Evaluation of the effect of different insecticides on the survival and capacity of 2 Eretmocerus mundus Mercet to control Bemisia tabaci (Gennadius) populations

1 Title 1 Evaluation of the effect of different insecticides on the survival and capacity of 2 Eretmocerus mundus Mercet to control Bemisia tabaci (Gennadius) populations 3 4 Authors 5 J. E. Gonzalez-Zamora, D. Leira, M.J. Bellido, C. Avilla 6 7 Affiliation 8 Departamento de Ciencias Agroforestales (Universidad de Sevilla) 9 Carretera de Utrera km 1, E-41013 Sevilla (Spain) 10 11 Corresponding author: 12 J.E. Gonzalez-Zamora 13 e-mail: [email protected] 14 Fax number: + 34 95 448 64 36 15 Phone number: + 34 95 448 64 59 16 17 18 19 20 Published in: Crop Protection 23 (2004) 611–618 21 doi:10.1016/j.cropro.2003.11.011 22 2 Abstract 23 Two different experiments were carried out to evaluate three insecticides. In the 24 first one, the effect of two insecticides, methomyl and indoxacarb, on pupae and 25 adults of the whitefly Bemisia tabaci (Gennadius) parasitoid Eretmocerus mundus 26 Mercet was evaluated under laboratory and greenhouse conditions, using sweet 27 pepper (Capsicum annuum L.) plants. In the second experiment, oxamyl was 28 tested to study its effect on the ability of E. mundus to parasitize and control B. 29 tabaci in sweet pepper plants, using a greenhouse cage evaluation. Methomyl and 30 indoxacarb caused low mortality of E. mundus pupae (17.6 and 7.8% 31 respectively), although methomyl mortality was significantly higher. Methomyl 32 produced 100% mortality on E. mundus adults with fresh and 24 hour-old 33 residues on leaves, significantly higher than the mortality produced by indoxacarb 34 (values ranged from 43.9 to 34.4%). The harmful effect of methomyl persisted for 35 a long time (up to 60 days). The results of the experiment with oxamyl showed 36 that E. mundus controlled whitefly population, without significant interaction 37 between the presence of the parasitoid and insecticide on whitefly mortality. 38 Whitefly mortality in the presence of the parasitoid was 87.8%, significantly higher 39 than the mortality in the absence of E. mundus (59.3%). Oxamyl did not produce 40 a significant effect on the emergence of E. mundus adults. Application of the 41 products in IPM programs is discussed. 42 43 Keywords: Eretmocerus mundus, Bemisia tabaci, indoxacarb, oxamyl, methomyl, sweet 44 pepper, parasitism. 45 46 3 Introduction 47 48 Eretmocerus mundus Mercet (Hymenoptera: Aphelinidae), a parasitoid of the 49 tobacco, cotton or sweet potato whitefly Bemisia tabaci (Gennadius) (Hemiptera: 50 Aleyrodidae), has a widespread distribution worldwide. This species is recognized 51 as one of the most important natural enemies of B. tabaci, and has generated a 52 lot of interest in countries where B. tabaci is a problem. The use of heavy chemical 53 control against this pest is also recognized to be involved in many of the outbreaks 54 of B. tabaci around the world, for different reasons: development of insecticide 55 resistance, negative effects on natural enemies, alteration of behaviour and 56 biology of the pest. 57 58 Outbreaks of this whitefly in different crops and countries have stimulated the 59 search for different biological control agents around the world. The most active 60 country in this respect is the U.S.A., where many parasitoid and predator species 61 have been tested. One of the most promising species is E. mundus (Goolsby et al., 62 1998; Hoelmer et al., 1999; Kirk et al., 2000), especially the strain obtained from 63 southeast Spain. The first time this species was collected in Murcia (Spain) on 64 cotton, in 1991-92, it exhibited a good tolerance to the different pesticides applied 65 regularly to the crop (Kirk et al., 2000). 