VOL. 34, NO. 3 SOUTHWESTERN ENTOMOLOGIST SEP. 2009

Effect of Two Insecticides on Hickory Shuckworm¹ (: ) and Predators of Pests

Francisco Javier Quiñones-Pando2, Socoro Héctor Tarango-Rivero2, and Carlos A. Blanco3

Abstract. Tebufenozide and chlorpyrifos were evaluated in the laboratory and field to find an insecticide more compatible with integrated pest management for pecan, Carya illinoinensis (Wangenh.) K. Koch. Different developmental stages (eggs, larvae, and/or adults) of six predators of pecan aphids were exposed to the insecticides. Control of hickory shuckworm, caryana (Fitch), by the insecticides and selectivity to native predators of pecan aphids were also tested in commercial orchards. Tebufenozide had no significant adverse effect on coccinellids, but killed eggs of the lacewings Chrysoperla rufilabris (Burmeister) and adults of Chrysoperla carnea Stephens. Chlorpyrifos was very toxic to all stages of crysopids, exhibiting ovicidal activity on multicolored Asian lady , Harmonia axyridis (Pallas). Both insecticides were effective in controlling hickory shuckworm in the field. Tebufenozide applied in orchards was innocuous, while chlorpyrifos killed beneficial . Chlorpyrifos significantly reduced the number of blackmargined aphids, Monellia caryella (Fitch). Tebufenozide because of its effectiveness in controlling hickory shuckworm and less detrimental impact on beneficial fauna is recommended rather than chlorpyrifos for integrated pest management. Also, tebufenozide is less toxic to human health and the environment.

Resumen. Los insecticidas Tebufenozide y chlorpyrifos fueron evaluados con el fin de determinar cuál de ellos es más afín a un programa de manejo integrado de plagas de nogal pecanero, Carya illinoinensis (Wangenh.) K. Koch. Diferentes estados de desarrollo (huevos, y/o adultos) de seis depredadores de áfidos de nogal fueron expuestos a estos insecticidas en el laboratorio, así como la efectividad de estos insecticidas en aplicaciones comerciales a huertos para controlar la plaga barrenador del ruezno, Cydia caryana (Fitch), y su selectividad a los depredadores de áfidos del nogal en el campo. Tebufenozide no mostró un efecto adverso en los coccinélidos pero causó mortalidad en huevos de alas de encaje Chrysoperla rufilabris (Burmeister) y adultos de Chrysoperla carnea Stephens. El insecticida chlorpyrifos fue bastante tóxico para todas las etapas de desarrollo de alas de encaje, teniendo también un efecto ovicida en la catarinita Harmonia axyridis (Pallas). Ambos insecticidas controlaron satisfactoriamente al ______1Cydia caryana (Fitch). 2Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias (INIFAP), Campo Experimental Delicias, km 2 carr. Delicias-Rosales; Cd. Delicias, Chihuahua, 33000 México. 3U.S. Department of Agriculture, Agricultural Research Service, Southern Management Research Unit, Stoneville, MS 38776. 141 Experiment Station Road, Stoneville, MS 38776. To whom correspondence should be addressed [email protected].

227 barrenador del ruezno. El uso de tebufenozide en huertos no tuvo un efecto adverso en los depredadores, mientras que chlorpirifos sí abatió a éstos, aunque este insecticida también redujo el número de áfidos amarillos de alas con márgenes negras Monellia caryella (Fitch). Debido a que tebufenozide fue efectivo contra el barrenador del ruezno y no redujo la fauna benéfica del nogal pecanero, su uso es más recomendado que el de chlorpyrifos en un programa de manejo integrado de plagas. Además, tebufenozide es menos tóxico a la salud humana y el ambiente.

