Comparative toxicities of some insecticides to Chrysoperla carnea (Chrysopidae: Neuroptera) and trichogramma brasiliensis (Trichogrammatidae: Hymenoptera), two arthropod natural enemies of cotton pests

Agriculture, Ecosystems and Environment, 15 (1986) 23--30 Elsevier Science Publishers B.V., Amsterdam -- Printed in The Netherlands

23

COMPARATIVE T O X I C I T I E S OF SOME INSECTICIDES T O CHR Y S O P E R L A C A R N E A (CHRYSOPIDAE: N E U R O P T E R A ) AND T R I C H O G R A M M A B R A S I L I E N S I S ( T R I CH O G RA MMA T ID A E : H Y M E N O P T E R A ) , TWO A R T H R O P O D N A T U R A L ENEMIES OF C O TTON PESTS

PARM PAL SINGH and GURDIAL CHAND VARMA Department of Entomology, Punjab Agricultural University, Ludhiana 141 001 (India) (Accepted for publication 1 August 1985)

ABSTRACT Singh, P.P. and Varma, G.C., 1986. Comparative toxicities of some insecticides to Chrysoperla earnea (Chrysopidae: Neuroptera) and Trichogramma brasiliensis (Trichogrammatidae: Hymenoptera), two arthropod natural enemies of cotton pests. Agric. Ecosystems Environ., 15: 23--30. Relative toxicities of nine insecticides recommended for the control of cotton bollworms were tested against the larvae of Chrysoperla carnea Stephens and adults of Trichogramma brasiliensis Ashmead under laboratory conditions in the Punjab, India. The insecticide concentrations studied were equivalent to those prescribed for field application. W h e n freshly emerged larvae of C. carnea were released on insecticide-treated food (eggs of Corcyra cephalonica Stainton) for 24 h, endosulfan, quinalphos, monocrotophos, phenthoate and fenitrothion caused 74--89% larval mortality over a 72-h period. Phosalone, carbaryl and cypermethrin were moderately toxic (34.1--38.1% mortality), while fenvalerate was the least toxic (19.2% mortality). The surviving larvae in all treatments successfully completed metamorphosis. W h e n T. brasiliens~s adults were released on treated host (C. cephalonica eggs), all these insecticides proved highly toxic (84--100% mortality in 24 h). Phosalone, monocrotophos and fenvalerate inhibited parasitism by 26--64%, but did not affect the emergence of parasitoid adults. The remaining six insecticides severely inhibited parasitism and emergence of parasitoid adults. Thus, phosalone and fenvalerate are relatively safe for the above-mentioned natural enemies and can provide selectivity in an integrated control programme for cotton bollworms.

INTRODUCTION With the advent o f the c o n c e p t of integrated pest m anagem ent (IPM), there has been a considerable change in the properties desired in insecticides (Metcalf, 1980). Generally, insecticides are considered suitable for IPM if t h e y combine efficient pest control with a minimum adverse influence on the activities of beneficial species. However, information a b o u t the effect

01674809/86/$03.50

© 1986 Elsevier Science Publishers B.V.

24 of insecticide applications on useful insects is generally lacking for most of the c o m p o u n d s and this makes the selection of insecticides appropriate for IPM difficult (Stevenson and Waiters, 1983). Cotton is the most important fibre crop of the world and is grown in about 80 countries, on more than 29.6 million hectares (Bottrell and Adkisson, 1977}. Throughout the world, boUworms are a serious menace to cotton growers. Even under IPM, the c o t t o n crop requires intensive sprays, which account for up to half of the total agricultural consumption of insecticides in several regions of the world (Kakkar, 1981; Croft and Whalon, 1982). As such, frequent insecticide applications over large areas are likely to have marked effects on the entire species complex of the crop, the use of chemicals favouring the survival of beneficial arthropods becomes imperative under such situations. The importance of biological control in c o t t o n pest management has been stressed by several workers (Bottrell and Adkisson, 1977), but only limited information is actually available a b o u t the selection of insecticides that are compatible with the natural enemies of the cotton pests. This paper is a preliminary examination of the relative toxicities of nine alternative insecticides, r e c o m m e n d e d for the integrated control of cotton bollworms, to Chrysoperla carnea Stephens (green lacewing} and Trichogramma brasiliensis Ashmead. C. carnea occurs in various cropping systems and is a valuable predator of more than 80 insect pests, including cotton bollworms. T. brasiliensis is an egg parasitoid of several lepidopterous pests and has shown promising results against bollworms in several countries. The entomophagous insects belonging to these two groups have been c o m m o n l y released in c o t t o n crops as biological control agents (Reynolds et al., 1982). MATERIALS AND METHODS All experiments were carried o u t in the Biological Control Laboratory, Department of Entomology, Punjab Agricultural University, Ludhiana, India, maintained at 25-+1°C and 6 9 -+ 5% relative humidity. Insecticides The selection of insecticides used in this study was based on the recommendations of the Punjab Agricultural University, Ludhiana for the integrated control of c o t t o n bollworms (Anonymous, 1983a). The formulations of these insecticides, as purchased from the market, were used after appropriate dilutions with tap water. The name of insecticides, formulations used, their prescribed field application rates and concentrations tested in this study are given in Table I. Rearing o f test insects Chrysoperla carnea and Trichogramma brasiliensis used in this study

