Insecticidal activity of some aromatic plants from Croatia against lesser grain borer
(Rhyzopertha dominica F.) on stored wheat
Irma Kalinovića, Vlatka Rozmana, Vlado Guberaca, Sonja Marića
a
Faculty of Agriculture in Osijek, Trg Sv. Trojstva 3, 31000 Osijek, Croatia
Abstract
Essential oils and plant dust of four Croatian aromatic plants (Lavandula officinalis Ch.,
Laurus nobilis L., Rosmarinus officinalis L., Thymus vulgaris L.), were tested for insecticidal
activity against lesser grain borer Rhyzopertha dominica F. on mercantile and seed wheat
under laboratory and storage conditions. The insecticidal effect was observed over the
exposure period up to 100% mortality of adults. The efficacy of the plant material was
compared to the control with no treatment. Doses of essential oils and plant dust were
recalculated on 5 kg wheat sample, as follows, 3,75 ml/sample of oils, and 37,5 dag/sample of
dust. In general, all essential oils exhibited strong insecticidal effect (100% mortality of adults
after 24h), with L. nobilis proved most effective in dust form (100% mortality of adults after
7 to 10 days of exposure) under storage conditions. In the control samples mortality of adults
was not recorded. Over the five months period, damage on wheat was found to be 30%, while
insect population increased up to 190%. No changes in quality of mercantile wheat flour, its
colour and flavour were recorded over the plant product treatment, however, each sample
retained the scent of the plants tested. On seed wheat, no negative effect on germination and
energy of germination was recorded. These aromatic plant products proved to be partial
substitutes for synthetic insecticides if applied to smaller stocks of stored wheat, and in order
to reduce contamination of food and environment.
Key words: Rhyzopertha dominica, aromatic plants, botanical insecticides, Lavandula
officinalis, Laurus nobilis, Rosmarinus officinalis, Thymus vulgaris, pest control
Introduction
Lesser grain borer, Rhyzopertha dominica (F.) is one of the primary pests on different types of
stored products, mainly grain. Conventional control measures have been carried out by using
insecticides applied directly on grain, or by gas fumigation. However, in silos and storages
in Croatia population of the pest has been increasing annualy, due to to the resistance on
fumigant doses applied (phosphine, in the first place), and frequent usage of very few
fumigants causing no depletion of the ozone layer. There is also growing concern about
accumulation of insecticide residues in treated grain with toxic effect on mammals.
Insecticide resistence in stored product pests has been observed in many other countries in the
world (Shaaya et al., 1997). One of the alternatives to overcome this problem is application
of natural products derived from aromatic plants with potential repellent and insecticidal
effect on lesser grain borer, and no harmful effect on human environment. Sighamony et al.
(1986) have reported favourable results with essential oil of black pepper, Piper nigrum L.
applied on lesser grain borer. Neem kernel extract of Azadirachta indica A. juss. Margosan –
O. and its constituent azadirachtin have also been demonstrated effective against this pest
species (Dunkel et al., 1990), (Rahim, 1998). In the last decade a lot of scientists (Weaver et
al., 199l; Obeng-Ofori and Hassanali, 1994; Jembere et al., 1995; Bekele et al., 1996; Bekele
et al., 1997) have studied insecticity, repellency, and toxicity of Ocimum genus (Ocimun

Corresponding author.
E-mail address: kirma@suncokret.pfos.hr (Irma Kalinović)
canum Sims., Ocimum kilimandscharicum L, Ocimum suave Wild., Ocimum kenyense L.) on
major stored pests including lesser grain borer. The newest studies have proved lethal toxicity
of the major components from O. kilimandscharicum and O. kenyense essential oils (Bekele
and Hassanali, 2001). In laboratory experiments favourable results in protection from the
insect species have been obtained with Rauwolfia serpentina L., Acorus calamus L., Messua
ferrea L. and Albizia lebbeck L. applied in the form of dust, ash and acids (Tiwari, 1994).
Plant essential oils of the species Cassia angustifolia L. and Pimpinella anisum L. have also
been reported to have contact, fumigant, and repellent effect on lesser grain borer (Xu, 1994),
as well as cedar oil with repellent and toxic activity against many stored pests including R.
dominica (Gebere-Amlak et al., 1997). Essential oils of mint, salvia, oregano, sweet basil,
laurel, rosemary, lavander, anise, ZP51 (Labiatae sp.oil), and edible oils of soybean, cotton,
rice and palm, with contact and fumigant alternative insecticides have been demonstrated
effective against Sitophilus oryzae L., S. zeamais Motsch., Callosobruchus maculatus F., R.
dominica, Oryzaephilus surinamensis L., and Sitotroga cerealella Oliv. (Shaaya et al., 1997).