Introduction

The State of Chihuahua produces most of the , Carya illinoinensis (Wangenh.) K. Koch, in Mexico on approximately 36,000 hectares. The crop is managed intensively, and use of insecticide accounts for 15% of production costs (Puente 2002). Blackmargined aphid, Monellia caryella (Fitch), and Tinocallis caryaefoliae (Davis) (Hemiptera: Aphididae) were the main pests of pecan in the 1970s. Control of these pests required the use of organophosphate and pyrethroid insecticides. Since then, the hickory shuckworm, Cydia caryana (Fitch), became an important pest in southern Chihuahua and is considered now the key pest throughout the state (Rojo and Cortes 1997). Aphids are problematic on pecans but are effectively controlled by native entomofauna when not disrupted by broad-spectrum insecticides (Tarango-Rivero and Chavez 1997, Tarango-Rivero et al. 2001). Such natural control is achieved by beneficial insects that demonstrate a density-dependent response to the number of aphids. The most important species of beneficials are Olla v-nigrum (Mulsant); convergent lady beetle, Hippodamia convergens Guerin-Meneville; Scymnus loewii Mulsant (Coleoptera: ); Chrysoperla carnea Stephens and Chrysopa nigricornis Burmeister (Neuroptera: Chrysopidae); Deraeocoris sp. (Hemiptera: Miridae); and several spider species (Tarango-Rivero et al. 1995). The predators Chrysoperla rufilabris (Burmeister) (Neuroptera: Chrysopidae) and multicolored Asian lady beetle, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), are released as biological control agents. Currently, the impact of natural enemies of hickory shuckworm in the region is not known. Excessive use of insecticide on pecans in Chihuahua resulted in resistance by blackmargined aphids (Quiñones-Pando and Flores 1990), and now it is common to observe resurgence of this pest after application of non-selective insecticides (Quiñones-Pando 1997). In recent years, the pest complex became more difficult to manage by natural enemies and/or pesticides, resulting in greater production costs because of the pecan nut casebearer, Acrobasis nuxvorella Neunzing (Lepidoptera: Pyralidae), and its distribution into most of the orchards of the state, together with abundant pentatomids and coreids. In Chihuahua, natural control of pecan nut casebearer can reach 64% by parasitism of pupae by three species of hymenopterans (Tarango-Rivero et al. 2003). Parasitism of aphid eggs can fluctuate between 20 and 100% (Tarango unpublished). An integrated pest management program, dependent on biological control, will greatly benefit the region if an efficacious and selective insecticide is used to control hickory shuckworm and pecan nut casebearer as well as aphids. A selective insecticide, tebufenozide, now is available for use on pecans in Mexico. Larvae that ingest this Lepidoptera-specific insecticide increase the amount of ecdysone in their hemolymph, which triggers a premature and defective molting process, and at the same time does not allow release of the eclosion

228 hormone. Larvae that ingest the insecticide are trapped between the new and old cuticles. Affected insects stop feeding 4-16 hours after ingesting tebufenozide. Death occurs hours to days later, depending on the insect species, developmental stage, and temperature (Friedländer and Brown 1995, Retnakaran et al. 1995, Dhadialla et al. 1998, Beckage 2000). Tebufenozide is efficacious for control of Lepidoptera and selective to biological control organisms. Brown (1994) reported that injection of tebufenozide into larvae of the codling , Cydia pomonella (L.) (Lepidoptera: Tortricidae), did not produce physiological effects on an endoparasitoid that developed inside the . No effects were noticed on an ectoparasitoid when larvae or adults were fed treated codling moth larvae. Other bioassays with Cotesia plutellae Kurdjumov and C. marginiventris (Cresson) (Hymenoptera: Braconidade) (Legaspi et al. 1999); insidious flower bug, Orius insidiosus (Say) (Hemiptera: Anthocoridae) (Pietrantonio and Benedict 1999); and C. flavipes (Cameron), Allorhogas pyralophagus Marsh, Catolaccus grandis (Burks), and cacti L. (Legaspi et al. 2000) demonstrated no adverse effect by tebufenozide. However, sublethal effects have been identified. For example, fecundity of Geocoris punctipes (Say) (Hemiptera: Lygaeidae) was less (Elzen and Elzen 1999), and Rumpf et al. (1998) found that tebufenozide at recommended doses did not affect Micromus tasmaniae (Walker), but increasing the concentration of the insecticide 10 times resulted in fewer eggs laid per female. The effect of tebufenozide and chlorpyrifos was evaluated on hickory shuckworm and important naturally occurring and introduced predators of pecan aphids in the laboratory and field.

