Efficacy of different commercially available MAT products in citrus in South Africa

Transcription

1 MALE ANNIHILATION TECHNIQUE (MAT) FOR THE ORIENTAL FRUIT FLY: Efficacy of different commercially available MAT products in citrus in South Africa ARUNA MANRAKHAN, JOHN-HENRY DANEEL AND ROOIKIE BECK Citrus Research International, PO Box 28, Nelspruit, 1200, South Africa SUMMARY The male annihilation technique (MAT) is recommended for control of the new fruit fly pest Oriental fruit fly, Bactrocera dorsalis, which is currently present in the north and north-eastern parts of South Africa. In MAT, B. dorsalis is targeted through deployment of stations or substrates containing a mixture of the male attractant, methyl eugenol (ME), and an insecticide. The aim of MAT is to realise high levels of male kill thereby reducing the number of matings and fruit fly population level. In South Africa, a number of MAT products are commercially available for control of the Oriental fruit fly. In 2014 and 2015, trials to determine the performance of these different MAT products for B. dorsalis control were conducted in Star Ruby grapefruit orchards in a farm near Letsitele, Limpopo Province. Two types of fibre board blocks containing ME and malathion: Invader-b-lok and B.I. Toolkit, were compared with drop applications of SPLAT Spinosad ME (ME and spinosad) and Last Call B.I. (ME and permethrin). Additionally, two application rates of Invader-b-lok were evaluated: 4 blocks per ha versus 12 blocks per ha. All MAT treatments were evaluated in combination with a standard fruit fly protein bait - M3 fruit fly bait station. As a control (no MAT), a treatment with only M3 fruit fly bait station was included in the field studies. In the field trials, efficacy of all treatments were evaluated using ME baited traps and traps baited with food-based attractants. An assessment of fruit was also carried out at harvest to determine fruit fly infestation. Results over the two years of study showed that numbers of B. dorsalis males were generally lower in blocks treated with MAT and M3 fruit fly bait stations compared to blocks treated with only M3 fruit fly bait stations. In the first year, there were no significant differences in catches of B. dorsalis males between the different MAT treatments. In the second year, significant differences in catches of B. dorsalis males were found between some of the MAT treatments. The fibre board blocks: Invader-blok and B.I. Toolkit, set at 12 units per ha as well as Last Call B. I. had significantly lower numbers of B. dorsalis males than the other treatments. A higher reduction in numbers of B. dorsalis males was observed in blocks treated with Invaderb-lok at 12 units per ha versus those treated with Invader-b-lok at 4 units per ha. No fruit fly infestation was found in Star Ruby grapefruit on trees at harvest. However, in the second year, B. dorsalis flies were reared from ground-collected Star Ruby grapefruit in blocks treated with only M3 bait stations and in blocks treated with Static Spinosad ME and M3 bait stations where average B. dorsalis male catches were above 5 flies per ME trap per week during the treatment. The conclusion from these field studies is that MAT is an essential component in the control of B. dorsalis. OPSOMMING Die mannetjie-uitwissingstegniek (MAT) word aanbeveel vir die beheer van die nuwe vrugtevliegplaag die Oosterse vrugtevlieg, Bactrocera dorsalis, wat tans in die noord noord-oostelike gedeeltes van Suid-Afrika teenwoordig is. Met die gebruik van MAT, word Bactrocera dorsalis geteiken deur die ontplooiing van lokstasies of substrate bevattende ʼn mengsel van die mannetjie lokmiddel, metiel-eugenol (ME) en ʼn insekdoder. Die doel van MAT is om hoë getalle mannetjies dood te maak en sodoende die aantal parings en die vrugtevlieg populasievlak te verminder. In Suid-Afrika is ʼn aantal MAT produkte kommersieel beskikbaar 54 TEGNOLOGIE CRI FEB/MAART 2017