Insecticidal activity of some monoterpenes (1,8-cineole and R-(+)-limonen) isolated from
essential oils of eucaliptus and citrus has been reported effective against R. dominica under
laboratory conditions (Prates et al., 1998).
Investigations of the mediterranean plants stated in our study have been carried out so far in
France with favourable results in protection of bean from Acanthoscelides obtectus Say.
(Regnault-Roger, C. and Hamraoui, A.,1993 a; 1993b; Regnault-Roger, C. et al., 1997).
First studies of aromatic plants from Croatian mediterranean area show that plant species of
Origanum vulgare L., Laurus nobilis L., Lavandula officinalis Ch., Rosmarinus officinalis L.,
Thymus vulgaris L. have insecticidal effect on S. granarius L. and A. obtectus if applied in
the form of dry ground leaves, stem and flower or as essential oils (Kalinović et al., 1997).
The present study is supplemental to the further investigations of aromatic plant species from
this area on growing population of resistant R. dominica as one of the major pests on stored
grain.
2. Materials and methods
2.1. Bioassay
Our investigation was conducted under laboratory and storage conditions. Laboratory
analyses were carried out in the laboratory of Department of Plant Protection at Agricultural
Faculty in Osijek. After the results obtained in vitro, two-year experiments were conducted in
storages for grain products at IPK "Oranica" d. o. o. Osijek over the winter season 2000, and
summer season 2001. Bioassay plan was based on infestation of mercantile and seed wheat by
the species of R. dominica. Prepared material was tested for insecticidal efficacy of the
aromatic plants: L. nobilis – laurel, L. officinalis – lavander, T. vulgaris – thyme, R. officinalis
– rosemary. All species were tested in two forms, as dry ground leaves, flower and stem, and
as essential oils. The treatments were compared to the control sample of untreated mercantile
and seed wheat. After the analyses completed, mercantile wheat was tested in reological tests
for fluor quality. Seed wheat was tested for energy of germination and germination.
2. 2. Plant materials
All tested plant species are descended from the island Mali Lošinj. In 1999 the plants were
collected, air-dried, ground in dust, and maintained under laboratory conditions at the
temperature of 25°C in black plastic bags. Essential oil products were purchased from "Ireks
aroma" d. d. Zagreb.
1. Lavandula officinalis Chaix. (L. angustifolia Mill.) – lavander
- dust (dry ground leaves, flower and stem)
- oil extract (content: linalyn-acetate, linalool, geraniol, lavandulol, borneol,
nerol, bornyl-acetate, cineole, pinene, camphor)
2. Laurus nobilis L. – lovor
- dust (dry ground leaves)
- oil extract (content: 1,8-cineole, benzaldehyde, piperidine, geraniol)
3. Rosmarinus officinalis L. – rosemary
- dust ( dry ground leaves and stem)
- oil extract (content: pinene, d-1-camphor, d-1-borneole, bornyl-acetate,
cineole)
4. Thymus vulgaris L. - thyme
- dust (dry ground leaves, flower, stem)
- oil extract (content: p-cymene, carvacrol, thymol, citral)
2.3. Insect species
Test insects were unsexed R. dominica adults of different age reared on wheat under
laboratory conditions (temp. 29±1°C, 70% r.h., 14% m.c.). All insects of the species collected
during 1999 in silos and storages in Croatia, were progeny strain of the phosphine resistant
generations.
2. 4. Control treatments
Control treatments were samples of untreated mercantile and seed wheat infested with R.
dominica.
2.5. Biological materials
The study was conducted on mercantile wheat (mixture of sorts) with 12,5% m.c. in silos of
IPK "Croatia" Osijek, and on seed wheat with 12% m.c. ("Žitarka" cultivar, I sort
reproduction, untreated seed), at Institute of Agriculture Osijek.
2.6.a Preliminary laboratory analyses
Mercantile wheat seeds were placed into Petri dish (7 cm in diameter). One dish was one
sample. Each sample contained 20 wheat seeds (cca 0,5 g) (12,5% m.c.). The prepared media
was infested with R. dominica reared in the laboratory of Departmant of Plant Protection.
Each sample was infested with 20 insects.