Materials and Methods

One- or 2-day-old eggs, third-instar larvae, and >3-day-old adults of the following six predators of pecan aphid were bioassayed at INIFAP (Instituto Nacional de Investigaciones Forestales y Agrícolas y Pecuarias [National Institute of Forestry Agricultural and Research]) Campo Experimental Delicias, Ciudad Delicias, Chihuahua, Mexico. Eggs, larvae, and adults of the multicolored Asian lady beetle were obtained from a laboratory colony at INIFAP. The insect was reared in 9-cm Petri dishes for development of larvae and pupae and 21 x 21 x 8.5-cm cages for adults where they oviposited on sewing thread and were fed 0.048 ml of eggs of Angoumois grain moth, Sitotroga cerealella (Olivier), and 20% honey every other day (Tarango-Rivero and Quiñones-Pando 2001). Pupae and adults of O. v-nigrum were obtained from nearby pecan orchards. Rearing this insect was similar to that for multicolored Asian lady beetle. F1 individuals were used. Convergent lady beetle adults were collected from pecan orchards and fields of alfalfa, Medicago sativa L. The diet was the same as that of the species described previously. Eggs of C. carnea were obtained from a local beneficial insect laboratory. Larvae and adults were maintained as described for multicolored Asian lady beetle. Eggs of C. rufilabris were produced at Rincon Vitola Insectaries (Oak View, CA) and supplied by Biotecno S. A. Rearing was the same as for multicolored Asian lady beetle. Field-collected eggs of C. nigricornis produced larvae and adults used in bioassays (F0). Eggs were not used because of parasitism (>80%).

229 Treatments used in bioassays and field tests were 1) tebufenozide (Confirm® 2F) applied at 0.6 ml (0.14 g of active ingredient) per liter of final solution, 2) Chlorpyrifos (Lorsban® 480 EM) at 1.5 ml (0.72 g A.I.) per liter, and 3) water (nontreated check). Latron® B-1956 at 0.5 ml per liter of final solution was added to the three treatments. Bioassays were on 15-20 coccinellid egg masses glued to sewing thread as described by Mizell and Schiffhauer (1990). Masses were dipped for five seconds into one liter of treatment solution and left to air dry on a paper towel in front of a fan. Each sewing thread was placed into a nontreated 30-ml plastic cup with small holes at the base and top to aid air circulation. The cups were suspended from the middle on carton grids, leaving the top and bottom not touching any surface. Larvae and adults of coccinellids and crysopids were placed into 30-ml plastic cups previously immersed in the treatment solutions and air dried as described previously. Larvae and adults were put into a treated cup and fed 0.028 ml of nontreated eggs of Angoumois grain moth. Crysopid eggs were placed on 1.5 x 1.5-cm Tuk® tape with glue on both sides, immersed into the respective treatment solution for five seconds, left to air dry, and put into nontreated plastic cups. Ten replications of each of four experimental units (egg masses of coccinellids, individual crysopid eggs, larvae, or adults) were tested. For tests of eggs, larval eclosion and dispersal (larva walking away from the chorion) were evaluated three times daily for 3 days. For tests of larvae and adults, the numbers of dead was recorded at 24, 48, and 72 hours after the initiation of the bioassays. In tests where insects of the check died (statistically significant differences), data were corrected according to Abbott (1925). Two pecan orchards were used. One orchard (El Arete) of 22 hectares, planted with Western and Wichita varieties of pecan trees was divided into plots 13 rows wide by 28 rows long to include both varieties in each treatment. Treatments consisted of approximately 325 trees each. With every plot and variety, a wing trap (Zoecon®) with pheromone (Zoecon®) for hickory shuckworm was installed on 1 July at 8-m high, on the northeastern side of the canopy and in the middle of the drip zone (Quiñones-Pando et al. 1994) to capture adults. Insecticides were applied by air on 15 September using 120 liters per hectare 6 days after the pheromone traps captured more than three adults per day on four consecutive nights. One day before application, seven Western variety trees were selected in the middle of each plot. On each tree, two compound leaves from different branches of growth from the current year were labeled. The numbers of yellow aphids and beneficial insects in the terminal shoot (including shoot, leaves, and fruits) were recorded. Abundance of aphids and beneficial insects were evaluated four times at 4-day intervals after application of insecticide. On 30 September (shuck opening), five clusters with five nuts each were removed from eight trees of each variety. Clusters were taken to the laboratory to determine the percentage of damaged shuck and shell caused by hickory shuckworm. A second orchard (Santa María) was divided into three plots: a) ‘plot 485’ of 22.7 ha sprayed on 5 July, b) ‘plot 450’ of 16.3 ha sprayed on 29 July, and c) nontreated check ‘plot 480’ of 17.3 ha. Tebufenozide, the only insecticide treatment used in the orchard, was applied with an air blaster mixing 600 ml of commercial product in 1,000 liters of water and 500 ml of ADH adjuvant, delivering 1,000 liters/ha. Effect of this insecticide was evaluated on O. v- nigrum, convergent lady beetle, green lacewings (Chrysoperla spp. and Chrysopa sp.), and on T. caryaefoliae and blackmargined aphids. Predators were counted on a terminal shoot. Also, aphids in a compound leaf of 30 Western variety trees per