66 67 Current pest control includes the use of pesticides, combined or not with natural 68 enemies. There are many reports and studies that present evidence of natural 69 enemies of B. tabaci that can remain active in different crops after the use of 70 some pesticides (Gerling, 1996; Gerling and Naranjo, 1998; Simmons and Jackson, 71 2000), especially parasitoids, such as E. mundus. Possible explanations for this 72 ability of parasitoids to remain in treated plots include the protection that 73 immature stages can obtain inside the host, as well as the type of compound 74 used, the incomplete coverage of the canopy or the timing of the application. 75 76 The presence of E. mundus in commercial plots treated routinely with pesticides 77 has also been reported by other authors (Rodriguez-Rodriguez et al. 1994; 78 4 Gonzalez-Zamora et al., 1996) in southeast Spain. They also studied the 79 parasitism on B. tabaci and Trialeurodes vaporariorum (West.) by different species 80 and the ability of E. mundus to control B. tabaci populations in sweet pepper, 81 melon, and tomato. In summary, these papers show the ability of different 82 whitefly parasitoids to establish and maintain a high level of parasitism in plots, 83 even when they are treated with pesticides. Different pesticides are considered to 84 be selective to this and other parasitoids and can be used together to obtain 85 control of the pest population below injury levels (Koppert Biological Systems, 86 2003). 87 88 Other papers have studied the combination of pesticides and parasitoids (with 89 special interest in Eretmocerus spp.) to control whitefly populations in different 90 conditions. For example, Birnie and Denholm (1992) used an extended laboratory 91 trial to test the capacity of E. mundus to control B. tabaci populations on cotton 92 with the application of cypermethrin, showing the ability of the parasitoid 93 population to recover after only one application of the compound. Devine et al. 94 (2000) revealed the potential of piperonyl butoxide to improve the level of E. 95 mundus parasitism on B. tabaci, by slowing the development of the whitefly, 96 increasing the parasitism in the treated whitefly population by 7-8%. Van Driesche 97 et al. (2001) demonstrated the possibility of using an insect growth regulator 98 (buprofezin) in combination with Eretmocerus eremicus Rose and Zolnerowich to 99 control T. vaporariorum and B. tabaci in poinsettias in commercial greenhouses. 100 101 The aim of this work was to study the effect of three insecticides on different 102 development stages (pupa and adult) of E. mundus, and the capacity of E. 103 mundus to control B. tabaci populations together with one of the insecticides, 104 presenting evidence of the capacity of this species to be used together with 105 insecticides. Two of these insecticides (methomyl and oxamyl) are currently used 106 in southeast Spain to control different pests, and the third (indoxacarb) has been 107 introduced recently to control caterpillars in different crops, including those with B. 108 tabaci infestation. Indoxacarb is a selective product that is compared with the 109 other two products, non-selective insecticides. These two insecticides can be 110 5 applied in different ways in order to confer selectivity. Results are discussed 111 considering the possibilities of using these products in a IPM program. 112 113 Material and Methods 114 115 Two different experiments were carried out to test the insecticides: in the first 116 one, methomyl (chemical name: S-methyl-N-[(methylcarbamoyl)oxy] 117 thioacetimidate) (commercial product Lannate® 20 L, Du Pont Iberica S.L.), and 118 indoxacarb (chemical name: (S)-7-chloro-3-[methoxycarbonyl-(4-trifluoromethoxy- 119 phenyl)-carbamoyl]-2,5-dihydro-indenol 1,2 -e[1,3,4]oxadiazine-4a(3H)-carboxylic 120 acid methyl ester) (commercial product Steward® 30 WG, Du Pont Iberica S.L.) 121 were tested on E. mundus pupae and adults; in the second one, oxamyl (chemical 122 name: methyl-N’,N’-dimethyl-N[(methylcarbamoyl)oxy]-1-thio-oxamimidate) 123 (commercial product Vydate® 10L, Du Pont Iberica S.L.) was tested to determine 124 its effect on the parasitism and capacity of E. mundus to control a population of 125 B. tabaci, using a greenhouse cage evaluation. 