Timely detection of Mediterranean fruit fly (Medfly) is very important so that eradication action can be taken on time. The larvae stage of this insect is the most dangerous stage as it is within the pulp of the fruit, making it hard to detect by visual inspection. In most countries at ports of entry the inspector check a small sample of fruit by visual inspection or by cutting the produce and searching for fungus and pests. This paper will investigate a quick, reliable and sensitive method to determine the presence of fruit flies. Our research focuses on developing the technology for detecting hidden infestations by using the Head Space-Soild Phase Micro Extraction (HS-SPME) method coupled with Gas Chromatography-Mass Spectrocopy (GC-MS) technique. Five different types of fruit were infested with an early stage of Medfly Ceratitis capitata Wiedemann (Diptera: Tephidae). We investigated to detect the differences in volatile organic compounds (VOC’s) between infested and non- infested fruits by using HS-SPME with (GC-MS). The results indicated that for few chemicals no significant differences between infested and non-infested fruit can be seen, especially in the fruits with first instar. However, in case of third instar larvae infested fruits significant differences in the chemicals can be seen as compare to non infested fruits and other instar infestations. These chemicals include ethyl (Z)-2 butenoate, 2-heptanone, anisole, β-cis-ocimene, 1,3,7-nonatriene,4,8-dimethy-,ethyl octyate, isoamyl caproate and 1β,4βh,10βh- guaia-5,11-diene, in apple. Ethyl (Z)-2-butenoate, (+)-2-bornanone, (-)-trans- isopiperitenol, methyl caprate, caryophyllene and farnesene in orange. Butanoic acid, 3-methyl-,2-methylbutul acetate, sabinene, β-myrcene, octanoic acid, methyl ester, dihydrocarvone, (-)-trans-isopiperitenol and ethyl laurate in mandarin. Butyl 2-methylbutanoate, terpinen-4-ol, P-menth-8-en-2-one, E-,(3E,7E)-4,8,12-trimethyltrideca-1,3,7,11-tetraene and dodecanoic acid, ethyl ester in lemon. Decane, 3-methyl-, p-menth-1,4(8)-diene, 1-undecene and α-cubebene in avocado. Thus, the VOC’s method could provide a possible tool for detecting tephritid larvae and this method could be adopted by industries importing and exporting fruit.
Mediterranean fruit fly Ceratitis capitata Wiedemann is species of invasive pest that affects fruit production and export worldwide. C. capitata attacks approximately 250 different species around the world [
This paper will evaluate the use of Head Space-Solid Phase Micro Extraction (HS-SPME) method coupled with Gas Chromatography-Mass Spectroscopy (GC-MS) technique as a potential technology for improving detection of hidden insect infestation inside fruit. According to [
Medfly colony were obtained from the Department of Agriculture and Food, Western Australia (DAFWA) and reared in the Murdoch University Laboratory, in Perth Australia. All the flies were reared under conditions: 23˚C ± 2˚C and 75% ± 5% RH, and 12:12-h (L:D) [
Royal Gola Apple (Malus domestica) from New South Wales, Valencia orange (Citrus spp.) from Western Australia, Hass avocado (Persea Americana) from South-West of Western Australia, Hicksons Mandarin (Citrus reliculata) from New South Wales and Eureka Lemon (Citrus limon) from New South Wales were obtained from the local fruit and vegetable market. The fruits were stored for 2 days under 2˚C; twenty ripe fruits from each variety were used in our experiment.
Fruits were cleaned with distilled water to remove any surface contaminants. Then, 30 eggs with 0.5 ml of water were transferred to each single fruit by using a sterile syringe. Fruits were divided into three groups (5 fruits in each group) for volatiles analysis at different stages of larvae, first, second and third instars. Each group used two fruits to monitor the progress of larval development by cutting the fruit to determine the larvae stage and to evaluate the level of infestation by using a microscope to see the larvae stages and remaining three fruits were used for volatile analysis. In addition, one group was sampled as non-in- fested fruits. All the fruits were placed and stored in laboratory at a temperature of 24˚C for 7 - 9 days; for the development of the larval stage. After collecting the volatile compounds as described in the next section, the various types of fruits were cut into small pieces and the number of larvae inside each fruit was counted.
