FEEDING INHIBITORS IN PEST CONTROL: EFECT OF HERB
Transkrypt
FEEDING INHIBITORS IN PEST CONTROL: EFECT OF HERB
POLISH JOURNAL OF ECOLOGY (Pol. J. Ecol.) 52 4 575–581 2004 Short research contribution Ma∏gorzata K¸YÂ Pedagogical University, Institute of Biology, Department of Ecology and Environment Protection, Podbrzezie 3, 30-054 Kraków, Poland, e-mail: [email protected] FEEDING INHIBITORS IN PEST CONTROL: EFECT OF HERB ADDITIONS TO FOOD ON THE POPULATION DYNAMICS OF THE LESSER GRAIN BORER RHYZOPERTHA DOMINICA F. (COLEOPTERA, BOSTRYCHIDAE). ABSTRACT: The populations of Rhyzopertha dominica, a dangerous pest in stored grains were investigated. This laboratory study assumed the hypothesis that the introduction of powdered leaves of Salvia officinalis L. and Artemisia absinthium L. containing feeding inhibitors into grain may delay the development and therefore reduce population size of R. dominica. These herbs were powdered and added at 0.5 g of herb per 40 g wheat. The research was conducted in optimum conditions of temperature and humidity (28ºC and relative humidity 60%). The insects used in the experiment were initially obtained from mature individuals of uniform age and were bred in glass containers with base area 28 cm2 covered with gauze. The experiments were continued for 310 days and the herb supplements were renewed each month. The results of the study show that the introduction of chemical substances contained in the powdered leaves of S. officinalis and A. absinthium into an optimal substrate (wheat) infested with R. dominica decreases its population size. These substances have properties that inhibit the feeding of this insect species. KEY WORDS: Rhyzopertha dominica F., population dynamics, sex ratio, mortality, feeding inhibitors, powdered herbs An important challenge in theoretical and applied ecology is to find an effective way to control granary and warehouse pests. A major obstacle is the fact that the application of chemical agents or the use of biological methods using parasites or predators is not possible. Intensive research programmes aimed at developing alternative methods to control these insects have been performed (Boczek 1979, Ignatow i c z 1980b, H a g s t r u m et al. 1990, L etellier et al. 1990, Collins et al. 2002). Some methods modify the environmental conditions, making them disadvantageous for the pests, by regulating temperature and humidity in storage facilities or by introducing harmless chemical substances such as feeding inhibitors, arrestants, repellents or attractants (L o s c h i a v o 1965, Nawrot 1973,1983, Nawrot and Czaplicki 1978, Ignatowicz and Weso∏owska 1994a, b, K∏yÊ 1998). Feeding inhibitors are chemical substances that discourage or prevent insects from feeding by affecting their taste sensors. These compounds have no toxic effects on the insects (Nawrot 1983). Natural feeding inhibitors are usually alka- 576 Ma∏gorzata K∏yÊ loids and glycosides occurring in wild or cultivated plants. The mechanism of their effect is complex and incompletely understood. It was found, however, that insects exposed to them usually starved and ceased to consume the nutritive material. This resulted in a decrease of body weight or even death if the feeding inhibitors were present for a sufficient time. Exposure of larvae to feeding inhibitors also resulted in metamorphic abnormalities and a loss of reproductive ability. (Wyrostkiewicz 1984). The subject of this study was the lesser grain borer, R. dominica, a destructive pest of stored grain. This species is an indigent warehouse pest and is included in the Polish register of pests subject to mandatory eradication. This study assumed the hypothesis that the introduction of powdered herbs containing feeding inhibitors into grain might retard development and therefore reduce the population size of R. dominica. Assessments of activity, development, and population dynamics were made on the basis of laboratory experiments. Wheat was used as a substrate because of its favourable qualities for the development