Introduction

The white spotted chafer, Protaetia brevitarsis (Coleoptera: Cetoniidae), is a phytophagous insect. P. brevitarsis is found in Korea, Japan, Taiwan, China, Europe, and the east Siberia. The adults measure between 17 to 24 mm and are active during the day. They feed on pollen, and fluids of trees and fruits. The larvae live in corrosive soil like farmyard manure or hays tack. In the fields, they appear from early July to late August. Some of them overwinter as adults, while most overwintering individuals are 3rd instar larvae (Park, 2002).

According to Dong-Ui-Bo-Gam, P. brevitarsis larvae have medicinal potential to treat liver cancer, liver cirrhosis, hepatitis, and accumulated fatigue. P. brevitarsis larvae have also been used as folk remedies to treat disease of the liver in Jeju Island, Korea. Recently, P. brevitarsis larvae were used to produce Cordyceps spp. and the study was designed to develop a preventative medicine against liver diseases (Park, 2002).

Since the recent increase in public interest regarding eco friendly agriculture, the possibility of using P. brevitarsis larva excrement as an organic fertilizer has been tested. In this study, investigation on the organic fertilizer applicability of P. brevitarsis larva excrement in corn cultivation was carried out.

Materials and Methods

Materials

Crop: White Sweet Corn (Zea mays)

White sweet corn (Chal Ok 4 Ho) was bought at Internet shopping mall (Fig. 1).

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Fig. 1.
White Sweet Corn (Zea mays) Nursery
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Nursery bed soil

Nursery bed soil (Evergreen) produced by the Corporation Seoul Bio, consisting of cocopeat (55~65%), feat moss (18~24%), vermiculite (5~8%), zeolite (2~4%), perlite (9~13%), water soluble fertilizer, wetting agent, etc. (Fig. 2), was used.

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Fig. 2.
Nursery bed soil (Evergreen)
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P. brevitarsis larva excrement

The excrement of P. brevitarsis which was bred in Kyungpook National University, Ecological entomology Lab (Fig. 3) was used.

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Fig. 3.
P. brevitarsis larva excrement
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Others

Tapeline (7.5 m, Fig. 4), insect net (Fig. 5), electronic scale (CAS, Fig. 6), etc.

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Fig. 4.
Tapeline (7.5m).
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Fig. 5.
Insect net
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Fig. 6.
Electronic scale (CAS)
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Methods

Corn growing in treated soil

Corn was cultivated in greenhouse located at Gunwi-gun, Kyungpook National University, Eco-friendly Agricultural technical education center. The soil was divided into 3 groups, namely, treated nursery bed soil (Exp2), untreated soil (control), and soil treated with P. brevitarsis larva excrement (Exp1).

In 2009, we planted 2 corn seeds in each treated soil, having 35 points. In each treated soil, width space was 5 points with 100 cm and length space was 7 points with 60 cm. A total of 70 corn seeds were planted in each treated soil on 29 Jun 2009 (Fig. 7, Fig. 8 ) and the corn was cultivated on 2 5 Sep 2009. In Exp2, we analyzed 20 packs of 50l nursery bed soil mixed with soil. In Exp1, we analyzed 20 packs of 10 kg of P. brevitarsis larva excrement mixed with soil.

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Fig. 7.
Sowing outline in 2009.
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Fig. 8.
Sowing location in 2009.
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In 2010, we planted 2 corn seeds in each treated soil having 20 points. In each treated soil, width space was 5 points with 100 cm and length space was 4 points with 60 cm. A total of 40 corn seeds were planted in each treated soil on 28 May 2010 Fig. 9, Fig. 10) and the corn was cultivated on 28 August 2010. In Exp2, we analyzed 10 packs of 50l nursery bed soil mixed with soil. In Exp1, we analyzed 10 packs of 10 kg of P. brevitarsis larva excrement mixed with soil.

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Fig. 9.
Sowing outline in 2010.
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Fig. 10.
Sowing location in 2010.
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Length comparison of corn from each treated soil

We measured the length of corn with a 7.5 m tapeline starting from the highest length of the corn. If the corn reached the ceiling of the greenhouse, the exact length was recorded. In 2009, the length of corn was recorded 11 times from 11 Jul to 25 Sep. In 2010, the length of corn was recorded 10 times from 24 Jun to 28 Aug.

