Okada, M., S. Abdulrachman, M. Arifin, and K. Nakayama. 1982. Studies on the seasonal prevalence, damage and control of the beanfly, Ophiomyia phaseoli (Tryon) as a pest of soybean, p. 195-206. In Research Report of Japan-Indonesia Joint Agricultural Research Project.
Muneo Okada1, Sarlan Abdulrachman2, Muhammad Arifin2,
and Kanenori Nakayama1
1 Agricultural Research Center, Yatabe, Tsukuba, Ibaraki, Japan
2 BORIF, CRIFC, Bogor, Indonesia
ABSTRACT
Seasonal prevalence of the beanfly, O. phaseoli (Tryon), which is the most important insect pest of soybean in Indonesia, and the damage on soybean caused by the beanfly were surveyed on soybeans which were cultivated six times in a year, every two monthes. Each farm was divided into insecticide treated plot and control plot. And also the test on cultural control method to the beanfly was conducted. These experiments were carried out at the Muara Experiment Substation of the Central Research Institute for Food Crops, Bogor, Indonesia, in 1979 to 1980.
Occurrence of the beanfly was observed throughout the year. There was difference in the abundances of the beanfly in each sowing time. The abundance of the beanfly was higher in the dry season than in the wet season. The highest population density was observed in the begining of the dry season. The peaks in each population density of the adult beanfly were recognized from the germination to two weeks after sowing. And second peaks of those were found within four to five weeks after sowing.
The growth periods of soybeans in each planting were ranged 87 to 101 days in insecticide treated plots. In control plots (non-treated plots), they took more 1 to 4 days. In general view, soybean had shorter growth period in dry season than in wet season.
Withered or dead soybean seedlings were observed from 20 days after sowing and most of survived seedings were suppressed their growth in control plots of all plantings by the attack of the beanfly. Finally, the seedling rates in control plots showed large differences as compared with insecticide treated plots, and the ratios of these were ranged 70% to 90%. Also in the main stem length, shorter ones were recorded in the control plots by the attack of the beanfly. The rates of polisired soybean grains in control plots to insecticide treated plots were ranged 78.6% to 37.5%.
As the cultural control method to the beanfly, in cases of soybean was cultivated under condition leaving the standing paddy stock after harvesting (ear plucking), and after soybean was sowed, the farm was mulched with paddy straw, a certain effect in disturbing the activity of the beanfly was recognized. Fewer damaged soybean stems, higher seedling rates, higher stem lengths and higher yields were recorded in those plots.
INTRODUCTION
There are many kinds of insect pests of soybean in Indonesia. The beanfly, Ophiomyia phaseoli (Tryon) (Diptera: Agromyzidae) is one of the most serious pests of soybean. The beanfly is a widely distributed seedling pest in Asia, Australia and Africa, and it attacks soybeans, cowpeas, lima beans, mung beans and winged beans (6).
The beanfly is a minute insect. Females are 2.2 mm and males are 1.9 mm in length, and they are shiny black in color, except for their legs, antennae, and wing veins, which are light brown. The fly oviposits mostly on the upper surface of the cotyledon and the primary leaf, and the hatched maggot then behaves like a leafminer, penetrating underneath the epidermis of the leaf until it reaches a vein. It then tunnels to the midrib and the leaf stalk, finally reaches to the stem near the ground surface. Pupation takes place in the stem and in the root zone. Infestation begins as soon as the plants appear above ground. Leaves of infested plants show the mines as pale, irregular lines; the plant becomes stunt and yellow and finally dies in case of seedling is infested seriously by the maggots.
Purpose of this study was ascertainment of the seasonal prevalence of the beanfly and realities of the damage caused by the beanfly. Accordingly, soybeans were cultivated six times in a year, every two monthes. The numbers of adult which immigrated to soybean were recorded. The growth of soybean and the influence on the yield of soybean caused by the beanfly were examined.
There are few reports on the control of the beanfly. At present, control of the beanfly is done by spraying Azodrin in the Central Research Institute for Food Crops. But it is not easy to get an insecticide for farmers who are a little agricultural income. It is in hopes that the control method without insecticide for the beanfly is established. Therefore, we studied also the cultural control for this pest. We got some knowledges in this experiment. This report thus describes the seasonal prevalence of Ophiomyia phaseoli, the damage and yield loss caused by O. phaseoli, and the cultural control for O. phaseoli.