After infestation completed, plant products were applied to the samples. Each sample was
treated with dust/wheat mixture (dose of 0,01g), and with oils (dose of 0,01ml) applied by
dripping on the Whatman No. 1 filter paper disc. All samples were covered with Petri dish
lids. Samples with the applied treatments were set up in 8 replications, meaning that we had
80 samples for both applied forms (oil and dust). The experiment was established under
controlled laboratory conditions (temperature 235 – 24°C; r. h. 70%, in dark).
Insecticidal activity was done by evaluation of test insect mortality with lens and
stereomicroscope. The samples were observed daily, over the exposure period up to 100%
mortality, and compared to the control with no treatment. Similarly, tests on seed wheat were
set up under the same laboratory conditions.
After the positive results from preliminary tests, recalculation of quality and doses for
treatment application was made on the basis of 5 kg wheat sample, as follows, 3,75 ml/sample
of oils, and 37,5 dag/sample of dust.
2.6.b Damages and the number of R. dominica population
100 pre-weighed wheat seeds were placed into the glass jars (250 ml) and infested with test
insects: 10 adults per jar (sample). Glass jars were covered with fine silky mesh. For each test
insect 10 replications were set up. Over the 5 months period, the samples were maintained at
29±1°C, and r. h. of 70±5%. The experiment was observed after 30 days period.
Population of the pests was determined. Fractions of undamaged and damaged grain, and
grain dust were separated and weighed.
2.6.c Qualitative analyses of tested mercantile wheat
Analysis of mercantile wheat was carried out in the laboratory for flour quality at "Belje"
MPI, Beli Manastir according to the standard technological methods by using farinograph,
ekstenzograph, and amilograph, with determination of organoleptic properties: scent, flavour
and colour.
Reological tests were done on 60% laboratory flour (after cleaning, wheat samples were
prepared for grinding by soaking in two phases: I – soaking in 13,5% m.c. and growing stale
for 24 h; II phase – soaking in 14% m.c. ½ h before grinding). The reological tests were
carried out after 5 days.
Dough properties were determined by farinograph from flour obtained over the grinding
proces (water absorption, dough progress, dough stability, soften level, quality No., and
quality group).
Dough properties over the elasticity process were determined by ekstenzograph (energy,
resistance, elasticity, and their relation).
Activity of alpha-amilase in wheat flour was determined by amilograph.
Samples of wheat (cca 100) broken in laboratory mixer, and poured with heated water were
prepared for organoleptic analysis for scent and flavour.
2.6.d Germination and energy of germination on seed wheat
Analysis of seed wheat was done in the laboratory at the Department of Plant Protection
according to the standard method of germination and energy of germination. Whatman No. 1
filter paper was used as a media. The experiment was established in 4 replications for 4
treatments and the control. On a wet filter paper 100 wheat seeds were placed per sample. The
samples were first kept at the temperature of 5-6°C for 7 days, and maintained at 20°C
afterwards. Energy of germination, and germination were determined after 4 and 7 days,
respectively.
2.7. Analyses under storage conditions
After the laboratory analyses completed, we set up an experiment in a storage for seed
products at IPK Osijek "Oranica" d. o. o. in winter season (November, December 2000).
Samples with wheat media (mercantile and seed) were weighed to 5 kg and packed into twolayered paper bags. Before sample infestation, test insects were separated in "mesh bags"
(made from silky mesh, with mesh openings of 0,3 mm in diameter), to make check up
easier. In each sample, 10 mesh bags with 10 adults, and 10 wheat seeds were placed.
Dose for dust treatments was 37,5 dag/sample, and dose with oil extract was 3,75 ml/sample.
Dust products were mixed with wheat. Oil extracts were applied by dripping on porous
impregnated strips, which were incorporated in the samples prepared.
All bags were sealed with adhesive tapes. Control treatment was infested wheat with no
application.The packed samples were placed on wooden palettes and maintained under
storage conditions ( Temperature of 5-7 °C, r.h. 67 – 78%).
The experiment was established in 4 replications. In total, 40 samples were set up for all the
treatments in two forms (dust and oil), applied on two types of media (seed and mercantile
wheat).
The samples were observed daily up to 100% mortality of test insects, as well as the
temperature and r. h. The samples were checked by lens on light, heated background.
Similarly, we set up an experiment in summer storage season (Jun, 2001), but the temperature
was 16-26°C, with r. h. of 69-79%.
2.8. Data analysis
The experiment was established by non-choice test in 8 replications (laboratory tests) and in 4
replications (storage tests).Mortality results were shown as timing series calculated from
means of daily mortalities for all the treatments tested. For each mean SE was counted.
