Journal of Entomology
Year: 2007 | Volume: 4 | Issue: 1 | Page No.: 51-55
ABSTRACT
Biological activity of Anchomanes difformis powder was assessed under prevailing atmospheric condition (28±2°C, 70-75 r.h.) in the laboratory on Sitophilus zeamais (Motschulsky), Tribolium castaneum (Herbst), Oryzaephilus mercator (Fauvel), Callosobruchus maculatus (Fabricius) and Lasioderma serricorne (Fabricius) at three treatment levels of 0.5, 1.0, 1.5 g of plant powder per 25 g food medium. Percentage beetle mortality was scored at 24, 48 and 72 h after treatment. The plant powder was found to be toxic on all the test beetles at 0.5 g treatments within 24 h of plant powder application except on L. serricorne. The highest mortality of 100% was recorded in C. maculatus after 72 h at 1.5 g treatment level thus; making C. maculatus most susceptible to A. difformis powder treatment. In a further evaluation of A. difformis on survival and development of C. maculatus, oviposition and adult emergence were significantly reduced in treatments compared to control. Generally, the bioactivity of A. difformis powder on development of immature stages and emergence of adult C. maculatus were more pronounced in 1.5 g treated grains. Thus, application of A. difformis plant powder could be employed in integrated pest management for C. maculatus control.
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How to cite this article
R.O. Akinkurolere, 2007. Assessment of the Insecticidal Properties of Anchomanes difformis (P. Beauv.) Powder on Five Beetles of Stored Produce. Journal of Entomology, 4: 51-55.
DOI: 10.3923/je.2007.51.55
URL: https://scialert.net/abstract/?doi=je.2007.51.55
DOI: 10.3923/je.2007.51.55
URL: https://scialert.net/abstract/?doi=je.2007.51.55
INTRODUCTION
Beetles are of great importance in grain storage systems, their activity on stored produce leads to losses both in quality and quantity. Control of these coleopterans is still dependent on synthetic chemical insecticides and this has almost completely kept at bay, the use of biological control techniques. Although chemical insecticides are effective and poses as solution to insect depredation, thy are however, plagued by many problems such as development of resistance in some major pests, high cost of procurement as well as public awareness of hazards posed to human health and the environment including ozone depleting potential (Golob and Webley, 1980; Credland, 1992; Zhang et al., 2000; Adedire and Akinkurolere, 2005). Therefore development of an alternative treatment that is none hazardous to human and environmentally friendly is urgently needed.
The use of plant materials for the protection of stored products is an old practice in developing countries and is very common among poor smallholder farmers in the tropics and subtropics (Golob and Webley, 1980; Delobel and Malonga, 1987; Akinkurolere et al., 2006). In the tropics, plant materials such as dried pepper and its inert dust have been in use as powders and admixtures for a long time. These have been found to reduce post-harvest losses of stored grains and grain legumes (Boeke et al., 2001).
Anchomanes difformis P. Beauv (family: Araceae) is a large herbaceous plant with stout prickly stem, which grows up to 3 m in height and has large divided leaves (Burkill, 1985). It is abundant in the wild forest of West Africa. Farmers in Southern Nigeria also grow it for making rubefacients and vesicants for external application and internal medication respectively (Burkill, 1985). The plant is considered to be a powerful purgative in Cote d’Ivoire and it is also used as a (snake/scorpion) poison antidote. Any of the plant parts: root, stem or leaves is used to treat urethra discharge, jaundice and kidney pains. A. difformis contains strong alkaloids (Adegoke et al., 1968), which have been used as medicine and poison by man for ages. Alkaloids are toxic chemical substances that act on the central nervous system.
This study was carried out to evaluate the lethal effect of the rhizome of A. difformis in powdered form against stored product beetles.