25 TABLE I Details of the insecticides tested against Chrysoperla carnea and Trichogramma brasiliens/s Common name

Formulation

Dosage (formulation) per hectare*

Concentration of active ingredient tested (%)

Endosulfan

Thiodan 35 EC (Hoechst Pharmaceuticals Ltd., Bombay) Zolone 35 EC (Voltas Ltd., Bombay) Ekalux 25 EC (Sandoz India Ltd., Bombay) Monocil 36 WSC (National Organic Chemical Industries Ltd., Bombay) Phendal 50 EC (Bharat Pulverising Mills Private Ltd., Bombay) Folithion 50 EC (Bayer India Ltd., Bombay) Sevin 50 WP (Union Carbide India Ltd., Calcutta) Ripcord 5 EC (Shell Research Ltd., Sittingbourne, Kent, U.K.) Fenval 20 EC (Searle India Ltd., Bombay)

2500 ml

0.25

1500 ml

0.15

2000 ml

0.14

1250 ml

0.13

1000 ml

0.14

2100 ml

0.30

2500 g

0.36

1000 ml

0.014

250 ml

0.014

Phosalone Quinalphos Monocrotophos

Phenthoate Fenitrothion Carbaryl

Cypermethrin

Fenvalerate

*Recommended dosage in about 350 l of water (Anonymous, 1983a).

were drawn from cultures being maintained the procedures described earlier (Varma and al., 1978, respectively). During more than 2 mental stage of these insects had been exposed

in the laboratory, following Shenhamer, 1983; Varma et years of rearing, no developto any insecticide.

Dosing Corcyra cephalonica Stainton eggs to be used as treated host were glued on cards {6 X 2 cm) and sprayed with an atomiser containing various individual insecticide concentrations, as described in Table I, up to the point of run off. Each card received about 0.5 ml of the spray fluid. Egg cards to be used as controls were sprayed with an equivalent volume of tap water. The treated egg cards were allowed to dry at room temperature before being used for toxicity studies.

26

Relative toxicity o f different insecticides to larvae of Chrysoperla carnea Freshly emerged larvae (< 24 h old) kept singly in glass vials (5 X 1 cm). were exposed to a 2 × 0.5 cm strip of card bearing sprayed eggs. The treated egg cards were removed after 24 h and replaced by those with untreated eggs. The larvae were provided daily with fresh food cards of untreated eggs until their death o r formation of pupae. Mortality observations were made every 24 h. Each treatment was replicated thrice with 10 larvae in each replicate.

Effect of different insecticides on survival, rate o f parasitism and emergence of Trichogramma brasiliensis Thirty T. brasiliensis adults were exposed to strips of insecticide-treated host egg cards (3 × 1 cm) and their mortality recorded after 24 h. On the fourth day, the rate of parasitism was recorded on the basis of percentage of host eggs which had attained a black colour, characteristic of T. brasiliensis parasitism. The emergence of parasitoid adults from the parasitised eggs was recorded on the ninth day. Each treatment, including control, was replicated six times. RESULTS AND DISCUSSION