Insect comparison in each treated soil

We selected corn from each treated soil for comparison of the insect population. In 2009, 10 corns were randomly selected and in 2010, 5 corns were randomly selected. Insects were collected using insect net and by hand. In 2009, the insects were collected 11 times from 11 Jul to 25 Sep and 10 times in 2010 from 24 Jun to 28Aug.

Results

Length comparison of corn from each treated soil

In 2009, we compared the length of corn from each treated soil. On average, corn growth rate from Exp 2 was higher and corn growth rate from the control was higher than Exp1 (Fig. 11, Fig. 12, Fig. 13, Fig. 14 ). Corn bloom time was faster in Exp2. The corn yield was higher in control and corn yield from Exp2 was higher than Exp1 (Table 1, Fig. 15). However, empty heads of grain were reported in Exp2. We also compared the thickness of th e corn roots and the following trend was observed Exp2 > control > Exp 1 (Fig. 16).

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Fig. 11.
Compare length of corn from each treated soil in 2009.
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Fig. 12.
Growth image of corn in July 22, 2009.
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Fig. 13.
Growth image of corn in August 18, 2009.
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Fig. 14.
Growth image of corn in September 18, 2009.
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Table 1.
Compare corn yield from each treated soil (2009)
Exp2 Control Exp1
Weight(g) Weight(g) Weight(g)
S1 482 M1 235 B1 36
S2 400 M2 476 B2 236
S3 138 M3 506 B3 598
S4 384 M4 778 B4 284
S5 344 M5 570 B5 70
S6 496 M6 402 B6 0
S7 340 M7 718 B7 116
S8 376 M8 484 B8 280
S9 318 M9 288 B9 332
S10 468 M10 546 B10 148
S11 434 M11 368 B11 162
S12 228 M12 560 B12 336
S13 322 M13 156 B13 144
S14 376 M14 678 B14 20
S14 376 M14 678 B14 20
S16 650 M16 174 B16 82
S17 128 M17 172 B17 294
S18 292 M18 124 B18 122
S19 454 M19 598 B19 106
S20 412 M20 354 B20 18
S21 522 M21 68 B21 88
S22 334 M22 324 B22 242
S23 354 M23 210 B23 68
S24 682 M24 360 B24 264
S25 624 M25 676 B25 6
S26 358 M26 52 B26 28
S27 514 M27 256 B27 40
S28 510 M28 454 B28 168
S29 212 M29 312 B29 0
S30 140 M30 334 B30 106
S31 508 M31 22 B31 108
S32 624 M32 158 B32 60
S33 540 M33 486 B33 262
S34 226 M34 516 B34 226
S35 254 M35 316 B35 134
Sum 13728 Sum 12791 Sum 5210
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Fig. 15.
Compare corn fruit from each treated soil (2009).
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Fig. 16.
Compare corn root from each treated soil (2009).
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In 2010, we compared the length of corn from each treated soil. On average, corn growth rate from Exp1 and Exp2 were similar. Corn growth rate for the control was least (Fig. 17, Fig. 18, Fig. 19, Fig. 20 ). The corn bloom time and corn yield were similar for Exp1 and Exp2. However, empty heads of grain were reported in Exp2 like in 2009 (Table 2, Fig. 21). We also compared the thickness of corn roots and the following order was recorded Exp2 >Exp1 > control. However, corn roots from treated soil were rotten. Therefore, the corn growth rate and corn yield were low as compared to year 2009 (Fig. 22).

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Fig. 17.
Compare length of corn from each treated soil in 2010.
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Fig. 18.
Growth image of corn in June 24, 2010.
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Fig. 19.
Growth image of corn in July 21, 2010.
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Fig. 20.
Growth image of corn in August 18, 2010.
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Table 2.
Compare corn yield from each treated soil (2010)
Exp2 Control Exp1
Weight(g) Weight(g) Weight(g)
S1 126 M1 6 B1 54
S2 102 M2 28 B2 112
S3 72 M3 26 B3 160
S4 0 M4 0 B4 166
S5 0 M5 0 B5 64
S6 146 M6 16 B6 118
S7 88 M7 0 B7 50
S8 256 M8 0 B8 202
S9 0 M9 0 B9 188
S10 32 M10 0 B10 100
S11 150 M11 26 B11 120
S12 230 M12 0 B12 74
S13 200 M13 0 B13 142
S14 12 M14 0 B14 162
S15 26 M15 0 B15 148
S16 104 M16 0 B16 66
S17 260 M17 0 B17 78
S18 214 M18 0 B18 80
S19 60 M19 0 B19 74
S20 0 M20 0 B20 42
Sum 2078 Sum 102 Sum 2200
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Fig. 21.
Compare corn fruit from each treated soil (2010).
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Fig. 22.
Compare corn root from each treated soil (2010).
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Tables 3, 4, and 5 present the statistical analysis of corn yield in 2009. Table 3 showed that there was no significant difference ( P >0.005) between control and Exp2. Tables 4 and 5 showed that there was significant difference ( P <0.001 ) between the two groups. Tables 6, 7, and 8 present the statistical analysis of corn yield in 2010. Tables 6 and 7 showed that there was significant difference ( P<0.001 ) between the two groups. Table 8 showed that there was no significant difference (P>0.005) between Exp1 and Exp2.

