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Abstract In order to select the longacting， low toxic， lowrisk and multifunctional new pesticides for the control of sugarcane borders and woolly aphids and precise and efficient application technology， the control effect of 10% monosultap·thiamethoxam granular formulation and 1% Bt·clothianidin granular formulation on sugarcane borders and woolly aphids were studied. The results showed that 10% monosultap·thiamethoxam GR and 1% Bt·clothianidin GR had good control effects on sugarcane borders and woolly aphids. They were ideal slowrelease， longacting， low toxic and multifunctional new pesticides used to control sugarcane borders and woolly aphids. They could be used alternately with other pesticides to delay the emergence and development of pest resistance to pesticides. The best dosage of the two pesticides in the field was 45 kg/hm 2. They could be mixed with fertilizer （1 200-1 800 kg/hm 2）， scattered in sugarcane ditches or at the base of sugarcane plants， and covered with soil or film from January to July. The control effect on dead heart seedlings damaged by borers could be up to above 79.2%， and the control effect on sugarcane woolly aphids could reach more than 98.8%. In comparison with the control group， the actual yield and sugar content of sugarcane increased by above 41 555 kg/hm 2 and 6.5% respectively. The application of slowrelease， longacting， strong systemic and multifunctional new agents with fertilizer around roots is convenient， precise and efficient， laborsaving， timesaving and environmentally friendly， and is worthy of being widely applied in sugarcane areas.
Key words Slowrelease and longacting agents; Precise application of pesticides; Sugarcane borders and woolly aphids; Control effect
Sugarcane borers are the most common and most serious pests in the sugarcane areas of Yunnan， belonging to typical boring pests. At present， the damage caused by a variety of sugarcane borers in the sugarcane areas of Yunnan is serious. At the seedling stage， the dead heart rate of sugarcane damaged by borers is 8.33%-65.82%. In the middle and later period， the proportion of sugarcane plants damaged by borers is 26.67%-96.67%， and the proportion of sugarcane joints damaged by borers is 4.43%-27.91%. The loss rate of sugarcane yield is 25.92% on average and 44.53% at most. The sugar content of sugarcane decreases 2.16% on average and 5.69% at most[1-4]. Sugarcane woolly aphid （Ceratovacuna lanigera Zehntner） is the main pest that appears most commonly and damages sugarcane most seriously in the sugarcane areas of Yunnan[1，5-6]. Under current production conditions， the yield of the damaged sugarcane has reduced by 18%-35.3% or above 45% at most. Sugar content in sugarcane has decreased by 5.48%-8.16%. The emergence rate of sugarcane seedlings developed from the damaged sugarcane has reduced by 19.7%-41.6%. In the fields with serous damage， the germination rate of perennial roots has declined by 57.7%-93.6%， and the decrease in sugarcane yield is more serious[6]. The main traditional methods to control sugarcane pests are spraying and scattering chemical pesticides， and some farmers often apply highly toxic （banned） pesticides， which can seriously pollute the environment and cause the resistance of pests to pesticides[1，7-16]. It is imperative to develop， promote and apply slowrelease， longacting and multifunctional new pesticides and precise and efficient pesticide application technology. 10% monosultap·thiamethoxam granular formulation is a slowrelease， longacting and multifunctional new pesticide developed and produced by Hebei Haoyang Chemical Co.， Ltd.， which are composed of two effective insecticidal ingredients monosultap and thiamethoxam. The product uses a new type of bamboo charcoal as a carrier， and it has a good slowrelease effect on the pesticide， effectively prolongs its persistence， and improves its effect. It can effectively control pests such as borers， aphids and thrips in the whole growth period of sugarcane. A new additive is added to the pesticide to promote crop growth and improve crop quality and yield. 1% Bt·clothianidin granular formulation is compounded by neonicotinoid insecticide clothianidin and biologically low toxic insecticide BT. Clothianidin is a highly effective， safe and highly selective new insecticide， and its function is similar to that of nicotinic acetylcholine receptors， while it has contact， stomach toxicity and systemic activities[17]. BT can produce two major types of mycin. In the alkaline midgut of insects， the intestinal tract can be paralyzed within a few minutes. The insects stop feeding， and the intestinal lining is quickly destroyed. As a result， the bacterial vegetative cells are easy to invade and penetrate the basal membrane of the intestinal tract to enter the hemolymph， and finally the insect dies due to hunger and sepsis[18]. In order to understand and master the two kinds of slowrelease， longacting and multifunctional new pesticides for the control of sugarcane borders and woolly aphids and their application technology， combined with planting management of sugarcane， an experiment on the control effect of 10% monosultap·thiamethoxam and 1% Bt·clothianidin granular formulation on sugarcane borders and woolly aphids in a field was conducted in 2017 to provide a basis for their promotion and application.