The analysis of compounds was focused on whole fruits. Various types of fruit were placed individually into 2 litre jars. One whole fruit was analysed in each jar. Volatiles were collected by solid phase micro extraction (SPME) fibre with 50/30 µm Carboxen/DVB/PDMS (2 cm) (Sigma-Aldrich, Bellefonte, USA) coating. The samples were collected by inserting the fibre into the jar and exposing to the headspace. VOC’s were collected on different times depending on the level of larvae inside the fruit. After sealing the jars for 16 hours at a temperature of 24˚C, the fibre was exposed to headspace for 2 hours which the optimized the HP-SPME extraction time. The desorption time of SPME fiber was 10 min in the injection port.
VOC’s were analyzed with (Gas chromatography Agilent GCMS 7820A equipped with a mass spectrometer detector 5977E (Agilent Technologies, USA) and a DB-35ms column (30 m × 250 µm × 0.25 µm) (Santa Clara, CA 95051, USA). The carrier gas was 99.999% helium supplied by (BOC, gas, Sydney, Australia). The GC-MS operation conditions were as follows: The temperature of the injector port was 270°C. The initial oven temperature was 50°C and increased to 250°C by (5◦C/min). The column Flow rate was 1:1 ml/min and splitless was 20 ml/min at 1.5 min. The total GCMS run time was 45 min. Three experimental replicates were taken for each type of fruit. Compound peaks were deconvoluted by AMDIS version 2.72 and identified by searching the NIST 2014 MS database (the US National Institute of Standards and Technology) with retention index confirmation. Three replications for each type of fruit were analysed, and the experiment were repeated two times to confirm the chemicals.
The limit of detection was evaluated with alkane standard C7-C30 (Supelco, Bellefonte, USA). One litre Erlenmeyer flasks (Bibby Sterilin, Staffordshire, Cat. No. FE 1 L/3 equipped with cone/screw-thread adapter (Crown Scientific, Code ST 5313) with 1.1 cm blue septa (Grace Davison Discovery Sciences, catalog: 6518 ) were used make stock and diluted standard. The stock standard of concentration was prepared by adding 4 µl of standard into sealed 1L Erlenmeyer flasks. Then, samples were diluted to ppb from ppm, ppt from ppb and ppq from ppt levels by transferring 1 mL of head space by syringe into another flask. After 1 hour of extraction time with 50/30 µm Carboxen/DVB/PDMS (2 cm) (Sigma- Aldrich, Bellefonte, USA) fibre at room temperature, the SPME fibre was injected into GC-MS with 270°C injection port. Each level was repeated two times.
The number of larvae inside the fruit was analysed by one way (ANOVA). For the comparison of volatile compounds between different instars, the peak area was analysed by software using the two way (ANOVA) test [
The fruits were dissected immediately after collection of the volatiles compounds for finding out the level of infestation. For the first instar, it was hard to calculate the number of larvae; so the data was calculated by counting second instar larvae. The results indicated there were significant differences in the level of hatching in avocado compared to other types of fruit, like apple, lemon, orange and mandarin in laboratory conditions. Average ± SD number of larvae per fruit was as follow: 8.06 ± 1.58 apple, 13.13 ± 1.21 orange, 11.93 ± 1.77 mandarin, 9.06 ± 1.81 lemon and 18.93 ± 1.10 avocado (