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Table 3.
Analysis of corn yield (g) in control and Exp2 (2009)
Group N Mean SD
Control 35 365.457 205.225
Exp2 35 392.229 145.253
t = -0.630 df = 61.2 P = 0.531
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Table 4.
Analysis of corn yield (g) in Exp1 and control (2009)
Group N Mean SD
Exp1 35 148.857 128.863
Control 35 365.457 205.225
t = -5.288 df = 57.2 P = 0.000
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Table 5.
Analysis of corn yield (g) in Exp1 and Exp2 (2009)
Group N Mean SD
Exp1 35 148.857 128.863
Exp2 35 392.229 145.253
t = -7.415 df = 67.0 P = 0.000
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Table 6.
Analysis of corn yield (g) in control and Exp2 (2010)
Group N Mean SD
Control 20 5.100 10.021
Exp2 20 103.900 90.383
t = -4.859 df = 19.5 P = 0.000
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Table 7.
Analysis of corn yield (g) in Exp1 and control (2010)
Group N Mean SD
Exp1 20 110.000 48.964
Control 20 5.100 10.021
t = 9.387 df = 20.6 P = 0.000
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Table 8.
Analysis of corn yield (g) in Exp1 and Exp2 (2010)
Group N Mean SD
Exp1 20 110.000 48.964
Exp2 20 103.900 90.383
t = 0.265 df = 29.3 P = 0.793

In 2010, corn growth rate, corn yield, and thickness of corn roots were inferior as compared to 2009, and this might be related to the difference in climatic conditions. As such, in 2010, there were more rainy days as compared to 2009 and the poor soil condition was related to the rotting of the corn roots.

In 2009 and 2010, the corn growth rate was best in Exp2, but there were lots of empty heads of grain. As a result, nursery bed so il successfully elongated the corn, but failed to properly develop the corn fruit.

In 2009 and 2010, the results were different for Exp1. In 2009, Exp1 recorded the worst performance for the studied criteria. In 2010, corn growth rate was similar for Exp1 and Exp2, but empty heads of grain were reported in Exp2, thereby suggesting that corn yield was better in Exp1 compared to Exp2. These findings support that P. brevitarsis larva excrement could be used as organic fertilizer.

Insect comparison in each treated soil

In 2009, we collected insects 11 times. According to cultivation time, different insects were observed. During early cultivation time, there were lots of Diptera. In middle cultivation time, lots of ants and aphids were collected and the presence of aphids was related to the occurrence of fungal disease. During the last time of cultivation, there were lots of Spodoptera litura larvae which damaged cornstalks and fruits, followed by presence of the insects in corn ( Table 9, Table 10, Fig. 23).

