Comparative Efficacies of Next-Generation Insecticides Against Yellow Stem Borer and Their Effects on Natural Enemies in Rice Ecosystem

Muhammad Matiar Rahaman, Michael Joseph Stout

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Comparative Efficacies of Next-Generation Insecticides Against Yellow Stem Borer and Their Effects on Natural Enemies in Rice Ecosystem

Muhammad Matiar Rahaman1, Michael Joseph Stout2

(Department of Agriculture, Pakutia College, Ghatail, TangailDepartment of Entomology, Louisiana State University, Baton Rouge, L)

The efficacies of some next-generation insecticides against the rice yellow stem borer (YSB),(Walk.), and their compatibilities with natural enemies were investigated during 2014 and 2015.Three newer insecticides, chlorantraniliprole 0.4%G, dinotefuran 20%SG, and methoxyfenozide 24%SC, and two commonly used insecticides, carbufuran 5G and quinalphos 25EC, were evaluated in the field for their efficacies against YSB and their non-target effects on natural enemies. Application of chlorantraniliprole 0.4%G at 10.96 kg/hm2resulted in the greatest reduction in YSB infestation (deadhearts and whiteheads) and greatest increase of yield compared to theuntreated control plots, followed by methoxyfenozide 24%SC at 0.41L/hm2, dinotefuran 20%SG at 0.15 kg/hm2, carbufuran 5G at 10.96 kg/hm2, and quinalphos 25EC at 1.50 L/hm2. All the insecticides reduced the numbers of predatorslady bird beetles, wolf spiders, carabid beetles, earwigs, green mirid bugs, and damselflies. Numbers of adults of the egg parasitoidssp,sp. andsp.were significantly reduced in insecticide-treated plots compared to untreated control plots. In all field trials, the harmful effects of the five insecticides were in the following rank order (least harmful to most harmful): chlorantraniliprole 0.4%G, carbufuran5G, dinotefuran 20%SG, methoxyfenozide 24%SC, and quinalphos 25EC. On the basis of reduction in YSB infestation, increase in grain yield, and compatibility with natural enemies, chlorantraniliprole 0.4%G was proved to be the best of all the insecticides for YSB management system, although the study suggested minimizing its retail price for enhancement of cost effectiveness in farmers’ fields.

insecticide; yellow stem borer; natural enemy; chlorantraniliprole; rice yield

Rice (L.) is one of the world’s most important crops, providing a staple food for nearly half of the global population (Heinrichs et al, 2017). Among the leading rice growing countries, Bangladesh occupies the third position in acreage and the fourth position in production (BRRI, 2012). About 84.67% of the total cropping area of Bangladesh is used for rice production, with annual production of 34.42 million tons from 10.4 million hectares of land (BBS, 2013). Demand for rice is increasing with the increase in population and is expected to remain high in Bangladesh in the future (Virmani et al,1997).

The rice crop can be attacked by more than 100 species of insects, and 20 of them can cause serious economic loss (Pathak, 1977; Heinrichs et al, 2017). Total yield loss from insect pests in rice is estimated to be about 30%–40% (Henrichs et al, 1979). In Bangladesh, the average loss caused by insect pests is estimated to be about 18% of the expected rice crop yield per year (Alam et al, 1983). Rice stem borers are the principal pests responsible for economic crop loss under field conditions in Bangladesh (Mahar and Hakro, 1979; Heinrichs et al, 2017). Among different stem borer species in Bangladesh, yellow stem borer (YSB) is reported to be the most abundant, comprising approximately 70% of borers (Rahaman et al, 2014). YSB is also considered as a major pest in other parts of Asia (Torii, 1971).

Larvae of rice stem borers bore into the stems of rice plants after hatching from eggs. Feeding within the stem cuts off supplies of photosynthates and nutrients to the upper parts of the affected stem. Attack by stem borers at the vegetative stage of plant growth produces symptoms called ‘deadhearts’ (DHs), while attack at the reproductive stage (at the time of panicle development) produces ‘whiteheads’ (WHs). Rice plants can compensate for low incidences of DHs, but 1%–3% loss of yield is expected for every percent of WHs (Pathak et al, 1971). The larvae and pupae have overlapping populations in the field, and larvae mostly remain concealed inside the stem and are difficult to control by spraying insecticides. Proper timing of insecticide application is critical to stem borer control (PhilRice, 2007). Careful timing of insecticide application can significantly reduce the amount of material used and increase selectivity. The insecticides can be applied when the stem borer damage reaches the economic threshold or economic injury level. An economic threshold of 5%–10% DHs has been suggested for stem borers (Henrichs et al, 1979).

