Ecopom dispensers for mating disruption in apple orchards

Franco Rama

• Introduction 
• Dispenser design
• Field trials
  • Trentino (Italy)
  • France
  • The Netherlands
• Conclusions
• References

Abstract - Mating disruption has became a valuable alternative to insecticide treatments, and growers and agricultural organisations increasingly demand reliable products in order to implement the method. Industries were hence prompted to supply enough material both to investigate the agronomic aspects of mating disruption and to enable large-scale applications. The work done in the past years made it possible to identify the limiting factors of the mating disruption technique, mainly with respect to orchard organisation and the size of insect populations. Since 1987 trials have been carried out to evaluate mating disruption as a control method against codling moth, Cydia pomonella  L., and leafroller species in apple orchards, using Isagro's Ecopom and Ecopom Combi dispensers. On the basis of these trials we were able to modify and optimise several factors, such as the amount of active ingredient/ha, the number of dispensers/ha, the amount of active ingredient/dispenser and the number of applications per season. The persistence of pheromone release in the field and the reproducibility of the manufacturing process of the dispensers became the most important elements to be defined. I here report the results of Isagro's efforts towards the development of an effective dispenser for mating disruption in apple orchards.

Key words - sex pheromone, mating disruption, dispensers, release rates, Cydia pomonella, leafrollers, Tortricidae

Introduction
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Our research aims at the development of mating disruption methods for the control of insect pests. Today, mating disruption is used, in combination with or instead of chemical treatments, to control insecticide-resistant populations of codling moth, Cydia pomonella, and to obtain fruit with no detectable pesticide residues at harvest, which will be processed into baby food. The objective of our studies is to provide a reliable mating disruption dispenser which can be utilised directly by the growers under various agronomic conditions.

Dispenser design

We conceived a simple dispenser that can contain large amounts of active ingredient and is especially suitable for the release of codling moth sex pheromone (Rama et al. 1990; Arsura et al. 1992; Charmillot et al. 1993). The dispensers are made of biodegradable, resin-treated filter paper and their shape makes it possible to easily hang them to the branches, thus avoiding the use of plastic or metal wires. Dispensers distributed by Isagro under the trade name Ecopom®, for the mating disruption against C. pomonella, contain codlemone, (E,E)-8,10-dodecadien-1-ol (E8,E10-12OH). Ecopom® Combi dispensers contain in addition (Z)-11-tetradecenyl acetate (Z11-14Ac), a pheromone component of a number of leafroller moths.

Table 1 Mating disruption of codling moth and leafrollers with different dispenser formulations and application rates (Trentino, Italy)

Year	Dispenser	Active ingredient			Dispenser/ha	Half-life (d)	Damage (%)
		Application (g/ha)		mg/dispenser
		1st	2nd
Codling moth
1987	Ecopom a	21	26	175	120 + 150	50	2.1
1988	Ecopom	50	30	250	200 + 120	39	1.5
1989	Ecopom	80	80	400	200 + 200	56	0.8
1990	Ecopom Combib	90	94	300	300 + 300	34	0.4
1991	Ecopom Combi	97	97	350	280 + 280	81 c	0.1
1992	Ecopom	88	-	320	275	34	1.1
1993	Ecopom	100	100	320	312 + 312	56	0.7
1994	Ecopom	75	75	250	300 + 300	20	0.4
1995	Ecopom	75	-	250	300	52	0.2
1995	Ecopom Combi	75	-	250	300	46	0.2
Leafrollers
1990	Ecopom Combi	116	-	300	400	-	3.1
1991	Ecopom Combi	83	83	300	275 + 275	-	1.4
1994	Ecopom Combi	75	-	250	300	110	1.0
1995	Ecopom Combi	60	-	200	300	72	0.9

^a Codlemone; ^b Codlemone + Z11-14Ac; ^c Applied April 10, for control of Pammene rhediella

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Trials have been carried out since 1987 (Rama et al. 1996) to optimise several factors, such as the quantity of attractant/ha, the number of dispensers/ha, the amount of active ingredient/dispenser, and the number of applications per season (Table 1).

