The use of sex pheromones against Zeuzera pyrina  L. and Cossus cossus  L. (Lepidoptera, Cossidae)

Edison Pasqualini, Stefano Vergnani, Davide Natale, Gianumberto Accinelli

• Introduction
• Materials and methods
• Results
• Discussion
• Conclusion
• References

Key words - sex pheromone, mass trapping, mating disruption, Zeuzera pyrina, Cossus cossus

Introduction
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Zeuzera pyrina  is a palearctic pest insect mainly distributed in the Southern Europe with temperate climate, Northern Africa and Middle East. It is a damaging pest for many forest plant and various fruit orchards, among which apple, pear, peach, plum, olive trees and so on. The larvae, which make an axial centripetal gallery, take one or two years to mature. The damages consist of the dry up of the shoots and other vegetative parts, buds, or the death of entire branches. In nurseries or young implantation, the damages could be particularly massive (Liotta & Giuffrida 1965; Castellari 1986; Tremblay 1986).

Cossus cossus is a palearctic pest insect with a large euroasiatic and northern-african distribution. It attacks a great number of plants included fruit trees (apple, pear, cherry, plum, quince, apricot, peach, olive, chestnut and vineyards too). The larva take two or three years to mature. They penetrate into the low parts of the plant, interesting both branches and trunks causing its death.

The chemical and biological control has always been problematic and often unresolved for both species. Therefore the use of synthetic pheromones applied according to the mass-trapping or mating disruption methods, seems to be a real possibility of control (Pasqualini et al. 1993, 1995, 1996).

In this report, the results of some experimentation carried out to test the efficacy of dispensers used for mass-trapping in both pests are reported, and the first results regarding the mating disruption method in C. cossus  too.

Materials and methods
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Serbios funnel trap were used: with wings the ones for mass-trapping in C. cossus , without wings for Z. pyrina. The pheromone blend was Z3-10Ac and Z5-12Ac in a 4:1 ratio for C. cossus , E2,Z13-18Ac and E3,Z13-18Ac in a 95:5 ratio for Z. pyrina. We used to put the traps at 1.7 m with respect to the plant and 1 m over the plant for C. cossus  and Z. pyrina  respectively.

Comparison between different dispensers for Z. pyrina

Six different dispensers were tested during 1995 (A-1804-1a, B-1804-2a and C-1804-3a from TNO; D from IPO; E from Russell '95 and F from ISAGRO), while four in 1996 (A-2703-10, B-2703-11 from TNO; C from Russell '96, D from Novapher and E from Russell '93). The pattern used was with randomised blocks.

Comparison between different dispensers for C. cossus 

Five different dispensers were tested in 1995 (A-1804-4-a, B-1805-4-a and C-1806-4-a from TNO; D from IPO and E from ISAGRO), while three in 1996 (A-2703-238, B-2703-239 from TNO and C from Novapher). The pattern used was with randomised blocks.

Every two weeks each type of dispensers from TNO in comparison was sent to the TNO Research Centre. In that Centre the release of the pheromone blend was detected through the gaschromatographic analysis. The sampling to the traps were effectuated week by week.

Comparison between different number of traps per hectare for C. cossus  and Z. pyrina 

The comparison was effectuated between 10 and 5 traps per hectare in the same field trials. For C. cossus  two repetitions has been effectuated; for Z. pyrina , three. The pattern was a double comparison.

Mating disruption in C. cossus  (1996)

The method consist of the application of a high number of dispensers to the orchard that doesn't make the males mate the females. About 500 dispensers per hectare, very easy to put on, have been collocated to the higher branches in reason of 2/3 on the border and the remaining 1/3 on the middle side of the field. The pheromone component was: Z5-dodecenyl acetate (200 mg/dispenser). The experimentation was carried out in two different field trials. Check traps, baited with Novapher dispenser, were collocated inside and outside the field trial at different high respect to the vegetation. The sampling to the traps were effectuated week by week. The samplings to the trunks were planned two times per season.

Investigations about Z. pyrina  adults trap approach

In previous and recent experiences some females were caught into the traps. This experience we thought to take information about pest approach to the trap, in particularly regarding females. For this reason some modified trap-systems was made: (1) funnel trap and pole (standard system); (2) funnel trap and pole with a sticky surface (about 10 cm in length just below the trap) around the pole; (3) funnel trap on a lateral support and a sticky surface (about 10 cm in length) both on proximal insertion of this one and on a prolongation of pole toward the high; (4) funnel trap and pole collocated between two plants with sticky surface on iron wires. All the traps used were Serbios model baited by a Russell 1996 dispensers.

Figure Z. pyrina : experimental conditions

Results
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Comparison between different dispensers for Z. pyrina  and C. cossus  (1995/96)

The data regarding the number of catches obtained in different field trials are reported (Tables 1, 2). They are expressed as average per week and elaborated trough the variance analysis (ANOVA), and LSD test (p < 0.05). The data have been transformed in log(x+1) before. The results show that the better dispenser in 1995 was from Isagro, while in 1996 was the dispenser 2703-239 from TNO.

Table 1 Z. pyrina  dispensers comparison: catches obtained in 1995 and 1996

Table 2 C. cossus  dispensers comparison: catches obtained in 1995 and 1996

Comparison between different number of traps per hectare for C. cossus  and Z. pyrina 

The results of comparisons, in different field trials between 5 and 10 traps per hectare, are reported (Table 3). The data regard the number of catches obtained, are referred to different years, and are expressed as total and average per trap/week and elaborated trough the variance analysis (ANOVA), and LSD test (p < 0.05). The data have been transformed in log(x+1) before.

