IOBC wprs Bulletin Vol 22(9), 1999

Zeuzera pyrina and Cossus cossus (Lepidoptera, Cossidae) control by pheromones: four years advances in Italy

Edison Pasqualini and Davide Natale

Abstract: The results of four years experimentation on Zeuzera pyrina L. and Cossus cossus L. (Lepidoptera, Cossidae) control by controlled release dispenser with pheromones are reported. The pheromone blend used was Z3-C10Ac+Z5-C12Ac in a 4:1 ratio for C. cossus and E2-Z13C18Ac+E3-Z13C18Ac in a 95:5 ratio for Z. pyrina. The mating disruption method applied in apple orchards for the first time against both the pests seems to show an encouraging confirmation. In three and two farms prepared for Z. pyrina and C. cossus respectively, the percentage of infestation in the trunks decrease within the treated field year by year, compared with the initial level and the level of infestation in the check fields. The trend shown up to now allows the control below a damaging threshold to be supposed. The map of infestation should point out the dynamic of population for both the pests. Regarding the mass trapping method any statistical difference between 5 and 10 traps/ha managed was relieved. A comparison between different dispenser types according with the monitoring was carried out as well. The best performer dispenser was by TNO for C. cossus and by Serbios for Z. pyrina. The trap type used was the pyramidal funnel with wings, eyes height collocated for C. cossus and without wings, at least 1m above the canopies for Z. pyrina. The employment of the biotechnological method by pheromones seems to be a sustainable way of control.

Key words: sex pheromone, mass trapping, mating disruption, monitoring, Zeuzera pyrina, Cossus cossus.

Introduction

Zeuzera pyrina L. and Cossus. cossus L. (Lepidoptera Cossidae) are xylophagous insect pests which, in the larval stage, tunnel in various broad-leaved and fruit trees among which apple, pear, peach, plum, hazelnut, olive trees and so on, weakening trunks and branches and involving desiccation and death.

The difficulty in the application of the traditional control methods, also because of high costs, suggested the eventuality to verify such alternative courses among the bio-technologies. The scientific objective of the research was the experimentation of different types of controlled-release pheromone dispensers using for the monitoring, mating disruption and mass trapping of both the pests.

Four years experimentation in the region Emilia-Romagna, on apple orchards, assumed as representative industrial orchards, involved several systems to be carried out: the trap design, their number and the relative collocation with respect to the canopy; the optimum type of dispenser for the monitoring/mass trapping and the mating disruption; the experimental pattern design to adopt in field according to the different trials.

We used to work in partnership with other organisations involved in a EU project: Netherlands Organisation for Scientific Applied Research TNO Plastics and Rubber Research Institute; Denka International B.V.; Servicio de Proteccio dels Vegetals; Consejo Superior de Investigaciones Cientificas-Centro de Investigacion y Desarrollo, Laboratorio de Entomologia y Análisis Ambiental (LEAAM); National Centre for Scientific Research "DEMOKRITOS" Institute of Biology-Entomology.

Material and methods

The starting point for the project was the availability to one of the partners (Denka International B.V) of proprietary methods to convert high-performance monomers and/or prepolymers (e.g., poly(meth)acrylates and block copolymers thereof) into a single device by means of radiation curing (UV- EB-, gamma radiation). Different device types, acting as a controlled-release reservoir for pheromones, were made available. The pheromone blend was Z3-C10Ac+Z5-C12Ac in a 4:1 ratio for C. cossus, E2-Z13C18Ac+E3-Z13C18Ac in a 95:5 ratio for Z. pyrina.

Regarding the comparison between different devices, the pattern carried out was always a randomised blocks with four replicates. In all the trials the traps or the single dispensers were put on before the pest flight starting and taken out at the end of the season. Every two weeks a sample of each type of dispenser was sent to the TNO Research Centre for the Gas-Chromatographic Analysis. Within the ambit of the mass trapping management, the sampling on trunks were carried out between April and May, every year, interesting the 100% of the plants in field. The sampling on shoots during summer period, regarded the 25% of the plants with all the top shoots. Weekly were the samplings at the traps. Where possible and necessary the Analysis of Variance (ANOVA) was employed by means of the LSD method (p<0,05).

The choice for the optimum trap/dispenser system

With respect to the monitoring and the mass trapping methods, the first step was pointing out the best trap/dispenser system. It entailed a comparison between different traps design; the optimum number per hectare to carry out in field; the optimum collocation as height with respect to the tree.