Relative toxicity o f different insecticides to larvae of Chrysoperla carnea The insecticides tested showed a wide range of toxicity to C. carnea larvae (Table II). On the basis of analysis of data by Duncan's multiple-range test, the insecticides could be divided into three groups, i.e., highly, moderately and least toxic. After 72 h exposure, endosulfan, quinalphos, monocrotophos, phenthoate and fenitrothion formed one group and were highly toxic (74.3--89.3% mortality). Phosalone, carbaryl and cypermethrin were moderately toxic (34.1--38.1% mortality), while fenvalerate was the least toxic (19.2% mortality). The mortalities after 48 h showed the same trend. For phosalone, low mortality (19.2%) was observed at the 24-h interval, but percentage mortality significantly increased to 34.2% over time. For other insecticides, the mortality pattern after 24 h was similar to that observed after 48 and 72 h. The larvae surviving exposure to insecticides were found to successfully complete metamorphosis. The low toxicity of phosalone to green lacewing has also been reported by Babrikova (1979), Franz et al. (1980) and Anonymous (1983b). Miszczak (1975} reported that fenitrothion and carbaryl are highly toxic to larvae of C. carnea. However, carbaryl proved moderately toxic to C. carnea in this study. Plapp and Bull (1978) have also reported carbaryl to have a low toxicity to these larvae. Cypermethrin and fenvalerate were among the safest compounds of

27 T A B L E II Relative toxicities o f different insecticides to larvae of Chrysoperla carnea at 25±1°C and 69± 5% relative h u m i d i t y Treatment

Concentration

(%)

Fenitrothion

0.30

Quinalphos

0.14

Phenthoate

0.14

Monocrotophos

0.13

Endosulfan

0.25

Cypermethrin

0.014

Phosalone

0.15

Carbaryl

0.36

Fenvalerate

0.014

Control

0.00

*Percent m o r t a l i t y (in angles) at various intervals w h e n exposed to treated host + for 24 h 24 h

48 h

72 h ++

90.0 a (100.0) 90.0 a (i00.0) 90.0 a

90.0 a (100.0) 90.0 a (100.0) 90.0 a

89.3 a (100,0) 89.3 a (100.0) 89.3 a

63.9 u (80.7) 75.0 a'b (93.3) 26.1 c (19.3) 19.2 e,d (10.8) 37.2 e (36.6) 17.2 c'd

66.2 a (83.6) 75.0 a ( 93.3~ 32.0 u ( 28.1~ 28.0 u ( 22.1~ 37.2 ~ (36.6) 23.4 ° ' c

76.9 a (94.9) 74.3 a ( 92.6~ 38.1 u ( 38.1~ 34.2 u ( 31.6~ 34.1 u (31.5) 19.2 ° ' c

( 8.8~

(15.8)

(10.8)

0.0 (0.0)

0.0 c (0.0)

0.0 c (0.0)

(100.0,).

(100.0)

(100.0)

*Average o f three replicates o f 10 larvae each. Data were analysed by D u n c a n ' s multiplerange test after t r a n s f o r m a t i o n o f percentage mortalities into angles. Means followed by a c o m m o n letter in a given c o l u m n do not differ significantly (P = 0.05). Figures in parentheses are back t r a n s f o r m a t i o n o f angles to p e r c e n t mortality. +Eggs o f Corcyra cephalonica. ++Corrected m o r t a l i t y by A b b o t ' s formula ( A b b o t , 1925). Mortality in control 10.5 (3.3)%.

those tested in this study. Pyrethroids have also been found to have marked low toxicity against C. c a r n e a larvae by other workers (Plapp and Bull, 1978; Niemczyk et al., 1979; Shout and Crowder, 1980; Rajakulendran and Plapp, 1982). Ishaaya and Casida (1981) reported that esterases present in the larvae of C. c a r n e a have unusually high hydrolysing activity against various synthetic pyrethroids and are a major factor in natural tolerance of these larvae to pyrethroids. Compared to the above-mentioned reports, the observations made in this study are unique in the sense that while earlier workers have based their conclusions on contact toxicity alone, the results reported in this study are founded on the combined effects of contact toxicity and feeding the predator with insecticide-treated prey. Such testing reflects a more

28 practical situation and has been recommended for the evaluation of pesticides for use with predators (Stevenson and Waiters, 1983). Effect o f different insecticides on survival, rate o f parasitism and emergence of Trichogramma brasiliensis Effect on survival When parasitoids were kept along with treated hosts' eggs for 24 h, high mortality was observed in all the treatments (Table III). Cypermethrin and fenvalerate caused 92.2 and 84.7% mortality, respectively, while the other seven insecticides resulted in 100% mortality of the parasitoids. While testing 20 commercial pesticides against Trichogramma cacoeciae, Franz et al. (1980) also observed that 18 of these (including endosulfan, phosalone and pyrethrum synergised with piperonyl butoxide) could not be used without disastrous effects on this parasitoid. TABLE III E f f e c t of d i f f e r e n t i n s e c t i c i d e s o n survival a n d e m e r g e n c e o f Trichogramma brasiliensie w h e n c o n f i n e d • + o w i t h t r e a t e d h o s t (Corcyra ccphalomca eggs) a t 2 5 - 1 C a n d 69+-5% relative h u m i d i t y Treatment

