Evaluation of modified waste brewer s yeast as a protein source for the control of the melon fly, Bactrocera cucurbitae (Coquillett)

Transcription

1 Proceedings of 6th International Fruit Fly Symposium 6 10 May 2002, Stellenbosch, South Africa pp Evaluation of modified waste brewer s yeast as a protein source for the control of the melon fly, Bactrocera cucurbitae (Coquillett) P. Sookar 1 *, S. Facknath 2, S. Permalloo 1 & S.I. Seewooruthun 1 1 Entomology Division, Ministry of Agriculture Food Technology and Natural Resources, Réduit, Mauritius 2 University of Mauritius, Réduit, Mauritius The attractancy to the melon fly, Bactrocera cucurbitae (Coquillett), and phytotoxicity of four baits locally prepared with waste brewer s yeast, were assessed in a plantation of calabash, Lagenaria siceraria Mol., in Mauritius with cloth ground-sheet catchers mounted below bait spots. Protein hydrolysate was used as the standard bait. No bait exhibited any phytotoxicity. As spot sprays, protein hydrolysate attracted significantly more melon flies than the prepared baits, brewer s yeast autolysed with fresh green pawpaw juice more than with papain, and brewer s yeast with papain more than with fresh or boiled pineapple juice.the efficacy of the same baits to control the melon fly was then assessed as weekly bait sprays in ridge gourd, Luffa acutangulata (L.) Roxb. Fruit fly infestation levels were initially high (40 80%) in all plots, but after 12 weeks, infestation was 100% in an untreated control, 2% with protein hydrolysate protection, 1% with yeast autolysed with papain, 2% with yeast autolysate with pawpaw, 6% with yeast autolysate with pineapple and 7% with the boiled yeast preparation. It is concluded that treated yeasts may offer a cost-effective fruit fly control method in Mauritius, and ways in which performance may be enhanced, and the implications of the different performances of the various assessment methods, are discussed. *To whom correspondence should be addressed. ento@intnet.mu INTRODUCTION In the Mauritian National Fruit Fly Control Programme initiated in 1994 (Soonnoo et al. 1996), imported protein hydrolysate has been used in bait sprays for the control of fruit flies, including the Natal fruit fly Ceratitis rosa Karsch, the Medfly C. capitata (Wiedemann), the ber fly Carpomya vesuviana Costa, the peach fruit fly Bactrocera zonata Saunders and the melon fly B. cucurbitae Coquillett. Bait sprays rely on the fact that both male and female fruit flies require protein for their growth and development. Their use limits the amount of insecticide used, leaving lower residues on crops and in the environment, and causing negligible harm to beneficial insects, such as pollinators and parasitoids (Galun et al. 1983). Apart from labour costs, the imported protein hydrolysate represents the biggest cost component of bait sprays in Mauritius, comprising approximately 15% of total costs (and 75% of non-labour costs) (Rasamimanana 1997). Shipping problems in the past have restricted the availability of protein hydrolysate at the right time. Clearly, the ability of Mauritius to produce its own bait from locally available materials could make a major contribution to reducing costs and thereby enhancing the sustainability of fruit fly control activities in the country. Waste brewer s yeast (WBY) has the potential to be developed into suitable locally-produced baits. Lloyd & Drew (1997) reported that WBY is a rich source of the B-complex vitamins, protein (providing all essential amino acids), and minerals. Bateman & Morton (1981) demonstrated that ammonia was responsible for attraction of fruit flies, but Drew & Fay (1988) questioned the role of ammonia, reporting that flies did show some attraction to weak ammonia solutions,but also that the relatively low level of response indicated that other volatiles were likely to play an important role. Wakabayashi & Cunningham (1991) found that a four-component mixture, made up of ammonium bicarbonate, linolenic acid, putrescine and pyrolidine, was as effective as the standard protein hydrolysates as food bait for melon flies. WBY has been successfully modified into bait for fruit fly control in Queensland, Australia (Lloyd & Drew 