Analysis of the results was employed by multi-factorial analysis of variance (ANOVA) for
every day over the exposure period. LSD test was used to compare significant differences
among the treatments. Data processing was conducted by "The SAS System for Windows 95"
according to GLM ANOVA model (general linear model). The results of germination analysis
and the results of analysis of energy of germination on seed wheat were conducted by oneway analysis of variance (ANOVA).
3. Results
3.1. Results of laboratory analyses
Positive results from preliminary tests proved the hypothesis of insecticidal activity of the
four plant species, which was the ground for further analyses under storage conditions.
Possible damages without introducing protective measures over the 5 months infestation with
R. dominica were estimated to be more than 30% under laboratory conditions, with the
population increase of up to 190% (Fig. 1, 2).
3.2. Results of analyses in winter season
Analysis of variance proved very high significant differences (P<0,001) among the plant
species tested, and their forms over the exposure period of 12 days. Significant differences
were compared by using LSD test for the plant species, and their forms.
Table 1 shows timing series of plant species efficacy over the exposure period, with the
values expressed in % of average daily mortality of the test insects. Means were counted from
4 replications, with SE calculated for each, and significant differences of means by LSD test
(a,b,c,d – statistic significance for level P<0,05). In the control treatment without application no
mortality was recorded (0%).
The shortest exposure for 100% mortality od R. dominica was obtained by L. nobilis essential
oil (24 h), followed by L. officinalis and R. officinalis, with 100% mortality and exposure
period of 48 h, and T. vulgaris with the same effect obtained after 72 h. Intensity of
insecticidal activity of the plant species tested was not statistically different, proving similar
efficacy against R. dominica in the form of essential oil over the winter storage season.
Treatments with dust required considerably longer exposure. The shortest exposure (after 9
days) with 100% mortality was obtained by L nobilis dust, followed by the remaining three
species with 100% mortality in 11 – 12 days. During the first 7 days no statistical differences
were recorded among the plant species, however, 8 day after exposure L. nobilis appeared
more effective than other species tested.
3.3. Results of analyses in summer season
Similarly to the results obtained over the winter season, differences among the treatments and
forms applied also appeared very highly significant in summer storage period. After 24 h
exposure, four plant species in the form of oil obtained 100% mortality, as the dust
applications in first five days of exposure exhibited equal intensity of insecticidal activity,
with L. nobilis having more intensive increase, and the shortest exposure of 8 days (Table 2).
3.4. Results of qualitative analyses of tested mercantile wheat
Results of the farinograph analyses show that dust and oil treatments of the plants tested (L.
officinalis, L. nobilis, R. officinalis and T. vulgaris) did not have negative effect on dough
properties (Table 3). Results of the ekstenzograph analyses (Table 4) show that the treatments
did not exhibit negative effect on the dough quality during the elasticity process. Activity of
alpha-amilase in the flour samples tested did not show differences in comparison to the
control, which means that no negative effect on gluten quality was recorded (Table 5).
Determintaion of colour, scent and flavour was conducted in the laboratory by organoleptic
method on ground mercantile wheat mixed with water. Each sample retained the scent of the
plants tested, without changes in flavour and colour.
3. 5. Results of qualitative analyses of tested seed wheat
Energy of germination and germination were tested on seed wheat (cultivar "Žitarka", I sort
reproduction). Results by ANOVA of energy of germination show no significant differences
among the treatments and the control(Table 6). Also, no significant differences were recorded
in germination of treated seed wheat and the control (Table 7).
4. Discussion
The results obtained under storage and laboratory conditions on mercantile and seed wheat
infested by R. dominica proved insecticidal efficacy of aromatic plants of this area: lavander,
laurel, rosemary, and thyme applied in the form of oil extract and dust, and compared to the
control with no treatment.
Insecticidal property of these plants was also reported by Regnault-Roger and Hamraoui,
1993a; 1993b; Regnault-Roger et al., 1993, examining mortality of A. obtectus Say. treated
wih essential oils and dust of the above plants.
The results of preliminary laboratory analyses showed the differences among the plants tested
on mercantile and seed wheat over the 8 day exposure as highly siginficant (P<0,001), as well
as the differences among the forms applied (P<0,001), which proved mortality of R.
dominica as the result of insecticidal activity.
On mercantile wheat, all these oil extracts showed 100% mortality of R. dominica at the
dosage of 0,01 ml/5 g wheat in 24 h, but in the control no mortality was recorded. Similar
results with oil extracts were obtained on seed wheat. This proved high susceptability of lesser
grain borer to the treatment in form of the essential oil extracts.