MATERIALS AND METHODS
Source of Insect Population/insect Culture
Adults of S. zeamais, T. castaneum, C. maculatus, O. mercator and L. serricorne used for this study were obtained from Experimental and Teaching Ranch Warehouse of Huazhong Agricultural University, Wuhan. The insects were later reared in our laboratory of stored-product and urban pests, Huazhong Agricultural University, Wuhan. The culture media and rearing conditions for the test beetles as described by Haines (1987), is shown in Table 1.
Plant Material
Anchomanes difformis used for the experiments were collected from Teaching and Research Farm, Federal University of Technology Akure, Nigeria. The rhizome part of A. difformis used was first dried naturally on laboratory benches. When dried, it was pulverized in a Kenwood blender and passed through a uniform size sieve. The plant powder was stored in airtight brown bottle and brought to China for the study.
Bioassay
Contact Toxicity Test
Plant powders at three concentrations namely, 0.5, 1.0 and 1.5 g each was measured into 9 cm diameter Petri-dishes containing 25 g of uninfected food medium and thoroughly mixed manually by agitating the dishes. Ten pairs of newly emerged adult beetles were introduced into each Petri-dish containing varying concentrations of plant powder/food medium complex. A control containing only the appropriate food medium without plant powder treatment was also infested with 10 couples of test beetles. The petri dishes were then covered to prevent insects from escaping. Each treatment was replicated three times and insect mortality was scored at 24, 48 and 72 h after treatment.
Effect of Powder on Fecundity
Clean cowpea (Vigna unguiculata (L.) Walp.) seeds treated with different plant powder concentrations as described above were infested with 2 pairs of 0-24 h old adult C. maculatus. After 72 h all insects (both dead and alive) were removed and the number of eggs was counted per treatment.
The number of adult emergence was assessed 30 days after treatment. Each test was done in three replicates. Control tests were also set up without plant powder treatment.
| Table 1: | Culture media and rearing physical conditions for test beetles (Haines, 1987) |
 | |
Data Analysis
There were 3 replicates in each sets of experiment. ANOVA and Tukey’s test were used for mean separation in SPPS for windows soft ware (version 10.0).
RESULTS
Contact Toxicity
Adult mortality of all the test beetles was low after treatment with A. difformis powder at 0.5 g (Table 2). The mortality rates of all the storage beetles (S. zeamais, T. castaneum, O. mercator, C. maculatus and L. serricorne) increased with increase in the concentration of A. difformis powder and with exposure period (Table 2-4). Mortality of 100% was recorded within 72 h of exposure to 1.5 g concentration of A. difformis powder for C. maculatus while mortalities of 65.00, 54.00, 40.00 and 25.00% were recorded after 72 h for T. castaneum, S. zeamais, O. mercator and L. serricorne respectively for the same treatment (Table 4). Overall susceptibility of the storage beetles to A. difformis powder was ranked in the following order: L. serricorne < O. mercator < S. zeamais <T. castaneum <C. maculatus respectively with C. maculatus being most susceptible.
Effect of A. difformis Powder on Fecundity of Adult C. maculatus
Percentage adult emergence after 30 days and average number of eggs laid by C. maculatus after 24, 48 and 72 h following treatment with various concentrations of A. difformis powder is represented in Table 5. There is significant difference (p ≤ 0.05) in the rate of oviposition in treated samples compared to untreated (control) seeds. Fewer eggs were laid (11.68, 16.36 and 23.33) per 24 h intervals in 1.5 g treated samples, while 0.5 g treated samples evoking the least ovicidal effect (39.23, 50.13 and 56.82 eggs). However, after 72 h all the three concentrations (0.5, 1.0 and 1.5 g) tested showed some level of ovicidal effect significantly different from the control. A. difformis powder at 1.5 g had significant effect (30.13) on adult emergence, different from all treatments; there was no significant difference in bruchids emergence between 0.5 g and blank control.