Materials and Methods
Test agents and sources
Test agents were 10% monosultap·thiamethoxam granular formulation and 1% Bt·clothianidin granular formulation， which were produced by Hebei Haoyang Chemical Co.， Ltd. The control agents were 3.6% bisultap granular formulation+70% thiamethoxam dispersible powder， which were also produced by Hebei Haoyang Chemical Co.， Ltd.
Control pests
Sesamia inferens Walker， Argyroploce schistaceana （Snellen）， Chilo infuscatellus （Snellen） and Ceratovacuna lanigera would be controlled.
General situation of the test field The test was carried out at the research base of Sugarcane Research Institute， Yunnan Province Academy of Agricultural Science in Kaiyuan. The sugarcane field can be irrigated， with convenient irrigation and drainage， flat terrain， medium fertility， clay soil， pH of 6.2 and organic matter content of 2.05%. The experimental site had been continuously used for sugarcane planting for many years. The sugarcane variety was ‘ROC22’， with twoyear perennial roots and row spacing of 1 m. The water and fertilizer management and the growth of sugarcane seedlings were uniform.
Test design
In the test， six treatments were set， including 45 and 60 kg/hm 2 of 10% monosultap·thiamethoxam GR， 45 and 60 kg/hm 2 of 1% Bt·clothianidin GR， 90 kg/hm 2 of 3.6% bisultap GR+ 600 g/hm 2 of 70% thiamethoxam ZF， and the control group （no application of pesticides）， and each treatment had four repetitions. There were 24 plots， and each plot had an area of 60 m 2. Random group arrangement was adopted.
Application time and method
At the end of March， the end of April and the end of May in 2017， the pesticides were applied one time during the process of intertill. After the pesticides and fertilizer were mixed， they were scattered at the base of sugarcane plants and covered with soil in time. In the control group， only fertilizer was applied. Other farming management was the same for all of the treatments.
Investigation of control effect and statistical analysis
In June 2017， the dead heart rate of sugarcane damaged by borers in the stable period of dead heart seedlings was investigated. The total number of sugarcane seedlings and the number of dead heart seedlings were surveyed to calculate the average dead heart rate. In July August， 50 sugarcane plants were investigated in each plot to record the number of plants damaged by woolly aphids， and then the proportion of sugarcane plants damaged by woolly aphids was calculated to assess the control effect. In the harvest period， all sugarcane plants were harvested to calculate the actual yield of sugarcane. Ten sugarcane stems were randomly selected from each treatment， and sugar content in sugarcane was detected with the American "Rudolph， Autopol 880+J257" automatic sugar content analysis system by using the second optical rotation method. The significance of difference between various treatments was analyzed by Duncans new multiple range test and the SAS 9.0 statistical analysis software. The formulas of some indicators are shown as follows： Dead heart rate=The number of dead heart seedlings/The total number of seedlings investigated×100%
The control effect of sugarcane borers=（Dead heart rate in the control group-Dead heart rate in the treatments）/Dead heart rate in the control group×100%
The proportion of sugarcane plants with woolly aphids=The number of plants with woolly aphids/The total number of seedlings investigated×100%
The control effect of sugarcane woolly aphids=（The proportion of plants with woolly aphids in the control group-The proportion of plants with woolly aphids in the treatments）/The proportion of plants with woolly aphids in the control group×100%
Results and Analysis
Control effects of various pesticides on sugarcane borders and woolly aphids
According to Table 1， 10% monosultap·thiamethoxam GR and 1% Bt·clothianidin GR had good control effects on sugarcane borders and woolly aphids. The control effects of sugarcane borers by 10% monosultap·thiamethoxam GR （45 and 60 kg/hm 2） and 1% Bt·clothianidin GR （45 and 60 kg/hm 2） were 80.0%-85.8% and 79.2%-83.3% respectively. The control effects of sugarcane woolly aphids by them were 98.8%-100% and 98.9%-100%. There was no significant difference between various treatments， and there was also no significant difference between these treatments and the control pesticides 3.6% bisultap GR （90 kg/hm 2）+ 70% thiamethoxam ZF （600 g/hm 2）.