The GC-MS response of the stock and diluted alkanes standard decreased form ppm (Parts per million) level to ppt (parts per trillion) level (
Standard | Formula | RIa | LOD (ppm)b | LOD (ppb)c | LOD (ppt)d | Linearity (r2)e |
---|---|---|---|---|---|---|
Octane | C8H18 | 729.1 | 100.061 | 33.394 | 5.050 | 0.948 |
Nonane | C9H20 | 899.9 | 141.900 | 57.492 | n.d | 0.988 |
Decane | C10H22 | 1000.8 | 224.999 | 74.246 | 4.395 | 0.957 |
Undecane | C11H24 | 1100.6 | 164.794 | 77.475 | 2.983 | 0.997 |
Dodecane | C12H26 | 1200.8 | 24.028 | 6.819 | n.d | 0.941 |
Tridecane | C13H28 | 1300.6 | 56.533 | 27.538 | n.d | 0.998 |
Tetradecane | C14H30 | 1399 | 22.945 | 7.431 | n.d | 0.960 |
Pentadecane | C15H32 | 1500.5 | 17.307 | 10.262 | 1.068 | 0.994 |
Hexadecane | C16H34 | 1600.6 | 6.798 | 3.440 | 2.070 | 0.944 |
Heptadecane | C17H36 | 1700.5 | 6.499 | 2.521 | 0.861 | 0.946 |
Octadecane | C18H38 | 1800.1 | 7.309 | 3.487 | n.d | 0.999 |
Nodaecane | C19H40 | 1900 | 13.734 | n.d | n.d | - |
Eicosane | C20H42 | 2000.8 | 15.983 | 4.987 | n.d | 0.955 |
Heneicosane | C21H44 | 2100 | 18.651 | n.d | n.d | - |
Tricosane | C23H48 | 2299.5 | 20.503 | n.d | n.d | - |
Tetracosane | C24H50 | 2400.8 | 15.119 | n.d | n.d | - |
Pentacosane | C25H52 | 2499 | 10.042 | n.d | n.d | - |
a = retention index; b = parts per million; c = parts per billion; d = parts per trillion; e = Regression coefficient.
There were many differences between compounds for each type of fruits and also between infested and non infested fruits. Some of the compounds were detected in one type of fruit, was found to be absent in another type. From the GC analysis, about 33 compounds from apple, 45 compounds from orange, 45 compounds from mandarin, 44 compounds from lemon, and 40 compounds from avocado were identified. All these compounds were identified by comparing with the retention index in the literature (NIST) and mass spectra in the NIST. We analysed 23 compounds each from apple (
In case of non infested apples, the main peaks were hexyl acetate, n-butyl 2 methylbutyrate, n-hexyl propionate and isobutyl caproate. Many compounds were detected in fruits infested with third instar larvae but not in fruits infested with first or second instar larvae or in non infested fruit and these included ethyl (Z)-2 butenoate, 2-heptanone, anisole, β-cis-ocimene, 1,3,7-nonatriene,4,8-dimethy-, ethyl octyate, isoamyl caproate, ethyl decylate and 1β,4βh,10βh-guaia-5,11-diene (
Compounds | RT | RI | RIL | Prob.% | Infested | Non-infested | ||
---|---|---|---|---|---|---|---|---|
1 instar | 2 instar | 3 instar | ||||||
Ethyl(Z)-2 butenoate | 5.45 | 848.9 | 830 | 89 | n.d. | n.d. | 0.77 | n.d. |
Propyl isobutyrate | 5.85 | 856.8 | 861 | 86 | 9.35* | 3.89* | 2.23* | 24.07 |
1-Hexanol | 6.26 | 872.3 | 860 | 89 | 35.51ns | 50.69* | 78.72* | 10.58 |
Styrene | 6.95 | 801.7 | 883 | 87 | 0.24 | 0.12 | 2.04 | n.d. |