of R. dominica (Go∏´biowska and Nawrot 1976, Ciesielska 1978). The results of the wheat-only variant were used as a control relative to the other experimental habitat – diet variants. In order to assess the influence of certain herbal plants on pest population dynamics, substrates of wheat with common sage (Salvia officinalis L.) and absinth sage-wort (Artemisia absinthium L.) were used. These herbs were powdered and added in a ratio of 0.5 g of herbs per 40 g of wheat. All experimental colonies were started with 40 adult individuals, each sex being represented in equal numbers and of the same age, according to the method suggested by Ciesielska (1971, 1978). The experimental variants were examined once a month; at which time further substrate was added in a fixed ratio of 0.5 g herbs to 40 g of grain, allowing the experiment to continue for a long-term. The insects were counted in sub-samples in glass containers with base area 28 cm2 covered with gauze or perforated containers to allow the circulation of air. The study was conducted in the optimal thermal and moisture conditions of 28ºC and 60% RH. All variants were repeated six times. Population dynamics assessments were based on population sizes and rates of population growth, the density of individuals in the batch, mortality and sex structure. The Chi-squared test in Statistica v. 5.5 s. 999 – FGPJI – N4 was used in statistical analysis. After adding powdered common sage to wheat, the population dynamics of R. dominica were characterised by low fluctuations in size from the beginning until the 250th day of development. The highest growth in population size occurred between the 250th and 340th day. At this time the population size reached its highest level at over 500 individuals per batch (Fig. 1). On a wheat substrate, the maximum population size was attained at day 190. However, on wheat with a common sage substrate the maximum size was reached on day 340. The addition of sage led to an almost 50% decline in the maximum population size relative to the control batch (with wheat substrate only, Fig. 1). The population dynamics of R. dominica on the substrate composed of wheat and sage-wort were characterized by two phases, a phase of population growth between the 40th and 220th day of culture and a decline in the population size from day 220 up to the end of the experiment on day 310. A peak in the population size was reached after 220 days (Fig. 1). Chi-squared analysis revealed that differences between population size on wheat substrate and wheat and herb (both sage and sage-wort) substrate were highly significant after the 70th experimental day. Between the 40th and 220th day, the rate of population growth exhibited almost cyclic fluctuations. Already after 70 days a short-term decline in population growth could be seen and a subsequent decline was apparent between days 160–280. The highest mortality at 64% after 220 days was noted on the wheat and sage substrate. Thereafter, the mortality rate decreased over time to 20% (Fig. 2). The addition of sage to substrate led to an increase in mortality compared to the control substrate. The mortality rate in the wheat and sage-wort substrate remained at a relatively low level throughout the experiment, although, it increased during the final two months to 25% and resulted in a decline in population size (Fig. 2). The addition of powdered sage to wheat did not influence the sex ratio of the populations. The sex ratio in the group of surviving individuals was close to 1.0, which indicates an equal number of males and females. A larger proportion of females (Y/X =0.8) was record- 577 Feeding inhibitors in pest control almost always above 1, indicating a prevalence of males. However, the proportion of the sexes was almost equal between days 160–220. During this period the population reached its maximum size (Fig. 1). Repellents, deterrents and feeding inhibitors have been used for a long time in pest eradication because the application of ed after 40 experimental days. In the final phase of population development, the proportion of males increased (Y/X >1), and this correlated with a population decline (Fig. 3). The sex ratio among dying individuals fluctuated between 0.3–0.9 indicating a high mortality of females (Fig. 4). In wheat with sage-wort, the sex ratio was number of individuals in culture 1000 800 600 400 200 0 0 30 60 90 wheat 120 150 180 days 210 wheat and sage 240 270 300 330 wheat and sage-wort Fig. 1. Comparision of population dynamics of Rhyzopertha dominica in different habitat and diet conditions. 