Effects of various pesticides on the yield and sugar content of sugarcane
Seen from Table 2， 10% monosultap·thiamethoxam GR （45 and 60 kg/hm 2） and 1% Bt·clothianidin GR （45 and 60 kg/hm 2） had significant effects on the increase of yield and sugar content of sugarcane. In comparison with the control group， the actual yield of sugarcane in various pesticide treatments increased by above 41 555 kg/hm 2， and the sugar content of sugarcane rose by more than 6.5%， while there was no significant difference between various pesticide treatments. Moreover， there was also no significant difference between the pesticide treatments and the control pesticides 3.6% bisultap GR （90 kg/hm 2）+ 70% thiamethoxam ZF （600 g/hm 2）.
Conclusions and Discussion
According to the above results， 10% monosultap·thiamethoxam GR and 1% Bt·clothianidin GR had good control effects on sugarcane borders and woolly aphids. They are ideal slowrelease， longacting， low toxic， and multifunctional new pesticides used for controlling sugarcane borders and woolly aphids. They can be used alternately with other pesticides to delay the emergence and development of pest resistance to pesticides. The best dosage of the two pesticides in the field was 45 kg/hm 2. They can be mixed with fertilizer （1 200-1 800 kg/hm 2）， scattered in sugarcane ditches or at the base of sugarcane plants， and covered with soil or film from January to July. It can effectively prevent the dead heart caused by borers in the early period， reduce the rate of plants damage by borers in the elongation period， and at the same time effectively prevent and control woolly aphids. For many years， sugarcane borders and woolly aphids have been controlled mainly by chemical agents. Commonly used agents are omethoate， methamidophos， anticarbocarb， chlorpyrifos， phorate， tebutaphan， etc.， and most of them are sprayed on sugarcane leaves or scattered in sugarcane fields[7-16]. Longterm application makes the pests resistant to pesticides， pollutes the environment， and kill natural enemies. The hightoxic and highresidue pesticides are banned in China， so it is urgent to provide the longterm low toxic lowrisk multifunctional new pesticides and accurate and efficient application technology for sugarcane farmers. In recent years， studies have shown that 30% Durivo SC， 40% Virtako WG， 3.6% dimehypo GR， 70% thiamethoxam ZF， 20% dinotefuran SG， 22% fipronil FS and other highefficiency and low toxic new agents have a good effect on the control of sugarcane borders and woolly aphids， but they have more or less limitations， which affects their promotion and application to a certain extent and the overall prevention and control effect[19-25]. In this study， the results revealed that 10% monosultap·thiamethoxam GR and 1% Bt·clothianidin GR had good control effects on sugarcane borders and woolly aphids. The two new pesticides are highly systemic and have a longlasting effect of more than 150 days. Their application is convenient， and the cost of the pesticides is only 600 yuan/hm 2. It is clearly seen that 10% monosultap·thiamethoxam GR and 1% Bt·clothianidin GR are the most ideal slowrelease， longacting， low toxic and multifunctional new pesticides for controlling sugarcane borders and woolly aphids. They are safe to beneficial organisms in a sugarcane garden and do not affect the environment and ecology， so they are worthy of widespread application in sugarcane areas.
