zero seed damage, while neem seed oil recorded 6.33 per cent seed damage. The untreated control recorded the maximum seed damage (15.67 %) at 12 MAT. The mean data revealed that Spinosad 45% SC @ 0.3 ml/kg and Deltamethrin 2.8% EC @ 0.4 ml/kg recorded zero seed damage, neem seed oil recorded 1.58 per cent seed damage whereas the untreated control recorded the maximum mean seed damage (8.08%).

The data presented in the table 4 showed that Spinosad 45 % SC @ 0.3 ml/kg and Deltamethrin 2.8 % EC @ 0.4 ml/kg completely prevented seed weight loss throughout the storage period. Neem seed oil @ 10 ml/kg recorded no seed weight loss up to 9 MAT, whereas the untreated control recorded increasing seed weight loss during the storage period. At 12 MAT, Spinosad 45% SC and Deltamethrin 2.8% EC recorded zero seed weight loss, followed by neem seed oil (0.87%).

The untreated control recorded the maximum seed weight loss (8.13%) at 12 MAT. The mean data revealed that Spinosad 45% SC @ 0.3 ml/kg and Deltamethrin 2.8% EC @ 0.4 ml/kg recorded zero seed weight loss, whereas the untreated control recorded the maximum mean seed weight loss (3.47%).

The data presented in the table 5 showed that seed germination gradually decreased with an increase in the storage period in all treatments. Deltamethrin 2.8% EC @ 0.4 ml/kg recorded the highest seed germination at 3, 6, 9 and 12 MAT, followed by Spinosad 45% SC @ 0.3 ml/kg. At 12 MAT, the highest seed germination was recorded in Deltamethrin 2.8% EC (86.66%), which was followed by Spinosad 45% SC (85.67%) and neem seed oil (84.33%). The untreated control recorded the lowest seed germination (68.33%) at 12 MAT. The mean data revealed that Deltamethrin 2.8% EC @ 0.4 ml/kg recorded the highest seed germination (92.41%), followed by Spinosad 45% SC @ 0.3 ml/kg (91.67%), neem seed oil recorded (90.33%), whereas the untreated control recorded the lowest mean seed germination (82.43%). All treatments maintained the seed germination of above IMSC standards up to 12 MAT. While in control the germination fell below IMSCS at 12 MAT.

The data presented in the table 6 showed that moisture content gradually increased with an increase in the storage period in most of the treatments. Deltamethrin 2.8% EC @ 0.4 ml/kg recorded the lowest moisture content at 3, 6, 9 and 12 MAT, whereas the untreated control recorded comparatively higher moisture content throughout the storage period. At 12 MAT, the lowest moisture content was recorded in Deltamethrin 2.8% EC (9.02%), followed by Spinosad 45% SC (9.06%) and neem seed oil (9.09%), while the untreated control recorded the highest moisture content (9.54%). The mean data revealed that Deltamethrin 2.8% EC @ 0.4 ml/kg recorded the lowest mean moisture content (8.84%), followed by Spinosad 45% SC @ 0.3 ml/kg (8.88%), neem seed oil recorded (8.93 %) whereas the untreated control recorded the highest mean moisture content (9.30%). The present investigation demonstrated that seed protectants effectively suppressed infestation of groundnut pods by Caryedon serratus during storage. Among the treatments, spinosad 45 % SC @ 0.3 ml kg -1 and deltamethrin 2.8 % EC @ 0.4 ml kg -1 were the most effective, while neem seed oil @ 10 ml kg -1 was the most effective botanical. The reduction in egg laying may be attributed to the ovipositiondeterrent, repellent and insecticidal properties of the treatments. The oil coating may also interfere with insect movement and respiration. Similar findings reported by Nadaf et al. (2010) [8] , Spinosad and deltamethrin exhibited sustained efficacy throughout the study, ensuring zero pods with eggs and no pod damage along with complete inhibition of adult emergence for three months and emphasized the potential of both botanical and chemical protectants for effective bruchid management. Similarly, Harish et al. (2012) [17] reported that neem oil at 10 % concentration resulted in only 2.3 eggs per 100 g groundnut pods and was statistically at par with castor oil (2.5 eggs). Harish et al. (2012) [17] similarly recorded complete inhibition of adult emergence with neem and castor oils at 10 % concentration. Bhogeesh et al. (2014) [10] reported spinosad 45 % SC as highly effective against Caryedon serratus, recording the lowest pod damage among insecticide treatments. Present findings were supported by Sakhare et al. (2018) [13] , who observed that increased infestation by Caryedon serratus resulted in deterioration of stored groundnut physiological quality. Sharma et al. (2021) [18] similarly recorded minimum pod damage and weight loss with neem oil. Similarly, Singh et al. (2022) [19] demonstrated that the development and infestation of Caryedon serratus in stored groundnut as lower moisture content results in lower chances of infestation. Gundreddy et al. (2023) [20] further identified neem oil as the most effective botanical followed by castor oil against Caryedon serratus for seed damage.

Conclusion

The present study concluded that the different seed treatments significantly influenced the infestation and seed quality parameters of stored groundnut seeds against Caryedon serratus. Among the evaluated treatments, Deltamethrin 2.8 % EC @ 0.4 ml/kg and Spinosad 45 % SC @ 0.3 ml/kg provided effective protection by preventing egg laying, adult emergence, seed damage and seed weight loss throughout the storage period. Among the botanical treatments, neem seed oil @ 10 ml kg -1 seed emerged as the most promising treatment. Deltamethrin recorded the highest mean seed germination followed by Spinosad, while neem seed oil @ 10 ml/kg proved to be the most effective botanical treatment. Deltamethrin 2.8 % EC @ 0.4 ml/kg and Spinosad 45 % SC @ 0.3 ml/kg along with neem seed oil @ 10 ml/kg treatments maintained comparatively lower moisture content and better seed quality during storage. Therefore, Deltamethrin, Spinosad and neem seed oil demonstrated potential for managing groundnut bruchid infestation and maintaining seed quality under storage conditions.

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21. How to cite this article: Nichat SK, Bhoge RS, Kadam UK, Palande PR, Sarnobat DH. Management of groundnut bruchid, Caryedon serratus, with seed protectants and their effect on stored groundnut seed. International Journal of Advanced Biochemistry Research. 2026;SP-10(10):234-240. doi: https://w ww.doi.org/10.33545/26174693.2026.v10.i10Sc.10284