Comparison between different traps design

Different traps design, for Z. pyrina capturing, were tested in three field trial. In 1995 eight designed were compared, in 1996 seven. The results are reported. The efficiency of each of them was evaluated by means of weekly samplings. The relative position of each trap was changed during the experimentation. The pattern used was with randomised blocks.

Comparison between different number of traps per hectare

In 1996 tests determining the minimum number of traps per hectare useful for the mass trapping method, with a trial ad hoc were performed. The comparison was effectuated between 10 and 5 traps per hectare in the same field trials.. The pattern was prepared in the following way: on alternate weeks 5 and 10 traps were collocated in each field. The pattern was a double comparison. Weekly samplings.

Comparison between different traps position

For both the pests two different traps position as height with respect to the tree were carried out: eyes height (1.70m ca) and 1m above the top shoots. In the period from 1996 to 1998, three and two trials for C. cossus and Z. pyrina respectively were followed.

Comparison between different dispenser types for C. cossus

In 1995 five different dispensers were compared: 1804-4-a, 1805-4-a and 1806-4-a by TNO; one by IPO and one by ISAGRO. In 1996 three devices were carried out: 2703-238 and 2703-239 by TNO and one by Serbios. In 1997 three devices were carried out as well: one by TNO, one by Isagro and one by IPO. In 1998 only two devices were compared: one by TNO and one by Serbios.

Comparison between different dispenser types for Z. pyrina

In 1995 six different dispensers were carried out: 1804-1a, 1804-2a and 1804-3a devices by TNO; one device by IPO; one by Russell '95 and one by ISAGRO. In 1996 five different dispensers: 2703-10, 2703-11 devices by TNO; one device by Russell '96, one by Novapher and one by Russell '93. In 1997 five different dispensers as well: Zp 19 and Zp 20 by TNO; one device by Serbios; one by Volcani Centre and one by Isagro. In 1998 only two devices were compared: one by Serbios and one by Isagro.

The mating disruption method for C. cossus

Consisting of the application of a large number of dispensers within the orchard in the way of disrupting the male in its mating behaviour, the method was carried out in the period from 1996 to 1998 in three different field trials. About 500 dispensers per hectare were collocated to the top branches in reason of 2/3 on the border and the remaining 1/3 on the middle side of the field. Each device was 200mg baited. Check traps (Serbios funnel type with wings, Isagro baited) were collocated inside and outside the field trial at different high respect to the vegetation. The efficiency of the method was evaluated by means of a comparison between the level of infestation in the trunks year by year.

Trials' characteristics

Trials' design

Farm	N. dispensers/ha	Borders	Centre	Check traps within	Check traps out
Tassani	560	370	190	4	4
Zama	560	360	180	2	5
Ravenna	250	166	84	3	2

The mating disruption method for Z. pyrina

The method was carried out in the period from 1997 to 1998 in three different field trials employing about 650 dispensers per hectare in reason of 2/3 on the border and the remaining 1/3 on the middle side of the field to the top branches. Each device was 200mg baited.

Check traps (Serbios funnel type without wings, Serbios baited) were collocated both in the field trial and the check at different high with respect to the vegetation. The efficiency of the method was evaluated by means of a comparison between the level of infestation in the trunks year by year.

Trials' characteristics

Trials' design

Farm	N. dispensers/ha	Borders	Centre	Check traps within 1997 1998		Check traps out 1997 1998
Fiumazzo	954	638	316	8	4	8	4
Conselice	960	640	320	6	4	6	4
Selbagnone	580	390	190	-	2	-	2

Results

The choice for the optimum trap/dispenser system

Comparison between different traps design

The results regarding Z. pyrina in the period 1995 and 1996 are reported. The traps were all baited with Isagro dispensers.

The funnel trap design without wings under the roof, seems to be the best solution useful both for the monitoring and the mass trapping, also because their manipulation (no glue and easy installation above the canopies). Regarding C. cossus the results of past experimentation were assumed. They showed a good efficiency by the funnel trap design as well, but with wings in that case.

Comparison between different number of traps per hectare

The results relative to 1995 and 1996 experimentation, are reported. The data are expressed as total and average per trap/week: they were transformed in log(x+1) before.

Both for C. cossus and Z. pyrina it wasn't possible to see any statistical differences between 5 and 10 traps to be placed in field.