Insecticides offer a practical method of insect control. Use of insecticides has positive impact on rice yields (Iqbal et al, 2000; Wakil et al, 2001; Misra and Panda, 2004; Dhuyo and Soomro, 2007; Bhutto and Soomro, 2010; Chakraborty, 2012; Abro et al, 2013), and insecticides are often highly effective, fast-acting, convenient and economical, making them the most powerful tools in pest management. But injudicious and indiscriminate use of insecticides in many cases causes or accelerates insecticide resistance (Khan and Khaliq, 1989), pest resurgence (Kushwaha, 1995), secondary pest outbreak (Heinrichs, 1994; Satpathi et al, 2005), environmental contamination (Kushwaha, 1995), persistent residual toxicity (Wakil et al, 2001), and destruction of populations of beneficial insects (Guan-Soon, 1990; Phillips et al, 1990; Debach and Rosen, 1991; Way and Heong, 1994).

In addition to pests, many beneficial insects are present in rice fields. These beneficial fauna, collectively known as natural enemies, are categorized as predators or parasites. Generally, predators (spiders, beetles, mirid bugs and earwigs) and egg parasitoids (sp,spandsp.) have been widely used as biological control agents for suppressing stem borers (Henrichs, 1994; Chakraborty, 2012). Conservation of predators, parasitoids and entomopathogens is an important component of modern integrated pest management (IPM). Pesticides that are less harmful to natural enemies can also be effective tools for IPM.

The use of selective insecticides that are effective against YSB and less toxic to beneficial fauna is of prime importance for managing the pest. The types and rates of insecticides and the negative effects of chemical insecticides on beneficial fauna have not been adequately tested in Bangladesh. In light of this deficiency, this study was undertaken to evaluate the efficacies of several next-generation insecticides against YSB and their toxic effects on the population densities of beneficial fauna in the rice field over two growing seasons.

MATERIALS AND METHODS

Field experiment

Field experiments were carried out at the Entomology Field Laboratory managed by Bangladesh Agricultural University, Mymensingh, Bangladesh during two Boro (irrigated rice) seasons from January to May in 2014 and from January to May in 2015. Experimental fields were located at 24o75′ N latitude and 90o50′ E longitude at an altitude of 18 m above sea level. Soil at this site belongs to the Sonatola series of non-calcareous dark grey soil. The physical and chemical properties of soil at 0–30 cm depth were analyzed at Hambolt Soil Testing Laboratory, Department of Soil Science, Bangladesh Agricultural University. The soil had a silty loam texture and granular consistency, having 0.74% organic carbon, 1.28% organic matter, 0.07 mg/kgavailable N, 10.30 mg/kg available P, 48.40 mg/kg exchangeable K, 9.00mg/kg available S, 3.30mg/kg available Zn with the pH of 6.8. The climate is subtropical, characterized by heavy rainfall during the month of April to September and scanty rainfall during October to March (Anonymous, 1960). Populations of YSB at this site were high and comprise about 70% of the rice borers (Rahaman et al, 2014). Yield losses at this location due to stem borers are estimated to be about 10.12%.

Seedling nurseries were prepared by puddling the soil. Weeds and stubble were removed from the field by hand.Seeds of rice variety BR29 were soaked in water in a bucket for 24 h, and then taken out of water and kept in gunny bags. After 72 h, sprouted seeds were sown in the wet nursery bed by hand. The seedlings were transplanted into the field in the last week of January and harvested in the last week of May in both the years. Urea, TSP (Tribasic sodium phosphate), muriate of potash (MP) and gypsum fertilizers were applied in the experimental plots at the rate of 220 kg/hm2, 148 kg/hm2, 124 kg/hm2and 99 kg/hm2, respectively. Full doses of TSP, MP and Gypsum were applied at the time of final land preparation. One third of the urea was top-dressed at the tillering stage, and the remainder was top-dressed at 45–50 d after transplanting (DAT). All agronomic practices were typical of commercial rice production in Bangladesh.

Experimental design

Identical experiments were conducted in the Boro seasons of 2014 and 2015. The experiments employed a randomized complete block design (RCBD) with six treatments and three replications. The entire experimental area was measured as 19.2m × 14.4m, which was divided into three equal blocks. Each block was divided into six plots, and the six treatments were allotted at random to the plots in each block. Thus, there were 18 (6×3) plots altogether in the experiment each year. The plot size was 10.0 m2(4.0 m×2.5m). Borders between plots were 0.6 m to facilitate cultural operations and insecticide applications. There were 16 rows of rice in each 10 m2plot and each row had 10 hills.