Dust applications showed considerably slower insecticidal activity against R. dominica in
comparison to essential oils which is indicated by high significant differences (P<0,001)
among the application forms tested. On mercantile wheat, the shortest exposure period (dose
of 0.01 g/5 g wheat) for 100% mortality of R. dominica was 15 days, obtained with the plants
of L. nobilis and R. officinalis. On seed wheat, similar results were obtained after 13 days
with dust of L. nobilis. These results indicate that laurel dust possesses stronger insecticidal
activity for control of R. dominica than dust of the remaining three plant species. This was
proved by investigations of other scientists (Obeng-Ofori et al., 1994, Jembere et al., 1995)
who recorded significant difference among essential oils and dust of O. kilimandscharicum in
control of the pest species. The authors emphasized that oils in 48 h obtained 100% mortality,
while dust of the plant did not exhibit insecticity. However, some authors (Bekele et al., 1997)
emphasized that dry leaves and essential oil of O. kenyense could be applied effectively
against lesser grain borer.
Over the 5 months experiment with samples without plant product applications, R. dominica
damaged 30% of wheat and increased population to 190%, indicating that without adequate
protection measures entire stored wheat mass could be completely damaged in a year.
Analyses in winter season of storages showed the differences among the treatments tested on
mercantile and seed wheat over the exposure period of 12 days as highly significant
(P<0,001), as well as the differences among the forms of application (P<0,001). By
application of oil extract of L. nobilis on mercantile and seed wheat, 100% mortality of R.
dominica was obtained with the shortest exposure of 24 h. Most effective plant species in dust
form was L. nobilis (100% mortality in 4 days on mercantile, and 10 days on seed wheat).
In experimental analyses over the summer storage period, the differences among the
treatments tested on mercantile wheat were again highly significant (P<0,001), but exposure
time was on average 2 days shorter than in winter storage period. Oil extracts of each plant
tested on mercantile and seed wheat obtained 100% mortality of R. dominica in 24 h,
whereas laurel again required the shortest exposure (8 days).
The results of efficacy of the plant species for winter and summer season under storage
conditions, show that oil extract forms exhibited considerably faster activity against lesser
grain borer than plant dust due to the higher concentrations of oil vapours. In summer season
100% mortality was obtained by shorter exposure time than in winter season due to the high
temperatures (16-26°C), whereas the plant species exhibited more intensive insecticidal, and
particularly fumigant effect.
From the available data, application of plant products under storage conditions have not been
entirely investigated. There are data (Xu, 1994) about effective control of R. dominica by
using combination of oil of C. angustifolia and malation that provide repellent effect over the
8 months period under simulated storage conditions.
To understand fully the necessity of plant product application in mercantile and seed wheat
protection, it was necessary to analyse quality of the samples tested, as tested plant products
can be applied commercially if there are no differences in comparison to the control samples
without application.
Qualitative flour analyses of tested mercantile wheat did not prove differences for both forms
of tested plant treatmants compared to the control without application. No changes were
recorded in colour or flavour of flour tested, but all samples retained intensive scent of the
aromatic plant species applied. This suggests that treated mercantile wheat should be
thouroughly cleaned from the remaining aromatic plant dust in the phase of first cleaning,
and before grinding, then in combination with active aeration the remaining scents could be
removed. After that, thoroughly washing, drying, conditioning and the main wheat cleaning
should be done. Further investigations regarding the analyses of organoleptic properties
(especially scents) should be focused on qualitative analysis of bakery products (bred, rolls,
paste etc.) made from flour of mercantile wheat treated with plant products.
Qualitative analysis of seed wheat did not prove negative effect on energy of germination and
germination of the cultivar "Žitarka" indicating that these plant products could be applied
commercially in seed wheat storaging. Similar results were reported in the study of ObengOfori (1995) who by application of vegetable oils of cotton, soybean, maize, peanuts and
palm against R. dominica on stored seed maize under laboratory conditions proved no
negative effect on maize germination. Our investigations (Kalinović et al., 1997) also proved
that tested plant products applied on seed wheat, and infested by grain weevil, did not exhibit
negative effect on germination.
From complete results obtained it can be concluded that plant products on the basis of L.
officinalis, L. nobilis, R. officinalis, and T. vulgaris can be applied as an alternative in stored
mercantile, and especially seed wheat protection against R. dominica on small-scale family
farms so as to decrease application of synthetic insecticides, and contamination of food and
environment.