Z. pyrina captures

Thesis	1995		Thesis	1996a		1996b
	Average week	p < ,05		Average week	p < 0,05	Average week	p < 0,05
BCS (no wings)	2,82	a	BCS	1,21	a	2,2	a
IMBUTO TRENTO (wings)	2,95	a	TRAPTEST	1,47	a	3,3	ab
TRAPTEST (dispenser hang up)	3,84	abc	SERBIOS (wings)	2,24	ab	3,3	ab
TRAPTEST	4,4	abc	SIATRAP (black line on wings)	2,28	ab	2,7	a
TRAPTEST (big)	5,24	bc	SIATRAP (with wings)	2,74	abc	4,2	c
PHEROCON	4,53	abc	SERBIOS (no wings)	3,88	bc	4	c
SIATRAP (no wings)	5,42	c	SIATRAP (no wings with "ciglia")	4,3	c	3,8	c
MASTRAP L. (wings)	3,62	ab

C. cossus: Captures obtained by different number of trap per hectare

Year	Thesis	Total captures	Average per trap	p < 0,05
1995	5 Traps	15	0,5	n. s.
	10 Traps	33	0,55
1996	5 Traps	17	0,34	n. s.
	10 Traps	10	0,1

Z. pyrina: Captures obtained by different number of trap per hectare

Year	Thesis	Total captures	Average per trap	p < 0,05
1995 A	5 Traps	40	1,14	n. s.
	10 Traps	50	0,71
1995 B	5 Traps	37	1,35	n. s.
	10 Traps	39	0,39
1996	5 Traps	40	1,14	n. s.
	10 Traps	28	0,28

Comparison between different traps position

Z. pyrina: Captures by different trap height

C. cossus: Captures by different trap height

As far as previous investigations, the traps show their best performance when placed at least 1m above the top shoots for Z. pyrina, and at eyes height for C. cossus.

Comparison between different dispenser types for C. cossus

1995 1996

Farm	TNO 1804-4-a	TNO 1804-5-a	TNO 1804-6-a	IPO	Isagro	Farm	TNO 2703-238	TNO 2703-239	Serbios
A	4	4	2	3	17	Ballardini	13 a	30 a	15 a
B	3	4	2	1	9	Marani	51 a	116 b	44 a
C	9	11	2	0	9	Vignoli	11 a	26 a	11 a
Total	16	19	6	4	35	Total	75	172	70

1997 1998

Farm	TNO	Isagro	IPO	Farm	TNO	Isagro
Pantanella	83 b	6 a	2 a	Ravenna 2	15	14
S. Nicolò	67 b	8 a	0 a	S. Nicolò	14	3
Total	150	14	2	Total	29	17

The TNO device gave out the best performance in all the comparisons. The capture values differ from one year to another in relation with the biological cycle of the pest and the different weather conditions.

Comparison between different dispenser types for Z. pyrina

1995 1996

Farm	TNO 1804-1-a	TNO 1804-2-a	TNO 1804-3-a	IPO	Russell	Isagro	Farm	TNO 2703-10	TNO 2703-11	Serbios	Russell
A	7	11	13	8	11	4	Bornazzini	0 a	1 ab	24 c	5 b
B	2	3	5	0	2	1	Conselice	2 a	4 ab	11 a	17c
C	2	4	5	2	2	2	Fiumazzo	3a	3a	1a	4a
Total	11	18	23	10	15	7	Total	5	8	36	26

1997 1998

Farm	TNO Zp 19	TNO Zp 20	Serbios	Volcani Center	Isagro	Farm	Serbios	Isagro	Total
Folli	0 a	3 a	158 c	14 a	49 b	Fiumazzo 2	3	20	23
Fiumazzo	1 a	0 a	31 b	3 a	16 a
Nicoli	3 a	2 a	19 a	1 a	9 a
Total	4	5	208	18	74

The Serbios device gave out the best performance in all the comparisons. The capture values differ from one year to another probably in relation whit different weather condition.

The mating disruption method for C. cossus

Farm Tassani

The comparison between the level of infestation relieved in trial field, shows a significant reduction in the second year (from 20.5 to 6.7%) with a decreasing, expressed as ratio, equal to 66%, while it remains constant on the 7% in the third. At the same time the level of infestation into the untreated side shows a regular trend, increasing in 10 percentage points from the first to the third year, with an increasing, expressed as ratio, equal to 70%. Also the captures realised, which provide an anticipation on the state of method during the season, testify the its good efficiency.

Sampling on trunks / captures

	Tested plants			Infested plants			% of infested plants			N. of holes				captures
Period	1996	1997	1998	1996	1997	1998	1996	1997	1998	1996	1997	1998	1996		1997	1998
Field trial	360	1370	1368	74	92	96	20,5	6,7	7	74	110	106	0		0	0
Check field	90	330	329	13	39	81	14,4	11,8	24,5	13	44	84	18		6	5

Farm Zama

The trend in the level of infestation both in the test and the control testify the efficiency of the method: the level of infestation in trial field records a reduction in the second year from 17.4 to 6.4% with a decreasing, expressed as ratio, equal to 63%. The percentage of infestation in the control decreases as well but only in 21% as ratio. Unfortunately, in the third year the orchard was cut down preventing the experimentation to be completed.

