310 JounNer oF THEAnrnnrcex Mosqurro Cournor, AssocrarroN Vor. 2, No, 3
EFFECTOF THREE PYRETHROIDSON BLOOD FEEDING AND FECUNDITY OF AEDESAEGYPTI
WEIDE LIUr, ROBIN G. TODD, aNoEUGENEJ. GERBERG,
ABSTRACT..Caged Aedesaegypti were exposed to a range of concentrations of d-phenothrin, d-allethrin and tetramethrin in a wind tunnel. Mortality, blood engorgement and egg production among these mosquitoes and their progeny were recorded. Tetramethrln ivaswas the most Effettive (LC56(LC"n of 0.00177o),0.d0l7Vo\, followed by d-phenothrin (LC560.00317o) andald i-allethrind-allethrin (!Cso(LCco 0.017o).0.017o), Blo(Blood engorgementwas decreased \ treatment with.each pyrethroid at the high concentrarion(0.0027a,0.003% antl 0.01% respectively).'increasbd Treatment with d-phenbthrin or d-allethrii decreased egg production, bur terramethrin oviposition.These effectshad ceasedin the F2.
IN"I'RODUCTION egg production of a susceptible strain of Aedes aegpti (Lir'n;aeus). Since pyrethroids are being Insecticide-inducedchanges in the fecundity used extensively, some as substitutes for of insectshave been reported by many authors. organophosphate and carbamate insecticides, Adkisson and Wellso (1962) noted that DDT the effect of pyrethroids upon insect fecundity number reduced the of offspring from house should be investigated. flies and pink bollworm. Knutson (1955, 1959) found that treating house flies and Drosophila melanogasterwith dieldrin resulted in a change in the fecundity of laboratory and field popu- MATERIALS AND METHODS lations. Organophosphates,such as malathion and diazinon. were found to reduce the num- A susceptible strain of Aa. aegyptiwasutilized. ber of offspring from houseflies (Hunter, et al. This strain had been reared in the laboratory at 1958).El-Khatib3 observed that the treatment Insect Control & Research, Inc. under stan- of larvae of Culex quinquzfascintusSay with dard conditions free from insecticides for temephosdepressed the fecundityof survivors. many years. Three to five day old females were Georghiou (1965)reported that isolan,a carbam- used for testing. ate, depressed the fecundity, longevity and The insecticides used were d-phenothrin amount of food consumed, in house flies. (Sumithrin@), 93.5%, d-allethrin (Pynamin Grosch (1975)noted that carbarylreduced the Forte@),9l.4Vo and tetramethrin (Neopynamin@), number of eggs of Braconhebetor. David and 90.8% The solvents were acetone and kerosene Vago (1967) have reported that adult D. (1:l). melanogastertreated with Bacillus thuringiensis Groups of 30-50 female mosquitoes were serotype l, showed reduced longevity and aspirated from a stock cage and placed in fecundity. circular metal cages, (9.5 cm diam, 5 cm deep, Liu and Georghioua found that rans both ends covered with nylon screen). Mosqui- permethrin, a pyrethroid, caused a significant toes were treated in the Gerberg wind tunnel decrease in blood engorgement and egg raft (American Biological Supply Co., Baltimore, production of Cx. quinquefasciatusfrom MD 21228). Several concentrations of each were determine the most pyrethroid resistant and susceptiblestrains. insecticide tested to injecting This paper describes the effect of three suitable. Treatment was achieved by tunnel, using a 0.1 ml pyrethroids, d-phenothrin, d-allethrin and the insecticide into the and its use is tetramethrin,on the blood feeding activityand micropipette. The wind tunnel described by Morgan and Retzer (1981). The wind speed was 250-400 ftlmin and the nozzle pressure was 6 psi. Ten sec after the mosqui- I Shanghai Institute of Entomology, Academia Sinica, 225, Chungking Road (S.), Shanghai, 200025, toes were exposed to the spray, the cages were Peoples Republic of China. removed from the tunnel. The mosquitoes 2 Insect Control & Research, Inc. 1330 Dillon were left in the treated cages to avoid addi- Heights Avenue, Baltimore, MD 21228. tional handling. Morgan and Retzer (1981) 3 El-Kharib, Z. 1983. Compatibility and biotic compared mortalities among house flies left in potential of different genotypes of Culzx quin4rcfascintus treated cages to those that had been trans- Say with reference to strategies for disrupting the ferred to clean cages. They found no signifi- Ph.D. Dissertation, Uni- development of resistance. cant differences. We exposed 200 mosquitoes, versity of California, Riverside. 242 p. in 4 replicates of 50 to each concentration. 4 Liu, Weide and G. P. Georghiou. Influences of in l0% sucrose solution, permethrin treatment on blood feeding and fecun- Cotton balls, soaked dity of Culex quinquefasciatusSay resistant and suscep- were placed on each cage. Mortality was tible to pyrethroid insecticides. (Unpublished data). recorded 4 to 6 hr following treatment with Snprrrusrn, 1986 Errncr or Tnmr Pvntrnnotos oN Arors AEGvPTI 3ll