Table 3 Z. pyrina  and C. cossus : catches obtained by different number of trap per hectare, 1994 to 1996

	1994		1995		1996
Thesis	Total	Average/trap	Total	Average/trap	Total	Average/trap
	Z. pyrina
5 traps	-	-	40	1.14 a	40	1.14 a
10 traps	-	-	50	0.71 a	28	0.28 a
	C. cossus
5 traps	15	0.33 a	15	0.5 a	17	0.34 a
10 traps	25	0.27 a	33	0.55 a	10	0.1 a

^a Differences not significant at p < 0.05

The data regarding both C. cossus  and Z. pyrina  are in contrast probably because of the small number of catches, nevertheless there aren't statistical differences.

Mating disruption for C. cossus 

Only one adult was caught in two field trials, while 6 have been caught in the external fields. For a first evaluation we have to wait the results from second sampling on trunks (the next winter).

Investigations about Z. pyrina  adults trap approach

The catches obtained shown by the different experimental configurations shown in Figure were, from left to right: 42 males (d); 22 (ab); 14 (a); 32 (bc). Numbers followed by different letters are significantly different at p < 0.05.

Unfortunately any female was caught both into the traps and sticky parts on poles. Any males was entrapped on sticky surface confirming that they enter into the traps by flying. Between catches from different experimental configuration the lower ones were obtained by configuration 2, perhaps because of the mobility of the traps.

Discussion
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The results obtained in the EU Project are substantially positive and encouraging, particularly concerning C. cossus . For that species a dispenser supplied by TNO has resulted more attractive than the best one available up to now, while the number of traps to set on each hectare could be reduced from 10 to 5. The results given during the first year about the mating disruption are encouraging. In fact in only one of the two experimental fields one adult has been caught even though the catches on the checked fields haven't been a lot. Because of the biological cycle of this species the first definitive results could be available only in the year 1998.

The results of many other researches about Z. pyrina  aren't unfortunately so much satisfactory because of the poor catches obtained with all compared dispensers. This is probably due to the pheromone blend or its release by the dispenser. Although the data obtained are insufficient to get any definite conclusion, it has been possible to observe that the catches are not different between 10 and 5 traps per hectare.

Regarding the fly approach trial, only males have been caught. Not one of them has been found on the sticky parts, therefore it seems the adults get into the trap by flying.

Conclusion
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In 1996 the EU Project AIR-3-CT94-1607 has come to the development of half prearranged program. At the moment, the information which come from the data processing, seem to show two parallel scenarios. The results are substantially positive and encouraging, concerning C. cossus . More experimentation has to be done with the mating disruption method, carried out for the first time in 1996. Waiting for new comforting data, two factors appear to condition the choice for one of the two methods: the specific environmental condition and the economic balance regarding the farm.

On the other hand, the results regarding Z. pyrina  are not so exciting. The trap-dispenser systems tested till now, didn't work yet at the best. If it is possible to suggest the best trap type (Serbios without wings) and its collocation with respect to the plant (1 m over the vegetation), the comparison between different dispenser type hasn't shown good results yet. Probably more data regarding the dispenser, such as the time of release and the doses of pheromone blend, have to be acquired. Moreover it isn't well known the behaviour of this pest, and a specific investigation on the specific ethology should be done. In any case it appears opportune to continue with new investigations, because dispensers more effective could make the mass trapping method applicable with our farm condition (2-3 hectares dimensioned). New investigations should begun regarding the mating disruption method, never tested before in our areas.

Acknowledgements

This Project "AIR-3-CT94-1607" is founded by EU Programme and developed in collaboration with the following partners: TNO Plastic and Rubber Research Centre (Coordinator) and Denka International B.V. (The Netherlands); Servei de Proteciò des Vegetales (SPV), Laboratorio de Entomologia Vegetales (SPV) and Laboratorio de Entomologia Y Anàlisis Ambiental (CSIS) (Spain); National Centre of Scientific Research "Democritos" (Greece).

References
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Castellari PL (1986) Zeuzera pyrina L. (Lepidoptera, Cossidae): indagini biologiche eprove in campo sullattrattività di miscele di componenti del feromone seesuale. Boll Ist Ent "G. Grandi", Univ Bologna 40, 239-270

Liotta G, Giuffrida I (1965) Osservazioni biologiche sulla Zeuzera pyrina L. in Sicilia (Lep. Cossidae). Boll Ist Ent Agr, Palermo 6, 29-60

Pasqualini E, Faccioli G, Antropoli A, Molfese M (1993) Zeuzera pyrina L. (Lepidoptera, Cossidae): indagini sull'attrattività di alcune miscele feromoniche di sintesi e confronto con femmine naturali. Boll Ist Ent "G. Grandi", Univ Bologna 47, 169-177

Pasqualini E, Barbara C, Antropoli A (1995) Indagini sulla distribuzione della popolazione, sulla dimensione del campione e sulle tecniche di campionamento per Zeuzera pyrina L. (Lepidoptera Cossidae). Boll Ist Ent "G. Grandi", Univ Bologna 49, 175-186

Pasqualini E, Civolani S, Vergnani S, Calzolari G (1996) I feromoni nella difesa da Zeuzera pyrina e Cossus cossus. L'inf Agr Verona 18, 69-75

Tremblay E (1986) Entomologia applicata - Vol. II. Ed Liguori, Napoli 344-350
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