126 127 A colony of B. tabaci was created from adults captured in the Seville province 128 (southwest Spain), from cotton and aubergine plants, and kept in an insect 129 rearing room, feeding on sweet pepper (Capsicum annuum L.) plants (cv. Largo 130 Italiano, Semillas Batlle S.A., C/Matadero 10, E-10100-Miajadas (Caceres, Spain)). 131 The biotype of B. tabaci was not determined. Adults of E. mundus were collected 132 in the regions of Almeria (southeast Spain) and Seville, on sweet pepper and 133 cotton plants, and reared on sweet pepper plants infested with B. tabaci nymphs. 134 The rearing room was kept at 26±2 ºC with a photoperiod of 16:8 (Light:Dark). 135 136 Experiment 1: Effect of methomyl and indoxacarb on Eretmocerus 137 mundus pupae and adults 138 139 Four young sweet pepper plants were selected for each treatment (i.e. product), 140 with 4-5 leaves each, to assess the effect of insecticides on E. mundus pupae. 141 They were infested with adults of B. tabaci, which were allowed to lay eggs for 142 6 48-72 hours and then removed from the plants. Development of the offspring was 143 followed until 2nd-3rd instar nymphs were present, then females of E. mundus 144 were introduced into the cages for oviposition, together with several males. The 145 plants were kept in the rearing room until the parasitoid pupa was observed inside 146 the whitefly pupal case: the form of the pupa was evident and the eyes took on a 147 cherry colour (Garrido et al. , 1982; Garrido, 1992). At that moment, a minimum of 148 twenty-five pupae per plant were marked with an indelible pen, and the plants 149 were put in a plastic greenhouse. The total number of pupae used in each 150 treatment was 115, 107, and 114 for indoxacarb, methomyl and the control, 151 respectively. The products were applied in that moment, using a trigger-operated 152 hand sprayer, at the recommended field rates: methomyl, 0.4 g a.i./l; indoxacarb, 153 0.0375 g a.i./l until run-off. A group of four plants was treated with water, as 154 control. 155 156 Counts were done every 3-4 days with the help of a 5x magnifying hand lens, 157 counting dead and live pupae and pupal cases from where an insect had emerged. 158 The experiment finished when all the adults had emerged. 159 160 The effect of the insecticides on E. mundus adults was evaluated by applying the 161 products and water at the same rates with the trigger-operated hand sprayer on 162 several sweet pepper plants with developed leaves. The products were allowed to 163 dry and then two types of cages were mounted: with fresh residues and with 164 twenty-four hour old residues. The methodology used was described in Jones et 165 al. (1995). 166 167 The experimental units (cages) consisted of 5-6 newly emerged adults of E. 168 mundus, confined to a Petri dish of 55 mm diameter and 14 mm height. The Petri 169 dishes were modified by replacing most of the bottom with organdy cloth 170 (subsequently inverted to become the top). The new bottom half of the Petri dish 171 was used as a template to cut out a circular section of sprayed leaf. The leaf discs 172 were fitted in the inner surface of a dish lid (now the bottom), with the bottom 173 leaf surface facing upwards. A cotton cloth moistened with water and honey was 174 7 put inside the cage. The parasitoids were collected from the rearing units and 175 briefly chilled before being introduced in the experimental units. The ventilated 176 dish bottom was replaced, becoming the top. Dish halves were secured using a 177 pair of clips, and the cages were put in a laboratory room. Six replicates per 178 treatment (with a total of 32-36 individuals per treatment) were used with the 179 fresh residues leaves, and eight replicates per treatment (with a total of 53-61 180 individuals per treatment) with the leaves with twenty-four hour old residues. The 181 adults were kept in the cages for twenty-four hours, then opened and the adults 182 counted, separating dead and live insects. 