Table 1. List of insecticides used in this study.

Six treatments are listed in Table 1. Of the five selected insecticides, Insecticides inT1 (carbufuran 5 G) and T5 (quinalphos 25 EC) are commonly used by farmers in Bangladesh, whereas the remaining insecticides in T2 (chlorantraniliprole 0.4% G),T3 (dinotefuran 20% SG) and T4 (methoxyfenozide 24% SC) were newer molecules and not commonly used in Bangladesh. The two conventional insecticides were obtained from a registered shop in sealed condition, and the others were provided directly from the manufacturers. All the insecticides are known to have systemic activity.

Insecticides were used at the rates specified in Table 1. These rates were within the ranges indicated on the labels for the insecticides and confirmed to be effective against YSB in a preliminary laboratory experiment. The doses of granular insecticides were weighed on an electric balance on the basis of plot size. Similarly, the doses of liquid insecticides were measured with micropipette and sprayed to the assigned plots uniformly. Granular insecticides were broadcast by hand in the plots with 2 cm standing water, and a hand pump sprayer was used for liquid insecticides. Monitoring of pest infestations was initiated at the beginning of the tillering stage, and insecticides were applied at two time points in the cropping season. The first application of insecticides was made at 35 DAT, when the early stages of DH symptoms were visible in some hills. The second application was made at 60 DAT when the early stages of whitehead symptoms were visible.

Assessment of YSB infestation and natural enemy populations

Pre-treatment observations were made at 24 h before the application of insecticides, whilepost-treatment observations were made at 5, 10 and 15 d after the application of insecticides. The number of DHs and number of WHs were counted from 20 hills selected randomly in each plot. Five rows on edges of plots were left as buffers, and observations were taken from the inner rows of each plot. The percentage of DH and WH were calculated by using the formulas:

d(%) =d/t× 100;

w(%) =w/t× 100

wheredandware the number of deadhearts and whiteheads symptom in 20 hills,tis the total number of tillers observed in 20 hills,dandware the percent ofdandw.

Incidences of natural enemies (predators) of YSB were observed at 1 d before and 5 d, 10 d and 15 d after applications of insecticides using the same plots that were used for evaluation of insecticide efficacies. Abundance of individual parasitoids per 20 hills was also observed at 10 d after spray. Visual observations were made to count the number of predators and parasitoids. Proper care was taken to not disturb natural enemies while observations were being made. Predators were identified with unaided sight, and parasitoid adults were identified using a magnifying glass. All data collection was made jointly by two persons. The natural enemies observed in experimental plots are listed in Table 2.

Table 2. List of natural enemies recorded in rice field.

Assessment of yield

For each plot, 20 hills were selected randomly and the grains were hand-threshed. Numbers of filled and unfilled grains and weights of filled grains were recorded. The yield data were adjusted to whole plot bases. There were some pests (leaf folder, leaf hopper, rice bug, and rice hispa) other than stem borers in plots, but the densities of these pests were generally negligible compared to the densities of stem borers, and yield reductions due to their infestations were not taken into consideration in the study. Freshly harvested grains contained approximately 22% moisture whereas normally dry grains have moisture content of 14%, therefore, the yield was adjusted to 14% moisture.

Calculation of cost-benefitratio

The cost-benefit ratio (c) was calculated for each insecticide by the following formula:

c= (t–u) /c

wheretis the value of treated crop,uis the value of untreated crop,cis the cost of insecticide application to treated crop.

Average price surveyed from rice growers and sellers was found to be 0.32USD/kg.

Data analysis

Data recorded for efficacy tests on DH, WH and yield from each replication were averaged over two years for statistical analysis, while data for effects on natural enemies were summed over the two years for analysis. Data pertaining to the infestation of YSB (DH and WH), yield and abundance of natural enemies were analyzed using analysis of variance (ANOVA) with SPSS version 11.5,and treatment means were separated using Duncan’s multiple range test (DMRT) at the 5% level of significance (Gomez and Gomez, 1984).