2-Heptanone | 6.97 | 891.7 | 871 | 83 | n.d. | n.d. | 17.72 | n.d. |
Anisole | 7.91 | 916.9 | 898 | 92 | n.d. | n.d. | 0.55 | n.d. |
Benzaldehyde | 9.44 | 895.7 | 982 | 79 | 0.33 | n.d. | 1.18 | n.d. |
Hexyl acetate | 11.42 | 973.7 | 984 | 88 | 419.33* | 411.08* | 396.33* | 544.26 |
n-Butyl 2 methylbutyrate | 12.41 | 1044.9 | 1019 | 84 | 210.68ns | 88.18* | 75.64* | 215.87 |
β-cis-Ocimene | 12.60 | 1049.9 | 1041 | 89 | n.d. | n.d. | 0.46 | n.d. |
2-Methylbutyl 2-methylbutyrate | 14.45 | 1105.3 | 1090 | 80 | 14.53 | n.d. | 19.05 | n.d. |
n-Hexyl propionate | 14.56 | 1085.3 | 1083 | 94 | 151.50ns | 81.41* | 80.19* | 139.94 |
1,3,7-Nonatriene,4,8-dimethy-, | 14.84 | 1108.3 | 1089 | 83 | n.d. | n.d. | 21.08 | n.d. |
Methyl caprylate | 15.11 | 1126.5 | 1108 | 76 | 0.6 | 0.35 | 5.23 | n.d. |
Dodecane | 17.40 | 1201.7 | 1200 | 81 | 1.19 | 5.22 | n.d. | n.d. |
Ethyl octyate | 17.39 | 1199.8 | 1175 | 95 | n.d. | n.d. | 48.4 | n.d. |
Decanal | 17.61 | 1199.6 | 1204 | 85 | 1.19 | 1.01 | 1.20 | n.d. |
Isoamyl caproate | 18.90 | 1252.4 | 1253 | 90 | n.d. | n.d. | 1.76 | n.d. |
Ethyl decylate | 22.86 | 1390.4 | 1381 | 88 | n.d. | n.d. | 1.07 | n.d. |
1β,4βh,10βh-Guaia-5,11-diene | 24.93 | 1462.1 | 1469 | 93 | n.d. | n.d. | 0.85 | n.d. |
*Means there are significant differences between infested fruit and non-infested fruit (LSD mean P ≤ 0.05). Prob% means percent of probability. ns means there are no significant differences between infested fruit and non-infested fruit (LSD mean P ≤ 0.05). n.d. means compounds are not detected. (RT) retention time, (RI) retention index, (RIL) Literature retention index (NIST).
Compounds | RT | RI | RIL | Prob.% | Infested | Non-infested | ||
---|---|---|---|---|---|---|---|---|
1 instar | 2 instar | 3 instar | ||||||
Ethyl (Z)-2-butenoate | 5.45 | 849.6 | 830 | 89 | n.d. | n.d. | 2.04 | n.d. |
β-phellandrene | 8.26 | 850.2 | 964 | 81 | 0.95 | n.d. | 11.38 | n.d. |
n-Butyl butyrate | 9.28 | 957.6 | 939 | 74 | 29.13ns | 57.79ns | n.d. | 32.76 |
L-β-Pinene | 10.00 | 975.6 | 970 | 31 | n.d. | 7.29ns | 38.72ns | n.d. |
Myrcene | 10.63 | 992.5 | 979 | 89 | 19.16ns | 40.7ns | 242.02* | 12.58 |
3-Carene | 11.21 | 1010.7 | 1005 | 89 | 124.85* | 252.90* | 115.88* | 22.92 |
D-Limonene | 11.88 | 1031.4 | 1018 | 86 | 389.93* | 614.20* | 799.27* | 49.73 |
β-cis-Ocimene | 12.60 | 1049.9 | 1041 | 81 | 1.22 | 5.34 | 24.95 | n.d. |
E-4,8-Dimethyl-1,3,7-Noatriene | 14.96 | 1121.2 | 1116 | 89 | 297.84* | 334.00* | 271.89ns | 180.519 |
Methyl caprylate | 15.11 | 1124.2 | 1134 | 91 | 4.35ns | 244.38* | 123.45* | 2.23 |
(+)-2-Bornanone | 15.67 | 1146.7 | 1141 | 87 | n.d. | n.d. | 0.76 | n.d. |
Isobutyl caproate | 15.94 | 1137.3 | 1118 | 78 | 348.61ns | 313.61* | 144.03* | 391.66 |
Ethyl octyate | 17.40 | 1153.8 | 1152 | 96 | 155.85* | 188.26* | 208.95* | 49.67 |
---|---|---|---|---|---|---|---|---|
(-)-trans-Isopiperitenol | 17.57 | 1206.0 | 1206 | 82 | n.d. | n.d. | 15.50 | n.d. |
Butyl(2E)-2-hexenoate | 18.63 | 1243.1 | 1243 | 92 | n.d. | 50.13 | 22.16 | n.d. |
Isoamyl caproate | 18.90 | 1252.6 | 1253 | 82 | 7.49 | 40.48 | 37.81 | n.d. |
Methyl caprate | 20.96 | 1324.4 | 1309 | 80 | n.d. | n.d. | 0.90 | n.d. |