70 60 50 40 % 30 20 10 0 40 70 100 130 160 190 220 250 280 310 days wheat wheat and sage-wort wheat and sage Fig. 2. Per cent of dead individuals in populations of Rhyzopertha dominica in different habitat and diet conditions. 578 Ma∏gorzata K∏yÊ chemical substances in granaries and warehouses is very limited. Therefore, it is important to understand the effect of biotic and abiotic factors and their combined influence on regulating population size in pests (W h i t e et al. 1983, C i e s i e l s ka 1992, 1994, Ciesielska and K∏yÊ 2002). This is the basis of formulating effective protection programmes against pests in which an ever larger role is assigned to plant-based substances (Boczek 1983, Baker and L os c h i a v o 1987). Studies concerning the influence of feeding inhibitors on foraging in herbivorous insects have demonstrated that 2.0 1.8 sex ratio 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 0 30 60 90 wheat 120 150 180 days 210 wheat and sage 240 270 300 330 wheat and sage-wort Fig. 3. Comparision of sex ratios in Rhyzopertha dominica in different habitat and diet conditions (individuals live). 1.4 1.2 sex ratio 1.0 0.8 0.6 0.4 0.2 0 0 30 60 wheat 90 120 150 180 days wheat and sage 210 240 270 300 330 wheat and sage-wort Fig. 4. Comparision of sex ratios in Rhyzopertha dominica in different habitat and diet conditions (individuals dead). 579 Feeding inhibitors in pest control individuals often fasted after consuming plants treated with antifeedants (Wyrostkiewicz 1984). Nawrot (1973, 1983) studied the effects of feeding attractants and repellents on the grain weevil Sitophilus granarius L. He demonstrated that barley groats, moist wheat grain and wheat and rye plumules were the most effective attractants for imagines. However, an alcohol extract from plumules of wheat and rye acted as a repellent. In further studies, Nawrot and Czaplicki (1978) showed that S. granarius imagines locate food by chemoreception and react to triglycerides in plumules. This was further confirmed by Tamaki and L oschiavo (1971) and Tamaki et al. (1971) who established the attractive potential of unsaturated triglycerides for Tribolium confusum Duv. Furthermore, mineral salts influence viability, life expectancy and reproduction in S. granarius and Tyrophagus putrescentiae Schrank (Ignatowicz 1979, 1980a and b). The latter author demonstrated that S. granarius has a high tolerance for excessive levels of inorganic salts. Nevertheless, substances with trace elements such as J, F and Hg caused high mortality. Potassium iodine causes a decrease in fertility in S. granarius. The mould mite, T. putrescentiae is relatively insensitive to an excess of calcium phosphate in its diet. Even at a high concentration complete inhibition of fertility or high mortality was not recorded. B a n a s i k and I g n a t o w i c z (1995) assessed the effects of certain species of powdered plants (called plant powders by these authors) for repelling or attracting individuals of S. granarius and Sitophilus oryzae L. and found that the repellent effect of the powders was increased when their concentration was raised in wheat grain. As effective repellents they suggest powdered tansy (Tanacetum vulgare L.), sweet clover (Melilotus officinalis L.), yarrow (Achillea millefolium L.) and purple deadnettle (Lamium purpureum L.). This study aimed at describing changes in the population dynamics of R. dominica when sage and sage-wort were added to its environment (and diet). The results