The persistence of dispensers in the field determines not only the success of the method, but also the cost of control by mating disruption. The half-life of the dispenser is affected by several variables such as size, nature of the support, pheromone load, inert adjuvants and, of course, by the agroclimatic conditions. In order to minimise these last effects, most studies have been carried out also in greenhouses at more or less constant temperature and wind speed.

During the experiments in 1994, a rapid emission of codlemone made it necessary to increase the life of the Ecopom dispenser (Table 1). In 1995, the formulation was modified by addition of a new release modulator which brought about a persistence of about 90 days (Figure), compared to only 30-40 days in 1994.

Figure Release rates from Ecopom and Ecopom Combi dispensers at Trentino 1995

Other important parameters are the linearity of pheromone release and the amount released per ha. Some authors claim a threshold of 10 mg/ha/hour as the lower limit to achieve good disruption against codling moth. Both Ecopom and Ecopom Combi dispensers show a rather constant release of 0.07 to 0.1 mg codlemone/hr during ca. 100 days, which would result in 20 to 30 mg codlemone/ha/hr at the recommended dispenser density of 300/ha. The average release rate for Z11-14Ac is slightly lower at 0.05 to 0.07 mg/hr.

Each dispenser was loaded with 250 mg of codlemone and, in the case of the Combi version, with 200 mg of Z11-14Ac; the dispensers contained also an antioxidant, a UV-screener and a release modulator.

In order to ensure a constant quality of the dispenser material, it was important to improve the reproducibility of the manufacturing process. The variability in pheromone charge among the different batches of dispensers was greatly improved by replacing a manual impregnation procedure (261 ± 34 mg codlemone/dispenser) with a mechanical semi-automatic procedure (253 ± 18 mg). In addition, scaling up the volume of production resulted in a better standardisation of the single dispensers.

Field trials
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During the last years, experimental field trials on mating disruption against Cydia pomonella  and apple leafrollers were carried out directly by extension organisations and farmers' associations, in order to test the potential and flexibility of the method. In 1995, more than 600 ha throughout Europe were protected by Ecopom or Ecopom Combi mating disruption dispensers.

The dispensers were applied twice in most orchards, in April/May and in June/July, at an average density of 300 dispensers/ha, external protection borders not included. The results of the more important applications are discussed below.

Trentino (Italy)
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About 200 ha of apple orchards, over ten different sites, were treated with a single application of Isagro's dispensers Ecopom Combi. The protection against codling moth was almost complete, with damages below the economic threshold (Table 2).

Table 2 Mating disruption of codling moth and leafrollers with with Ecopom Combi dispensers (Trentino, Italy, 1995)

The application of mating disruption reduced the number of insecticide treatments, from an average of three in 1994, to occasional curative treatments in 1995. The control by mating disruption was comparable with that obtained by insecticide sprays in the control plots.

Even the attack of apple leafrollers Adoxophyes orana and Pandemis heparana was satisfactorily contained below 1%; only at two sites it was necessary to spray insecticides due to a high pest population: at Caldonazzo and Mezzocorona, 7% and 15% of shoots infested after blooming led to a damage at harvest of about 2.2% and 5%, respectively.

In Alto Adige, the area treated with a single distribution of Ecopom Combi was limited to 11 ha, divided into 9 farms. No chemical were sprayed either before the application of mating disruption or during the season. The results indicate an excellent protection against codling moth, with damage levels below 0.3%.

France
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The growing resistance of codling moth in Southern France to the most commonly used insecticides has been of great concern over the last few years. Our trials started in 1993 in a few selected areas, where the population of codling moth was known to be substantial and required frequent insecticide sprays to be controlled.

After the positive results obtained in the first year, the treated area increased in 1994 and 1995, expanding also to regions where the pressure of codling moth was not so critical. The results obtained from trials done in cooperation with G.R.C.E.T.A. (Basse Durance) in the last three years are shown in Table 3 (Navarro et al. 1995). It is noteworthy that satisfactory control of codling moth was achieved even in spite of the drastic reduction of insecticide sprays.

In the same region, further trials were carried out in collaboration with the Cooperative Sicoly (Table 3). Two applications of 300 dispensers/ha were done each year, using Ecopom Combi in 1993, and Ecopom in 1994 and 1995.