230 treatment were recorded. Data were recorded 0, 7, and 14 days after application of insecticide. Data were analyzed as a completely randomized design using SAS (SAS Institute 1988).

Results

Bioassays. Tebufenozide was innocuous to coccinellid eggs, with no significant differences in hatching or dispersal of larvae as compared to the effect that water plus adjuvant might have produced (Table 1). The insecticide slightly affected the dispersal of recently hatched C. rufilabris. Chlorpyrifos had an ovicidal effect on multicolored Asian lady beetle and a lesser effect on O. v-nigrum, which tends to remain in contact with its own chorion for several hours after eclosion, offering more contact time with the contaminated surface. The impact of chlorpyrifos on the two species of chrysopids was similar; most recently hatched larvae died in contact with the chorion.

Table 1. Mortality (%) Produced by Tebufenozide and Chlorpyrifos on Eggs of Four Predators of Pecan Aphids Eclosion and larval Eclosion and larval Failure to Treatment dispersala mortalityb hatch Harmonia axyridis Nontreated 100 a 0.0 0.0 b Tebufenozide 100 a 0.0 0.0 b Chlorpyrifos 0.0 b 0.0 100 a P > F 0.0001 -- 0.0001 Olla v-nigrum Nontreated 100 a 0.0 b 0.0 Tebufenozide 100 a 0.0 b 0.0 Chlorpyrifos 10.0 b 80.0 a 10.0 P > F 0.0001 0.0001 0.3811 Chrysoperla carnea Nontreated 90.0 a 0.0 b 10.0 Tebufenozide 80.0 a 5.0 b 15.0 (5.5)c Chlorpyrifos 5.0 b 80.0 a 15.0 (5.5) P > F 0.0001 0.0001 0.7278 Chrysoperla rufilabris Nontreated 100 a 0.0 b 0.0 b Tebufenozide 85.0 b 15.0 b 0.0 b Chlorpyrifos 0.0 c 87.5 a 12.5 a P > F 0.0001 0.0001 0.0010 Means followed by the same letter in a column are not statistically different at P = 0.05 (Tukey). aEclosion and dispersal = hatched larvae remained for a period of time on the chorion, then walked on the cup surface. bEclosion and dead = hatched larvae remained for a period of time on the chorion and died there. cCorrected mortality (in parenthesis) using Abbott’s formula.