limonene-1,2-dial | 21.38 | 1340.8 | 1342 | 84 | 4.59 | 13.56 | 57.27 | n.d. |
Octanoic acid n-butyl ester | 21.58 | 1346.5 | 1348 | 87 | n.d. | 66.55 | 3.22 | n.d. |
Eugenol | 21.88 | 1356.0 | 1337 | 90 | n.d. | 0.25 | 9.79 | n.d. |
Caryophyllene | 23.54 | 1414.4 | 1424 | 87 | n.d. | n.d. | 52.50 | n.d. |
Valencen | 25.38 | 1478.2 | 1474 | 86 | 885.93ns | 755.80* | 636.74* | 903.59 |
Farnesene | 25.70 | 1488.9 | 1499 | 84 | n.d. | n.d. | 42.70 | n.d. |
*Means there are significant differences between infested fruit and non-infested fruit (LSD mean P ≤ 0.05). Prob% means percent of probability. ns means there are no major differences between infested fruit and non-infested fruit (LSD mean P ≤ 0.05). n.d. means compounds are not detected. (RT) retention time, (RI) retention index, (RIL) Literature retention index (NIST).
Compounds | RT | RI | RIL | Prob.% | Infested | Non-infested | ||
---|---|---|---|---|---|---|---|---|
1 instar | 2 instar | 3 instar | ||||||
Butanoic acid, 3-methyl- | 5.42 | 849.8 | 830 | 88 | n.d. | n.d. | 2.86 | n.d. |
2-methylbutul acetate | 6.64 | 882.0 | 868 | 81 | n.d. | n.d. | 1.2 | n.d. |
1R-a-Pinene | 8.47 | 932.8 | 922 | 85 | 1.16 | 5.87 | n.d. | n.d. |
Mesitylene | 9.74 | 968.0 | 956 | 82 | 0.71ns | n.d. | n.d. | 4.26 |
Sabinene | 9.96 | 973.9 | 975 | 89 | n.d. | n.d. | 129.64 | n.d. |
Terebenthene | 10.00 | 970.0 | 975 | 87 | n.d. | 49.52 | 168.13 | n.d. |
β-Myrcene | 10.63 | 992.5 | 979 | 89 | n.d. | n.d. | 86.54 | n.d. |
3-Carene | 11.21 | 1010.7 | 1005 | 89 | 3.24ns | 25.88* | 25.99* | 0.24 |
D-Limonene | 11.88 | 1031.4 | 1018 | 89 | 625.23* | 751.71* | 907.88* | 518.48 |
Moslene | 12.90 | 1059.5 | 1047 | 85 | 5.08* | 17.68ns | 57.21* | 22.13 |
p-menth-1,4(8)-diene | 13.64 | 1088.3 | 1080 | 83 | 3.27 | 9.92 | 32.33 | n.d. |
Octanoic acid, methyl ester | 15.14 | 1126.5 | 1109 | 84 | n.d. | n.d. | 3.75 | n.d. |
(-)-Terpinen-4-ol | 16.74 | 1178.9 | 1161 | 84 | n.d. | 6.62 | 51.19 | n.d. |
α-Terpineol | 17.11 | 1192.5 | 1172 | 88 | n.d. | 3.22 | 20.46 | n.d. |
Dihydrocarvone | 17.37 | 1197.4 | 1189 | 80 | n.d. | n.d. | 43.36 | n.d. |
Dodecane | 17.40 | 1200.1 | 1200 | 89 | 4.03ns | n.d. | n.d. | 4.62 |
(-)-trans-Isopiperitenol | 17.44 | 1206.0 | 1206 | 85 | n.d. | n.d. | 8.03 | n.d. |
p-Mentha-1(7),8(10)-dien-9-ol | 20.03 | 1340.5 | 1340 | 82 | n.d. | n.d. | 2.64 | n.d. |
Tridecane | 20.28 | 1299.9 | 1300 | 81 | 3.59ns | 2.79ns | n.d. | 4.01 |
1,2-Cyclohexanediol, 1-methyl-4-(1- | 21.37 | 1338.8 | 1342 | 96 | n.d. | 3.25 | 19.49 | n.d. |
(-)-β-Elmene | 22.80 | 1388.1 | 1387 | 83 | n.d. | 2.55 | 3.97 | n.d. |
(+)-epi-Bicyclosesquiphellandrene | 23.79 | 1421.7 | 1428 | 81 | 0.41 | 0.87 | 1.98 | n.d. |
Ethyl laurate | 27.73 | 1598.7 | 1580 | 90 | n.d. | n.d. | 1.23 | n.d. |
*Means there are significant differences between infested fruit and non-infested fruit (LSD mean P ≤ 0.05). Prob% means percent of probability. ns means there are no significant differences between infested fruit and non-infested fruit (LSD mean P ≤ 0.05). n.d. means compounds are not detected. (RT) retention time, (RI) retention index, (RIL) Literature retention index (NIST).