1997). Following preliminary studies in Mauritius, neutralized WBY was used as a source of protein to replace the imported protein hydrolysate in the bait sprays for the eradication of the oriental fruit fly, Bactrocera dorsalis Hendel (Seewooruthun et al. 1998). While good results were obtained as shown by the success of the B. dorsalis eradication campaign (Seewooruthun et al. 2000), the neutralized WBY was found to damage the nozzle O-rings of knapsack sprayers and showed phytotoxicity effects on young leaves of pawpaw and cucurbits. The Indian Ocean Commission Regional Fruit Fly Control Programme, set up in 1996, carried out preliminary studies on the modification of WBY with imported papain enzyme powder to produce an autolysate. Tested in McPhail traps in orchards, the autolysate was found to be as effective as the

2 296 Proceedings of the 6th International Fruit Fly Symposium currently imported product (Gopaul et al. 2000a,b). This study assessed boiled WBY, and WBY modified with papain, fresh pawpaw juice and fresh pineapple juice, at two levels: 1. Field assessment of bait attraction to wild flies and phytotoxicity to crop plants 2. Field assessment of baits in sprays for the control of the melon fly. MATERIALS AND METHODS The experimental treatments (with the concentration ratios of protein bait/malathion 57% EC insecticide/water) were as follows: Hydrolysate: standard protein hydrolysate (2/0.7/ 97.3). Papain:WBY modified with papain enzyme powder (0.8% w/v) for 24 hours (12.5/0.7/86.8). Pawpaw: WBY modified with pawpaw juice (4% v/v) for 24 hours (12.5/0.7/86.8). Pineapple: WBY modified with pineapple juice (4% v/v) for six hours (12.5/0.7/86.8). Boiled: boiled WBY (12.5/0.7/86.8). Field assessment of bait attraction and phytotoxicity The experiment was carried out in a plantation of calabash, Lagenaria siceraria Mol., of about 0.75 ha at Rivière Baptiste, Moka (20 13 S, E), a vegetable-growing locality, 390 m a.s.l., with a mean annual rainfall of 603 mm and annual temperatures between 18.6 C and 23.0 C (Anon. 1999). The crop was at the bearing stage. The trial was set up on 4 September 2000 and lasted one week. Five treatments were compared in three completely randomized blocks. Tagged shoots (20 leaves or more, including young and mature leaves) were placed above 1.5 m 2 white cloth catchers mounted on stands at a height of 10 cm. The test procedures involved 25-ml spot sprays of bait, applied under the foliage with a hand-held atomizer at approximately 08:30. Dead insects were collected, preserved, identified and counted hourly for five hours, and also on the second and third day. Leaves were examined for scorching or damage daily for one week following bait application. Data were log-transformed to meet the assumption of homogeneity, and then analysed by analysis of variance (ANOVA), and the means separated by the Duncan multiple range test. Field assessment of baits for fruit fly control in ridge gourd The experiment was carried out in ridge gourd, L. acutangulata (local variety) at Bois Marchand Agricultural Centre and Arsenal Seed Production Centre of the Ministry of Agriculture, Pamplemousses (20 6 S, E), m a.s.l. with a mean annual rainfall of 603 mm and annual temperatures between 18.9 C and 29.2 C (Anon. 1999). At each site there were three experimental plots of 100 m 2, at least 250 m apart. Seedlings of ridge gourd were transplanted on 3 October Additional to the experimental treatments was one untreated plot that served as a control. Bait application started on 14 December 2000 and continued weekly for 12 weeks. The baits were applied as spot sprays under the foliage of the plants on a weekly basis at the rate of 12 l/ha in 480 spots of 25 ml each. Samples of 15 fruits (each between 75 and 150 g) were taken from each plot at weekly intervals from the date the treatments were applied. Fruits were examined for fruit fly punctures, weighed and placed in separate plastic containers on a layer of sand, for a period of 5 to 7 days to evaluate infestation. A fruit with at least one fruit fly puncture was considered as infested. The sand was sieved and the collected pupae were counted and placed in a small cage of cm and emerged flies were identified