The damage recorded at Les Horizons in 1994 was mainly due to the short persistence of dispensers of about 30-40 days. With the new formulation in 1995 the attack was reduced below the economic threshold, without any chemical treatment while the control plot received twelve insecticide sprays (Table 3). Interesting results were obtained also at two new sites in 1995, where mating disruption was applied for the first time: at Laroche in the previous year the damage had been held below the threshold by five chemical treatments, while at Chaurchaire the history of the orchard showed a high pressure by codling moth which required seven chemical sprays with a damage at harvest of about 25%. The application of mating disruption decreased the damage to 3.7% without any preliminary chemical treatment, despite the average of 2.17 larvae per cardboard traps caught in the autumn. Three sprays of phosalone were applied in August due to the early exhaustion of dispensers which showed, according to GC analysis, a lower pheromone content than expected.

Table 3 Mating disruption of codling moth and leafrollers with Ecopom dispensers in apple orchards of the G.R.C.E.T.A. and the Sicoly cooperatives (France) during three consecutive years, 1993-1995

Site	Area			Dispenser applications			Damage (%)			Insecticide treatments (in control plots)
	'93	'94	'95	'93	'94	'95	'93	'94	'95	1993	1994	1995
Grand Vignes	1.5	4.0	3.9	3	3	2	1.5	0	1.4	2 (5)	1 (10)	3 (14)
Barjac	0.9	9.0	2.4	3	3	2	0.5	0	0.7	3 (10)	4 (14)	1 (6)
Chaîne		3.1			2			0			3 (15)
Grand Mas		6.6			2			0.6			9 (20)
La Glacière		3.5			2			0			2 (14)
La Courtoise		5.3			1			0.5			7 (11)
M. Blanc		3.3			3			0			1 (15)
Mas de Roy		4.6			2			0			3 (17)
Mas de Nages		2.7			2			1.3			4 (14)
Les Clapiers		4.6			2			0.3			6 (15)
Les Horizons	4.8	4.8	3.8				0.1	4.3	0			0 (12)
Milliat		2.0						0.6
Chavas		1.3						1.5
Laroche			0.3					0.5	0.4		(5)	3 (8)
Chaurchaire			0.4				5	25	3.7		(7)	3 (10)

In 1995, further trials were coordinated by the Mallemort Experimental Station P.A.C.A., the results are shown in Table 4 (Deschanel & Florac 1996). The highest damage was recorded in a pear orchard at La Barthelasse, where the pressure of codling moth was very strong: in the control plot, pheromone traps caught a total of 533 moths requiring 13 chemical treatments for a 2%-damage at harvest. At Ventron-Cavaillon, 219 codling moths were trapped in the control plot, the damage at harvest could have been due to an insufficient pheromone release during the last part of the season.

At all sites, the mating disruption treatment led to a highly significant reduction of insecticide sprays, while a high degree of protection was maintained.

The Netherlands
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Experiments were also done in The Netherlands for two years in cooperation with ProAgro and IPO-DLO (van Deventer et al. 1996). Ecopom Combi dispensers were used at 300 dispenser/ha and two applications in 1994; and at 400 dispenser/ha with a single application in 1995. The results are shown in Table 5. Protection against codling moth was comparable with that obtained with the traditional pest management program, consisting of three insecticide sprays.

Table 4 Mating disruption (MD) of codling moth with Ecopom dispensers in apple orchards of the P.A.C.A. cooperative (France, 1995)

Site	Area (ha)	Damage (%)		Insecticide treatments
		MD	Control	MD	Control
Verdier-Cavaillon	4.0	0.1	1.0	4	15
Brunel-St. Remy	2.4	0.75	0.1	1	6
Cestier-Eyragues	3.8	0.2	0.1	2	12
Giacqui-St. Gilles	3.9	1.4	0.1	3	14
Gautier-Velorgues	2.9	1.45	-	6	12
Ventron-Cavaillon	2.4	6.1	-	7	14
Manguin-La Barthelasse	2.8	16.3	2.0	5	13

The attack by apple leafrollers, in 1994, was slightly above the economic threshold of 1% and thus not completely satisfactory, even if part of this damage could have been due to Spilonota ocellana. This species uses Z8-14Ac as main pheromone component (Arn et al. 1992, 1996), which is not included in Ecopom Combi dispensers.