2 Figure 1. Male annihilation products commercially available in South Africa: (A) Invader-b-lok, (B) Static Spinosad ME, (C) Last call B.I. and (D) B.I. Toolkit vir die beheer van die Oosterse vrugtevlieg. Gedurende 2014 en 2015, is proewe in Star Ruby pomeloboorde op ʼn plaas naby Letsitele, Limpopo Provinsie uitgevoer, om die werking van hierdie verskillende MAT produkte vir die beheer van B. dorsalis te bepaal. Twee tipes veselbordblokke, bevattende ME en malathion: Invader-b-lok en B.I. Toolkit, is met druppeltoedienings van SPLAT Spinosad ME (ME en spinosad) en Last Call B.I. (ME en permethrin) vergelyk. Twee toedieningsdigthede van Invader-b-lok is addisioneel geëvalueer: 4 blokke per ha teenoor 12 blokke per ha. Alle MATbehandelings is in kombinasie met ʼn standaard vrugtevlieg proteïenlokaas, die M3 vrugtevlieg lokaasstasie, geëvalueer. As ʼn kontrole (geen MAT), is ʼn behandeling met slegs M3 vrugtevlieg lokaasstasies in die veldstudies ingesluit. In hierdie veldproewe, is die effektiwiteit van alle behandelings geëvalueer deur gebruik te maak van ME-lokvalle en lokvalle wat met voedsel-gebaseerde lokmiddels gelaai is. ʼn Opname is tydens die oestyd geloods om vrugtevlieg besmetting te bepaal. Resultate oor twee jaar verkry dui daarop dat die getalle van B. dorsalis mannetjies oor die algemeen laer in blokke wat met MAT en M3 vrugtevlieg lokaasstasies behandel is as in vergelyking met blokke wat slegs met M3 vrugtevlieg lokaasstasies behandel was. In die eerste jaar was daar geen betekenisvolle verskille in vangste van B. dorsalis mannetjies tussen die verskillende MAT-behandelings nie. In die tweede jaar, was daar betekenisvolle verskille in die vangste van B. dorsalis mannetjies tussen sommige MATbehandelings. Die veselbordblokke: Invader-blok en B.I. Toolkit, geplaas teen 12 eenhede per ha asook Last Call B.I., het aansienlik laer getalle B. dorsalis mannetjies as die ander behandelings gehad. ʼn Groter verlaging in getalle van FEB/MARCH 2017 TECHNOLOGY CRI 55

3 Figure 2. Mean catches of (A) B. dorsalis males in ME baited traps and (B) B. dorsalis females in Biolure and Torula Yeast baited traps in Star Ruby grapefruit orchards under different male annihilation treatments in a farm near Letsitele, Limpopo Province South Africa in 2014 and B. dorsalis male catches were significantly affected by treatment during the treated period in 2014 and 2015 (Kruskal- Wallis test: 2014: P=0.003; 2015: P< ). There were no significant differences in catches of B. dorsalis females under the different male annhilation treatments over the two study years (Kruskal-Wallis test: 2014: P=0.243; 2015: P= 0.498). B. dorsalis mannetjies is waargeneem in blokke wat met Invader-b-lok teen 12 eenhede per ha behandel was, in vergelyking met blokke wat met Invader-b-lok teen 4 eenhede per ha behandel was. Geen vrugtevlieg besmetting is op Star Ruby pomelos, nog op die bome, tydens oes gevind nie. In die tweede jaar is B. dorsalis vlieë egter geteel uit Star Ruby pomelos wat vanaf die grond versamel is, in blokke wat slegs met M3 lokaasstasies behandel is en in blokke wat met Static Spinosad ME plus M3 lokaasstasies behandel is, waar die gemiddelde B. dorsalis mannetjie vangste meer as 5 vlieë per ME lokval per week tydens die behandeling was. Vanuit hierdie veldstudies is die gevolgtrekking dat MAT ʼn noodsaaklike komponent in die beheer van B. dorsalis. INTRODUCTION The Oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) is currently present in the north and north-eastern areas of South Africa (Manrakhan et al., 2015). In Africa, B. dorsalis was reported to cause important damage on commercial fruit such as mango and citrus (Goergen et al., 2011; Leonhardt et al., 1989; Mwatawala et al., 2006; Rwomushana et al., 2008; Vayssieres et al., 2009). Bactrocera dorsalis is listed as a quarantine pest in Europe and in United States of America. It is therefore important that fruit being exported is free of this pest. Studies conducted in and outside of Africa have shown that B. dorsalis can be effectively controlled using a combination of protein bait application (protein bait sprays or use of bait stations) and methyl-eugenol based male annihilation technique (MAT) (Fay et al., 1997; Grout and Stephen, 2013; Seewooruthun et al., 2000; Vargas et al., 2010). Recent studies conducted in Kenya have shown that MAT on its own was able to reduce B. dorsalis infestation on mangoes (Ndlela et al., 2016). MAT involves the use of male lures as long distance stimuli (Cunningham, 1989b; Foster and Harris, 1997). In MAT, the male lure is combined with an insecticide, and the mixture is incorporated in a carrier (gel or an absorbent surface like a wooden block). MAT carriers are 56 TEGNOLOGIE CRI FEB/MAART 2017