We wish to express our thanks to Dr. S. Toda, Dr. Suryatna Effendi, Dr. Soehardjan and Ir. Wedanimbi Tengkano for their kind advices and supports. Thanks are also due to Prof. Dr. M. Sasakawa, Kyoto Prefectural University, for identifying the specimens of the present study.
MATERIALS AND METHODS
1. Test 1. Seasonal prevalence of the beanfly, O. phaseoli, and influence on the growth and yield of soybean caused by the beanfly
The test was carried out at the Muara Experiment Farm Field (alluvial soil) of the Central Research Institute for Food Crops, Bogor, Indonesia, in 1979 - 1980. Soybeans (variety; ORBA) were cultivated six times, every two monthes from July, 1979 to August, 1980 as mentioned below. Insecticide treated plot sprayed with Karphos or Azodrin which were effective for controlling the beanfly, and control plot (nontreated plot) were prepared in each planting.
1st planting was sowed on 23rd, July,1979
2nd planting was sowed on 24th, September, 1979
3rd planting was sowed on 26th, November, 1979
4th planting was sowed on 23rd, January, 1980
5th planting was sowed on 3lst, March, 1980
6th planting was sowed on 23rd, May, 1980
The area of one test plot in each planting was 80 m2, and each planting had two replications. Each plot was divided into two treatment plots, one of them was insecticide treated plot and another was control plot. Karphos or Azodrin was sprayed in insecticide treated plot two times, after one week and two weeks from sowing, with 0.05% active ingredient at the rate of 600 liter per hectare.
Soybean was sowed in sowing hole with three or four seeds per one hill after plowing. The width between ridges was 40 cm interval, the distance between hills was placed at interval of 20 cm, and sowing holes were made by dibble (it is called tugal in Indonesia).
As for fertilizer, CaO was broadcasted at the rate of 400 kg per hectare. 40 kg of urea, 130 kg of TSP and 60 kg of potassium sulfate per hectare were applied on every row as basic fertilizer.
Neighboring four fields were used for this experiment, but the background of previous crops in those fields was not uniform.
Survey: The numbers of adult beanfly, which immigrated to soybean, were recorded on 100 hills per one plot in each plot. This survey was conducted during 8 to 9 o'clock from just after germination through 35 days after sowing.
Besides, the growth of main stem length, yield and harvested crop were surveyed and the influence on soybean caused by the beanfly was calculated.
2. Test 2. Cultural control of the beanfly, O. phaseoli
The test was conducted at the Muara Experiment Farm Field (alluvial soil) of the Central Research Institute for Food Crops, Bogor, Indonesia. The field just after the paddy rice was harvested by the method of ear plucking (it is called ani-ani in Indonesia) was adopted for this test.
Soybean (variety: No. 1667) was sowed in the test plots on 9th of August, 1980, as mentioned below.
1st plot : After paddy stock was dug out and was released from the plot, plowing was done, and seed was dibbled.
2nd plot : Paddy stock was mowed from the surface of ground and was released from the plot. Seed was dibbled without plowing.
3rd plot : Paddy stock was mowed at 10 cm height from ground and paddy straw was released from the plot. Seed was dibbled without plowing.
4th plot : Ear of rice was harvested by the method of ear plucking. Seed was dibbled under that condition. (The growth of rice was poor and the weight of air-dried paddy straw was about 1.5 ton per hectare).
5th plot : After the same treatment with 2nd plot was done, ground was covered with paddy straw at the rate of about 2.5 ton (air-dried condition) per hectare, and paddy straw was left until harvesting time.
6th plot : After the same treatment with 5th plot was done, paddy straw had been scheduled to burned up, but it could not be done by the influence of a rainfall. Then, paddy straw was removed from the plot after one week from sowing.
7th plot : Same treatment with 1st plot was done and Furadan granule was applied on row at the rate of 30 kg per hectare, at the same time with fertilizer.
8th plot : Same treatment with 1st plot was done and Azodrin emulsion was sprayed with 0.05% active ingredient at the rate of 600 liter per hectare after one week and two weeks from sowing.
The cultural conditions of soybeans in eight test plots were the same with test 1. The area of each plot was 14.4 m2, and two replications were prepared.