Concentration (%)

*Percent mortality a f t e r 24 h

*Percent parasitisation o f h o s t eggs after 4 days

Emergence of adults u p to 9 d a y s

Quinalphos Phenthoate Endosulfan Cypermethrin Carbaryl Fenitrothion Fenvalerate Phosalone Monocxotophos Control

0.14 0.14 0.25 0.014 0.36 0.30 0.'014 0.15 0.13 0.00

100.0 100.0 100.0 9 2 . 2 +3.1 100.0 100.0 84.7-+5.0 100.0 100.0 0.0

0.0 2 . 9 -+ 0.7 3.0 + 0 . 8 3.0 + 0.8 3.1± 1.1 3.3± 1.4 35.5± 3.1 68.3+10.7 73.3+27.5 99.0-+ 1.9

No emergence No emergence No emergence No emergence No e m e r g e n c e No e m e r g e n c e Emerged and healthy Emerged and healthy Emerged and healthy Emerged and healthy

*Mean o f six r e p l i c a t e s +- S.D.

Effect on rate o f parasitism Of the insecticides that caused 100% mortality of T. brasiliensis adults, a very low rate of parasitism (< 5%) was observed for endosulfan, phenthoate, fenitrothion and carbaryl (Table III). A complete inhibition of parasitism was observed for quinalphos. However, in the case of phosalone and monocrotophos treatments, parasitism to the extent of about 70% was observed. This indicates comparatively delayed toxic action of these insecticides, as parasitoids died only after parasitising the eggs. Navrajan Paul et al. {1979) have also reported high toxicity of endosulfan and high rates of parasitism for phosalone and monocrotophos when T. brasiliensis adults were exposed to insecticide-treated host eggs. However, Franz et al. {1980) found > 99% inhibition of parasitism by phosalone. In the case of cypermethrin and fenvalerate, which had relatively low

29

toxicity to T. brasiliensis adUlts, the rate of parasitism was only 3 and 35.5%, respectively (Table III). This is even less than that for phosalone and monocrotophos, which caused complete mortality of parasitoids during 24 h exposure: This suggests that these insecticides probably had some irritating or repellent effect on T. brasiliensis adults so that even the surviving parasitoids did not like to settle on the host eggs and thus failed to parasitise them. This interesting point suggests a need for further study of this aspect as it supports the idea that rather than recording mortality after contact with a pesticide, it is more appropriate to study the change in beneficial capacity of an entomophagous arthropod, because their performance can be reduced by even a sub-lethal dose (Franz et al., 1980). Bull and House (1983) and Tipping and Burbutis {1983) have also reported that application of perrnethrin, a synthetic pyrethroid, on host eggs significantly reduces the rate of parasitism by Trichogramma pretiosum and Trichogramma nu b ilale , respectively. E f f e c t on emergence

In the case of phosalone, monocrotophos and fenvalerate treatments, in which 35.5--73.3% of host eggs were parasitised, healthy adults emerged from the parasitised eggs. No parasitoids emerged from other treatments. Other workers have also reported no apparent adverse effect of insecticide residues present outside the parasitised host eggs on the emergence of the parasitoid (Navarajan Paul et al., 1976; Bull and House, 1983; Tipping and Burbutis, 1983). Thus, these results show that phosalone and fenvalerate are relatively safe to both C. carnea and T. brasiliensis and can provide important selectivity in integrated control programmes for cotton pests. Further evaluation of these insecticides in semi-field or field tests, following the procedure suggested by Stevenson and Walters (1983), is recommended.