4 deployed to effect high mortality of fruit fly males which would then cause population suppression through a reduction in the number of matings and production of fertile offspring (Cunningham, 1989a). Methyl eugenol (ME) is the male lure used to target B. dorsalis (Cunningham, 1989b). Currently in South Africa, a number of male annihilation methods (MAT methods) such as wooden blocks impregnated with ME and malathion (e.g. Invader-b-Lok, B.I. ToolKit), Specialised Pheromone and Lure Application Technology (SPLAT) containing ME and spinosad such as STATIC Spinosad ME (Vargas et al., 2008) and gels containing ME and permethrin (e.g. Last Call B.I.) are commercially available for B. dorsalis control. Previous field studies in Hawaii have revealed differences in attractiveness of different ME based MAT treatments such as SPLAT-MAT-ME with spinosad and gel with ME and an organophosphate to B. dorsalis males (Vargas et al., 2009; Vargas et al., 2008). To date, however, there is very little knowledge on the relative field efficacy of different MAT treatments in suppressing B. dorsalis populations. In this study, we compared the efficacy of different MAT products in suppressing B. dorsalis populations in citrus orchards. We also determined the control efficacy of different densities of one MAT product - the Invader-b-lok. MATERIALS AND METHODS Study site In 2014 and 2015, studies were conducted in Star Ruby grapefruit orchards in a farm near Letsitele (S23º E30º ), Limpopo Province, for a period of 14 weeks between February and June. Treatments Five male annihilation treatments (Fig. 1) were compared: (1) Invader-b-Lok (River BioScience (Pty) Ltd, Humewood, South Africa) placed at 4 units per ha. (2) Invader-b-Lok (River BioScience (Pty) Ltd, Humewood, South Africa) placed at 12 units per ha. (3) STATIC Spinosad ME (Dow Agro Sciences Southern Africa (Pty) Ltd, Bryanston, South Africa) applied at 300 ml per ha. The product was placed in rolled up paper cylinders which were distributed in the orchard at every 49 m. In each cylinder, 5 ml of Static Spinosad ME were placed. (4) Last call B.I. (Insect Science (Pty) Ltd, Tzaneen, South Africa) applied at 150 g/ha. Last Call B.I. was applied as drops using an applicator, with each drop containing 0.05 g of the product. Ten drops were placed per tree in the orchard, being careful to avoid contact with the fruit. (5) B.I. Toolkit (Insect Science (Pty) Ltd, Tzaneen, South Africa) placed at 12 units per ha. All treatments included a bait application treatment - M3 fruit fly bait station (Green Trading CC, Brits, South Africa). M3 fruit fly bait stations were placed on every second tree in the orchard with a resulting density of 240 stations per ha. A control treatment of only M3 fruit fly bait stations (No MAT) was also included in the trial. There were 2 replicate blocks per treatment in each orchard. Each treatment was applied to a block of about 1 ha of Star Ruby grapefruit orchard. Treatments remained exposed within treated blocks for a period of 12 weeks. Fruit fly monitoring Three attractants were used for monitoring B. dorsalis adult population levels: (1) Torula Yeast (ISCA Technologies Inc., Riverside, California), (2) Biolure Fruit fly (Chempac (Pty) Ltd, Suider Paarl, South Africa) and (3) Invader lure containing ME (River BioScience (Pty) Ltd., Humewood, South Africa). Torula yeast and 3-component Biolure were contained in Chempac Bucket traps (Chempac (Pty) Ltd, Suider Paarl, South Africa). Torula yeast was prepared as 1 tablet in 300 ml of water which was then poured into the trap. In the Torula Yeast traps the capturing mechanism was by drowning. The ME dispenser Invader lure, was placed in Lynfield traps (River BioScience (Pty) Ltd., Humewood, South Africa). A dichlorvos strip was placed inside the ME baited Lynfield trap and Biolure baited Chempac Bucket trap to kill attracted flies. Traps were hung about 1.5 m above ground. In a treatment block, there were 2 traps of all attractants except ME. For ME, only one trap was placed in a treatment block in order FEB/MARCH 2017 TECHNOLOGY CRI 57