and counted. RESULTS AND DISCUSSION Field assessment of bait attraction and phytotoxicity Table 1 shows the catches by the different baits. Baits caught significantly more males than females (sex ratio was 2.69 : 1), although the sex ratio of catches did not significantly differ among the experimental treatments. In total catches, hydrolysate was significantly superior to the pawpawtreated WBY, which was superior to the papaintreated WBY which was in turn superior to the others. There was a significant difference in attraction of the baits with regard to time-of-day. All the tested baits caught all flies before 11:30 on every day. Catch inspection ended at 14:30 every day. It is possible that the flies were again active at dusk, in which case they would have been collected the following morning. Christenson & Foote (1960) reported that B. dorsalis devoted more time in the field searching for food in the morning hours, immediately after a prolonged period of inactivity during the night, and that during the day the flies spent less time on feeding. The treatments gave some indication of decreas-

3 Sookar et al.: Modified waste brewer s yeast as a protein source for control of melon fly 297 Table 1. Mean number ± S.E. of melon flies collected per day per collector over a three-day period using different attractants. Catch Hydrolysate Papain Pawpaw Pineapple Boiled Females 4.0 ± ± ± ± ± 0.0 Males 8.3 ± ± ± ± ± 0.3 Totals* 12.3 ± 6.4 a 1.0 ± 1.0 c 2.0 ± 0.6 b 0.3 ± 0.3 d 0.3 ± 0.3 d *Means followed by the same letter were not significantly different at the 5% significance level. ing in effect over time: on the third day after bait application, papain and pawpaw-treated WBY and protein hydrolysate attracted melon flies, while pineapple-treated and boiled WBY showed no attraction. Bait treatments did not differ significantly between themselves with regard to days elapsed. No non-target insect was collected, although other insects might have fed on the bait and died outside the catcher. No bait showed any phytotoxicity to the calabash leaves. This is attributed to the non-toxic nature of the reagents in the enzymatic degradation of yeast cells. Preparations were not highly acidic nor alkalinic. The pineapple juice preparation contained citric acid but had a ph of only 6.47, and contained no additional salt. Field assessment of baits for melon fly control The only fruit fly species that was obtained from the reared fruits was B. cucurbitae. The other two cucurbit-attacking species in Mauritius the Ethiopian fruit fly Dacus ciliatus Loew and the Indian Ocean cucumber fly D. d emmerezi Bezzi (Orian et al. 1960) were not found. Data obtained from July 1996 to December 1998 from Plaisance Experimental Station during the eradication programme of B. dorsalis showed that the melon fly was the most important fruit fly in cucurbits in Mauritius (Anon. 1997, 1998). Most of the infested fruits were malformed. Table 2 shows the levels of infestation to ridge gourd over the 12 weeks of the experiment. Initial damage levels ranged from 40 to 80%, gradually decreasing to less than 35% in the treated plots after a period of five weeks, with less than 15% damage in plots treated with papain, pawpaw and pineapple. Six weeks of treatment were required to lower the level of infestation to less than 10% in plots treated with papain and pawpaw, another two for the plots treated with protein hydrolysate and pineapple. The level of damage in the untreated plot reached more than 90% in the third week and 100% in the seventh. Some factors may have contributed to the substantial infestation in treated plots. Treatments Table 2. Percentage infestation of ridge gourds by melon fly in plots protected by different baits over 12 weeks. Week Control Hydrolysate Papain Pawpaw Pineapple Boiled Mean (7 12)* *Average values for weeks 7 to 12, i.e. after infestation reached saturation in the unprotected control plots. For comparison of the protection obtained by the different experimental baits, the mean level of infestation over the last six weeks was selected as reflecting the final and stable infestation levels after melon fly populations had stabilized, and that in the unprotected plot had reached saturation.