Table 5 Mating disruption (MD) of codling moth and leafrollers with Ecopom Combi dispensers in apple orchards (The Netherlands, 1994-1995)

Site	Area (ha)	Technique	Damage (%)		Sprays
			Codling moth	Leafrollers
Alphen a/d Maas - South (1994)	1.4	MD	0.2	0.7	-
Alphen a/d Maas - North (1994)	3.0	IPM-treated	0.15	0.5	3
Deil - East (1994)	2.0	MD	0.15	1.3	-
Deil - West (1994)	4.0	IPM-treated	0.05	0.75	2
Deil - East (1995)	2.0	MD	0.4	0.3	-
Deil - West (1995)	4.0	IPM-treated	0.3	0.7	3
Geldermalsen - South (1995)	2.0	MD	4.6	0.6	-
Geldermalsen - North (1995)	5.0	IPM-treated	14.3	0.2	4

In 1995, the number of dispensers was raised to 400 per ha and this, in conjunction with the second, consecutive use of mating disruption, improved the results at Deil keeping the attack by leafrollers below 1%. A second orchard was treated with pheromones in 1995: at Geldermalsen the population of codling moth was larger, but no initial chemical treatment was used. At mid-July, no fruit penetration was recorded in both plots, while in August the attack ranged from 0 to 1.2% in the mating disruption and from 2 to 3.4% in the control plot. The damage then increased and at harvest it ranged between 3 and 6.6% in the mating disruption plot, while the control plot showed an attack between 5.2 an 19.2%.

Conclusions
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The practical trials carried out in three European countries clearly demonstrate that mating disruption using Isagro's Ecopom dispensers kept fruit damage by codling moth below the economic threshold in most cases. The current formulation is designed to be applied twice per season, but in some cases, even a single application could be sufficient. Further studies to extend dispenser life are going on.

It should be reminded that mating disruption is not an appropriate method under all circumstances; its correct application requires a high degree of preparation of both the advisory staff and the growers, in order to evaluate the biological, ecological, topographical, and technical limitations. Mating disruption is not a general method of protection from insect pests, and should be used only if the characteristics of the orchard fulfil well-defined requirements and if all necessary precautions are adopted.

References

Arn H, Tóth M, Priesner E (1992) List of sex pheromones of Lepidoptera and related attractants, 2nd ed. International Organization for Biological Control, Montfavet

Arn H, Tóth M, Priesner E (1996) The pherolist. Internet edition: Http://www.nysaes.cornell.edu/ pheronet

Arsura E, Capizzi A, Orlandini L, Rama F (1992) Mating disruption in the experience of Isagro - EniChem Agricoltura, pp 6-9 in C Ioriatti, H Arn (eds.) Use of Pheromones and Other Semiochemicals in Integrated Control. IOBC/WPRS Bulletin 15(5)

Charmillot PJ, Pasquier D, Rama F (1993) Un nouveau diffuseur homologué pour la lutte par confusion en verger. Rev. Suisse Vitic. Arbor. Hort. 25, 123-128

Deschanel I, Florac M (1996) Lutte par confusion sexuelle contre le carpocapse. Phytoma 482, 19-21

Navarro E, Aymard J, Navarro A (1995) La confusion sexuelle. Expérimentation d'une nouvelle technique de lutte contre le Carpocapse des pommes et des poires. Phytoma 478, 60-63

Rama F, Capizzi A, Arsura E (1990) Mating disruption in the control of codling moth and apple leafrollers in orchards, p.23 in Proc. IOBC/WPRS Meeting "Pheromones in Mediterranean Pest Management", Granada

Rama F, Ioriatti C, Rizzi C, (1996) Sette anni di esperienze con la confusione sessuale nel contenimento di carpocapsa e ricamatori del melo. Informatore Fitopatologico in press

van Deventer P, Minks AK, Rama F (1996) Experiments of simultaneous control of codling moth and apple leafrollers by mating disruption, in Proc. Workshop "Mating disruption of leafrollers in fruit orchards", S. Michele a/Adige (Italy), September 3-4, 1996, in press
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