Studies have shown that under the conditions of different sugarcane areas， periods and planting methods， the population structure and occurrence dynamics of sugarcane borders and woolly aphids are different， and the damage intensity of sugarcane production and the loss of yield and sugar content of sugarcane are also different[2， 6， 26-31]. Therefore， further research is needed to determine the effect of 10% monosultap·thiamethoxam GR and 1% Bt·clothianidin GR on the control of sugarcane borders and woolly aphids and the yield and sugar content of sugarcane under the conditions of different sugarcane areas， planting methods and production levels.
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Key words Slowrelease and longacting agents; Precise application of pesticides; Sugarcane borders and woolly aphids; Control effect
Sugarcane borers are the most common and most serious pests in the sugarcane areas of Yunnan， belonging to typical boring pests. At present， the damage caused by a variety of sugarcane borers in the sugarcane areas of Yunnan is serious. At the seedling stage， the dead heart rate of sugarcane damaged by borers is 8.33%-65.82%. In the middle and later period， the proportion of sugarcane plants damaged by borers is 26.67%-96.67%， and the proportion of sugarcane joints damaged by borers is 4.43%-27.91%. The loss rate of sugarcane yield is 25.92% on average and 44.53% at most. The sugar content of sugarcane decreases 2.16% on average and 5.69% at most[1-4]. Sugarcane woolly aphid （Ceratovacuna lanigera Zehntner） is the main pest that appears most commonly and damages sugarcane most seriously in the sugarcane areas of Yunnan[1，5-6]. Under current production conditions， the yield of the damaged sugarcane has reduced by 18%-35.3% or above 45% at most. Sugar content in sugarcane has decreased by 5.48%-8.16%. The emergence rate of sugarcane seedlings developed from the damaged sugarcane has reduced by 19.7%-41.6%. In the fields with serous damage， the germination rate of perennial roots has declined by 57.7%-93.6%， and the decrease in sugarcane yield is more serious[6]. The main traditional methods to control sugarcane pests are spraying and scattering chemical pesticides， and some farmers often apply highly toxic （banned） pesticides， which can seriously pollute the environment and cause the resistance of pests to pesticides[1，7-16]. It is imperative to develop， promote and apply slowrelease， longacting and multifunctional new pesticides and precise and efficient pesticide application technology. 10% monosultap·thiamethoxam granular formulation is a slowrelease， longacting and multifunctional new pesticide developed and produced by Hebei Haoyang Chemical Co.， Ltd.， which are composed of two effective insecticidal ingredients monosultap and thiamethoxam. The product uses a new type of bamboo charcoal as a carrier， and it has a good slowrelease effect on the pesticide， effectively prolongs its persistence， and improves its effect. It can effectively control pests such as borers， aphids and thrips in the whole growth period of sugarcane. A new additive is added to the pesticide to promote crop growth and improve crop quality and yield. 1% Bt·clothianidin granular formulation is compounded by neonicotinoid insecticide clothianidin and biologically low toxic insecticide BT. Clothianidin is a highly effective， safe and highly selective new insecticide， and its function is similar to that of nicotinic acetylcholine receptors， while it has contact， stomach toxicity and systemic activities[17]. BT can produce two major types of mycin. In the alkaline midgut of insects， the intestinal tract can be paralyzed within a few minutes. The insects stop feeding， and the intestinal lining is quickly destroyed. As a result， the bacterial vegetative cells are easy to invade and penetrate the basal membrane of the intestinal tract to enter the hemolymph， and finally the insect dies due to hunger and sepsis[18]. In order to understand and master the two kinds of slowrelease， longacting and multifunctional new pesticides for the control of sugarcane borders and woolly aphids and their application technology， combined with planting management of sugarcane， an experiment on the control effect of 10% monosultap·thiamethoxam and 1% Bt·clothianidin granular formulation on sugarcane borders and woolly aphids in a field was conducted in 2017 to provide a basis for their promotion and application.