Compounds | RT | RI | RIL | Prob.% | Infested | Non-infested | ||
---|---|---|---|---|---|---|---|---|
1 instar | 2 instar | 3 instar | ||||||
Sabinene | 9.96 | 973.2 | 975 | 89 | 21.21ns | 238.72 | 399.21 | n.d. |
D-Limonene | 11.88 | 1031.4 | 1018 | 89 | 352.62* | 625.74* | 767.11* | 95.4 |
Butyl 2-methylbutanoate | 12.40 | 1044.8 | 1026 | 85 | n.d. | n.d. | 0.99 | n.d. |
Benzene,1-methyl-3-(1-methylethenyl)- | 13.91 | 1089.2 | 1099 | 84 | 6.26ns | n.d. | n.d. | 10.88 |
(E)4,8-Dimethyl-1,3,7-Noatriene | 14.88 | 1119.0 | 1116 | 86 | 277.41 | 136.05 | 183.96 | n.d. |
Methyl caprylate | 15.11 | 1126.5 | 1109 | 86 | 3.87ns | 55.20* | 317.42* | 2.81 |
Limonene oxide, trans- | 15.51 | 1139.4 | 1130 | 88 | 7.88ns | n.d. | n.d. | 10.09 |
(+)-2-Bornanone | 15.67 | 1146.7 | 1141 | 86 | n.d. | 8.11 | 18.83 | n.d. |
Terpinen-4-ol | 16.79 | 1178.9 | 1161 | 84 | n.d. | n.d. | 86.01 | n.d. |
α-Terpineol | 17.11 | 1192.5 | 1172 | 83 | 5.97 | 36.04 | 179.05 | n.d. |
P-Menth-8-en-2-one,E- | 17.57 | 1088.3 | 1080 | 82 | n.d. | n.d. | 5.79 | n.d. |
Hexyl 2-methylbutyrate | 18.51 | 1238.6 | 1232 | 90 | 29.81* | 14.20ns | 46.60* | 11.84 |
Tridecane | 20.28 | 1299.9 | 1300 | 81 | 2.13ns | n.d. | n.d. | 3.15 |
Decanoic acid, methyl ester | 20.96 | 1324.1 | 1309 | 81 | n.d. | 13.41 | 31.97 | n.d. |
Limonene-1,2-diol | 21.37 | 1340.8 | 1342 | 93 | 4.16ns | 42.17* | 7.96ns | 4.4 |
(-)-β-Elmene | 22.80 | 1388.1 | 1387 | 88 | 122.59* | 106.96ns | 35.50ns | 77.31 |
7-epi-a-selinene | 26.05 | 1501.0 | 1503 | 85 | 87.3 | 190.56 | n.d. | n.d. |
E-Nerolidol | 27.02 | 1534.9 | 1548 | 85 | 65.53* | 31.74ns | 47.65ns | 0.87 |
(3E,7E)-4,8,12-Trimethyltrideca-1,3,7,11-tetraene | 27.38 | 1547.3 | 1557 | 55 | n.d. | n.d | 1.98 | n.d. |
Dodecanoic acid, ethyl ester | 27.72 | 1559.2 | 1566 | 87 | n.d. | n.d. | 0.8 | n.d. |
Intermedol | 29.20 | 1610.9 | 1630 | 81 | n.d. | 7.52ns | 122.58* | 4.23 |
*Means there are significant differences between infested fruit and non-infested fruit (LSD mean P ≤ 0.05). Prob% means percent of probability. ns means there are no significant differences between infested fruit and non-infested fruit (LSD mean P ≤ 0.05). n.d. means compounds are not detected. (RT) retention time, (RI) retention index, (RIL) Literature retention index (NIST).