183 184 A similar test was performed to study methomyl persistence in sweet pepper plant 185 leaves. Different groups of plants were selected, and in each group one of the 186 plants was treated with water and the others with methomyl at the previous rate. 187 The plants were allowed to dry and after different time periods, ranging from 188 seven to sixty-two days after treatment, cages were mounted with leaf discs from 189 plants treated with methomyl and water. The number of adults introduced in each 190 cage varied between eight and thirteen. The adults were introduced in the cages 191 as explained above, and after twenty-four hours the cages were opened and the 192 number of dead and live adults counted. Treated plants and cages were kept in 193 laboratory conditions. 194 195 Experiment 2: Effect of oxamyl on the capacity of Eretmocerus mundus 196 to control Bemisia tabaci 197 198 The experimental design studied two levels (presence and absence) of two factors 199 (parasitoid and insecticide). There were, therefore, four treatments: 1) application 200 of oxamyl, 2) application of oxamyl and introduction of E. mundus, 3) introduction 201 of E. mundus, and 4) no application of oxamyl and no introduction of E. mundus 202 (control). Each treatment was replicated four times, using one sweet pepper plant 203 per treatment and replicate, making a total of 16 plants. 204 205 8 The plants were infested with B. tabaci adults in the rearing room, allowed to lay 206 eggs for three days only on one leaf and then removed. The plants were kept in 207 the rearing room and, after nine days, first and second instar whitefly nymphs 208 were present on the leaves. The number of nymphs per leaf ranged from 132 to 209 198. Plants were then maintained in a greenhouse inside a metallic structure 210 covered with organdy for the rest of the experiment. 211 212 Oxamyl was applied at a rate of 0.028 g a.i./plant (equivalent to 500 g a.i./ha, 213 with 18,000 plants/ha) in treatments 1) and 2). It was applied on a weekly basis, 214 a maximum of eight times, beginning the same day the plants had been put in the 215 greenhouse. The oxamyl was diluted in 100 ml of water per plant. The pH of the 216 broth was adjusted to 4.5-5.5 with phosphoric acid. A drip irrigation system was 217 used to water the plants, simulating the normal irrigation management of this 218 crop, and the broth was injected with a previous-pressure sprayer in the irrigation 219 system. 220 221 E. mundus was introduced in treatments 2) and 3) at a total rate of 12 to 18 222 females per replicate, following the recommended ratio proposed by Jones et al. 223 (1999). Adult parasitoids were placed in the cages in two to four separate 224 introductions, beginning on the first day that the plants were put in the 225 greenhouse. 226 227 Plants were evaluated every 3-4 days during the first two weeks, and then weekly 228 until all the adults of B. tabaci and E. mundus emerged. The number of living 229 whitefly nymphs and pupae, the number of parasitized whitefly nymphs and 230 parasitoid pupae, and the number of pupal cases from where an adult (whitefly or 231 parasitoid) had emerged were counted. This experiment included only one 232 generation of the whitefly B. tabaci and the parasitoid E. mundus. 233 234 Analysis of variance was performed on mortality and parasitism (Statistical 235 Graphics Corporation, 1999) in both experiments, with the transformation of 236 z=arcsin p , where p is mortality or parasitism. A 2x2 factorial analysis was applied 237 9 in experiment 2. If treatments were significant at P < 0.05, then differences 238 between means were determined using the LSD test at 95% confidence level. 