RESULTS

Efficacies of insecticides on DH symptoms

Significant differences(<0.05) in incidence of DHs among the treatments were observed at 5, 10 and 15 DAS of the first spray. All insecticides provided more than 60% reduction of YSB over the 15-d observation period, but overall the greatest reductions in DHs were observed in T2 treatment. At 10 DAS, densities of DHs were significantly lower in T2 than the other, although numbers of DHs in all treatments were lower than in control (Table 3). Patterns at 5 DAS were similar,and all insecticides reduced DH number compared to the control, with T2 and T4 providing superior control relative to carbofuran, dinotefuran and quinalphos. At 15 DAS, T2treatment again provided the best control, followed by T4, T1 and T3.

Efficacies of insecticides on WH symptoms

Insecticide treatments also significantly affected WH incidences at 5, 10, and 15 d after the second insecticide application (Table 4). Numbers ofWHs were significantly lower in all treatments compared to the control. Generally, T2 was the most effective treatment, followed by T4, T3, T1 and T5, although differences among the latter four treatments were not always statistically significant (Table 4).

Fig. 1. Effects of insecticides (two applications) on rice yields.

T1, Carbufuran 5G; T2, Chlorantraniliprole 0.4%G; T3, Dinotefuran 20%SG; T4,Methoxyfenozide 24%SC; T5, Quinalphos 25EC; T6,Untreated control.

Data represent Mean ± SE (= 3), and the samelowercase letters indicateno significant difference at the 0.05 level bythe Duncan’smultiple range test.

Table 3. Effect of insecticides on deadheart symptoms before and after the first spray (2014–2015). %

T1, Carbufuran 5G; T2, Chlorantraniliprole 0.4%G; T3, Dinotefuran 20%SG; T4,Methoxyfenozide 24%SC; T5, Quinalphos 25EC; T6,Untreated control; NS, No significance; DBS, Days before spray; DAS, Days after spray.

Means within a column followed by the same lowercase letter(s) are not significantly different by the Duncan’smultiple range test at<0.05;**,Significant at 1% level.

Table 4. Effect of insecticides on whitehead symptoms before and after the second spray (2014–2015). %

Table 4. Effect of insecticides on whitehead symptoms before and after the second spray (2014–2015). % TreatmentWhitehead in each plot (Mean ± SE, n = 3)Reduction over control (%) 1 DBS5 DAS10 DAS15 DAS5 DAS10 DAS15 DAS T11.73±0.262.02±0.14c2.75±0.09b3.45±0.18bc85.3681.7677.69 T21.77±0.230.98±0.17e1.23±0.06d2.22±0.21e92.8991.9485.64 T31.84±0.151.56±0.09d2.00±0.11c2.92±0.20cd88.6986.7381.12 T41.64±0.301.25±0.16de1.86±0.06c2.49±0.15de90.9487.6683.90 T51.72±0.362.65±0.05b3.04±0.23b3.91±0.08b80.7979.8474.72 T61.86±0.1413.80±0.16a15.08±0.17a15.47±0.38a––– LSD0.050.8410.3300.3540.632 Level of significanceNS****** CV(%)26.254.934.496.85 F-test0.0912219.4222239.030651.320

T1, Carbufuran 5G; T2, Chlorantraniliprole 0.4%G; T3, Dinotefuran 20%SG; T4,Methoxyfenozide 24%SC; T5, Quinalphos 25EC; T6,Untreated control; NS, No significance; DBS, Days before spray; DAS, Days after spray.

Means within a column followed by the same lowercase letter(s) are not significantly different by the Duncan’smultiple range test at P<0.05;**, Significant at 1% level.

Effects of insecticides on rice yields

Grain yields differed significantly among insecticide treatments (=39.29,<0.05) (Fig. 1). Yields from the treated plots were higher than yields from non-treated (control) plots. The highest yields were observed in T2 followed by T4. Yields in T3 were significantly lower than T2, but higher than T1 and T5 treatments.

Estimation of cost-benefit ratio

T1 was the most expensive of the insecticides, but itresulted in the greatest reductions in YSB infestations. Thecfor T2 was 13.08, withthatwas 12.99 for T1 and13.16 for T5. The highestcwas recorded in T3 (50.69), followed by T4 (21.26), although these treatments gave lower yields than T2 (Table 5).

Effects of insecticides onthe non-target predators

Population densities of predators and other non-target arthropods (lady bird beetles, wolf spiders, carabid beetles, earwigs, green mirid bugs) and damsel flies (DF) were all significantly influenced by the application of insecticides (Fig. 2). Patterns of abundance were similar for the different non-target organisms. The highest numbers of non-targets were found in the control (untreated) plots. Among the plots treated with insecticides, the highest numbers were in T2, whereas the lowest in T5 (Fig. 2, Supplemental Tables 1 to 6). Numbers in the other treatment were intermediate between T2 and T5, although differences were not always statistically significant. Reductions in abundances of non-targets were on average about twice as high in T5 than T2.

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Table 5. Cost-benefitratios (Rc) of five insecticides.

T1, Carbufuran 5G; T2, Chlorantraniliprole 0.4%G; T3, Dinotefuran 20%SG; T4,Methoxyfenozide 24%SC; T5, Quinalphos 25EC; T6,Untreated control.c, Benefit-cost ratio.

Effects of insecticides on densities of adult egg parasitoids of YSB

Densities of three adult egg parasitoids of YSB significantly differed with treatment, and for all the three parasitoids for both sprays, densities were significantly higher in untreated plots than in treated ones (Table 6). At 10 d after the first spray, the densities of the parasitoids were significantly higher in T2 than inthe others, and densities were the lowest in T5. Patterns in parasitoid densities were similar after the second spray. Reductions of parasitoid densities ranged from 40% to 80% after the first spray and 17% to 78% after the second spray(Table 7)

DISCUSSION

Efficacies and economics of different insecticides against YSB

Use of insecticides reduced injury and yield loss from YSB. DHs were reduced by 68% to 82% relative to the control, and WHs were reduced by 80% to 92% relative to the control. Yields were increased over the control by 25%–40%. These results are similar to the previous reports (Karthikeyan et al, 2007; Bhutto and Soomro, 2009; Misra, 2010; Abro et al, 2013; Islam et al, 2013),which indicates that insecticides reduce the injury by rice stem borers and increase yields. Iqbal et al (2000) observed that granular insecticides (Furadan 3G, Padan 4G, Rotap 4G and Thimet 3G) show better efficacy against rice stem borer than emulsifiable concentrates (Fastac 5EC and Regent 300 EC), which is partially incompatible with the findings of this study. In this study, the granular insecticide, chlorantraniliprole 0.4%G, gave better results than the emulsifiable and soluble concentrate insecticides (methoxyfenozide 24%SC, dinotefuran 20%SG and quinalphos 25EC). But another granular insecticide, carbufuran 5G, was less effective than methoxyfenozide 24%SC and dinotefuran 20%SG, but more effective than quinalphos 25EC. This result disagrees with Roy (2015) who reported that reduction of YSB infestation over control and maximum yield given by carbufuran 5G is superior to other sprayable (EC) insecticides. Wakil et al (2001) and Mishra et al (2007)also showed that carbufuran significantly reduces the incidences of rice stem borers. Rath et al(2015) reported that the insecticide dinotefuran at 150 g/hm2is effective against rice stem borers, which agrees with the present study.

Fig. 2.Reductions in abundances of non-target organisms relative to untreated plots at 10 d after the first (A) and the second (B) applications of insecticides.

LBB, Ladybird beetle; WS, Wolf spider; CB, Carabid beetle; EW, Earwig; GMB, Green mirid bug; DF, Damsel fly.

Table 6. Effects of insecticides on numbers of adult egg parasitoids of yellow stem borer at 10 d after the first spray.

T1, Carbufuran 5G; T2, Chlorantraniliprole 0.4%G; T3, Dinotefuran 20%SG; T4,Methoxyfenozide 24%SC; T5, Quinalphos 25EC; T6,Untreated control.

Means within a column followed by the same lowercase letter(s) are not significantly different by the Duncan’smultiple range test at<0.05;**,Significant at 1% level.

Theccalculated in the present study (Table 5) differed somewhat from other reports (Roshan, 2006; Hugar et al, 2009), which showed that insecticides more effective against stem borer infestations give the highest yields and the greatestcas well. In this study, chlorantraniliprole 0.4%G showed the highest efficacy in reducing infestations and producing the highest yields,but lowerc(13.08) (Table 5). This difference might be due to improper computation of the critical dose or to a high and imbalanced market price of the new insecticides. This hypothesis is largely supported by Sarao and Kaur (2014) who reported that the new 0.4%GR (chlorantraniliprole) of 40 g/hm2moleculeFertara is effective in the management of rice stem borers and give the highestcof 23.67, followed by 50 g/hm2.

Table 7. Effects of insecticides on numbers of adult egg parasitoids of yellow stem borer at 10 d after the second spray.

T1, Carbufuran 5G; T2, Chlorantraniliprole 0.4%G; T3, Dinotefuran 20%SG; T4,Methoxyfenozide 24%SC; T5, Quinalphos 25EC; T6,Untreated control.

Means within a column followed by the same lowercase letter(s) are not significantly different by the Duncan’smultiple range test at<0.05;**,Significant at 1% level.

Harmful effects of insecticides on natural enemies

Of the insecticides tested, chlorantraniliprole 0.4%G consistently had the smallest effect on populations of natural enemies and other non-targets. Carbufuran 5G generally had less effect on predators and parasitoids than the newer insecticides dinotefuran 20% SG and methoxyfenozid 24%SC. In all cases quinalphos 20EC gave the highest reduction of natural enemies compared to the control(Supplemental Tables1 to 6). The results agree with the previous reports (Mollah et al,2012; Islam, 2012; Rahman, 2013; Ray, 2013), but partially disagree with Khusakul et al (1979), which reported that application of carbufuran granules is very effective against stem borer but severely reduces the population of predatory spiders and other predators, e.g.. Miyata and Saito (1982) reported that malathion (organophosphate) is less toxic to predators because of low cuticular penetration.In this study, another organophosphate insecticide (quinalphos 25EC) was found highly toxic to the predators compared to the other insecticides.

The reduction percentageof predator numbers in insecticide-treated plots relative to the control were lower than those in parasitoid numbers. Thus, it appears that the egg parasitoids of YSB were more sensitive to insecticides than the non-target predators. Results of this study are more or less similar with the findings of Chakraborty (2010) who found numbers of,andper 10 hills as 1.70, 3.42 and 2.21 at the vegetative stage of paddy in the pesticide treated field as 5.48, 10.21 and 6.34 were recorded in the pesticide untreated field. At the mid-tillering stage, the numbers were 1.51, 0.42 and 4.21, in the pesticide treated field and 5.32, 2.11 and 9.67, respectively in the pesticide untreated paddy field. To our knowledge, no previous observations of the effects of insecticides on YSB egg parasitoids have been made previously.

CONCLUSIONs

All the tested insecticides significantly reduced damage caused by YSB. The newer insecticide chlorantraniliprole 0.4%G was highly effective at reducing stem borer infestations in rice. Generally, the efficacies of the four other insecticides were, in order to the effectiveness, methoxyfenozide 24%SC, dinotefuran 20%SG, carbufuran 5G and quinalphos 25EC. The insecticide chlorantraniliprole 0.4% G had the lowest toxicity and quinalphos 25EC had the highest toxicity to natural enemies and non-targets in rice ecosystem. The efficacy results were due in part to the greater conservation of natural enemies in chlorantraniliprole-treated plots. Considering its efficacy against stem borer and its relatively benign effects on natural enemies, the insecticide chlorantraniliprole 0.4%G is to be preferred over the other insecticides for controlling YSB. However, the high cost of chlorantraniliprole is a barrier to its widespread use. The insecticides methoxyfenozide 24%SC and dinotefuran 20%SG could also be advised to manage rice stem borer for better efficacy against the pest and cost effectiveness.

Acknowledgements

Authors express sincere gratitude to the authorities of United States Department of Agricultureand BangladeshAgricultural University Research System for sponsoring the funds, and thank the Department of Entomology, Bangladesh Agricultural University for providing all necessary infrastructural facilities. Authors also express immense indebtedness to Patrocom (BD) Ltd., Indofil Industries Ltd. and Auto Crop Care Ltd. for supplying their newly released test trial insecticides.

SUPPlemental DATA

The following materials are available in the online version of this article at http://www.sciencedirect.com/science/ journal/16726308; http://www.ricescience.org.

Supplemental Table 1. Effects of insecticides on populations of ladybird beetle (LBB) after the first and second application of insecticides.

Supplemental Table 2. Effect of insecticides on wolf spider populations after the first and second spray.

Supplemental Table 3. Effect of insecticides on carabid beetle after the first and second spray.

Supplemental Table 4. Effect of insecticides on populations of earwigs after the first and second spray.

Supplemental Table 5. Effect of insecticides on populations of green mirid bugs after the first and second spray.

Supplemental Table 6. Effect of insecticides on damsel fly after the first and second spray.

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Copyright ? 2019, China National Rice Research Institute. Hosting by Elsevier B V

This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Peer review under responsibility of China National Rice Research Institute

http://dx.doi.org/10.1016/j.rsci.2019.04.002

17 February 2018;

29 September 2018

Muhammad Matiar Rahaman(m_rahaman06@yahoo.com); Michael Joseph Stout (mstout@agcenter.lsu.edu)

(Managing Editor: Wang Caihong)