Compounds | RT | RI | RIL | Prob.% | Infested | Non-infested | ||
---|---|---|---|---|---|---|---|---|
1 instar | 2 instar | 3 instar | ||||||
1-Heptanal | 7.36 | 898.8 | 882 | 88 | 1.04ns | 0.81ns | n.d. | 0.44 |
Sulcatone | 10.48 | 973.9 | 964 | 80 | 0.58ns | 33.85* | 1.35ns | 0.53 |
Hexyl acetate | 11.42 | 973.7 | 984 | 84 | 0.51ns | n.d. | n.d. | 0.23 |
D-Limonene | 11.88 | 1031.4 | 1018 | 90 | 23.56* | 114.96* | 131.75* | 94.70 |
Moslene | 12.90 | 1058.3 | 1047 | 86 | 0.75* | 51.88* | 2.87ns | 7.19 |
Decane, 3-methyl- | 13.31 | 1070.5 | 1072 | 82 | n.d. | n.d. | 0.22 | n.d. |
---|---|---|---|---|---|---|---|---|
p-menth-1,4(8)-diene | 13.88 | 1088.3 | 1080 | 81 | n.d. | n.d. | 0.38ns | 1.49 |
1-undecene | 14.00 | 1091.7 | 1088 | 79 | n.d. | n.d. | 0.13 | n.d. |
E-4,8-Dimethyl-1,3,7-Noatriene | 14.88 | 1119.0 | 1116 | 86 | 16.19 ns | 14.31* | 2.02* | 11.69 |
α-Terpineol | 17.11 | 1192.5 | 1172 | 81 | n.d. | 6.41 | 0.19 | n.d. |
1,2,6-Dimethylundecane | 17.81 | 1214.6 | 1216 | 81 | 0.45 | 1.21 | 0.55 | n.d. |
Limonene glycol | 21.38 | 1338.2 | 1342 | 83 | n.d. | 2.69 | n.d. | n.d. |
α-Cubebene | 21.66 | 1348.4 | 1350 | 82 | n.d. | n.d. | 0.22 | n.d. |
Meraneine | 22.03 | 1361.3 | 1342 | 85 | n.d. | 0.41 | n.d. | n.d. |
(4R,4aS,6S)-4,4a-Dimethyl-6-(prop-1-en-2-yl)- 1,2,3,4,4a,5,6,7-octahydronaphthalene | 24.79 | 1457.4 | 1475 | 82 | 0.32ns | 10.64* | 2.54ns | 0.61 |
1β,4βh,10βh-Guaia-5,11-diene | 24.93 | 1462.0 | 1469 | 83 | 1.55ns | n.d. | n.d. | 1.64 |
Valencen | 25.38 | 1479.9 | 1492 | 89 | 61.82ns | 3.31* | 14.60* | 61.13 |
*Means there are significant differences between infested fruit and non-infested fruit (LSD mean P ≤ 0.05). Prob% means percent of probability. ns means there are no significant differences between infested fruit and non-infested fruit (LSD mean P ≤ 0.05). n.d. means compounds are not detected. (RT) retention time, (RI) retention index, (RIL) Literature retention index (NIST).