| Table 2: | Effect of 0.5 g Anchomanes difformis powder on adults of five stored product beetles |
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| Each value is the percentage mean±standard error of three replicates. Means followed by different letter (s) vertically are significantly different at p≤0.05 by Tukey’s test | |
| Table 3: | Effect of 1.0 g Anchomanes difformis powder on adults of five stored product beetles |
 | |
| Each value is the percentage mean±standard error of three replicates. Means followed by different letter (s) vertically are significantly different at p≤0.05 by Tukey’s test | |
| Table 4: | Effect of 1.5 g Anchomanes difformis powder on adults of five stored product beetles |
 | |
| Each value is the percentage mean±standard error of three replicates. Means followed by different letter (s) vertically are significantly different at p≤0.05 by Tukey’s test | |
| Table 5: | Percentage adult emergence after 30 days and average number of eggs laid by C. maculatus after 24, 48 and 72 h following treatment with various concentrations of A. difformis powder |
 | |
| Means followed by the same letter vertically are not significantly different at p≥0.05 by Tukey’s test | |
DISCUSSION
Rhizome powder of A. difformis provided good protection against all the test beetles at 72 h post-treatment. C. maculatus was the most susceptible of five cereal beetles tested with 100% mortality within 72 h while L. serricorne with 25% mortality is the least susceptible to A. difformis (Table 4). Since mortality increased as the exposure period increases, it shows that the toxic volatile components of A. difformis have some level of persistence.
Similarly, Chiranjeevi and Sudhakar (1996) reported that in many villages in Africa, farmers often mix plant materials with stored grains against pest infestation. Whole plants or parts of plant rather than their powders are often used, presumably because they are easy to remove from the stored grains (Casewell, 1976; Delobel and Malonga, 1987).
This experiment shows that powders made from A. difformis significantly reduce the population of all the storage beetles used in this study. Though A. difformis powder showed no insecticidal activity at low concentration in some of the tests at 24 h after treatment, significant (p≤0.05) mortality occurred 72 h after treatment in all the beetles. It also hampered oviposition and emergence of C. maculatus. While feeding on whole or fragmental grains, beetles might pick up a lethal dose of the treatment thus resulting in stomach poisoning. The action of A. difformis on these beetles could therefore be linked to contact toxicity and stomach poisoning (Chander and Ahmed, 1985; Adedire and Lajide, 2001). Fine particles of A. difformis powder could block the spiracles of the beetles thereby impairing respiration and causing death. The results obtained from this study are in agreement with earlier reports (Ofuya, 1990; Niber, 1994; Lajide et al., 1998) that powder of some tropical plants could be admixed with grains in storage in order to protect them from damage by storage beetles. Considering the ease of powder application by farmers, A. difformis rhizome powder could be admixed with maize grains or cowpea seeds in order to protect them against some of the most serious pests of stored products.
REFERENCES
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Direct Link - Credland, P.F., 1992. The structure of bruchid eggs may explain the ovicidal effects of oils. J. Stored Prod. Res., 28: 1-9.
Direct Link - Delobel, A. and P. Malonga, 1987. Insecticidal properties of six plant materials against Caryedon serratus (Ol.) (Coleoptera: Bruchidae). J. Stored Prod. Res., 23: 173-176.
CrossRefDirect Link - Niber, T.B., 1994. The ability of powders and slurries from ten plant species to protect stored grain from attack by Prostephanus truncatus horn (Coleoptera: Bostrichidae) and Sitophilus oryzae L. (Coleoptera: Curculionidae). J. Stored Prod. Res., 30: 297-301.
CrossRefDirect Link - Ofuya, T.I., 1990. Oviposition deterrence and ovicidal properties of some plant powders against Callosobruchus maculatus in stored cowpea (Vigina unguiculata) seeds. J. Agric. Sci., 115: 343-345.
Direct Link - Zhang, H.Y., Y. Ziniu and D. Wangxi, 2000. Isolation, distribution and toxicity of Bacillus thuringiensis from warehouses in China. Crop Prot., 19: 449-454.
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