Materials and Methods
Test agents and sources
Test agents were 10% monosultap·thiamethoxam granular formulation and 1% Bt·clothianidin granular formulation， which were produced by Hebei Haoyang Chemical Co.， Ltd. The control agents were 3.6% bisultap granular formulation+70% thiamethoxam dispersible powder， which were also produced by Hebei Haoyang Chemical Co.， Ltd.
Control pests
Sesamia inferens Walker， Argyroploce schistaceana （Snellen）， Chilo infuscatellus （Snellen） and Ceratovacuna lanigera would be controlled.
General situation of the test field The test was carried out at the research base of Sugarcane Research Institute， Yunnan Province Academy of Agricultural Science in Kaiyuan. The sugarcane field can be irrigated， with convenient irrigation and drainage， flat terrain， medium fertility， clay soil， pH of 6.2 and organic matter content of 2.05%. The experimental site had been continuously used for sugarcane planting for many years. The sugarcane variety was ‘ROC22’， with twoyear perennial roots and row spacing of 1 m. The water and fertilizer management and the growth of sugarcane seedlings were uniform.
Test design
In the test， six treatments were set， including 45 and 60 kg/hm 2 of 10% monosultap·thiamethoxam GR， 45 and 60 kg/hm 2 of 1% Bt·clothianidin GR， 90 kg/hm 2 of 3.6% bisultap GR+ 600 g/hm 2 of 70% thiamethoxam ZF， and the control group （no application of pesticides）， and each treatment had four repetitions. There were 24 plots， and each plot had an area of 60 m 2. Random group arrangement was adopted.
Application time and method
At the end of March， the end of April and the end of May in 2017， the pesticides were applied one time during the process of intertill. After the pesticides and fertilizer were mixed， they were scattered at the base of sugarcane plants and covered with soil in time. In the control group， only fertilizer was applied. Other farming management was the same for all of the treatments.
Investigation of control effect and statistical analysis
In June 2017， the dead heart rate of sugarcane damaged by borers in the stable period of dead heart seedlings was investigated. The total number of sugarcane seedlings and the number of dead heart seedlings were surveyed to calculate the average dead heart rate. In July August， 50 sugarcane plants were investigated in each plot to record the number of plants damaged by woolly aphids， and then the proportion of sugarcane plants damaged by woolly aphids was calculated to assess the control effect. In the harvest period， all sugarcane plants were harvested to calculate the actual yield of sugarcane. Ten sugarcane stems were randomly selected from each treatment， and sugar content in sugarcane was detected with the American "Rudolph， Autopol 880+J257" automatic sugar content analysis system by using the second optical rotation method. The significance of difference between various treatments was analyzed by Duncans new multiple range test and the SAS 9.0 statistical analysis software. The formulas of some indicators are shown as follows： Dead heart rate=The number of dead heart seedlings/The total number of seedlings investigated×100%
The control effect of sugarcane borers=（Dead heart rate in the control group-Dead heart rate in the treatments）/Dead heart rate in the control group×100%
The proportion of sugarcane plants with woolly aphids=The number of plants with woolly aphids/The total number of seedlings investigated×100%
The control effect of sugarcane woolly aphids=（The proportion of plants with woolly aphids in the control group-The proportion of plants with woolly aphids in the treatments）/The proportion of plants with woolly aphids in the control group×100%
Results and Analysis
Control effects of various pesticides on sugarcane borders and woolly aphids
According to Table 1， 10% monosultap·thiamethoxam GR and 1% Bt·clothianidin GR had good control effects on sugarcane borders and woolly aphids. The control effects of sugarcane borers by 10% monosultap·thiamethoxam GR （45 and 60 kg/hm 2） and 1% Bt·clothianidin GR （45 and 60 kg/hm 2） were 80.0%-85.8% and 79.2%-83.3% respectively. The control effects of sugarcane woolly aphids by them were 98.8%-100% and 98.9%-100%. There was no significant difference between various treatments， and there was also no significant difference between these treatments and the control pesticides 3.6% bisultap GR （90 kg/hm 2）+ 70% thiamethoxam ZF （600 g/hm 2）.