Survey: The numbers of adult beanfly, which immigrated to soybean, were recorded on 100 hills per one plot in each plot. The observation was continued, during 8 to 9 o'clock, from just after germination through 35 days after sowing. 15 soybean plants per one plot were collected from every plot, and the number of plants attacked by the beanfly were surveyed. Beside the growth of main stem length, yield and harvested crop were examined and the influence on soybean caused by the beanfly was calculated.
RESULTS
Test 1. The rainy days, rainfall, maximum and minimum temperature in each month during test period were given in Table 1. It was rain more than 100 mm in every month, the essential dry season was not recognized. But, July to August in 1979 and May to July in 1980 were the weather looked like dry season. The wet season was from September in 1979 to April in 1980, the peak of it was January.
There was difference of the climate condition as mentioned above, and moreover, the background of previous crop was not same in each planting. Accordingly, the considerable differences in the growth and yield of soybean were observed among each planting. Especially, in the soybean sowed in January, the germination ability was weak and the germination rate was low. But this experiment could be smoothly completed, in general view.
(1) Seasonal prevalence of the beanfly, O. phaseoli
Occurrence of the beanfly was observed throughout all plantings (Fig. 1). There were a little differences of its abundances in each planting. But in general view, the peaks in each population density of adult beanfly which immigrated to soybean were observed from the germination to two weeks after sowing. After that, the population densities of the beanfly decreased, and the second peaks of it were recognized within four to five weeks after sowing.
In the comparison of abundances of the beanfly among each planting, the highest population density was observed on the soybean sowed in May, and its peaks appeared on 6th day and 25th to 26th day after sowing. The second higher population density was found on the soybean sowed in July, and its peak was recognized from 7th to 11th day after sowing.
On the soybeans sowed in September, November, January and March, the population densities of the beanflies were remarkably lower than on the soybeans sowed in May and July. And the differences of the population densities among those were trifling, and also the peaks of the population densities were not apparent.
In the contrast with seasonal prevalence and meteorological phenomena table (Table 1), the abundance of the beanfly was higher in the dry season than in the wet season and also the population density of the beanfly was higher on the soybean sowed in May than on the soybean sowed in July. The highest population density of the beanfly was in the begining of the dry season. Though abundances of the beanfly and the rainfall during two weeks after each sowing were shown in Table 2, it was not clear that the relation between the abundance and rainfall.
(2) Influence of the beanfly, O. phaseoli to the growth and yield of soybean
Growth period : The growth period of soybean in insecticide treated plot was shortest in the plot sowed in March (87 days) and it was longest in the plot sowed in November (101 days). In the other planting, they were ranged within 91 to 96 days. In control plot, they took more 1 to 4 days and their delays were 0 to 2 days in the flowering time (Table 3).
Seedling rate : The seedling rates of each planting were ranged within 80% to 90%, but the germination ability of soybean sowed in January was weak and also its germination rate was poor as about 60%. But in control plots of each planting, the withered soybean seedlings caused by the beanfly appeared from 20 days after sowing and finally, the number of plants at harvesting time in each planting showed large differences as compared with insecticide treated plots (Table 4).
Though the ratios of seedling number in control plots to insecticide treated plots showed 90% in soybeans sowed in January and July, those in the soybeans sowed in the other months were ranged from 70% to 90%, and it in the plot sowed in September was 28.2% decrease as 71.8%.
Main stem length: Main stem lengths of soybean in the early stage, in the middle stage of growth period and in the harvesting time were given in Table 5. Though, there was not difference between insecticide treated plot and control plot in the soybean sowed in March, the shorter stem lengths were observed in control plots as compared with insecticide treated plots in the other plantings. And they showed the same tendency through the whole growth periods. Especially, in the soybeans sowed in September, November and January when the elongation of main stem length was higher, ten cm differences were observed. The coefficient of variation of main stem length among the hills in the soybean sowed in May was as follows, and it was also recognized that the variation among the hills in control plot was larger than in insecticide treated plot.
Number of root nodule: Numbers of root nodules of 15 soybean plants in each plot were calculated (Table 6). The control plots had fewer root nodules per one soybean stem as compared with the insecticide treated plots through every planting.