Sampling on trunks / captures

	Tested plants		Infested plants		% of infested plants		N. of holes		captures
Period	1996	1997	1996	1997	1996	1997	1996	1997	1996	1997
Field trial	407	405	71	26	17,4	6,4	75	32	0	0
Check field	48	50	5	4	10,4	8,3	5	4	6	1

Farm Ravenna

The results collected seem to support completely the method: the infestation in the test decrease in 77 percentage points, while in the control it increase in 11 percentage points. The trend in the capture seem to be a further confirmation, even if the results from the next year are expected.

Sampling on trunks / captures

The mating disruption method for Z. pyrina

Farm Fiumazzo

The comparison between the level of infestation in the trunks, shows a reduction relieved in the trial field from 18 to 6,9%, with a decreasing, expressed as ratio, equal to 62% The infestation in the check field increases in 15 percentage points as ratio (from 14 to 16,2%). The captures realised during the two seasons supply a sound support to the method looking at the differences between the test and the control. Not at all expected the reading of the result regarding the sampling on the top shoots which provide an anticipation on the state of method, but open to the course state of the season as well.

Sampling on trunks / captures / sampling on shoots

Farm Conselice

The level of infestation in the trunks decrease both in the test and the control but at different percentage values: 87.5% and 50% expressed as ratio respectively in test and control. The starting level of infestation, at low values, is to underline.

Sampling on trunks / captures / sampling on shoots

Farm Selbagnone

The method was employed in 1998 for the first time, therefore the comparison with next year sampling on the trunks is to wait for. Anyway, looking at the comparison between the number of captures realised and the different level of infestation on the shoots, in the test and the control, the state course can be assumed encouraging, even in consideration of the starting values.

1998 sampling on trunks / captures / sampling on shoots

	Tested plants	Inf. plants	% inf. plants	n. holes	captures	Tested shoots	Inf. shoots	% inf. shoots
Field trial	1138	158	13,97	178	1	5934	62	1,04
Check field	662	63	9,51	68	12	3274	80	2,44

Conclusion

In 1998 a four years program based on the experimentation of new versatile controlled dispensers to employ for Zeuzera pyrina L. and Cossus cossus L. (Lepidoptera Cossidae) control with pheromones came to the end. The program was carried out in the ambit of the EU Project AIR-3-CT94-1607 in partnership with Netherlands Organisation for Scientific Applied Research TNO Plastics and Rubber Research Institute; Denka International B.V.; Servicio de Proteccio dels Vegetals; Consejo Superior de Investigaciones Cientificas-Centro de Investigacion y Desarrollo, Laboratorio de Entomologia y Análisis Ambiental (LEAAM); National Centre for Scientific Research "DEMOKRITOS" Institute of Biology-Entomology.

The experimentation involved the development of several systems linked to the employment of new dispensers. The optimum trap/dispenser system, useful both for the monitoring and the mass trapping, among different designs compared between them, was characterised. Regarding C. cossus the best solution seems to be the funnel trap with wings under the roof at eyes height placed. The best performing dispenser was that one by TNO. Regarding Z. pyrina the best solution seems to be the funnel trap without wings under the roof 1m above the canopy placed. The best performing dispenser was by Serbios.

Regarding both the pests mass trapping management, any statistic differences were found out by means of a comparison between 5 and 10 traps per hectare, therefore the choice is for the minimum number. The mating disruption method managed against both the pest pointed out very encouraging results. The efficiency of the method, evaluated by means of a comparison between the level of infestation on the trunks from one year to another, seems to be supported by a reduction below a damaging threshold. A systematic sampling on 100% of the plants in field wanted moreover to draw the dynamic of the population. Regarding C. cossus on the only trial lasted three years the infestation decreased in 66 percentage points, from 20.5 the first year to 7% the third. Regarding Z. pyrina on the trial with level of infestation at 18% the first year, we relived a decreasing in two years equal to 62 percentage points. For both the pests the difference between test and control in the number of captures realised, which provide an anticipation on the state course during the season, testify the efficiency by the method. Instead, the sampling at the infestation on the top shoots, which provide an anticipation on the state of the method as well, results to be open to the changing weather conditions and agronomic practices. final assessment, after four years development for Z. pyrina L. and C. cossus L. control with pheromones, can be considered positive, even if more investigations are hoped for, allowing a confirmation also under an economic outline.

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