239 Abbot’s formula (Abbot, 1925) was used to correct the mortality in experiment 1. 240 241 Voucher specimens of the parasitoid are maintained by the first author in the 242 Department collection (Departamento de Ciencias Agroforestales, Universidad de 243 Sevilla). 244 245 Results 246 247 Experiment 1: Effect of methomyl and indoxacarb on Eretmocerus 248 mundus pupae and adults 249 250 Methomyl significantly increased the mortality of E. mundus pupae parasitizing B. 251 tabaci (Figure 1) seven days after application (F=4.7, d.f.=2, 9, P=0.04), while 252 indoxacarb was not significantly different from the control. Mortality increased 253 three days later to 17.6 % in methomyl, greater than indoxacarb and the control, 254 with 7.8 and 5.1% mortality respectively (F=8.20, d.f.=2, 9, P=0.009). 255 256 Both insecticides significantly increased the mortality of E. mundus adults (Figure 257 2), though methomyl was more harmful (100 % mortality in both cases, with fresh 258 and 24 hour-old residues in leaves) than indoxacarb (43.9% and 34.4%, 259 respectively), with F=59.8, d.f.=2, 6, P<0.0001, and F=84.60, d.f.=2, 9, 260 P<0.0001, for fresh and 24 hour-old residues respectively. 261 262 The harmful effect of methomyl on E. mundus adults lasted up to sixty days after 263 application (Figure 3A), when the mortality was still significantly higher than the 264 control treated with water. The mortality was corrected with the Abbot’s formula 265 and adjusted to a curve (Figure 3B; R2 = 0.88; P<0.01). At least 55 days were 266 required for adult mortality after treatment with methomyl to drop to 50%. 267 268 16 References 437 438 Abbot, W.S. 1925. A method of computing the effectiveness of an insecticide. J. 439 Econ. Entomol. 18, 265-267. 440 441 Birnie, L. C. and Denholm, I. 1992. Field simulators: a novel approach to 442 evaluating the impact of pesticides on beneficial arthropods in the laboratory. 443 Aspects of Applied Biology 31, 105-112. 444 445 Cabello Garcia, T., Gomez, M., Barranco, P., Lucas, M., and Belda, J. E. 1997. 446 Evaluation of oxamyl against homoptera pests in greenhouse-grown pepper, 447 applied with drip irrigation. Ann. appl. Biol. 130 (supplement) Test of 448 Agrochemicals and Cultivars 18, 2-3. 449 450 Devine, G. J., Wright, D. J., and Denholm, I. 2000. A parasitic wasp (Eretmocerus 451 mundus Mercet) can exploit chemically induced delays in the development rates of 452 its whitefly host (Bemisia tabaci Genn.). Biol. Control 19, 64-75. 453 454 Dinter, A., and Kratz, T. 2000. Impact of field treatments with the insecticide 455 Lannate 20 L (a.i. methomyl) on foliage and ground dwelling arthropods. 456 IOBC/WPRS Bull. 23, 127-135. 457 458 Dinter, A., and Wiles, J.A. 2000. Safety of the new DuPont insecticide 459 “Indoxacarb” to beneficial arthropods: an overview. IOBC/WPRS Bull. 23, 149-156. 460 461 Foltyn, S., and Gerling D. 1985. The parasitoids of the aleyrodid Bemisia tabaci in 462 Israel: development, host preference and discrimination of the aphelinid wasp 463 Eretmocerus mundus. Entomol. exp. appl. 38, 255-260. 464 465 Garrido, A. 1992. Pesticides toxicity over pupae of Cales noacki Howard (Hym.: 466 Aphelinidae). IOBC/WPRS Bull. 15, 56-60. 467 468 17 Garrido, A., Tarancon, J., and del Busto, T. 1982. Incidencia de algunos 469 plaguicidas sobre estados ninfales de Cales noacki How., parasito de Aleurothrixus 470 floccosus Mask. An. INIA-Ser. Agric. 18, 73-96. 471 472 Gerling, D. 1996. Status of Bemisia tabaci in the Mediterranean countries: 473 opportunities for biological control. Biol. Control 6, 11-22. 474 475 Gerling, D., and Naranjo, S. E. 1998. The effects of insecticide treatments in 476 cotton fields on the levels of parasitism of Bemisia tabaci (Gennadius) s.l. Biol. 477 Control 12, 33-41. 