Yield: The yields were vary in each planting by the influence of the different weather conditions in each planting, and further, by ununiform background of previous crops in each test plot as mentioned before. Though the yield was good in the soybean sowed in
November, the growth of soybean was generally poor in the other plantings, especially the yield of soybean sowed in May was lower. But in spite of those circumstances, the considerable different yields were got between insecticide treated plot and control plot (Table 7). Namely, though the weights of cleaned grains in control plots were about 75% as compared with insecticide treated plots in the soybeans sowed in July and in March, they were lower than 50% in the other plantings, especially in the soybean sowed in November, it was 37.5%.
Test 2. The germination and growth of soybean were normal. But as the soil fertilities were not uniform in each plot, the difference of the influence to soybeans caused by the beanfly among each treatment could not be cleared.
Number of damaged soybean plant caused by the beanfly: Fifteen plants per one plot were randomly collected in each plot, and the number of plants attacked by the beanfly was surveyed (Table 8). In the consideration among each treatment, percentages of the damaged plants caused by the beanfly were more than 97% in the 1st and 2nd plots which paddy stock was released from those plots regardless of plowing.
The 3rd plot which paddy stock was left at 10 cm height above ground had 87% damaged plants. The 4th plot harvested the ear of rice only and, the 5th and 6th plots covered the ground with paddy straw had fewer damaged plants as 70% to 73%. The damage of the 7th plot treated with Furadan was 47% and it of the 8th plot treated with Azodrin was 7%. The effect of Furadan was considerably lower than Azodrin. Though the 1st to 6th plots had more damaged plants as compared with the Azodrin treated plot, the 4th to 6th plots which paddy stock or paddy straw were left in the plots had fewer damaged plants as compared with the plots which paddy straw was released.
Growth and yield : The seedling rates were surveyed in the flowering time as the withered soybean seedlings caused by the beanfly were observed from 20 days after sowing (Table 9). The highest seedling rate was observed in the Azodrin treated plot, and the 2nd higher seedling rate was found in the 4th plot harvested the ear of rice only and left the paddy stock in the plot. But the significant differences were not recognized among each plot, because of the large differences of the seedling rates were observed generally among each plot.
The main stem length showed the superior trend in the plots mulched with paddy straw and in the plot treated with Azodrin as compared with the other plots, and its tendency was continued to the harvesting time (Table 10). The yields of 1st, 2nd, 3rd, 4th, 5th, 6th, 7th and 8th plots were 10.26, 8.96, 5.13, 9.39, 11.39, 8.17, 10.43 and 12.00 kg per 100 m2 respectively. Though the yield also showed the higher trend in the plot covered with paddy straw and in the plot treated with Azodrin as compared with the other plots, the significant differences were not recognized among each plot because the large differences of the yields were found among each plot.
DISCUSSION
1. Seasonal prevalence of the beanfly, O. phaseoli
It is known that three species resembled closely, Ophiomyia phaseoli, Melanagromyza sojae and M. dolichostigma attacking to soybean occur in Java Island and attack on the different parts of the soybean plant. They have caused enoumuos lossess annually to soybean.
The attack of M. sojae starts as soon as the seedling emarge, with eggs laid singly on the lower surface of the leaf. The larvae tunnel through the leafpetiole and pupate in the stem at ground level (6). M. dolichostigma larvae attack and feed on the growing tip of the soybean stem at most stage of plant development (6). Among these pests, the beanfly, O. phaseoli is the most serious soybean pest in Indonesia (10). M. dolichostigma is less destructive than M. sojae (6). For the purpose of securing the seasonal prevalence of the beanfly, soybeans were cultivated six times in a year, every two monthes, from July in 1979 to August in 1980. The numbers of adult beanfly on soybean were recorded from just after germination through 35 days after sowing. It was very difficult to found up O. phaseoli only from three species mentioned above in a field. But regarding the differences in the population densities of three species, it was supposed that most of the number recorded in this experiment were the adult of O. phaseoli.
The peaks in each population density of the adult beanfly were observed from germination to two weeks after sowing. After that, the population densities of the beanfly decreased and the second peaks of those were recognized within four to five weeks after sowing.