Effects of various pesticides on the yield and sugar content of sugarcane
Seen from Table 2， 10% monosultap·thiamethoxam GR （45 and 60 kg/hm 2） and 1% Bt·clothianidin GR （45 and 60 kg/hm 2） had significant effects on the increase of yield and sugar content of sugarcane. In comparison with the control group， the actual yield of sugarcane in various pesticide treatments increased by above 41 555 kg/hm 2， and the sugar content of sugarcane rose by more than 6.5%， while there was no significant difference between various pesticide treatments. Moreover， there was also no significant difference between the pesticide treatments and the control pesticides 3.6% bisultap GR （90 kg/hm 2）+ 70% thiamethoxam ZF （600 g/hm 2）.
Conclusions and Discussion
According to the above results， 10% monosultap·thiamethoxam GR and 1% Bt·clothianidin GR had good control effects on sugarcane borders and woolly aphids. They are ideal slowrelease， longacting， low toxic， and multifunctional new pesticides used for controlling sugarcane borders and woolly aphids. They can be used alternately with other pesticides to delay the emergence and development of pest resistance to pesticides. The best dosage of the two pesticides in the field was 45 kg/hm 2. They can be mixed with fertilizer （1 200-1 800 kg/hm 2）， scattered in sugarcane ditches or at the base of sugarcane plants， and covered with soil or film from January to July. It can effectively prevent the dead heart caused by borers in the early period， reduce the rate of plants damage by borers in the elongation period， and at the same time effectively prevent and control woolly aphids. For many years， sugarcane borders and woolly aphids have been controlled mainly by chemical agents. Commonly used agents are omethoate， methamidophos， anticarbocarb， chlorpyrifos， phorate， tebutaphan， etc.， and most of them are sprayed on sugarcane leaves or scattered in sugarcane fields[7-16]. Longterm application makes the pests resistant to pesticides， pollutes the environment， and kill natural enemies. The hightoxic and highresidue pesticides are banned in China， so it is urgent to provide the longterm low toxic lowrisk multifunctional new pesticides and accurate and efficient application technology for sugarcane farmers. In recent years， studies have shown that 30% Durivo SC， 40% Virtako WG， 3.6% dimehypo GR， 70% thiamethoxam ZF， 20% dinotefuran SG， 22% fipronil FS and other highefficiency and low toxic new agents have a good effect on the control of sugarcane borders and woolly aphids， but they have more or less limitations， which affects their promotion and application to a certain extent and the overall prevention and control effect[19-25]. In this study， the results revealed that 10% monosultap·thiamethoxam GR and 1% Bt·clothianidin GR had good control effects on sugarcane borders and woolly aphids. The two new pesticides are highly systemic and have a longlasting effect of more than 150 days. Their application is convenient， and the cost of the pesticides is only 600 yuan/hm 2. It is clearly seen that 10% monosultap·thiamethoxam GR and 1% Bt·clothianidin GR are the most ideal slowrelease， longacting， low toxic and multifunctional new pesticides for controlling sugarcane borders and woolly aphids. They are safe to beneficial organisms in a sugarcane garden and do not affect the environment and ecology， so they are worthy of widespread application in sugarcane areas.
Studies have shown that under the conditions of different sugarcane areas， periods and planting methods， the population structure and occurrence dynamics of sugarcane borders and woolly aphids are different， and the damage intensity of sugarcane production and the loss of yield and sugar content of sugarcane are also different[2， 6， 26-31]. Therefore， further research is needed to determine the effect of 10% monosultap·thiamethoxam GR and 1% Bt·clothianidin GR on the control of sugarcane borders and woolly aphids and the yield and sugar content of sugarcane under the conditions of different sugarcane areas， planting methods and production levels.
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