478 479 Gerling, D., and Sinai, P. 1994. Buprofezin effects on two parasitoid species of 480 whitefly (Homoptera: Aleyrodidae). J. Econ. Entomol. 87, 842-846. 481 482 Gonzalez-Zamora, J. E., Gallardo, J. M., and Garcia, M. M. 1997. Toxicity of 483 different pesticides on pupae of Eretmocerus mundus Mercet (Hymenoptera: 484 Aphelinidae) parasitizing Bemisia tabaci (Genn.) (Homoptera: Aleyrodidae). 485 IOBC/WPRS Bull. 20, 114-120. 486 487 Gonzalez-Zamora, J.E., Rodriguez-Rodriguez, M. D., Mirasol Carmona, E., 488 Manzanares Ruiz, C., Moreno Vazquez, R., Rodriguez Rodríguez, M. P., and 489 Lastres Garcia-Teston, J. 1996. Evolución del parasitismo en Bemisia tabaci 490 (Genn.) y Trialeurodes vaporariorum (West.) (Homoptera: Aleyrodidae) en 491 invernaderos en Almería. Bol. San. Vegetal-Plagas 22, 373-389. 492 493 Goolsby, J., Ciomperlink, M. A., Legaspi, B. C., Legaspi, J. C., and Wendel, L. E. 494 1998. Laboratory and field evaluation of exotic parasitoids of Bemisia tabaci 495 (Gennadius) (Biotype "B") (Homoptera: Aleyrodidae) in the Lower Rio Grande 496 Valley of Texas. Biol. Control 12, 127-135. 497 498 18 Heinz, K. M., and Parrella, M. P. 1998. Host location and utilization by selected 499 parasitoids of Bemisia argentifolii (Homoptera: Aleyrodidae): implications for 500 augmentative biological control. Environ. Entomol. 27, 773-784. 501 502 Helyer, N. L., Ledieu, M. S., Hussey, N. W., and Scopes, N. E. A. 1984. Early 503 season integrated control of whitefly on tomatoes using oxamyl. British Crop 504 Protection Conference Monograph, 293-297. 505 506 Hoelmer, K., Kirk, A., and Simmons, G. 1999. An overview of natural enemy 507 explorations and evaluations for Bemisia in the U.S. Proceedings of the Fifth 508 International Conference on Pests in Agriculture-ANPP, 7-9 December 1999, 509 Montpellier, France, 689-696. 510 511 Jones, W. A., Ciomperlik, M. A., and Wolfenbarger, D. A. 1998. Lethal and 512 sublethal effects of insecticides on two parasitoids attacking Bemisia argentifolii 513 (Homoptera, Aleyrodidae). Biol. Control 11, 70-76. 514 515 Jones, W. A., Greenberg, S.M., and Legaspi, B. 1999. The effect of varying 516 Bemisia argentifolii and Eretmocerus mundus ratios on parasitism. Biocontrol 44, 517 13-28. 518 519 Jones, W. A., Wolfenbarger, D. A., and Kirk, A. A. 1995. Response of adult 520 parasitoids of Bemisia tabaci (Hom.: Aleyrodidae) to leaf residues of selected 521 cotton insecticides. Entomophaga 40, 153-162. 522 523 Kirk, A. A., Lacey, L. A., Brown, J. K., Ciomperlink, M. A., Goolsby, J., Vacek, D. C., 524 Wendel, L. E., and Napompeh, B. 2000. Variation in the Bemisia tabaci s.l. species 525 complex (Hemiptera:Aleyrodidae) and its natural enemies leading to successful 526 biological control of Bemisia biotype B in the USA. Bull. Entomol. Res. 90, 317- 527 327. 528 529 Koppert Biological Systems. 2003. http://www.koppert.nl 530 19 531 Rodriguez-Rodriguez, M. D., Moreno, R., Tellez, M. M., Rodriguez-Rodriguez, M. 532 P., and Fernadez-Fernandez, R. 1994. Eretmocerus mundus (Mercet), Encarsia 533 lutea (Masi) y Encarsia transvena (Timberlake) (Hym.,Aphelinidae) parasitoides de 534 Bemisia tabaci (Homoptera, Aleyrodidae) en los cultivos horticolas protegidos 535 almerienses. Bol. San. Vegetal-Plagas 20, 695-702. 536 537 Sharaf, N., and Batta, Y. 1985. Effect of some factors on the relationship between 538 the whitefly Bemisia tabaci Genn. (Homop., Aleyrodidea) and the parasitoid 539 Eretmocerus mundus Mercet (Hymenopt., Aphelinidae). Z. ang. Ent. 99, 267-276. 540 541 Simmons, A. M., and Jackson, D. M. 2000. Evaluation of foliar-applied insecticides 542 on abundance of parasitoids of Bemisia argentifolii (Homoptera: Aleyrodidae) in 543 vegetables. J. Entomol. Sci. 35, 1-8. 