231 The effect on larvae was similar to the previously described general pattern. No larvae died when tebufenozide was used and all larvae were dead after the first 24 hours of exposure to chlorpyrifos, except O. v-nigrum with 2.5% survival after 72 hours (Table 2). According to a scale by Pietrantonio and Benedict (1999), chlorpyrifos with 75% mortality was slightly toxic to this predator during the first 24 hours and very toxic at 48 hours and after. This insecticide was also toxic during the first 24 hours to the other predators.

Table 2. Larval Mortality (%) of Five Species of Predators of Pecan Aphid Exposed to Tebufenozide and Chlorpyrifos Exposure time (hours) Treatment 24 48 72 Harmonia axyridis Not treated 0.0 b 2.5 b 10.0 b Tebufenozide 0.0 b 0.0 b 0.0 b Chlorpyrifos 100 a 100 a 100 a P > F 0.0001 0.0001 0.0001 Olla v-nigrum Not treated 0.0 b 0.0 b 5.0 b Tebufenozide 2.5 b 7.5 b 10.0 (5.3)a b Chlorpyrifos 75.0 a 97.5 a 97.5 (97.4) a P > F 0.0001 0.0001 0.0001 Chrysoperla carnea Not treated 0.0 b 0.0 b 0.0 b Tebufenozide 0.0 b 0.0 b 0.0 b Chlorpyrifos 100 a 100 a 100 a P > F 0.0001 0.0001 0.0001 Chrysoperla rufilabris Not treated 0.0 b 7.5 b 17.5 b Tebufenozide 0.0 b 0.0 b 0.0 c Chlorpyrifos 100 a 100 a 100 a P > F 0.0001 0.0001 0.0001 Chrysopa nigricornis Not treated 0.0 b 0.0 b 0.0 b Tebufenozide 0.0 b 0.0 b 0.0 b Chlorpyrifos 100 a 100 a 100 a P > F 0.0001 0.0001 0.0001 Means followed by the same letter in a column are not significantly different at P > 0.05 (Tukey). aCorrected mortality (in parenthesis) using Abbott’s formula.

Adult O. v-nigrum and multicolored Asian lady beetle were not affected by tebufenozide during the 72 hours of the bioassays (Table 3). Convergent lady beetle showed a slight, not significant, effect to the insecticide that might be attributed to experimental error. The first two species of predators were greatly affected by chlorpyrifos. The convergent lady beetle was affected to a lesser

232 degree, with many dead but never reaching 100% mortality as did the other predators. Only C. carnea exhibited slight sensitivity to tebufenozide, resulting in corrected morbidities of <20%. Adult mortality produced by chlorpyrifos was similar to the effect on the larvae of these species -- 100% mortality after only 24 hours. Evaluation in the Field. Tebufenozide controlled hickory shuckworm, with only 3.5% damaged shuck and 2.5% damaged shell of the Western variety of pecan (Table 4). Chlorpyrifos had no treatment effects but 17 and 7% of the previously described damage. A possible explanation might be that Confirm insecticide has longer residual effect (Retnakaran et al. 1995), important because of the long oviposition period of this pest (Tarango-Rivero and Nava 1998).