4 298 Proceedings of the 6th International Fruit Fly Symposium Table 3. Relative performance of different WBY baits against melon fly, as a percentage of the performance of commercial protein hydrolysate, when assessed by laboratory assay (Sookar 2003), field catcher (Table 1) and field control (Table 2). Attractant Method Papain Pawpaw Pineapple Boiled Laboratory Catcher Control were applied after fruit set started, so that fruits were already infested; to be effective, treatments should have started 5 10 weeks earlier (before blossom) to control the initial fruit fly population. Furthermore, the technique of bait spraying to control fruit flies is most effective when it is done area-wide so that the possibility of reinvasion is minimized (Permalloo et al.1998;sookar & Khayrattee 2000). Our treated areas were small, and prone to reinvasion from the unprotected control plots and from a group of untreated commercial cucurbit fields approximately 5 km away. CONCLUSION With regard to the assessment methods, the findings of the different research approaches did not closely match each other. The relatively poor performance of the WBY preparations in the fieldattractancy test (Table 1) was not matched by the assessment of actual control performance (Table 2), in which the WBY preparations nearly matched (or surpassed) the commercial hydrolysate. Table 3 shows the data from these tables converted to show the performance of WBY baits as percentages of the performance of the hydrolysate, along with results from an earlier laboratory study (Sookar, 2003). In discriminating between WBY baits, all three methods showed the papain and pawpaw baits to be superior to the pineapple and boiled baits. Comparing WBY baits with the hydrolysate itself, however, the good performance of the WBY baits in control trials was not predicted by the earlier studies, and by the field catcher study in particular. The important conclusion is drawn that the different baits when used in the laboratory, catcher and control trials, may not perform in similar ways, so that the simpler methods may not accurately predict eventual control performance. In similar studies with B. cucurbitae in Pakistan, however, Stonehouse et al. (2002a,b) found a similarity between relative performances in the laboratory and field, the effectiveness of a bait of boiled meat broth as a percentage of commercial protein hydrolysate being 69 in the laboratory and 66 using field catchers. The relationships between relative performances of different baits by different assessment methods deserves future study. With regard to the performance of WBY baits,the results are generally encouraging, and indicate that the preparations may be viable control methods. It may be possible to further enhance the performance of WBY preparations. Other parts of the pineapple plant apart from the fruit may contain high amounts of bromeline, and could be evaluated for protein autolysis. The percentage solids of WBY may be increased further by boiling before the addition of protein digesters, thereby increasing the yields of volatiles such as ammonia and compounds like linolenic acid, putrescine and pyrolidine, which will attract the melon fly. Lloyd & Drew (1997) obtained a higher relative attractancy of modified yeast slurry in field tests by using more concentrated bait, and by increasing the solid content from 18% to 50%. Research may also be necessary to assess the shelf life of the prepared baits, and how this may be extended. Eventually, an economic assessment for commercial usage would be required before large-scale production of the attractant could begin. ACKNOWLEDGEMENTS We would like to thank the Ministry of Agriculture, Food Technology and Natural Resources, Mauritius, for providing facilities for carrying out the experiment, Mr Sookareea, Research and Development Officer at the Ministry of Agriculture, and Mr A. Ragoo, Lecturer at the University of Mauritius for assistance with statistics. We are grateful to all the staff of the Entomology Division for assistance, Mr P. Ascooram, brewer at the Mauritius Breweries Ltd, for providing waste brewer s yeast for the experiment. We also thank the farmers and staff of Bois Marchand Agricultural Centre and Arsenal Seed Production Centre who kindly agreed to collaborate with us in the