544 545 Simmons, G. S., and Minkenberg, O. P. 1994. Field-cage evaluation of 546 augmentative biological control of Bemisia argentifolii (Homoptera: Aleyrodidae) in 547 southern California cotton with the parasitoid Eretmocerus nr. californicus 548 (Hymenoptera: Aphelinidae). Environ. Entomol. 23, 1552-1557. 549 550 Statistical Graphics Corporation. 1999. Statgraphics Plus for Windows version 4.0. 551 552 Van Driesche, R., Hoddle, M. S., Lyon, S., and Sanderson, J. 2001. Compatibility of 553 insect growth regulators with Eretmocerus eremicus (Hymenoptera: Aphelinidae) 554 for whitefly (Homoptera:Aleyrodidae) control on poinsettias: II Trials in 555 commercial poinsettia crops. Biol. Control 20, 132-146. 556 20 Figure captions 557 558 Figure 1. Percentage mortality of Eretmocerus mundus pupae parasitizing 559 Bemisia tabaci treated with methomyl ( ), indoxacarb ( ), and control ( ). 560 Treatments with different letters in the same day are significantly different with 561 95% of confidence, using the LSD test. Vertical bars indicate the standard error 562 of the mean. 563 564 Figure 2. Percentage mortality of Eretmocerus mundus adults treated with 565 methomyl, indoxacarb, and the control, with fresh and 24-hour old residues. 566 Treatments with different letters are significantly different with 95% of 567 confidence, using the LSD test. Vertical bars indicate the standard error of the 568 mean. 569 570 Figure 3. Percentage mortality of Eretmocerus mundus adults treated with 571 methomyl over a period of 60 days, (A) compared with the control treated with 572 water; methomyl ( ), water ( ); and (B) mortality corrected using Abbot’s 573 formula and with an adjusted curve (R2=0.88, P<0.01). Vertical bars indicate 574 the standard error of the mean. 575 576 Figure 4. Cumulative percentage mortality of Bemisia tabaci larvae in the 577 experiment with oxamyl, (A) considering the four treatments, oxamyl ( ), 578 oxamyl plus Eretmocerus mundus ( ), E. mundus ( ), and control ( ); and (B) 579 considering the treatments with E. mundus ( ), and without parasitoids ( ). 580 Vertical bars indicate the standard error of the mean. 581 582 Figure 5. Effect of oxamyl on Eretmocerus mundus parasitizing Bemisia tabaci 583 larvae. (A) Percentage evolution of parasitized whitefly larvae treated with 584 oxamyl ( ) and water ( ); and (B) Cumulative percentage emergence of 585 Eretmocerus mundus adults from Bemisia tabaci larvae treated with oxamyl ( ) 586 and water ( ). Vertical bars indicate the standard error of the mean. 587 588 21 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 Figure 1 615 616 0 5 10 15 20 25 day 3 day 7 day 10 days after treatment % mortality b ab a a b a 22 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 Figure 2 641 642 0 20 40 60 80 100 water indoxacarb methomyl % mortality fresh 24 hours a b c c b a 23 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 Figure 3 677 678 0 20 40 60 80 100 010 20 30 40 50 60 % mortality 0 20 40 60 80 100 010 20 30 40 50 60 days after treatment % mortality A B 24 679 Figure 4 680 681 682 683 684 685 686 687 688 0 20 40 60 80 100 3 7 10 14 21 28 35 42 49 52 days after parasitoid introduction % mortality of whitefly larvae 0 20 40 60 80 100 3 7 10 14 21 28 35 42 49 52 days after parasitoid introduction % mortality of whitefly larvae A B 25 689 690 691 692 Figure 5 693 694 695 696 0 10 20 30 40 3 7 10 14 21 28 35 42 49 52 days after parasitoid introduction % parasitized whitefly larvae 0 10 20 30 40 3 7 10 14 21 28 35 42 49 52 days after parasitoid introduction % parasitoid emergence A B 21 14 10 7 3 100 80 60 40 20 0 28 35 42 49 52 days after parasitoi d introducti on % mortality of whitefly larvae whitefly larvae % mortality of days after parasitoi d introducti on 52 49 42 35 28 21 14 10 7 3 100 80 60 40 20 0 whitefly larvae % mortality of days after parasitoi d introducti on 52 49 42 35 28 21 14 10 7 3 100 80 60 40 20 0 whitefly larvae % mortality of days after parasitoid introducti on 52 49 42 35 28 21 14 10 7 3 100 80 60 40 20 0