Table 3. Mortality (%) of Adults of Six Species of Predators of Aphids Exposed to Tebufenozide and Chlorpyrifos Exposure time (hours) Treatment 24 48 72 Harmonia axyridis Not treated 0.0 b 0.0 b 0.0 b Tebufenozide 0.0 b 0.0 b 0.0 b Chlorpyrifos 100 a 100 a 100 a P > F 0.0001 0.0001 0.0001 Olla v-nigrum Not treated 0.0 b 2.5 b 2.5 b Tebufenozide 0.0 b 0.0 b 0.0 b Chlorpyrifos 97.5 a 100 a 100 a P > F 0.0001 0.0001 0.0001 Hippodamia convergens Not treated 0.0 b 2.5 b 7.5 b Tebufenozide 2.5 b 2.5(0) b 5.0 b Chlorpyrifos 77.5 a 92.5 (92.3)a a 95.5 (94.6) a P > F 0.0001 0.0001 0.0001 Chrysoperla carnea Not treated 0.0 b 5.0 b 17.5 c Tebufenozide 2.5 b 5.0 (0) b 32.5 (18.2) b Chlorpyrifos 100 a 100 a 100 a P > F 0.0001 0.0001 0.0001 Chrysoperla rufilabris Not treated 0.0 b 0.0 b 10.7 b Tebufenozide 3.6 b 7.1 b 17.9 (8.1) b Chlorpyrifos 100 a 100 a 100 a P > F 0.0001 0.0001 0.0001 Chrysopa nigricornis Not treated 0.0 b 7.5 b 7.5 b Tebufenozide 0.0 b 0.0 b 10.0 (2.7) b Chlorpyrifos 100 a 100 a 100 a P > F 0.0001 0.0001 0.0001 Means followed by the same letter in a column are not significantly different at P > 0.05 (Tukey). aCorrected mortality (in parenthesis) using Abbott’s formula.

233 Table 4. Damage (%) by Cydia caryana to Two Pecan Varieties Using Two Insecticides and a Nontreated Check, El Arête Orchard, Cd. Delicias, Chihuahua, 2000 Treatment Damaged shuck (%) Damaged shell (%) Western Not treated 16.5 a 7.5 Tebufenozide 3.5 b 2.5 Chlorpyrifos 17.0 a 7.0 P > F 0.0413 0.1361 Wichita Not treated 43.0 a 18.5 a Tebufenozide 16.0 b 12.0 b Chlorpyrifos 18.0 b 6.0 b P > F 0.0007 0.0294 Means followed by the same letter in a column are not significantly different at P = 0.05 (Tukey).

Wichita pecans were more affected by hickory shuckworm because this variety is attacked earlier in the season (Tarango-Rivero and Nava 1998), causing 43.0 and 18.5% shuck and pecan shell damage, respectively, in the nontreated check (Table 4). Both insecticides were moderately effective on this variety. Insignificant effects were perhaps because of the lateness of the application. These results also support previous findings that this pest should be controlled differently on different varieties of pecan. Monitoring early and chemical control (if necessary) should be used for Wichita pecans, while Western variety should be inspected later. Chlorpyrifos was the only insecticide that controlled aphids, reducing their abundance to §10% only 4 days after application (Table 5). In tebufenozide and check plots, aphids survived for 4-7 days after application of insecticide, but never

Table 5. Effect of an Application of Insecticide on Blackmargined Aphid and Their Predators, El Arete Orchard. Cd. Delicias, Chihuahua, 2000 Days after application Treatment 0 4 7 11 16 Monella caryella/leaf Not treated 2.0 b 6.3 a 5.9 a 1.9 ab 1.3 ab Tebufenozide 2.9 b 4.2 a 3.1 ab 2.9 a 2.7 a Chlorpyrifos 6.2 a 0.5 b 0.6 b 0.7 b 0.7 b P > F 0.002 0.0001 0.0006 0.009 0.026 Predatorsa/terminal shoot Not treated 0.6 1.0 ab 0.6 0.3 0.3 Tebufenozide 1.7 1.8 a 1.3 0.7 0.4 Chlorpyrifos 1.4 0.3 b 0.3 0.3 0.3 P > F 0.073 0.001 0.058 0.272 0.956 Means followed by the same letter in a column are not significantly different at P = 0.05 (Tukey). aOlla v-nigrum, Chrysoperla spp. and Chrysopa sp.