show that the addition of chemical substances found in powdered sage and sagewort into R. dominica substrates causes a decline in population size in this species. These substances act as feeding inhibitors for this insect. Sage is particularly effective at slowing population growth and the number of individuals is kept at a low level. The total population size is four times lower compared to the size of control populations on a wheat substrate. Only the maximum population size is significantly lower in case of the addition of sage-wort . The maximum population size, as in the case of sage, is almost half the maximum population size of those kept on pure wheat. Moreover, the addition of sage-wort causes the population’s sex ratio to shift in favour of males and in effect evens out the sex ratio. This is expressed in the value of the index oscillating around 1, while in wheat it is less than 1. An increase in this value takes place by reason of greater female mortality. It may be presumed that females are more susceptible to the effects of feeding inhibitors. The results obtained demonstrate that: 1. The addition of powdered herbs S. officinalis and A. absinthium to an optimal substrate for R. dominica causes a decline in the population size of this pest species. 2. Chemical substances found in S. officinalis and A. absinthium possess feeding inhibitors properties for R. dominica. 3. The addition of sage-wort to a wheat substrate causes the sex structure to shift in favour of males. Moreover, the addition of herbs to the wheat substrate increases female mortality. It may be presumed that females are more susceptible to the effects of feeding inhibitors. REFERENCES Baker J. E., L oschiavo S. R. 1987 – Nutritional ecology of stored-product insect (In: Nutritional Ecology of Insects, Mites, Spiders, and Related Invertebrates. Eds: F. Jr. Slansky, J. C. Rodriquez) – John Wiley & Sons, New York, pp. 321–344. Banasik K., Ignatowicz S. 1995 – Odstraszajàce w∏aÊciwoÊci proszków roÊlinnych i ich zastosowanie w ochronie magazynowanych produktów przed szkodnikami. [Repellent characteristics of plant powders and their use in protection of stored goods against pests] – Mat. 42 Zjazdu PTE, Poznaƒ, pp. 6–7. (in Polish) Boczek J. 1979 – Zwalczanie szkodników produktów spo˝ywczych – tendencje Êwiatowe. [Pest eradication in the food industry – world tendencies] – Ochrona RoÊlin 6: 3–4. (in Polish) 580 Ma∏gorzata K∏yÊ Boczek J. 1983 – Antyfidanty i mo˝liwoÊci ich wykorzystania w walce ze szkodnikami roÊlin [Antifeedants and their usage in plant pests] – Ochrona RoÊlin 6: 3–4. (in Polish) Ciesielska Z. 1971 – Studies on interspecific competition between Rhizopertha dominica F. (Col., Bostrychidae) and Oryzaephilus surinamensis L. (Col., Cucujidae) – Ekol. Pol. A, 19: 263–276. Ciesielska Z. 1978 – Interaction among populations of granary beetles (Sitophilus granarius L., Rhizopertha dominica F. and Oryzaephilus surinamensis L.) – Ekol. Pol. 4: 5–44. Ciesielska Z. 1992 – Tendencies to migration in granary beetle populations. – Proc. Int. Symp. on Stored-Grain Ecosystems. Winnipeg, pp. 80–82. Ciesielska Z. 1994 – Dynamics and expansion of populations of stored beetles populations. – Proc. Int. Working Conf. on Stored-products Protection. Canberra, pp. 500–508. Ciesielska Z., K∏yÊ M. 2002 – AktywnoÊç migracyjna populacji kapturnika zbo˝owca Rhyzopertha dominica (F.) (Coleoptera, Bostrychidae). [Migration activity of the population of Rhyzopertha dominica F. (Col. Bostrychidae] – Annales Academiae Paedagogicae Cracoviensis. Folia 7. Studia Zoologica I: 25–37. (in Polish) Collins P. J., Daglish G. J., Bengston M., Lambkin T. M., Pavic H. 2002 – Genetics of Resistance to Phosphine in Rhyzopertha dominica (Coleoptera: Bostrychidae) – J. of Economic Entomology: 95, (4): 862–869. Go∏´biowska Z., Nawrot J. 1976 – Szkodniki magazynowe [Warehouse pests] – PWRiL, Warszawa 273 pp. (in Polish) Hagstrum D. W., Vick K. W., Webb J. C. 1990 – Acoustical monitoring of Rhyzopertha dominica (Coleoptera: Bostrychidae) populations in stored wheat – J. of Economic Entomology 83, (2): 625–628. Ignatowicz S. 1979 – Effect of inorganic salts upon biology and development of acarid mites. III. Effects of relative humidity and mineral salts upon fecundity and longevity of copra mite, Tyrophagus putrescentiae (Schrank) (Acarina, Acaridae) – Pol. Pismo Entomol. 