From the result, it is found that the adult beanfly immigrates and oviposits to soybean from germination to two weeks after sowing, namely from 5 days to 14 days after sowing, and the eggs hatch, the adults emerge pass through larvae and pupae, from four to five weeks after sowing. It takes about three to four weeks. According to Prasadja and Supriadi, the egg stage takes 2 to 4 days, the larval stage occupies about 10 days and the pupal stage requires a further 9 to 10 days (4). So the total is about 23 days. The occurrence of two peaks in each seasonal prevalence of the adult beanfly almost coincide with above life cycle. Accordingly, in the control of this pest, the measure for control should be taken for ten days from germination, and as the second peak exists, it is important to make uniform the sowing time in an area. It is reported that the most damaging time of the beanfly infestation is within only one week after crop emergence (1, 9).
In this experiment, Karphos or Azodrin was sprayed twice, after one week and two weeks from sowing in each planting and it was effective for controlling the beanfly.
Difference in the adult abundance between the insecticide treated plot and control plot was not observed during three weeks after sowing. The result was considered to be due to the small area of each plot arranged in adjoining position. But in the second peak, difference of the adult abundance was recognized, namely a few adults were counted in the insecticide treated plot owing to the effect of insecticide and many adults were recorded in the control plot.
Occurrence of the beanfly was observed in the whole sowing times. But differences in the abundance of the beanfly were recognized in each sowing time, regardless of a rainfall during two weeks after sowing. The highest population density of the beanfly was observed on soybean sowed in May in this experiment. The second higher population density was found on soybean sowed in July. The low population densities were recorded in the other plantings, especially the lowest density was on soybean sowed in January. As it has been related that abundance of the beanfly is more in the dry season than in the wet season (11), the result of this experiment could support it. But because the highest population density of the beanfly was recognized on soybean sowed in May, it was considered that the highest population density of it was in the begining of the dry season. In the consideration between the abundance of the beanfly and the rainfall during two weeks after sowing (Table 2), the relation between the abundance and rainfall was not clear. Namely, it was seemed that the change of weather, which is called dry season and wet season, worked severely on the seasonal prevalence of the beanfly during a year. There is a lot of rain in Bogor, the distinction between dry season and wet season is not so apparent as it is in the central and east Java where is main producing area of soybean. Accordingly, it is necessary to reexamine whether the highest population density is in the whole dry season or only in the bigining of the dry season, in the area where the difference between dry season and wet season is clear.
2. Influence of the beanfly, O. phaseoli to the growth and yield of soybean
Considerable difference was recognized on the growth of soybeans between insecticide treated plots and control plots throughout all plantings. The withered or dead soybean seedlings caused by the beanfly appeared from about 20 days after sowing in control plots of each planting. Finally, the seedling rates in control plots showed large difference as compared with insecticide treated plots. Also the main stem length of soybeans escaped death was lower in control plots, and the coefficient of variation among the stumps was larger in control plots. Soybean in control plots had fewer root nodules and also in the growth period, they took delay. Consequently, the yield of soybeans showed great decrease in control plots as compared with insecticide treated plots. It was considered that the differences in the growth and yield of soybeans, as mentioned above, between insecticide treated plot and control plot were to be due to the difference of the damage caused by the beanfly. But it was not recognized that the relation between the abundance of the beanfly, and influence on the growth and yield of soybeans. The rates of cleaned grain-weight in control plots against insecticide treated plots in soybeans sowed in May and July, when the higher population densities of the beanfly were recorded, were 78.6% and 74.5% respectively. On the other side, the rate of it was 52.6% in soybean sowed in January, when the population density of the beanfly was lowest. These reasons are not apparent. The farms used test were arranged into neighboring four farms. The plots sowed in July, September and November, had not been interfered until soybeans were sowed after paddy rice was harvested in June, 1979. The plots sowed in January and March had been cultivated peanut, and in the plot sowed in May, peanut was cultivated two times before soybean was sowed. It was supposed that the different background of previous crops as mentioned above, had larger influence on the growth and yield of soybeans than the influence of the beanfly. Anyhow, it had showed heavy damage by the beanfly that the rates of cleaned grain-weight in control plots to insecticide treated plots were ranged 78.6% to 37.5%. We had observed the farms where most of soybeans were withered or died by the attack of the beanfly. It was considered to be due to the restriction of soil moisture in dried farms and the obstacle of meristem caused by the attack of the beanfly. This experiment was carried out in Bogor, where was a lot of rain, and the limitation of soil moisture was not found after soybean was sowed. Accordingly, in soybean cultivated in the dry season, it is supposed that larger injury may be caused than the damage in this experiment. It was reported that the ORBA variety was suffered about 85% dead plants during dry season (8).