234 reached the action threshold. Later, abundance decreased following a typical density fluctuation influenced by abiotic factors and the effect of predators (Tarango-Rivero et al. 1995). Results from the field differed from what was found in the laboratory. Chlorpyrifos did not significantly reduce the number of predators, when these were grouped as the total number of O. v-nigrum and eggs and adults of lacewings (Tables 6 and 7). Predators were more abundant (only significantly different from chlorpyrifos 4 days after application) in the tebufenozide plots. Application of tebufenozide did not affect the abundance of blackmargined or black aphids, or the aphid predator when compared with the nontreated check.

Table 6. Effect of Application of Tebufenozide Insecticide on Abundance of Aphids (Monellia caryella and Tinocallis caryaefoliae) and Predators, Santa María Orchard, Cd. Delicias, Chihuahua Aphids/compound leaf Predators/terminal shoot Olla Hippodamia Treatment M. caryella T. caryaefoliae Lacewings v-nigrum convergens 1 week after application Not treated 6.6 0.03 0.13 0 0.03 Tebufenozide 6.7 0 0.07 0.13 0

P > F 0.976 0.321 0.398 0.039 0.321

2 weeks after application Not treated 6.8 0.03 0.37 0.07 0 Tebufenozide 3.9 0 0.40 0.03 0

P > F 0.045 0.321 0.853 0.561 .

Table 7. Effect of Application of Tebufenozide Insecticide on Abundance of Aphids (Monellia caryella and Tinocallis caryaefoliae) and Predators, Santa María Orchid, Cd. Delicias, Chihuahua Aphids/compound leaf Predators/terminal shoot Olla Hippodamia Treatment M. caryella T. caryaefoliae Lacewings v-nigrum convergens 1 week after application Not treated 9.5 0.03 1.03 0.17 0 Tebufenozide 7.1 0.1 1.16 0.23 0

P > F 0.128 0.412 0.622 0.564 .

2 weeks after application Not treated 16.2 0.30 0.97 0.30 0.03 Tebufenozide 12.3 0.07 1.23 0.43 0.03

P > F 0.195 0.064 0.511 0.544 0.640

235 Discussion

Tebufenozide effectively controls hickory shuckworm depending on timing of application and pecan variety. Wichita pecans should be monitored early. Western variety should be inspected later in the growing season. The insecticide is also relatively safe for common pecan pest predators, making it an ideal tool for an integrated pest management program with the possibility of biological and chemical control of pests acting simultaneously in the field. This is the least toxic synthetic insecticide available in the Mexican market to date, which fits well into community demands with urban growth spreading into agricultural areas. Chlorpyrifos is moderately effective in controlling hickory shuckworm and pecan aphids for a short time. But because of its great potential for detrimentally affecting beneficial fauna that control other pests and contamination of the environment, its use should be limited. Although chlorpyrifos is not very persistent in the pecan agroecosystem, the abatement of beneficial fauna caused by this non-selective insecticide can persist for a long time. In recent years, abundant aphids in the pecan pest complex have forced growers to use broad-spectrum insecticides, but no insecticide controls lepidopterous and aphid pests simultaneously without problems of pest resurgence and/or contamination of the environment. Therefore, it is important to identify selective insecticides against these pests and/or find the most appropriate time to implement control with less-selective insecticides. We described the important benefits of tebufenozide in the agroecosystem, but because not all pest control should rely on only one alternative or product, other Lepidoptera-active compounds and insecticides that control aphids in a selective way should be identified.

Disclaimer

Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the INIFAP nor the U.S. Department of Agriculture.

Acknowledgment

We are thankful to Ing. Homero Chávez and Mr. Alfredo Chávez for allowing us to work in their orchards. The Comité Estatal de Sanidad Vegetal, Biotecno S.A., Dow AgroSciences (Ing. Oscar Rivera), M. C. Noé Chávez, Luis Carlos Pérez- F., Juan Manuel Martínez F., Dr. Juan D. López Jr., Dr. Julio Bernal, Susana Fredín, and Dr. Bonnie Pendleton made invaluable contributions to this report; we thank them all.

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