The effect of companion plants on Lygus feeding damage to bean




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16th IFOAM Organic World Congress, Modena, Italy, June 16-20, 2008
Archived at http://orgprints.org/12179

The effect of companion plants on Lygus feeding damage to bean.

Szafirowska, A..1, Kolosowski, S.1

Key words: Lygus, bean seeds, organic farming, companion plants

Abstract

The aim of research was to find out the protective effect of companion plants against lygus bugs (Lygus spp.) in organic production of bean (Phaseolus vulgaris L..). The field experiment was conducted during 2004 and 2005. Bean were sown on three dates: May 10, 25, June 10. As companion plants the following species were applied: red beet (Beta vulgaris L.), dill (Anethum graveolens L.), marigold (Tagetes erecta L.) and sage (Salvia officinalis L..). At harvest the bean seeds were examined for the presence of seed-pitting caused by lygus bugs. The lowest percentage of damaged seeds, demonstrated the samples obtained from plots cultivated in the close proximity of dill and marigold The number of pitted seeds depended on the date of seeds sowing and the year of experiment.

Introduction

Pest occurrence is a severe problem in organic vegetable cultivation, especially in the area of an intensive vegetable production. Less mobile pests and those of a specific host range could be controlled by crop rotation. However, this method is not effective in the control of highly mobile, non specific pests such as aphids and lygus bugs (Lygus spp). In Poland the escalation of the occurrence of lygus bugs on many vegetable species had been noticed in recent years (Szwejda 2006). In bean cultivation the pest causes reduction of the yield quality and quantity. Lygus bug’s saliva contains the enzymes and amino acids toxic for the plant tissue, thus causing buds and flowers shedding and casting off young pods (Hori 1975). The pests also feed on immature seeds by spitting on the seed surface making shallow hollows (pits) with irregular jagged edges (Szwejda 1978). These pits can be found on the whole seed surface except for the stigma vicinity.

While looking for natural methods of pest control the allelopathy effect of plants can be used. It is known that some plant species stimulates or inhibits other species growth. However, the allopathic relation between plant and insect is not well recognised. Some authors obtained promising results when planting the main crop in the close proximity of species controlling insects occurrence. Kostal & Finch (1994) found a significant reduction in the number of eggs laid by cabbage root fly owing to the companion effect of some plant species. Legutowska and Klepacka (2001) observed a reduction of Trips tabaci L. on leek grown in an intercropping with snap bean.

The aim of studies was to examine the effect of several plant species used for companion planting in organic bean cultivation to protect against lygus bugs seed piercing.



Materials and methods

The experiments were conducted in the experimental organic field in the Research Institute of Vegetable Crops at Skierniewice in Poland during 2004-2005. The field had been subjected to the control-certified system accepted for organic production in the EU (EC Regulation 2092/91). Bean seeds were sown on the 10 m2 plots with 5 rows on the plot spaced by 45 cm. Two side rows were planted with companion species such as: red beet, dill, marigold and sage. Bean plants used as the companion plant made the control treatment. Bean was sown on three dates: May 10, 25 and June 10. At the same time the companion species were sown. Marigold and sage were used as transplants. The experiment was set by the random block method in four replicates.



Lygus bugs were caught with an entomological net (4x25 catching per plot). The dynamics of lygus bug occurrence was observed at the onset and at full blossoming, the beginning of pod formation and fully formed pods, which means from the second decade of June until the end of August. The number of larvae and imagoes per 1 row meter was counted. The seeding plants were harvested according to the sowing date at September 1, 10 and 20. The total seed yield was examined for the presence of pitted specimens. The seeds with hollows on the seed coat with traces of puncturing on the cotyledons endosperm were recognized as contaminated, following the method of Szwejda (1978). The composition of the Heteroptera division was determined down to species following Korcz methods (1977). Results were subjected to the statistical analysis of variance with the significant differences pointed out on the basis of Newman-Keuls test at p=0.05

Results

In both years of research, lygus bugs appeared in a high intensity although more numerously in 2005 (fig.1). The average number of bugs caught on 1 row meter during the whole observation period amounted to 69,5 in the first year and 82,8 in the second one. There were some differences in the occurrence and number of insects in both years of research. In 2005 lygus bugs were noted in the high intensity from the second decade of June until the end of July. In 2004 the pests were less frequent and appeared about two weeks later. This fact, as well as both experimental factors, affected the number of pitted seeds as it is shown in the table 1. Less damaged seeds was observed in 2004 than in 2005. The average percent of pitted seeds was 9,20 and 12,07 respectively as compared to the total yield of bean seeds. The later the sowing date, the more pitted seeds were observed. It was especially visible in the first year, when the seed pods of the earliest sowing were too hard as the lygus started feeding. The most delicate pods of the last sowing date were damaged the worst. The very dynamic occurrence of insects in the second year did not give much chance to the earliest sown bean. The longer feeding period of lygus resulted in a higher level of damage to seeds of all the examined sowing dates. The selected companion plant species significantly influenced the percentage of pitted bean seeds especially in the second an third date of sowing. In the last two cases there were large differences between control and other treatments and in 2005 the differences were significant. The most effective plant species were dill and marigold, which caused a significant decrease in the number of damaged seeds during both years of research. The stage of companion plant development played some role in bean protection. Better developed companion plants in July and August provided the stronger protection a
gainst lygus feeding.