Acknowledgments
This study was funded by Ministry of Science of Republic of Croatia. We are grateful to the
employees of IPK "Oranica" d. o. o. Osijek for providing storage facilities, and to the
laboratory stuff of "Belje" MPI d. d. Osijek for mercantile wheat analyses. We also thank
"Ireks aroma" d. o. o. Zagreb for their assistance in providing necessary essential oil extracts.
References
Bekele, A. J., Obeng-Ofori, D. and Hassanali, A., 1996. Evalution of Ocimum suave (Willd) as a
source of repellents, toxicants and protectants in storage against three stored product insect pests.
International Journal of Pest Management 42, 139-142.
Bekele, A. J., Obeng-Ofori, D. and Hassanali, A., 1997). Evaluation of Ocimum kenyense
(Ayobangira) as source of repellents, toxicants and protectants in storage against three major
stored product insect pests. Journal of Applied Entomology 121, 169-173.
Bekele, A. J., and Hassanali, A., 2001. Blend effects in the toxicity of the essential oil constituents of
Ocimum kilimandscharicum and Ocimum kenyense (Labiateae) on two post-harvest pests.
Phytochemistry 57, 385-391.
Dunkel, F., Weaver, D., Puyvelde, L., Cusker, J. L. and Serugendo, A., 1990. Population supression
effects of Rwandan medicinal plant, Tetradenia riparia (Hochst.) Codd (Lamiaceae) on stored
grain and bean insects. Proc. 5th Int. Conf. on Stored-prod. Protection, Bordeaux, 1990 Vol. III:
1609-1618.
El-Nahal, A. K. M., Schmidt, G. H. and Risha, E. M., 1989. Vapours of Acorus calamus oil-a space
treatment for stored-product insects. Journal of Stored Products Research 25, 217-223.
Gebre-Amlak, A. B., Phillips, T. W., Cuperus, G. W., Anderson, S. A., Eisenbraun, E. J. and
Payne, K., 1997). Repellency and toxicity of cedar oils to stored product insect pests. 1997
ESA Annual Meeting, Madison, USA.
Jembere, B., Obeng-Ofori, D., Hassanali, A. and Nyamasyo, G. N. N., 1995). Products derived from
the leaves of Ocimum kilimandscharicum (Labiatae) as post-harvest protectants against the
infestation of three major stored product insect pests. Bulletin of Entomological Research 85, 361367.
Kalinović, I., Martinčić, J., Rozman, V. and Guberac, V., 1997. Insecticidal activity of
substances of plant origin against stored product insects. Ochrana Rostlina 33, 135-142.
Obeng-Ofori, D., Adgeh, B. J. and Hassanali, A., 1994). Products derived from the leaves of Ocimum
kilimandscharicum as postharvest grain protectants. The 6th International Working Conference on
Stored-product Protection. Canberra, Australia. Conference handbook: 85.
Prates, H. T., Santos, J. P., Waquil, J. M., Fabris, J. D., Oliveira, A. B. and Foster, J. E., 1998.
Insecticidal activity of monoterpenes against Rhyzopertha dominica (F.) and Tribolium
castaneum (Herbst). Journal of Stored Products Research 34, 243-249.
Rahim, M., 1998. Biological activity of azadirachtin-enriched neem kernel extracts against
Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae) in wheat. Journal of Stored Products
Research 34, 123-128.
Regnault-Roger, C., Hamraoui, A., Holeman, M., Theron, E. and Pinel, R., 1993. Insecticidal effect of
essential oils from Mediterranean plants upon Acathoscelides obtectus Say. (Coleoptera,
Bruchidae), a pest of kidney bean (Phaseolus vulgaris L.). Journal of Chemical Ecology 19, 12331244.
Regnault-Roger, C. and Hamraoui, A., 1993 a. Efficiency of plants from south of France used as
traditional protectants of Phaseolus vulgaris L. against its Bruchid, Acanthoscelides obtectus
(Say.). Journal of Stored Products Research 29, 259-264.
Regnault-Roger, C. and Hamraoui, A., 1993 b. Effects of essential oils from aromatic plants on
Acanthoscelides obtectus Say., pest of kidney bean (Phaseoulus vulgaris L.). Acta Botanica
Gallica 140, 217-222.
Shaaya, E., Kostjukovski, M., Eilberg, J. and Sukprakarn, C., 1997. Plant oils as fumigants
and contact insecticides for the control of stored-product insects. Journal of Stored
Products Research 33, 7-15.