5 not to add to any control effects. The distance between each trap in a block was approximately 30 m. Adult fruit fly trapping in each block was initiated 1 week before start of treatment and was carried out on a weekly basis during the treated period. Attractants and insecticides were renewed after 6 weeks. With the Torula yeast traps, water was added whenever required in order to maintain the liquid level to the original level when first baited. Catches were identified to species and sex. Fruit damage assessment Each year, a fruit damage assessment was carried out at harvest where 500 fruit in each block were selected at random on the trees (10 fruit on each of 50 trees) and visually examined for fruit fly stings. Any suspected damaged fruit were brought to the lab, weighed and reared individually in aerated containers to determine percentage infestation and degree of infestation. In the second year, 9-10 fruit showing fruit fly damage symptoms were collected from the ground from each block. The fruit collected from the ground were weighed and incubated in aerated plastic containers over a layer of fine sand for a period of 8 weeks to determine fruit fly infestation rates. RESULTS AND DISCUSSION Treatments with MAT had significantly lower catches of B. dorsalis males than treatments without MAT (only protein bait application) over the two years of study (Fig. 2). These results strongly support the inclusion of MAT for B. dorsalis control in areas affected by the pest in South Africa and concur with results of previous suppression and eradication programmes whereby MAT was used in combination with bait application for control of B. dorsalis (Fay et al., 1997; Manrakhan et al., 2011; Seewooruthun et al., 2000). During the treated period in 2014, there were no significant differences in B. dorsalis male catches between the different MAT treatments and even between the two densities of Invaderb-lok (Fig. 2). However during the treated period in 2015, STATIC Spinosad ME had higher catches of B. dorsalis males compared to the other MAT treatments. The STATIC Spinosad ME used in the 2015 trial was from the same batch used in the previous year. The date of manufacture of the STATIC Spinosad ME product used was May Since STATIC Spinosad ME effectively controlled B. dorsalis males in 2014, it is likely that the efficacy of the product was compromised in the second year due to long storage on shelf before use (more than a year of storage after manufacture). Although there were no significant differences in efficacy of control between the two densities of Invader-b-lok tested, the percentage reduction of B. dorsalis males (from pre-treatment to during treatment) was higher for blocks treated with Invader-b-lok at 12 units per ha (97% and 86% in 2014 and 2015 respectively) than for those treated with Invader-b-lok at 4 units per ha (94% and 11% in 2014 and 2015 respectively). These results indicate that when using Invader-b-lok, the rate recommended on the label of the product (10-12 units per ha) would be able to suppress numbers of B. dorsalis at a faster rate than when using lower Invader-b-lok densities. In 2014 and 2015, there were no significant differences in catches of B. dorsalis females between the different treatments (Fig. 2). This was possibly due to similar protein bait application method M3 fruit fly bait station used in all the treatments. In the two years of study, no fruit fly damage was recorded on grapefruit at harvest on the trees. In the second year, B. dorsalis flies were reared from Star Ruby grapefruit collected from the ground in blocks treated with only M3 bait stations and in blocks treated with STATIC Spinosad ME plus M3 bait stations. The numbers of B. dorsalis flies reared per kg of ground collected Star Ruby grapefruit in blocks treated with only M3 bait stations and in blocks treated with STATIC Spinosad ME plus M3 bait stations were 0.35 ± 0.35 and 0.49 ± 0.49 respectively. In the two treatments with positive fruit fly infestation, B. dorsalis male catches were on average above 5 flies per trap per week. The current established threshold of 3 B. dorsalis males per ME baited trap per week set by the Department of Agriculture Forestry and Fisheries during the fruiting season would be conservative but is at the same time an attain- 58 TEGNOLOGIE CRI FEB/MAART 2017