Figure 1: Occurrence intensity of Lygus spp.

Tab. 1: The effect of companion plants on the percentage of pitted seeds in the total bean yield.

Compa-nion species

2004

Mean

2005

Mean

10 May*

25

May


10 June

10

May


25

May


10 June

Red beet

3,75

14,11

17,48

11,78

9,70aA

16,83abB

10,59aA

12,37

Dill

1,23

8,70

14,93

8,29

11,60aA

10,72aA

6,55aA

9,62

Marigold

1,85

6,95

10,67

6,49

8,66aA

10,84aA

7,33aA

8,94

Sage

3,23

8,15

11,71

7,69

11,49aA

14,14abA

7,79aA

11,14

Control

3,82

13,54

17,83

11,73

13,10aA

19,35bB

22,43bB

18,29

Average

2,78 a

10,3 b

14,52 c

9,20

10,91

14,38

10,94

12,07

*date of bean sowing; the small letters refer to data in columns, the big ones to data in rows

Discussion

The use of a diversified pest suppressive agro-ecosystem is of growing interest in agriculture. Plant cultivation in a well established ecosystem facilitates pest management and the biodiversity can be used as an important tool in pest control. As Finch and Collier (2000) stated, insects found a host plant faster and easily, when it was clearly visible and not surrounded by weeds or other plants. On the other hand the majority of pests prefer to colonise on a green surface, therefore appropriate companion plants can easily deceive females and invite them to resign from laying eggs on the main crop.

There is scarce literature on the discussed particular subject. The best examined pest in the context of companion plant cultivation are aphids, cabbage root fly or trips. Wiech (1993) received a positive effect in the reduction of aphid occurrence on cabbage by papilionaceous companion planting. Legutowska and Klepacka (2001) found a positive influence of carrot, snap bean and clover on the percentage of strongly damaged leek plants by trips (Trips tabaci). In Finch et al. (2003) studies three marigold species (Tagetes erecta, Tagetes patula and Tagetes tenuifolia), which reduced the number of eggs laid by cabbage root fly females.The obtained results proved that appropriate species used as a companion plant can control the bean seed pitting to some extent. The best protection against lygus feeding provided dill and marigold used as the companion plants in organic bean cultivation.

Conclusion

Bean sown in the first decade of May produced the lowest percentage of pitted seeds. The biggest number of damaged seeds was obtained from the latest sowing date (June 10). The early sowing and right companion species like dill or marigold seems to be useful in protecting against bean seed piercing. It is an important tool, especially in organic farming, because of the lack of effective pesticides allowed to use in this kind of agriculture production.



References

Finch S., Billiad H., Collier R.H, (2003): Companion planting – do aromatic plants disrupt host – plant finding by the cabbage root fly and the onion fly more effectively than non-aromatic plants, Entomologia Experimentalis et Applicata 109: 183-195.

Finch S., Collier R.H (2000): Host-plant selection by insects a theory based on “appropriate/ inappropriate” landing by pest insects of cruciferous palnts. Entomologia Experimentalis et Applicata 96: 91-100.

Hori K, (1973): Digestive carbohydrates in the salivary glandand midgut of several phytophagous bugs, Comp, Bioch & Phys, Part B vol, 50 (1): 145-151.

Korcz A, (1977): Biologia morfologia i występowanie Lygus campestris zmieniak złocieniowca oraz innych gatunków z rodzaju Lygus (Heteroptera, Miridae) w Polsce, Prac, Nauk, IOR, t, XIX z 1:209-240.

Legutowska H., Klepacka K, (2001): Wspolrzedna uprawa pora z roznymi gatunkami roslin a wystepowanie szkodliwej fauny, Leek intercropped with different plant varieties and occurrence of injurious fauna, Prog, In Plant Prot, 41(2): 544-547.

Szwejda J, (1978): Studies on seed-pitting of bean caused by lygus bugs (Heteroptera: Miridae), Biul Warz, 21: 201-218.

Szwejda J. 2006. Pest management in ecological production of vegetables in Poland. ANN. Warsaw Agric. Univ. 27: 5-15.



Wiech K, (1993): Wpływ współrzędnej uprawy późnej kapusty z koniczyną białą i fasolą szparagową na występowanie szkodliwej i pożytecznej entomofauny. Rozprawa habilitacyjna, AR Kraków: 74

1 Research Institute of Vegetable Crops, ul. Konstytucji 3 Maja 1/3, 96-100 Skierniewice, Poland. E-mail aszafir@inwarz.skierniewice.pl, Internet www.inwarz.skierniewice.pl



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