n-hexyl propionate were decreased with increase in instars. From these results, it shows that the level of larvae can change the profile of compounds as also reported by [
In case of non infested oranges, the main peaks were β-myrcene, 3-carene, D- limonene, E-4,8-dimethyl-1,3,7-noatriene, methyl caprylate, isobutyl caproate, ethyl octyate and valencen. Many compounds were detected in fruits infested with third instar larvae but not in fruits infested with first or second instar larvae or in non infested fruit and these included ethyl (Z)-2-butenoate, (+)-2-bor- nanone, (-)-trans-isopiperitenol, methyl caprate, caryophyllene and farnesene (
The highest peaks which were recorded in non infested lemon are sabinene, D-limonene, (E)4,8-dimethyl-1,3,7-noatriene, methyl caprylate, α-terpineol, (-)- β-elmene, 7-epi-a-selinene and intermedol. The results indicated that fruit infested with third instar of larvae recorded a high number of target compounds. These compounds were butyl 2-methylbutanoate, terpinen-4-ol, P-menth-8-en- 2-one,E-, (3E,7E)-4,8,12-trimethyltrideca-1,3,7,11-tetraene and dodecanoic acid, ethyl ester (
Sulcatone, D-limonene, E-4,8-dimethyl-1,3,7-noatriene and valencen were the main peaks in avocado fruits. There were some new peaks associated with avocado infestation especially with third instar infestation; these compounds included decane, 3-methyl-, p-menth-1,4(8)-diene, α-terpineol, 1,2,6-dimethylun- decane and α-cubebene. There were significant differences between infested and non infested avocado fruit in different stages of larvae; these include D-limo- nene, E-4,8-dimethyl-1,3,7-noatriene and valencen for third instar infested fruit. In second instar of larvae, sulcatone, D-limonene, moslene, E-4,8-dimethyl- 1,3,7-noatriene and valencen. In first instar, they were D-limonene and moslene. Some of chemicals increased in concentration with increase in the level of infestation like D-limonene. Similar results were observed in case of orange, mandarian and lemon. However, 1-heptanal, E-4,8-dimethyl-1,3,7- noatriene and α-terpineol decreased in concentration with increase in the level of infestation (
In summary, if we compare all five fruits infested with third instar larvae, the major identifying components for each fruits infested with third instar are 1-hexanol, hexyl acetate, n-butyl 2 methylbutyrate and n-hexyl propionate for apple; 3-carene, D-limonene, isobutyl caproate, E-4,8-dimethyl-1,3,7-noatriene and valencen for orange; 3-Carene and D-limonene for mandarin; Sabinene, D- limonene, (E) 4,8-dimethyl-1,3,7-noatriene, hexyl 2-methylbutyrate, (-)-β-el- mene, 7-epi-a-selinene and e-nerolidol for lemon and finally D-dimonene and valencen were from avocado (
In conclusion, this paper showed that different types of fruit produce, different volatile organic compound profile as detected by GC-MS and with various larvae instars. Some of these compounds are specifically associated with Medfly infested fruit. In fruits infested with Medfly, the presence of volatile compounds like styrene, decanal in apple, l-β-pinene, β-cis-ocimene, isoamyl caproate, limonene-1,2-dial in orange, terebenthene, p-menth-1,4(8)-diene, (-)-β-elmene, (+)-epi-bicyclosesquiphellandrene in mandarin, sabinene, (E)4,8-dimethyl-1,3, 7-noatriene, α-terpineol in lemon and 1,2,6-dimethylundecane, α-terpineol in avocado can demonstrate distinction between non-infested and infested fruits. We have shown how Medfly can increase or decrease some of the fruit volatiles. Our results indicate that these volatiles levels, emitted from fruit with an early stage of larvae infestation can be detected by the HS-SPME GC-MS method. Recently, volatiles compound detection technology has been successfully used in different postharvest cases for early infested detection of insects and fungus. Fruit infested with Medfly or other insect eggs, release unique volatile compound. These compounds can be exploited to provide tools for improved pest detection. Finally, this research provides the basis for determining the larvae infested by the HS-SPME GC-MS method. Also, it can be used to assess the applicability of this technology for detection of other species of fruit fly, different type of fruits and different number of larvae. We recommend the use this technology in quarantine areas or prior of the importation of fruit for early detection of any infestation in the fruits by fruit flies.
Al-Khshemawee, H., Agarwal, M., Du, X. and Ren, Y.L. (2017) Detection of Mediterranean Fruit Fly Larvae Ceratitis capitata (Diptera: Tephidae) in Different Types of Fruit by HS-SPME GC-MS Method. Journal of Biosciences and Medicines, 5, 154-169. https://doi.org/10.4236/jbm.2017.53017