d-phenothrin or d-allethrin. The remaining Table l The toxicity of three pyrethroids to Aedzs mosquitoes were then allowed to feed uPon a aegyPti adults. rabbit for 25 min. Treatment with tetramethrin Mortality Vol caused rapid knockdown followed by recovery after several hours. Mosquitoes subjected to Conc. % d-phenothrinz d-allethrins tetramethrins tetramethrin were therefore provided with 0.001 30.2 blood 24 hr later, at which time mortality was 0.0015 6.5 38.5 noted. 0.002 8.0 49.4 Feeding was accomplished by placing the 0.0025 67.1 circular metal cage on the abdomen of the 0.003 46.5 rabbit and fastening it with a belt. The 0.004 76.0 91.8 mosquitoes were able to feed through the 0.005 ,1 a nylon screening. After the blood meal, the 0.006 0.008 t4.o numbers of engorged mosquitoes were counted 0.01 52.0 and released into a mosquito cage (12 x 12 x 0.015 92.0 l2 in.). A plastic container of water, lined with Check 05 0.0 ,-t paper towelling, was placed in the cage for LCrn 0.0031 0.01 0.0017 oviposition. The number of eggs were counted LCrt 0.0053 0.017 0.005 each day. I Mortality based upon 200 mosquitoesper con- In order to evaluate blood feeding and egg centration and correctedby Abbott's formula. production by the F1 and F2 generations, 20 2 Wind speed 250 ftlmin. females were aspirated from the stock cage and 3 Wind speed400 ftlmin. placed in a circular metal cage and fed on a rabbit. Blood engorgement and oviposition were then recorded as above. Engorgement ratios were calculated by comparing the per- bioresmethrin. These authors speculate that centage of treated females engorged with the leg fracture was caused by excitation by this percentage of controls engorged. The LC5s pyrethrcid. Engorgement among the Fl of values were obtained graphically. treated mosquitoes was normal, compared to that of the controls, suggesting that insecticide induced suppression of blood feeding is a RESULTS AND DISCUSSION transient phenomenon, confined to the gener- We found that the droplet distribution ation which is treated. obtained in the tunnel at 400 ftlmin was more Table 3 shows the differences in egg produc- uniform than at 250 ftlmin and that mortality tion of females treated with the 3 pyrethroids. was slightly higher. Thus at 250 ftlmin the Egg production was most markedly reduced by LC5s for d-phenothrin was 0.0031%, while at d-allethrin; down to 69% and 45% in the low 400 ftlmin, a0.003% concentration gave 56.5% and high doses respectively compared with the mortality. The results of these trials are given control. Tetramethrin showed no effect upon in Table l. Tetramethrin proved the most egg production. Egg production of mosquitoes effective of three pyrethroids, followed by treated with d-phenothrin was increased by d-phenothrin and d-allethrin. 33% at the low dose, but decreased by 30% at Blood engorgement was inhibited among the the high dose relative to the control. The egg surviving Ae. aegpt| as shown in Table 2. production of the F1 of the d-phenothrin Significant depression of engorgement was treated population was considerably less than found at the highest dose level of all 3 in the control; 75% and 58% in the low and -The pyrethroids, as revealed by the ,-test. high doses respectively. There was, however, engorgement ratios were; tetramethrin 0.57, no significant difference in egg production in d-phenothrin 0.50, d-allethrin 0.40. Depres- the F2 compared with the control, indicating a sion of blood feeding was less at dose levels of reversion to normal production. The phenom- ca. or below the LC3e. This finding agrees with enon of insecticidetreatment causing insectsto that of Liu and Georghiou (unpublished data) produce more eggs has been noted before; for using permethrin against Cx. quinquefasciahu. example, Knutson (1955) reported that D. The mechanism of this depressive effect upon melanogaster produced 7.6Vc more eggs when engorgement is unknown. We noticed that treated with a sublethal dose of dieldrin. Afifi many mosquitoes lost one or more of their legs and Knutson (1956) reported house flies after treatment; this may be related to the treated with dieldrin produced 62.9% and depression since this was not noticed among 9.3% more eggs respectivelythan the control in the controls. Similar observations were made the F1 and F2 generations. Ouyer and Knutson by Khoo and Sutherland (1981) with (1957) found that malathion treatment in-
I 312 Jounuel oF THEAnrsnrcaN Mosqurro coNrnor, Assocrarron vor., 2. No. 3
Table 2. The effect of three pyrethroids on blood engorgement of Aedzs aegypti.