3. Cultural control of the beanfly, O. phaseoli
The measure for controlling the beanfly should be taken within two weeks after sowing, in considerating the result of survey on the seasonal prevalence of the beanfly as mentioned above. For the purpose of finding the cultural control method which could avoid the damage of the beanfly, the differences in the injury caused by the beanfly were examined among plowing-plot, rice stubble managements-plots, Azodrin treated-plot sowing applied after one week and two weeks from sowing, Furadan treated-plot which applied at the same time with fertilizer and control plot. Soybean plants were randomly collected in each plot after 23 days from sowing and number of damaged soybean plants caused by the beanfly were surveyed. The lowest damage was observed in Azodrin treated-plot. Second lower damage was recorded in the plot harvested the ear of rice only by ear plucking and Furadan treated-plot. Comparatively light damage was found in the plots covered with paddy straw regardless of plowing as compared with the plot left 10 cm height-paddy stock and the plot removed paddy stock. Above result showed that the lower damage caused by the beanfly was obtained in case of soybean was sowed in the farm left paddy stock after harvested the ear only, and in the farm mulched with paddy straw after sowing. It is supposed as the reason that paddy stock and paddy straw mulch are useful for physical prevention to immigration of the beanfly. The growth of rice of previous crop was poor and the weight of air-dried paddy stock was about 1.5 ton per hectare in the plot where the ear of rice only was harvested by ear plucking, and soybean was sowed under that condition. Therefore, if the growth of rice was average and the weight of air-dried paddy stock was about 2.5 ton, it was supposed that standing paddy stock was more useful for preventing to immigration of the beanfly. But there is a report, in case of soybean was cultivated in the farm where left paddy stock after harvested the ear only, paddy stock resulted yield losses on soybean due to the shading effect (4). This can be attributed to the shading effect on soybean, caused the plant to etiolate (5).
The highest seedling rate was observed in the Azodrin treated-plot and second was found in the plot harvested the ear of rice only and left the paddy stock in the plot. But no significant difference was observed among each plot, because of the large differences of the seedling rates were recognized among each plot. Also on the growth and yield, higher growth and yield were recorded in the plot treated with Azodrin and in the plot mulched with paddy straw. According to Prasadja and Supriadi (4), paddy straw mulch always gave a lower percentage of germination compared to no stubble-plot, standing paddy stock-plot and other plots, but nevertheless it still produced high yield. This can be attributed to better soil conditions for plant growth. Lal (3) mentioned that mulching with crop residue at the rate of 4-6 tons/ha decreases soil temperature and maintains favorable soil structure by more intensive soil flora and fauna activity. In addition, Dadson and Boateng (2) stated that soil moisture conservation and reduced crusting are more crucial to emergence of soybean than decreased soil temperature. Furthermore, mulching increases the plant height, the number of nodes on the main stem and the number of pods per plant (4). High yield in rice straw mulch can be attributed to the high number of pods produced per plant (4). Therefore, poor germination may be compensated for by profuse branching and increased yield per plant (7).
CONCLUSION
Occurrence of the beanfly, Ophiomyia phaseoli (Tryon), which is the most serious insect pest of soybean in Indonesia, and influence to soybean caused by the beanfly were examined, and also a few tests on control method of the beanfly were carried out.
1. The peak in the population density of adult beanfly which immigrated to soybean were observed from germination to two weeks after sowing. After that the population density decreased and the second peak of it was recognized within four to five weeks after sowing. The more abundance of the adult beanfly was found in the dry season than in the wet season. And the most abundance of the adult was recorded in the begining of the dry season.
2. Withered or dead soybean seedlings were observed and most of survived seedlings were suppressed their growth in control plot, by the attack of the beanfly. The rates of cleaned soybean grain in control plots to insecticide treated plots were ranged 78.6-37.5%.
3. As cultural control method to the beanfly, the method sowed soybean in the farm left the standing paddy stock after harvested the ear of rice only, and the method mulched the farm with paddy straw after sowed soybean, showed a certain effect in disturbing the activity of the beanfly.
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