Sighamony, S., Anees, I., Chandrakala, T. S. and Osmani, Z., 1986. Efficacy of certain indigenous
plant products as grain protectants against Sitophilus oryzae (L.) and Rhyzopertha dominica (F.).
Journal of Stored Products Research 22, 21-23.
Tiwari, S.N., 1994. Efficacy of some plant products as grain protectants against Rhyzopertha dominica
(F.) (Coleoptera, Bostrichidae). International Journal of Pest Management 40, 94-97.
Weaver, D. K., Dunkel, F. V., Ntezurubanca, L., Jackson, L. L. and Stock, D. T., 1991. The efficacy
of linalool, a major component of freshly-milled Ocimum canum Sims (Lamiaceae), for protection
against postharvest demage by certain stored product Coleoptera. Journal of Stored Products
Research 27, 213-220.
Xu, H., 1994). Biological activities of essential oils from plants against stored- product insects, and
analysis of their toxic components. The 6th International Working Conference on Stored-product
Protection. Canberra, Australia. Conference handbook: 88.
Fig. 1. Damage caused by R. dominica in untreated wheat during 5 months
100%
90%
80%
damage %
70%
60%
50%
dust of grain
damaged grain
undamaged grain
40%
30%
20%
10%
0%
27.07.2001.
27.08.2001.
27.09.2001.
27.10.2001.
27.11.2001.
examine date
Fig. 2. R. dominica population in untreated wheat during 5 months
average No. of adults/samples
20
18
dead
16
alive
8,9
14
0
12
10
7
5,1
0
8
6
10
11,7
8,5
4
8,9
10,1
2
0
27.07.2001.
27.08.2001.
27.09.2001.
examine date
27.10.2001.
27.11.2001.
Table 1
Insecticidal activity of plant treatments against R. dominica in summer season
(LSD test)
Rhyzopertha dominica
Exposition
Mortality %
1. day
2. day
3. day
Lavandula
officinalis
x  SE
95,0  2,9a
100,0  0,0a
x  SE
1. day
2. day
3. day
4. day
5. day
6. day
7. day
8. day
9. day
10. day
11. day
12. day
a
12,5  2,5
17,5  2,5a
27,5  4,8a
35,0  5,0a
42,5  4,8a
52,5  4,8a
57,5  4,8a
65,0  2,9b
72,5  2,5c
90,0  4,1b
100,0  0,0a
Oils treatments
Laurus
nobilis
Rosmarinu
s officinalis
x  SE
x  SE
a
100,0  0,0
97,5  2,5a
100,0  0,0a
Dust treatments
x  SE
x  SE
a
20,0  4,1
15,0  2,9a
a
25,0  2,9
22,5  2,5a
37,5  4,8a
32,5  2,5a
a
40,0  4,1
37,5  2,5a
45,0  6,5a
45,0  2,9a
a
57,5  4,8
55,0  5,0a
a
70,0  4,1
60,0  4,1a
90,0  4,1a
72,5  2,5b
a
100,0  0,0
85,0  2,9b
95,0  2,9a
100,0  0,0a
Thymus
vulgaris
x  SE
92,5  4,8a
97,5  2,5a
100,0  0,0a
x  SE
15,0  5,0a
22,5  2,5a
27,5  4,8a
35,0  5,0a
45,0  6,5a
47,5  6,3a
52,5  6,3a
62,5  2,5b
75,0  2,9c
82,5  2,5c
95,0  2,9b
100,0  0,0a
* meas followed by same letter in superscript within each row are not
significantly different (p<0,05)
Table 2
Insecticidal activity of plant treatments against R. dominica in winter season
(LSD test)
Rhyzopertha dominica F.
Exposition
Mortality%
1. day
Lavandula
officinalis
x  SE
100,0  0,0a
x  SE
1. day
2. day
3. day
4. day
5. day
6. day
7. day
8. day
9. day
10. day
a
20,0  4,1
22,5  4,8a
30,0  4,0a
47,5  2,5a
57,5  2,5a
67,5  2,5b
82,5  2,5b
90,0  4,1b
100,0  0,0a
Oil treatments
Laurus
Rosmarinus
nobilis
officinalis
x  SE
x  SE
a
100,0  0,0
Thymus
vulgaris
x  SE
a
100,0  0,0
Dust treatments
x  SE
x  SE
a
22,5  4,8
15,0  2,9a
a
30,0  4,1
22,5  2,5a
42,5  4,8a
32,5  2,5a
a
47,5  7,5
45,0  2,9a
57,5  4,8a
55,0  5,0a
a
87,5  2,5
72,5  2,5b
97,5  2,5a
85,0  2,9b
a
100,0  0,0
95,0  2,9b
100,0  0,0a
100,0  0,0a
x  SE
17,5  4,8a
25,0  2,9a
37,5  4,8a
47,5  4,8a
57,5  4,8a
67,5  4,8b
77,5  4,8b
90,0  4,1b
95,0  2,9b
100,0  0,0a
* means followed by same letter in superscript within each row are not
significantly different (p<0,05)
Table 3
Results of farinograph
Oil
treatments
FARINOGRAM
Water
absorb
%
Dough
progress
min.