50: 289–298. Ignatowicz S. 1980a – Effects of calium phosphate surplus in foot upon fecundity, life span and development of copra mite, Tyrophagus putrescentiae (Schrank) (Acarina, Acaridae) – Pol. Pismo Entomol. 50: 289–298. Ignatowicz S. 1980b – Effect of inorganic salts upon longevity and reproduction of the granary weevil, Sitophilus granarius L. (Coleoptera, Curculionidae) – Pol. Pismo Entomol. 50: 299–307. Ignatowicz S., Weso∏owska B. 1994a – Potential of common herbs as grain protec- tants repellent effect of herb extracts on the granary weevil, Sitophilus granarius L. – Proc. Int. Working Conf. on Stored-products Protection 2: 790–794. Ignatowicz S., Weso∏owska B. 1994b – Owadobójcze i odstraszajàce w∏aÊciwoÊci naparów z roÊlin zielarskich [Insecticidal and repellent characteristics of herbal infusions] – Ochrona roÊlin 38, (9): 14–15. (in Polish) K∏yÊ M. 1998 – Wp∏yw sproszkowanej sza∏wii lekarskiej i bylicy pio∏unu na dynamik´ liczebnoÊci i migracje populacji Rhizopertha dominica F. (Coleoptera: Bostrychidae) – [The effect of powdered sage and wormwood on the dynamics of abundance and migrations of the population of Rhizopertha dominica F. (Coleoptera: Bostrychidae)] – Mat. Konf. PTE Wiad. Entomol., Supl. Poznaƒ, pp. 171–172. (in Polish) L etellier C., Haubruge E., Gaspar Ch. 1990 – Activité biologique de deux regulateurs de croissance a l`egard de Sitophilus zeamais, Sitophilus granarius et Rhizopertha dominica – Belg. J. Zool. 120, 1(C): 43–44. (in French) L oschiavo S. R. 1965 – The chemosensory influence of some extracts of brewer`s yeast and cereal product on the feeding behavior of the confused flour beetle, Tribolium confusum (Coleoptera: Tenebrionidae) – Ann. Entomol. Soc. Am. 58: 576–588. Nawrot J. 1973 – Wst´pne badania nad atraktantami pokarmowymi i repelentami dla chrzàszczy wo∏ka zbo˝owego (Sitophilus granarius L.). [Introductory researches on the food attractants and repellents for the beetles of granary weevil (Sitphilus granarius L.)] – Prace Nauk. Inst. Ochr. RoÊl. 15, (2): 179–186. (in Polish) Nawrot J. 1983 – Podstawy do zwalczania wo∏ka zbo˝owego (Sitophilus granarius L.) (Coleoptera: Curculionidae) przy u˝yciu naturalnych zwiàzków chemicznych wp∏ywajàcych na zachowanie si´ chrzàszczy. [Principles for grain weevil (Sitophilus granarius L.) (Coleoptera, Curculionidae) control with use of natural chemical compounds affecting the behaviour of beetles] – Prace Nauk. Inst. Ochr. RoÊl. 24, (2): 173–197. (in Polish) Nawrot J., Czaplicki E. 1978 – Zachowanie si´ chrzàszczy wo∏ka zbo˝owego (Sitophilus granarius L.) w obecnoÊci niektórych substancji ekstrahowanych z produktów zbo˝owych – [The behavior of the grain weevil (Sitophilus granarius L.) in the presence of certain substances extracted from grain products] – Zesz. Probl. Post´pów Nauk Rolniczych, 202: 183–191. (in Polish) Tamaki Y., L oschiavo S. R. 1971 – Effect of synthesized triglicerydes on agregation behaviour of the confused flour beetle, Tribolium confusum. J. Insect Physiol. 17: 1239–1244. Feeding inhibitors in pest control Tamaki Y., L oschiavo S. R., Mc. Ginnis A. J. 1971 – Triglicerides in wheat germ as chemical stimuli eliciting aggregation of the confused flour beetle, Tribolium confusum (Coleoptera, Tenebrionidae) – J. Agric. Food Chem. 19, (2): 285–288. White N. D. G., Wright V. F., Watters F. L., Mills R. B. 1983 – Future directions and 581 current problems for stored-product entomology – Bull. Entomol. Soc. Am. 29: 35–37. Wyrostkiewicz K. 1984 – Antyfidanty – substancje hamujàce ˝erowanie owadów – szkodników roÊlin. [Antifeedants – substances controlling insect foraging – plant pests] – WszechÊwiat, 85, (7): 166–168. (in Polish) (Received after revising May 2004)