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Table 9.
Number of insects in each treated soil (2009)
Treated soil / Class Order Family Genus Species sp.
Exp2 8 18 19 19 5
Control 8 12 13 13 3
Exp1 5 11 12 12 4
Total 9 26 30 30 7
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Table 10.
List of insects during cultivation time
Taxonomy Number of insects
Taxonomy Years Sites
Order Family Sience Name 2009 2010 Exp2 Control Exp1
Orthoptera Pyrgomorphidae Atractomorpha lata 1 2 2 1
Orthoptera Acrididae Oxya japonica japonica 3 30 20 7 16
Hymenoptera Tenthredinidae Athalia rosae ruficornis 2 2
Hymenoptera Formicidae Camponotus japonicus 41 9 32
Diptera Sarcophagidae Helicophagella melanura 2 2
Diptera Sarcophagidae sp2. 3 2 1
Diptera Calliphoridae Phaenicia sericata 3 1 2
Diptera Muscidae Musca domestica 1 2 3
Diptera Agromyzidae Chlorops oryzae 3 1 2
Diptera Tabanidae Atylotus horvathi 1 1
Diptera Asilidae sp6. 1 1
Diptera Asilidae sp10. 1 1
Diptera sp3. 4 2 1 1
Diptera sp4. 7 5 1 1
Diptera sp5. 1 1
Diptera sp8. 1 1
Coleoptera Chrysomelidae Altica caerulescens 2 2
Coleoptera Chrysomelidae Monolepta quadriguttata 4 3 1
Coleoptera Coccinellidae Coccinella septempunctata 2 1 2 1
Coleoptera Coccinellidae Propylea japonica 3 3
Coleoptera Elateridae Aeoloderma agnata 1 1
Hemiptera Lygaeidae Nysius plebejus 1 1
Hemiptera Coreidae Riptortus clavatus 1 1
Hemiptera Coreidae Cletus schmidti 7 3 3 1
Hemiptera Pentatomidae Dolycoris baccarum 1 1 1 1
Homoptera Delphacidae Sogatella furcifera 1 1
Homoptera Aphididae Rhopalosiphum maidis 65 15 47
Homoptera Fulgoridae Limois emelianovi 1 1
Homoptera Derbidae Diostrombus politus 1 1
Odonata Libellulidae Sympetrum eroticum 1 1
Neuroptera Chrysopidae sp7. 1 1
Lepidoptera Noctuidae Prodenia litura 22 15 7
Lepidoptera Noctuidae sp9. 3 1 2
Lepidoptera Hesperiidae Parnara guttatus 2 1 1
Lepidoptera Pyralidae sp1. 1 1
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Fig. 23.
Observed insects in 2009.
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In 2010, we collected insects 10 times. There were lots of Oxya japonica japonica during cultivation time which damaged corns (Fig. 2 4 ). Also, we could observe Cletus schmidti, Atractomorpha lata, etc (Table 10, Table 11, Fig. 25).

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Fig. 24.
Ankertrass of O. japonica japonica (2010).
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Table 11.
Number of insects in each treated soil (2010)
Treated soil / Class Order Family Genus Species sp.
Exp2 5 8 8 8 3
Control 2 4 4 4 0
Exp1 3 4 4 4 1
Total 9 11 11 11 3
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Fig. 25.
Observed insects in 2010.
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Species observed in 2009 were more than in 2010. The corns were damaged by O. japonica japonica in 2010 and it seems that the O. japonica japonica eggs were overwintering in greenhouse and hatched in 2010.

Discussion

This study was performed to evaluate the applicability of the P. brevitarsis larva excrement as organic fertilizer. The soil was divided into 3 groups, namely, treated nursery bed soil, untreated soil, and soil treated with P. brevitarsis larva excrement. We investigated corn growth rate and insect population in 2009 and 2010.

In 2009, we compared length of corn from each treated soil. Corn growth rate in Exp2 was higher. The nursery bed soil seems to properly elongate corn, but effective elongation of corn was observed in control. Corn elongation was less effective using P. brevitarsis larva excrement, but in 2010, corn growth rate was similar for Exp1 and Exp2. Different results were recorded in 2009, suggesting that P. brevitarsis larva excrement could be used as organic fertilizer.

Upon comparison of corn fruits from each treated soil, empty heads of grain were reported in 2009 and 2010 for Exp2. The nursery bed soil seems to be improper for the elongation of corn. Also, comparison of corn roots from each treated soil revealed that Exp2 was best in 2009 and 2010. Exp1 was the worst in 2009 and the control was the worst in 2010. Especially, in 2010, there were lots of rainy days as compared to 2009 and the soil condition was poor. Therefore, in 2010, the corn roots were rotten. Using proper nutrients and proper fertilizer is crucial in corn cultivation.

Since this study was performed in greenhouse, there were not lots of insects. In 2009, the insect population was different during cultivation time. In 2010, there were lots of Oxya japonica japonica during cultivation, resulting in lots of damaged corn. As a result, understanding the ecology and management of these insects is crucial to minimize crop damage.

Conflict of Interest

The authors declare that t hey have no competing interests.

Acknowledgments

This work was carried out in part as a research for the Bachelor’s Degree for Jungmoon Cha in Kyungpook National University.

References

1 

Park K.T. Development of the mass-rearing technique of Protaetia species for the increase of the farmer's income . Chuncheon: The Kangwon National University. , 1 - 93 .