Dough
stability
min.
Resistention
min.
Soften
level
FJ
Quality
No.
Quality
group
Lavender
63,9
1,6
0,9
2,5
95
50,4
B2
Laurels
64,5
1,7
0,8
2,5
80
54,8
B2
Rosemary
63,6
1,7
0,9
2,6
85
56,0
B1
Thyme
63,7
2,0
0,5
2,5
80
55,3
B1
Control o
62,5
1,8
0,9
2,7
80
56,0
B1
Dust
treatments
FARINOGRAM
Water
absorb
%
Dough
progress
min.
Dough
stability
min.
Resistention
min.
Soften
level
FJ
Quality
No.
Quality
group
Lavender
65,1
1,7
1,0
2,7
75
55,6
B1
Laurels
65,0
1,5
0,8
2,3
90
54,1
B2
Rosemary
65,4
1,5
1,0
2,5
80
56,2
B1
Thyme
63,5
1,7
0,6
2,3
80
58,5
B1
Control o
62,5
1,8
0,9
2,7
80
56,0
B1
Table 4
Results of ekstenzograph on tested mercantile wheat
Oil
treatments
EKSTENZOGRAM
energy
cm2
resistance
EJ
elasticity
mm
relation
EJ/mm
Lavender
71,1
515
115
4,47
Laurels
64,5
350
125
2,80
Rosemary
70,1
390
126
3,09
Thyme
64,2
350
125
2,80
Control o
75,4
450
125
3,87
EKSTENZOGRAM
Dust treatments
energy
cm2
resistance
EJ
elasticity
mm
relation
EJ/mm
Lavender
57,7
320
128
2,50
Laurels
63,3
365
125
2,92
Rosemary
69,5
370
127
2,91
Thyme
69,0
405
139
2,91
Control o
75,4
450
116
3,87
Table 5
Results of amilograph and flour quantity on tested mercantile wheat
AMILOGRAM
Oil
treatments
Start of
swelling
oC
Max. temp.
oC
Time for
making paste
min.
Max.
viscosity
AJ
Lavender
57,1
82,6
17,0
810
Laurels
55,6
81,1
17,0
810
Rosemary
56,1
82,3
17,4
830
Thyme
55,0
82,6
18,4
830
Control o
57,1
88,6
19,0
890
AMILOGRAM
Dust
treatments
Start of
swelling
oC
Max. temp.
oC
Time for
making paste
min.
Max.
viscosity
AJ
Lavender
55,0
83,5
19,0
930
Laurels
58,9
82,3
15,6
800
Rosemary
55,9
86,2
20,2
1030
Thyme
55,3
80,8
17,0
800
Control o
57,1
88,6
19,0
890
Quantity of wheat flour
%
treatments
oil
dust
Lavender
70,67
69,32
Laurels
69,48
74,62
Rosemary
66,59
68,74
Thyme
69,24
69,27
Control o
70,48
Table 6
Results of energy of germination on tested seed wheat
Energy of germination %
Oil
Dust
Treatments
average
average
91,25
90,50
Lavender
90,75
90,75
Laurels
91,25
91,00
Rosemary
90,75
90,50
Thyme
90,25
90,25
Control 0
Energy of germination (ANOVA)
Source of variations
Oil
Dust
F
F
treatments
0,617
0,304
error
total
LSD0,05 = 1,4224
LSD0,05 = 1,4116
LSD0,01 = 1,9484
LSD0,01 = 1,9336
Table 7
Results of germination on tested seed wheat
Treatments
Lavender
Laurels
Rosemary
Thyme
Control 0
Germination %
Oil
average
91,75
91,00
91,75
91,00
92,00
Dust
average
92,00
92,00
91,50
91,25
92,00
Germination (ANOVA)
Source of variations
Oil
Dust
F
F
treatments
0,5505
0,4976
error
total
LSD0,05 = 1,7244
LSD0,05 = 1,5854
LSD0,01 = 2,3621
LSD0,01 = 2,1718