REFERENCES Abbot, W.S., 1925. A method of computing the effectiveness of an insecticide. J. Econ. Entomol., 18: 265--267. Anonymous, 1983a. Punjab Agricultural Handbook. Punjab Agricultural University, Ludhiana, India, pp. 108--111. Anonymous, 1983b. Annual report of All-India Coordinated Research Project on Biological Control of Crop Pests and Weeds. Indian Institute of Horticultural Research, Bangalore, Section IARI, pp. 1--5. Babrikova, T., 1979. The effect of pesticides on the individual stages of the common lacewing (Chrysopa carnea Steph.) Rastenievud. Nauki, 16: 106--115. Bottrell, D.G. and Adkisson, P.L., 1977. Cotton insect pest management. Annu. Rev. Entomol., 22: 451--481. Bull, D.L. and House, V.S., 1983. Effects of different insecticides on parasitism of host eggs by Trichogramma pretiosum Riley. Southwest. Entomol., 8: 46--53. Croft, B.A. and Whalon, M.E., 1982. Selective toxicity of pyrethroid insecticides to arthropod natural enemies and pests of agricultural crops. Entomophaga, 27 : 3--21.

30 Franz, J.M., Bogenschutz, H., Hassan, S.A., Huang, P., Naton, E., Suter, H. and Viggiani, G., 1980. Results of a joint pesticide test programme by the Working Group: Pesticides and Beneficial Arthropods. Entomophaga, 25: 231--236. Ishaaya, I. and Casida, J.E., 1981. Pyrethroid esterase(s) m a y contribute to natural pyrethroid tolerance of larvae of the c o m m o n green lacewing. Environ. Entomol., 10: 681--684. Kakkar, A.K., 1981. Pesticide Market for Cotton In Punjab -- Farmers's viewpoint. M.Sc. Thesis, Punjab Agricultural University, Ludhiana, India, 60 pp. Metcalf, R.L., 1980. Changing role of insecticides in crop protection. Annu. Rev. Entotool., 25: 219--256. Miszczak, M., 1975. Toksycznosi niektorych pestycydow dla zlotooka pospolitego (Chrysopa carnea Steph.) Neuroptera: Chrysopidae. Rocz. Nauk Roln., Ser. E, 5: 31--41. Navarajan Paul, A.V., Mohanasundaram, M. and Subramanian, T.R., 1976. Effect of insecticides on the survival and emergence of the egg parasite, Trichogramma spp. Madras Agric. J., 63: 557--560. Navarajan Paul, A.V., Dass, R., Ahmed, R. and Parshad, B., 1979. Effect of some insecticides on parasitism by the parasitoid Triehogramrna brasiliensis (Ashmead)(Trichogrammatidae: Hymenoptera). Z. Angew. Entomol., 88: 399--403. Niemczyk, E., Misczak, M. and Olszayk, R., 1979. Toksyczno~ pyretroid6w dla o w a d 6 w drapiezinych i pasozytniczych. Rocz. Nauk Roln., E, 9: 105--115. Plapp, F.W., Jr. and Bull, D.L., 1978. Toxicity and selectivity of some insecticides to Chrysopa carnea a predator of the tobacco budworm, Environ. Entomol., 7 : 431--434. Rajakulendran, S.V. and Plapp, F.W., Jr., 1982. Comparative toxicities of five synthetic pyrethroids to the tobacco b u d w o r m (Lepidoptera: Noctuidae), an ichneumoid parasite Compoletis sonorensis and a predator, Chrysopa carnea. J. Econ. Entornol., 75: 769--772. Reynolds, H.T., Adkisson, P.L. and Smith, R.F., 1982. Cotton insect pest management. In: R.L. Metcalf and W. L u c k m a n (Editors), Introduction to Insect Pest Management. Wiley Interscience, N e w York, 577 pp. Shour, M.H. and Crowder, L.A., 1980. Effects of pyrethroid insecticideson the c o m m o n green lacewing. J. Econ. Entomol., 73: 306--309. Stevenson, J.H. and Walters, J.H.H., 1983. Evaluation of pesticides for use with biological control. Agric. Ecosystems Environ., 10: 201--215. Tipping, P.W. and Burbutis, P.P., 1983. Some effects of pesticide residues on Trichog r a m m a nubilale (Hymenoptera: Trichogrammitidae). J. Econ. Entomol., 76: 892-896. Varma, G.C. and Shenhamer, M., 1983. Some observations on the biology of Chrysoperla carnea (Stephens) (Chrysopidae: Neuroptera). J. Res., Punjab Agric. Univ., 20: 222-223. Varma, G.C., Maninder and Singh, B., 1978. The growth of population of Trichogramma brasiliensis Ashmead. J. Entomol. Res., 2: 209--211.