Mosquitoes Blood Blood meal Number x engorSement Sample replicates Total Surv* Number 7o ratio d-phenothrin 0.00170 50x4,30x1220 218 202 92.7 0.97 0.002Vo 50x2 100 78 65 83.3 0.87 0.003vo 50x4,30x2 260 147 7l 48.3 0.50 2,4 CheckI 50x4,30x2 260 258 247 95,7 1.00 F1 of d-phenothrin 0.00r% 20xI 20 l9 95.0 0.95 0.003Vo 20xI 20 l8 90.0 0.90 Check 2 20xl 20 9n r00.0 1.0 F2of d-phenothrin 0.00lVo 20xI 20 20 100.0 t.0 0.003Vo llxl ll ll 100.0 t.0 Check 3 20xI 20 20 100.0 t.0 d-allethrin 0.006% 50x5 250 209 t52 72.7 0.76 0.jlVo 50x5 250 94 36 38.3 0.40 2.6b Check 4 50x3 150 150 r43 95.3 1.00 Ft of d-allethrin 0.0067o 20xI 20 20 100.0 l.ll 0.0170 20xI 20 20 100.0 l.ll Check 5 20xI 20 l8 90.0 1.00 tetramethrin 0.0ol7o 50x2, 30x 2 160 109 87 79.8 0.84 0.0O2Vo 50x3,30x2 210 104 56 53.E 0.57 2.4 Check6 50x2,30x2 160 155 147 94.8 1.00 F1 of tetramethrin 0.00r% 20x I 9(\ 20 100.0 1.00 0.002Vo 20x I 20 20 100.0 1.00 Check7 20x I 20 20 100.0 1.00 * Survivors. " df = 12,P<0.05; b df = 8, P<0.05;" df, = 9, P<0.05.
creased egg production in house flies. The Referenees Cited occurrence of increased egg production follow- Adkisson, P. L. and S. G. Wellso. 1g62. Effect of ing a low dose treatment and decreased pro- DDT poisoning on the longevity and fecundity of duction following a high dose treatment, does the pink bollworm. Econ. Entomol. 55:842-845. appear tq have been reported J. not previously. Afifi, S. E. D. and H. C. Knutson. 1956. Reproduc- Insecticidal treatment generally reduced egg tive potential, longevity, and weight of house flies production rather than increasing it. which survived one insecticidal treatment. J. Econ. CONCLUSIONS Entomol. 49:301-303. David, P. H. and C. Vago. 1967. Influence des Blood engorgement decreased among Ae. toxines des Bacillus thuringienni sur divers caracteres aeglpti suwivors which had been treated with physiologique des Drosophiles adultes. Entomophaga d-phenothrin, d-allethrin and tetramethrin at a I2:153-159. high dose (ca. LC56) and at a low dose (
Table 3. The effect of three pyrethroids on the egg production of Aedes aeglpti.
Mosquitoes Egg production Egg Number x Blood Vo production Sample replicates Total Surv* meal Total increase ratio d-phenothrin 0.0017o 30x4 120 I 13 72 4747 65.9 1.33 0.003Vo 30x4 120 77 40 I 393 34.8 0.70 CheckI 30x4 120 120 I l5 5699 49.6 1.00 Ft of d-phenothrin o.00r% 20xI 20 20 1406 70.3 0.75 0.003Vo 20xI 20 90 I 100 55.0 0.58 Check 2 20xI 20 20 188I 94.1 1.00 Fp of d.phenothrin 0.00lVo 20xI 20 20 1530 /b.5 0.94 0.0037o ll x I ll ll 988 89.8 l.l0 Check 3 20xI 20 9n 1633 81.3 1.00 d-allethrin 0.006vo 50x2 100 60 4l tl74 28.6 0.69 0.Utvo 50x2 100 40 l8 340 18.9 0.45 Check4 50xI 50 49 49 2041 41.7 l.00 Fr of d-allethrin 0.00670 20xI 20 20 1683 84.2 l.08 0.UlVo 20xI 20 20 t77| 88.6 l.l4 Check 5 20xI 20 20 t554 77.7 1.00 tetramethrin 0.0OlVo 30x2,50xl t l0 78 66 1747 26.5 0.89 0.02% 30x2, 50x I ll0 55 28 883 31.5 1.06 Check 6 30x2,50x I l l0 109 103 3071 29.8 1.00 * Survivors.
Khoo, B. K. and D. J. Sutherland.1981. Leg fracture potential in house flies in response to dieldrin. in adult mosquitoes induced by bioresmethrin. Misc. Publ. Entomol. Soc.Am. l:29-32. Mosq.News 4l:802-804. Morgan, N. O. and H. J. Retzer.1981. Aerosol wind Knutson, H. C. 1955.Modification in fecundity and tunnel for vector insecticide evaluation. J. Econ. Entomof. 74:389-392. life span of Drosophilnruelanogaster Meig. following Ouyer, M. T. and H. Knutson. 1957.Reproductive sublethalexposure to insecticides.Ann. Entomol. potential, longevity, and weight of house flies Soc.Am. 48:35-39. following treatment of larvae with malathion. J. Knutson, H. Q, 1959. Changes in reproductive Econ.Entomol. 50:490-493.