5 Sookar et al.: Modified waste brewer s yeast as a protein source for control of melon fly 299 experiment. Last but not least, we would like to record the valuable help of Dr John Stonehouse, Imperial College, U.K., in revising the manuscript. REFERENCES ANON Entomology Division. In: Annual Report for the Year Agricultural Services of the Ministry of Agriculture, Food Technology and Natural Resources, Mauritius. ANON Entomology Division. In: Annual Report for the Year Agricultural Services of the Ministry of Agriculture, Fisheries and Natural Resources, Mauritius. ANON Annual Report of the Meteorological Services. Republic of Mauritius. BATEMAN, M.A. & MORTON, T.C The importance of ammonia in proteinaceous attractants for fruit flies (Family: Tephritidae). Australian Journal of Agricultural Research 32: CHRISTENSON, L.D. & FOOTE, R.H Biology of fruit flies. Annual Review of Entomology 5: DREW, R.A.I. & FAY, H.A.C Comparisons of the roles of ammonia and bacteria in the attraction of Dacus tryoni (Froggatt) (Queensland fruit fly) to proteinaceous suspensions. Journal of Plant Protection in the Tropics 5: GALUN, R., GOTHILF, S., CHAMBERS, D.L. & SHARP, J.L Responses of tephritid fruit flies to baits. In: Final Report, Project I-78-79, BARD. Beit-Dagan, Israel. GOPAUL, S., PRICE, N.S., SOONNOO, R., STONEHOUSE, J.M. & STRAVENS, R. 2000a. Technologies of fruit fly monitoring and control in the Indian Ocean Region. In: Indian Ocean Regional Fruit Fly Programme Final Report GOPAUL, S., ZENZ, N. & PRICE, N.S. 2000b. Local production of protein bait for fruit fly monitoring and control. In: Price, N.S. & Seewooruthun, S.I. (Eds) Proceedings of the Indian Ocean Commission Regional Fruit Fly Symposium, Flic en Flac, Mauritius LLOYD, A. & DREW, R.A.I Modification and testing of brewery waste yeast as a protein source for fruit fly bait. In: Allwood, A.J. & Drew, R.A.I. (Eds) Proceedings of the Symposium on the Management of Fruit Flies in the Pacific ORIAN, J.E.A. & MOUTIA, L.A Fruit flies (Trypetidae) of economic importance in Mauritius. Revue Agricole et Sucrière de l Ile Maurice 39: PERMALLOO, S., SEEWOORUTHUN, S.I., JOOMAYE, A., SOONNOO, A.R., GUNGAH, B., UNMOLE, L. & BOOD- RAM, R An area wide control of fruit flies in Mauritius. In: Lalouette, J.A., Bachraz, D.Y., Sukurdeep, N. & Seebaluck, B.D. (Eds) Proceedings of the 2nd Annual Meeting of Agricultural Scientists, Food and Agricultural Research Council, Réduit, Mauritius RASAMIMANANA, H Base Economique pour l Amelioration de la Gestion des Mouches des Fruits. Indian Ocean Regional Fruit Fly Programme Report of Activities, September November SEEWOORUTHUN, S.I., SOOKAR, P., PERMALLOO, S., JOOMAYE, A., ALLECK, A., GUNGAH, B. & SOONNOO, A.R An attempt at the eradication of the oriental fruit fly, Bactrocera dorsalis Hendel, from Mauritius. In: Lalouette, J.A., Bachraz, D.Y., Sukurdeep, N. & Seebaluck, B.D. (Eds) Proceedings of the 2nd Annual Meeting of Agricultural Scientists, Food and Agricultural Research Council, Réduit, Mauritius SEEWOORUTHUN, S.I., PERMALLOO, S., SOOKAR, P. & SOONNOO, A.R The oriental fruit fly, Bactrocera dorsalis, eradicated from Mauritius. In: Price, N.S. & Seewooruthun, S.I. (Eds) Proceedings of the Indian Ocean Commission Regional Fruit Fly Symposium, Flic en Flac, Mauritius SOOKAR, P. & KHAYRATTEE, F.I Melon fly control at Plaine Sophie, Mauritius. In: Price, N.S. & Seewooruthun, S.I. (Eds) Proceedings of the Indian Ocean Commission Regional Fruit Fly Symposium, Flic en Flac, Mauritius SOOKAR, P Modification and laboratory evaluation of waste brewer s yeast, a local substitute for protein hydrolysate in melon fly bait. Proceedings of the Annual Meeting of Agricultural Scientists, Food and Agricultural Research Council, Réduit, Mauritius. In press. SOONNOO, A.R., SMITH, E.S.C., JOOMAYE, A., PERMALLOO, S. & GUNGAH, B A large scale fruit fly control programme in Mauritius. In: Chua, T.H. & Khoo, S.G. (Eds) Proceedings of the 2nd Symposium on Problems and Management of Tropical Fruit Flies, Kuala Lumpur, Malaysia STONEHOUSE, J.M., ZIA, Q., MAHMOOD, R., POSWAL, A. & MUMFORD, J.D. 2002a. Single-Killing-Point laboratory assessment of bait control of Fruit Flies (Diptera: Tephritidae) in Pakistan. Crop Protection 25: STONEHOUSE, J.M., AFZAL, M., ZIA, Q., MUMFORD, J.D., POSWAL, A. & MAHMOOD, R. 2002b. Single-Killing- Point field assessment of bait and lure control of fruit flies (Diptera: Tephritidae) in Pakistan. Crop Protection 25: WAKABAYASHI, N. & CUNNINGHAM, R.T Four-component synthetic food bait for attracting both sexes of the melon fly (Diptera: Tephritidae). Journal of Economic Entomology 84: