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Journal of Applied Sciences & Environmental Management, Vol. 8, No. 2, Dec, 2004, pp. 77-83

Evaluation of Feeding Stimulant Mixed with Chemical and Bio Insecticides on Certain Lepidopterous Pests and their Natural Enemies in Cotton and Soybean Fields

Plant Protection Research Institute, A.R.C., Dokki, Giza, Egypt
*E-mail address: Mmandarawy@yahoo.com
Corresponding author*

The Efficiency of feeding stimulants (Bioenhencer) was studied alone and in combinations with chemical insecticides or entomopathogens against the defoliating pests, Spodoptera littoralis (Boisd.) and Spodoptera exigua Hbn. (in fields of cotton and soybean) and the bollworms Pectinophora gossypiella Saunders and Earias insulana Boisd. (in cotton field), at Kafr El-Sheikh governorate during the season 2003. Its adversely influence on the natural enemies associated these pests in the two fields, were also undertaken. Laboratory results indicated that the feed stimulant was exhibited at a high degree of efficiency against the target lepidopterous larvae when combined with the chemical insecticide and the bioinsecticides. But no obvious effect was found when it was used alone. Field results indicated that, the addition of Bioenhencer (5%) to the chemical and bio insecticides enhanced their activity, where the damaged rate significantly affected in these treated plots as compared to the untreated ones, on both cotton and soybean fields. Moreover, bioenhancer and the bioinsecticide had the least harmful effect on the entomophagous insect populations. @JASEM

Massive applications of insecticide result in adverse effects on beneficial organisms, leaves their residues in the food and result in environmental pollution. Accordingly, chemical control of pests has declined in many countries by using the regulatory mechanisms, environmental activism and using biological control items and increasing their efficiency. This has necessitated the use of target specific compounds with low persistence and an increase in emphasis on integrated pest management (Sharma et al. 2000). Therefore, the uses of behavioral chemicals, which include general categories of feeding stimulants and semiochemicals have broad potential applicability. Also, adding of feeding stimulants to chemical insecticides and entomopathogens may be benefits in increasing the effectiveness of the control and were allowed the application dosages of insecticides to be reduced (Chandler, 1993; Hough-Goldstein et al., 1991 and Potter & Watson 1983).

In Egyptian cotton fields, the cotton leaf worm, Spodoptera littoralis (Boisd.) and the lesser cotton leafworm (Beet armyworm) Spodoptera exigua Hbn. are among the most serious defoliators threaten the crop. Also, the cotton boll worms, the pink bollworm, Pectinophora gossypiella Saunders and the spiny bollworm, Earias insulana Boisd. cause the greatest part of cotton yield losses (Amin et al., 2001). As well, foliage-eating insects are present in all soybean fields throughout the growing season. Younger plants, which have not begun to bloom or to fill pods, can tolerate greater foliage damage than the plants that are fruiting, (El-Kifl et al., 1974; Hamed, 1977 and Tantawy et al., 1989).

The present work was designed to evaluate the effect of a feeding stimulant (Bioenhancer) in combination with chemical insecticides or the bacterial insecticide Bacillus thuringiensis against S. littoralis, S. exigua (in cotton and soybean fields), P. gossypiella and E. insulana (in cotton fields) through laboratory and field experiments. In addition, the adversely influence of these combinations on the natural enemies associated with the target pests were estimated under field conditions.

Bioenhancer: An insect feeding stimulant and attractant. It contains 35% active ingredients (disaccharides, hydrolyzed starch, whey and vegetable oil) and 65% inert ingredients. Its rate of application was 5%/feddan.

Selecron: Selecron 6 EC, 8 EC. Formulation: (Organic phosphate insecticide), O-(4- bromo-2- chlorophenyl) O- ethyl S- propyl phosphoro-thioate. It was applied at a rate of 750cm³/feddan.

Reldan: (Chlorpyrifos-methyl) 2 EC, 25% WP, 1% G, 6 1b/gal oil. Formulation: O, O-dimethyl O-(3, 5, 6-trichloro-2-pyridimyl) phosphorothioate). It was applied at a rate of 0.005-0.75, a.i./A. in laboratory the concentrations of 0.025, .05, 0.1, 0.2, 0.4 and 0.8 ppm was used.

Dursban: 48% EC. It was applied at a rate of 1liter /feddan. In the laboratory the concentrations were of 0.05, 0.1, 0.2, 0.4 and 0.8 ppm.

Bioinsecticides: Dipel 2X: (Selective bacterial insecticide) B. thuringiensis subsp. kurstaki 32000 International Units/mg. It was applied at a rate of 200g / feddan.

Agerin: B. thuringiensis 32000 International Units/mg. It was applied at a rate of 250g/ feddan. In the laboratory, the concentrations used were 10x10⁵, 20x10⁵, 40x10⁵, 80x10⁵and 160x10⁵I.U. for S.littoralis and 5x10⁴, 10x10⁴, 20x10⁴, 40x10⁴, 80x10⁴and 160x10⁴I.U. for P. gossypiella and E. insulana.

Biofly: Beauveria bassiana fungus applied at rate of 100cm³ / 100 liter water.

Laboratory experiments: S. littoralis, P. gossypiella and E. insulana were kept under the laboratory conditions of 27±1°C and 65±5% R.H.. S. littoralis was reared according to the technique used by Ibrahim (1974), while P. gossypiella and E. insulana were reared according to the technique described by Abdel- Hafez et al. (1982). Castor leaves, cotton bolls were dipped in each compound and left for drying, then offered to the 4^th S. littoralis, 1^st instar P. gossypiella and E. insulana larvae.

Three replicates of ten larvae each into a cup (6x7.5cm) were fed on caster bean leaves (for S. littoralis) and the cotton bloom (for P. gossypiella and E. insulana) contaminated with bioenhancer and bioinsecticides for a period of 48 hours. Pests treated for 24 only with the chemical insecticides. Then surviving larvae were put in cups free of treatment till pupation. Mortality was recorded daily. Also, the percentage of pupation and emerged adults were estimated. (2) Before the treatment, larvae were starved for sixth hours in order to obtain rapid simultaneous ingestion of the offered food. (3). The control was conducted using the castor-bean leaves and blooms dipped in water only and left to dry.

Field experiments: Cotton field: Experiments were carried out at Sakha Research Station, (Kafr El-Sheikh governorate) during 2003 season. Cotton variety “Giza 88 was planted ont 24 March 2003. An area of about a feddan was chosen and divided into 24 equal plots in randomized complete blocks. Each plot was about 42m² = 6mx7m in size. The plots were specified for 8 treatments with 3 replicates and the untreated (control). Treatments included the bioenhancer, agerin, biofly, the chemical insecticides (reldan for leafworm & dursban for bollworms) and their combinations with bioenhancer (½ bioenhancer+ ½ agerin, ½ bioenhancer+ ½biofly and ½ bioenhancer+ ½ each of the chemical insecticide).

Soybean field: Soybean “Giza 111” was planted on June 15^th 2003. An area of about half feddan was chosen and divided into 30 equal plots in randomized complete blocks. Each plot was about 42m² = 6mx7m in size. The plots were specified for 10 treatments with 3 replicates and the untreated (control). Treatments included the bioenhancer, dipel 2x, agerin, biofly, the chemical insecticides (selecron) and their combinations with bioenhancer ((½ bioenhancer+ ½ dipel 2x ; ½ bioenhancer+ ½ agerin; ½ bioenhancer+ ½biofly and ½ bioenhancer+ ½ selecron).

According to the size of eaten part of leaf (the defoliation is measured as a percentage of the leaf area destroyed by the pests); the cumulative damage caused by the defoliator larvae was estimated by scoring the damage (0 to 5) of each of 100 randomly chosen leaves. Rate of infestation was calculated according to the formula given by Kasopers (1965). As for the damage caused by the bollworms, 50 cotton bolls were randomly chosen from each treatment and inspected for any symptoms of infestation, and the percentage of infested bolls subsequently calculated. For predators, samples were taken by 5 randomly double sweeping net strokes/plot (10-strokes/ treatment). The collected predators were transferred to the laboratory for identification and counting. In case of parasitoids, 30 of each of the defoliating larvae were collected weekly and transferred to the laboratory, where each larva was kept in a glass vial (6x10cm) covered with muslin cloth and provided daily throughout their developmental period with fresh green top shoots of plants. Emerging parasitoids were collected daily, identified and the percentage of parasitism was calculated

Spray applications: Used pesticides were applied by means of 20L. knapsack sprayer using a total volume of 200 L/feddan. Different treatments were applied in bi-weekly interval in the second treatment.

Statistical analysis: Laboratory data: The LC₅₀ was determined by using Finney (1952) and corrected according to Abbott’s formula (1925).

Field Data: Data were statistically analyzed by ANOVA and mean values were separated by the least significant difference (L.S.D.) procedure (Snedecor and Cochran, 1980) at P = 5%. Percent reduction in each treatment was calculated using Henderson’s formula (Henderson & Tilton, 1955).

Laboratory experiments: Data presented in table (1) show that the LC₅₀ values of 4^th instar S. littoralis larvae were 0.00, 69.57x10⁵ I.U., 0.060 ppm for bioenhancer, agerin (after 72 hours of treatment) and reldan (after 24 hours of treatment) alone. Respective values were 38.46x10⁵I.U. and 0.052 ppm for the combinations of different agerin and reldan concentrations with 5% of bioenhancer. For newly hatched of P. gossypiella and E. insulana larvae, the LC₅₀ values were 0.00 & 0.00, 10.43 x10⁴ I.U. & 8.36 x10⁴ I.U., 0.079 & 0.096 ppm 6.47 x10⁴ I.U. & 4.92 x10⁴ I.U. and 0.056 & 0.071 ppm for bioenhancer, agerin, dursban, agerin + bioenhancer and dursban + bioenhancer, respectively. The results indicated that the feed stimulant was exhibited highest degree of efficiency against target lepidopterous larvae when combined with both chemical insecticide and bioinsecticides. But when it was used alone, it had no obvious effects. In agreement to our findings Naguib et al. (1994) indicated that E. insulana larvae were more susceptible to bio-compounds than P. gossypiella larvae. While P. gossypiella larvae were more susceptible to esfenvalerate as insecticide than E. insulana. Chandler (1993) observed that the insect feeding stimulant (Konsume 5%) mixed with diflubenzuron increased the fall armyworm, Spodoptera frugiperda (Smith) larval mortality significantly as compared with diflubenzuron alone.

Table 1: Laboratory bioassay and comparative toxicity of bioenhancer alone, bioinsecticides (after 72 hours of treatments) and chemical insecticides concentrations in combinations with bioenhancer (after 24 hours of treatments) against S. littoralis, P. gossypiella, E. insulana and S. cretica larvae.

Treatments	LC₅₀		Slope	Confidence limits (P 0.05)
Treatments	LC₅₀		Slope	LC₅₀
S. littoralis
Bioenhancer	0.00		0.00	0.00
Agerin	69.57x 10⁵		1.26	55.09 : 91.23
Reldan	0.060		1.66	0.049 : 0.072
Agerin+ Bioenhancer	38.46x 10⁵		1.38	31.45 : 46.91
Reldan+ Bioenhancer	0.052		1.74	0.042 : 0.064
P. gossypiella
Agerin	10.43 x 10⁴		1.20	7.69 : 13.30
Dursban	0.079		1.77	0.061 : 0.095
Agerin+ Bioenhancer	6.47 x 10⁴		1.15	4.01 : 8.68
Dursban+ Bioenhancer	0.056		1.74	0.039 : 0.070
E. insulana
Agerin		8.36 x 10⁴	1.20	5.81 : 10.78
Dursban		0.096	1.59	0.076 : 0.12
Agerin + Bioenhancer		4.92 x 10⁴	1.61	3.01 : 6.38
Dursban + Bioenhancer		0.071	1.63	0.052 : 0.088

Field experiments: Pests treatments: 1^st In cotton field (Cotton defoliating and bollworms): Data in table, 2 and Fig.1 show that the reduction in the defoliating damage was estimated as 12.87, 22.40, 17.49, 34.98, 42.16, 30.42 and 26.35% for bioenhancer, agerin, biofly, reldan, ½ bioenhancer+½ reldan, ½ bioenhancer+½ agerin and ½ bioenhancer+½ biofly, respectively. The damage of bollworms was reduced to 18.54, 38.76, 29.22, 61.81, 69.09, 56.76 and 50.86% at different treatments, respectively. Cotton leaves damaged by the cotton leafworm were significantly higher in the control as compared to treatments. In case of bollworms, reldan and other combined treatments were significantly different from the untreated control. Neither bioenhancer treatment as significantly different from either agerin and biofly treatments or the untreated control.

Months	% of average damage in different treatments
Months	Control	Bioen- hancer	Agerin	Biofly	Reldan or Dursban	½ Bioen.+ ½ Reldane or Dursban		½Bioen.+ ½ Agerin	½ Bioen.+ ½ Biofly
	*Cotton Leafworm
July	25.36	24.86	22.00	23.50	19.00	17.17	20.80		21.60
Aug.	34.74	29.47	26.03	27.93	22.63	19.76	23.56		24.81
Sept.	43.86	36.23	32.64	34.34	25.95	23.18	27.96		30.16
Overall	34.65	30.19	26.89	28.59	22.53	20.04	24.11		25.52
% Reduction		-12.87	-22.40	-17.49	-34.98	-42.16	-30.42		-26.35
L.S.D. 5% (weekly)	4.3019
	**Bollworms
July	9.00	6.50	4.50	6.00	3.50	3.00	3.00		4.50
Aug.	30.00	24.00	18.00	20.50	9.50	7.50	11.50		13.25
Sept.	50.00	42.00	32.00	36.50	21.00	17.00	24.00		26.00
Overall	29.67	24.17	18.17	21.00	11.33	9.17	12.83		14.58
% Reduction		-18.54	-38.76	-29.22	-61.81	-69.09	-56.76		-50.86
L.S.D. 5% (weekly)	11.6428

*Pre-treatment (Control)=17.05 1st spray (June 28^th) & 2nd spray (July 19^th); **Pre-treatment=3.00 Sprayed at July 26^th

2^nd In soybean field (Defoliators): Soybean leaves damaged by the various defoliator larvae (e.g. S. littoralis and S. exigua) were reduced to 9.40, 25.54, 30.41, 23.42, 48.21, 54.20, 34.21%, 38.41 and 29.53% for bioenhancer, dipel 2x, agerin, biofly, selecron, ½ bioenhancer+½ selecron, ½ bioenhancer+½ dipel 2x, ½ bioenhancer+½ agerin and ½ bioenhancer+½ biofly, respectively (Table 3 and Fig.2). Defoliator larvae damages were significantly higher as the control compared with the treatments of dipel 2x, agerin, biofly and selecron alone or in combinations. Neither bioenhancer treatment as significantly different from dipel 2x, agerin and biofly (alone or combined with bioenhencer) treatments or the untreated control. These results agree with those of Pfrimmer (1983) who stated that the addition of feeding stimulants to a synthetic pyrethroid applied, to control the lepidopterous larvae in cotton field, at half the normal rate resulted in control equal to applications at the full rate. Abdally et al. (1987) decided that coax did not significantly increase mortality of Heliothis spp. when added, at 2 kg/ha, to the microbial insecticides but caused as much mortality as they did when applied alone. Chandler (1994) found that the addition of the feeding stimulant (Konsume) to the insect growth regulator (RH-5992) resulted in higher levels of S. frugiperda larval mortality in corn field. Plants treated with Konsume resulted in a significant reduction in damage by S. frugiperda compared with the untreated control. However, plants treated with Konsume alone did not provide needed levels of economic fall armyworm control (as the findings are observed with the spray table test). Moreover, feeding raspberry leaves treated with B. thuringiensis + feeding stimulants (e.g. Pheast) to larval Choristoneura rosaceana, resulted in a 93% greater mortality than that observed in larvae feeding on Bt alone (Li and Fitzpatrick, 1997).

Table 3. .Effect of bioenhencer and its combinations in reducing the damage rate caused by defoliator pests in Kafr El-Sheikh soybean fields, 2003.

Months	% of average damage in different treatments
Months	Control	Bioen- hancer	Dipel 2X	Agerin	Biofly	Selecron	½Bioen.+ ½ Selecron	½Bioen.+ ½ Dipel 2X	½Bioen.+ ½ Agerin	½ Bioen.+ ½ Biofly
July	29.00	27.3	22.00	20.80	23.15	14.20	10.00	19.35	17.35	20.00
Aug.	40.75	35.15	30.46	28.27	31.17	21.06	19.56	25.42	24.16	29.55
Sept.	57.34	52.30	42.17	39.38	43.00	30.55	28.65	38.84	36.75	40.00
Overall	127.09	115.15	94.63	88.45	97.32	65.81	58.21	83.61	78.26	89.55
Mean	42.36	38.38	31.54	29.48	32.44	21.94	19.40	27.87	26.09	29.85
% Reduction		-9.40	-25.54	-30.41	-23.42	-48.21	-54.20	-34.21	-38.41	-29.53
L.S.D. 5% (weekly)	8.1871

Pre-treatment (Control) =23.00 1^st spray (July 25^th) & 2^nd spray(Aug. 8^th)

Effect on Natural enemies: 9^th Predators: A. In cotton field: Predaceous species collected during the period of the experiment were: six coleopterous, Cocinella undecimpunctata L., Cydonia vicina var. nilotica Muls and Scymnus spp. (interruptus Goeze, syriacus Mars. and globossus var. pieceus Ws.) (Cocinellidae) and Paederus alfierii Koch (Staphylinidae); two hemipterous Orius spp. (albidipennis Reut. and laevigatus Fieb.) (Anthocoridae); one neuropteran Chrysoperla carnea Steph. (Chrysopidae). The mean number of predators collected, during the period of experiment, from bioenhancer, agerin, biofly, reldan, ½ bioenhancer+½ reldan, ½ bioenhancer+½ agerin and ½ bioenhancer+½ biofly treated plots, were 12.98, 12.25, 11.39, 7.22, 8.56, 12.59 and 11.78 individuals (Table, 4& Fig.1). Correspondent number in the control was 13.53 predators. These results indicated that bioenhancer and the bioinsecticide had the least harmful effect on the entomophagous insect populations. Bioenhancer, agerin and biofly treatments were insignificantly different from either their combined treatments or the untreated control. While significant differences between control or bioenhancer treatment and the chemical insecticides alone or in combination with bioenhancer were found.

Table (4): Effect of bioenhencer and its combinations on the average numbers of predator adult species collected after the different treatments in cotton fields, season 2003.

Months	% of average damage in different treatments
Months	Control	Bioen- hancer	Agerin	Biofly	Reldan or Dursban	½ Bioen.+ ½ Reldane or Dursban	½Bioen.+ ½ Agerin	½ Bioen.+ ½ Biofly
July	19.50	18.75	17.84	16.67	11.00	12.17	18.17	17.00
Aug.	11.25	10.84	10.25	9.34	5.50	6.83	10.42	10.00
Sept.	9.84	9.34	8.67	8.17	5.17	6.67	9.17	8.33
Overall	13.53	12.98	12.25	11.39	7.22	8.56	12.59	11.78
% Reduction		-4.07	-9.46	-15.82	-46.64	-36.73	-6.95	-12.93
L.S.D. 5% (weekly)	3.9602

Pre-treatment (Control) =25.00

In soybean field: The predaceous species collected during the period of the experiment were: six coleopterous, C. undecimpunctata, C. vicina var. nilotica, C. vicina var. subsignata Pic. and Scymnus spp. (interruptus and syriacus) (Cocinellidae) and P. alfierii (Staphylinidae); two hemipterous Orius spp. (albidipennis and laevigatus) (Anthocoridae); one neuropteran C. carnea (Chrysopidae). The overall of the average numbers of predators collected in the three months of plantation from the control, bioenhancer, dipel 2x, agerin, biofly, selecron, ½ bioenhancer+½ selecron, ½ bioenhancer+½ dipel 2x, ½ bioenhancer+½ agerin and ½ bioenhancer+½ biofly plots, reached 35.03, 33.28, 32.30, 31.23, 28.73, 16.80, 17.75, 32.70, 31.78 and 29.84 individuals, respectively, (Table,5 & Fig.,2). As shown in the table and figure the predators attracted to bioenhancer treated plots, which was less harmful to them. Bioenhancer, agerin and biofly treatments were insignificantly different from either their combined treatments or the untreated control. While significant differences between control or bioenhancer treatment and the chemical insecticides alone or in combination with bioenhancer were found.

Table (5) Average numbers of predators counted at different treatments in soybean fields, season 2003.

Months	% of average damage in different treatments
Months	Control	Bioen- hancer	Dipel 2X	Agerin	Biofly	Selecron	½Bioen.+ ½ Selecron	½Bioen.+ ½ Dipel 2X	½Bioen.+ ½ Agerin	½ Bioen.+ ½ Biofly
July	10.75	10.00	9.75	9.00	8.75	4.25	5.50	10.00	9.50	9.00
Aug.	10.00	9.33	9.05	8.60	8.10	4.63	5.00	9.20	8.90	8.21
Sept.	13.03	12.20	11.75	11.88	10.88	6.75	6.25	12.00	11.88	11.25
Overall	35.03	33.28	32.30	31.23	28.73	16.80	17.75	32.70	31.78	29.84
Mean	11.68	11.09	10.77	10.41	9.58	5.63	5.92	10.90	10.59	9.95
% Reduction		-6.61	-9.56	-12.15	-18.20	-52.86	-50.46	-7.83	-10.43	-16.71
L.S.D. 5% (weekly)	1.7787

Pre-treatment (Control) = 9.00

Parasitoids: In cotton field: The solitary larval hymenopteran endoparasitoid Microplitis rufiventris Kok. was recorded from 26^th July till 31^st August 2003 on S. littoralis larvae. The percentage of parasitism in the untreated plots was 20, 20 23.33 and 6.67% on July 26^th, Aug. 3^rd, Aug. 10^th and Aug. 17^th, respectively. These percentage increased during the same period in the plots treated with the feeding stimulant (Bioenhencer (5%)) to be 33.33% + 5 direct collecting cocoons, 40% + 3cocoons, 23.33% + 4 cocoons, 1 open cocoon and 3 cocoons on July 26^th, Aug. 3^rd, Aug. 10^th, Aug. 17^th and Aug. 31^st respectively. Also, 3 and 4 cocoons of the same parasitoid was appeared in the plots treated with agerin and bioenhancer on Aug. 3^rd and Aug. 10^th. The safety of chemical and bioinsecticide with or without feeding stimulant on different predatory and parasitoidspecies was previously reported by Patel and Yadav (1995) who found that the chemical insecticide (monocrotophos) was effective for reducing the pest population of Amrasca biguttula biguttula, in cotton fields in Anand, Gujarat, India and it had an adverse effect on the chrysopid predator Chrysopa scelestes. Attique and Ghaffar (1996) observed that in Pakistan cotton fields the predator populations in the treated plots with insecticides like Promet (furathiocarb) and Confidor (imidacloprid) were lower than in the untreated control. Also, Tillman (1996) studied the susceptibility of certain insecticides for both males and females of the parasitoids, Cardiochiles nigriceps, Cotesia marginiventris, and Microplitis croceipes, of Heliothis virescens, where thiodicarb and oxamyl were appeared less toxicity than acephate. Esfenvalerate was the least toxic pyrethroid to females of C. marginiventris. Studebaker et al. (1999) stated 18.8% 62.5 and 62.8% mortality in Orius insidiosus by the treated cotton leaves with the selected insecticides spinosad, imidacloprid and indoxacarb, respectively. Fipronil and cyhalothrin caused 100% mortality. O. insidiosus adults ceased and never resumed feeding, after exposure to imidacloprid-treated leaves.

In conclusion, the use of the chemical and bio insecticides resulted in significant levels of the defoliators and the boll worms larval control on both cotton and soybean fields as compared with the untreated plots. Addition of insect feeding stimulant to the chemical and bio insecticides provided significant effect to the defoliators and the bollworms mortality as compared to the use of the chemical and bio insecticides alone. Field results confirmed our laboratory findings, which indicated that the use of insect feeding stimulant enhanced the activity of the different insecticides and increase the larval mortality. So, feeding stimulants often reduce insecticide use and increase the efficacy of the insecticide or entomopathogen combined. Moreover, feeding stimulants attracted more the natural enemies and reduced the effects of pesticides on non-target insects, where the parasitoids and predators have been minimal.

ACKNOWLEDGEMENTS

The authors wish to thank Prof. Dr. El-Heneidy (Biological control Dept., Plant Prot. Res. Inst.) for his advise and reviewed the manuscript. Dr. El-Torkey, A. (Dept. of Taxonomy) is thanked for his help in identifying the different parasitoids and predators in these studies

REFERENCES

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