6 able goal if MAT treatments, bait application and orchard sanitation are being implemented. Since all MAT products were found to be equally effective at least in the first year of this study, the choice of products for use in the field would be highly dependent on the cost, availability and registration status of the products. ACKNOWLEDGMENTS We are grateful to Dr Tertia Grove, Agricultural Research Council, for suppport provided in this study. We acknowledge field support of Big Boy Thobela. We are indebted to Gustav van Veijeren and Petrus Botha for providing us farm access and for all the field support. We acknowledge River Bioscience (Pty) Ltd, Insect Science (Pty) Ltd and Dow Agrosciences Southern Africa (Pty) Ltd for the MAT products provided in this study. This study was funded by Citrus Research International (Pty) Ltd. REFERENCES CUNNINGHAM, R.T., 1989A. Male Annihilation, In: Robinson, A.S., Hooper, G. (Eds.), Fruit flies: Their Biology, Natural Enemies and Control. Elsevier, Amsterdam, pp CUNNINGHAM, R.T., 1989B. Parapheromones, In: Robinson, A.S., Hooper, G. (Eds.), Fruit flies, their biology, natural enemies and control. Elsevier, Amsterdam, pp FAY, H.A., DREW, R.A.I., LLOYD, A.C., The eradication program for Papaya fruit flies (Bactrocera papayae Drew & Hancock) in North Queensland, in: Allwood, A.J., Drew, R.A.I. (Eds.), Management of fruit flies in the Pacific. A regional symposium. ACIAR, Nadi, Fiji, pp FOSTER, S.P., HARRIS, M.O., Behavioural manipulation methods for insect pest management. Annual Review of Entomology 42, GOERGEN, G., VAYSSIERES, J.-F., GNANVOSSOU, D., TINDO, M., Bactrocera invadens (Diptera: Tephritidae), a new invasive fruit fly pest for the Afrotropical region: Host Plant Range and Distribution in West and Central Africa. Environmental Entomology 40, GROUT, T.G., STEPHEN, P.R., Controlling Bactrocera invadens by using protein bait and male annihilation. SA Fruit Journal 12(4), LEONHARDT, B.A., CUNNINGHAM, R.T., RICE, R.E., HARTE, E.M., HENDRICHS, J., Design, effectiveness, and performance criteria of dispenser formulations of trimedlure, an attractant of the Mediterranean fruit fly (Diptera: Tephritidae). Journal of Economic Entomology 82, MANRAKHAN, A., HATTINGH, V., VENTER, J.-H., HOLTZHAUSEN, M., Eradication of Bactrocera invadens (Diptera: Tephritidae) in Limpopo Province, South Africa. African Entomology 19, MANRAKHAN, A., VENTER, J.H., HATTINGH, V., The progressive invasion of Bactrocera dorsalis (Diptera: Tephritidae) in South Africa. Biological Invasions 17, MWATAWALA, M.W., DE MEYER, M., MAKUNDI, R.H., MAERERE, A.P., Seasonality and host utilization of the invasive fruit fly, Bactrocera invadens (Dipt., Tephritidae) in central Tanzania. Journal of Applied Entomology 130, NDLELA, S., MOHAMED, S., NDEGWA, P.N., ONG'AMO, G.O., EKESI, S., Male annihilation technique using methyl eugenol for field suppression of Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) on mango in Kenya. African Entomology 24, RWOMUSHANA, I., EKESI, S., GORDON, I., OGOL, C.K.P.O., Host plants and host plant preference studies for Bactrocera invadens (Diptera: Tephritidae) in Kenya, a new invasive fruit fly species in Africa. Annals of the Entomological Society of America 101, SEEWOORUTHUN, S.I., PERMALLOO, S., GUNGAH, S., SOONNOO, A.R., ALLECK, M., Eradication of an exotic fruit fly from Mauritius, In: Tan, K.H. (Ed.), Area-wide control of fruit flies and other insect pests. Penerbit Universiti Sains Malaysia, Penang, pp VARGAS, R.I., PINERO, J.C., MAU, R.F.L., JANG, E.B., KLUNGNESS, L.M., MC INNIS, D.O., HARRIS, E.B., MCQUATE, G.T., BAUTISTA, R.C., WONG, L., Area-wide suppression of the Mediterranean fruit fly, Ceratitis capitata, and the Oriental fruit fly, Bactrocera dorsalis, in Kamuela. Journal of Insect Science 10:135. insectscience.org/ VARGAS, R.I., PINERO, J.C., MAU, R.F.L., STARK, J.D., HERTLEIN, M., MAFRA-NETO, A., COLER, R., GETCHELL, A., Attraction and mortality of oriental fruit flies to SPLAT-MAT-methyl eugenol with spinosad. Entomologia Experimentalis et Applicata 131, VARGAS, R.I., STARK, J.D., HERTLEIN, M., NETO, A.M., COLER, R., PINERO, J., Evaluation of SPLAT with spinosad and methyl eugenol or cue-lure for "attract-and-kill" of Oriental and melon fruit flies (Diptera: Tephritidae) in Hawaii. Journal of Economic Entomology 101, VAYSSIERES, J.-F., KORIE, S., AYEGNON, D., Correlation of fruit fly (Diptera: Tephritidae) infestation of major mango cultivars in Borgou (Benin) with abiotic and biotic factors and assessment of damage. Crop Protection 28, TEGNOLOGIE CRI FEB/MAART 2017