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Cotton Insect Pest Management

Randall G. Luttrell,* Tina Gray Teague, and Michael J. Brewer

AbstractCotton production is challenged worldwide by a diversity of arthropod pests that require management to prevent or reduce crop damage. Advances in arthropod control technologies and improved insect and crop management systems have dramatically reduced levels of arthropod damage and the need for insecticidal control of several key pests in cotton over the past 30 yr. The near-complete eradication of boll weevil (Anthonomous grandis Boheman) from the United States and the worldwide deployment of transgenic cottons expressing insecticidal proteins of Bacillus thuringiensis (Bt cot-ton) are among the most notable advances. Insects and mites are highly adaptable, and new pest problems have emerged that continue to challenge or limit cotton production and profitability. In this update of cotton insect pest management, we review evolv-ing technologies for cotton arthropod management, the purposeful deployment of resistance management programs, dynamic responses of arthropod pests to manage-ment actions, and improved integration of insect and crop management systems. We emphasize ecological context, including varying spatial scales of management, and the adaptive capacity of the arthropods impacted by management decisions as continuing influences on humankind’s effort to limit arthropod damage to cotton.

Extraordinary changes in management of insects and mites attacking cotton (Gossypium L.) have transpired since Ridgway et al. (1984) reviewed cotton

protection practices in the previous Agronomy Monograph, Cotton. Reviews pub-lished subsequent to that period (Frisbie and Adkisson, 1985; Frisbie et al., 1989; Luttrell et al., 1994; Luttrell, 1994; Fitt, 1994; Ramalho, 1994; Sugonyaev, 1994; Smith, 1998; Fitt, 2000; Hardee and Harris, 2003; Wu and Guo, 2005; Allen, 2008; Spurgeon, 2008; Wu et al., 2008; Naranjo and Luttrell, 2009) provide detailed information on cotton insects and chronicle changes in insect management strategies in response to new pests, advances in control technologies, and changing management struc-tures associated with insect resistance management and government regulations. Of particular relevance are comprehensive reviews by Matthews and Tunstall (1994), King et al. (1996), and Dickerson et al. (2001).

Abbreviations: IPM, integrated pest management; NAWF, nodes above white flower.

Randall G. Luttrell, USDA-ARS, Southern Insect Management Research Unit, 141 Experiment Station Rd., Stoneville, MS 38776. Tina G. Teague, University of Arkansas, Division of Agriculture and Arkansas State University, 245 Agriculture Bldg., Jonesboro, AR 72467 (tteague@astate.edu). Michael J. Brewer, Texas A&M AgriLife Research, 10345 Hwy. 44, Corpus Christi, TX 78406 (mjbrewer@ag.tamu.edu). *Corresponding author (randy.luttrell@ars.usda.gov).doi:10.2134/agronmonogr57.2014.0072

Copyright © 2015. ASA, CSSA, and SSSA, 5585 Guilford Road, Madison, WI 53711, USA. Cotton. 2nd. ed. David D. Fang and Richard G. Percy, editors. Agronomy Monograph 57.

Published August 6, 2015

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Any modification in production practices or insect management approaches may impact the abundance and diversity of insects in an agronomic cropping system. Cotton production has a long history of evolving insect pest problems—for better or worse—often triggered in reaction to insecticides (Luttrell et al., 1994). Ridgway et al. (1984) concluded “that the world cotton crop will continue to be threatened by insect pests, and insecticides will continue to be essential for protecting the crop.” They also suggested that insecticides could be used more selectively in conjunction with improved surveillance and decision-making approaches. The most important key pests recognized at that time were the helio-thines referred to as Heliothis spp. in the original review [Helicoverpa zea (Boddie), Heliothis virescens (F.), Helicoverpa armigera (Hubner)], pink bollworm [Pectinophera gossypiella (Saunders)], boll weevil, and Egyptian cotton leafworm [Spodoptera literoralis (Boisduval)].

In this current review, we continue to emphasize the ecological context of cotton insect management with a special focus on the adaptive capacity of arthro-pods targeted directly or indirectly by control activities. We also recognize the intricate ecological connections of insects and mites to cotton and the need to integrate pest management practices into more sustainable crop production sys-tems. The managed cotton production environment affords resources that fuel insect and mite population growth. Monitoring plant development and cot-ton plant response to insect injury in conjunction with routine assessments of arthropod populations provides the critical information needed to maintain prof-itable and efficient cotton production. Evolving management practices encourage dynamic pest problems in cotton, and socio-economic influences often define boundaries of management capabilities to address new pest problems. Linkages to private and government research and developments, services, regulations, and incentives have been notable in past advancements of cotton entomology, given cotton’s place as a global commodity and its worldwide cultivation.

Major advancements have been made in the management of the key pests listed by Ridgway et al. (1984). The pest status of all six of those specifically ref-erenced has been dramatically reduced through deployment of new technologies and/or coordinated management systems. Transgenic cottons expressing insec-ticidal proteins derived from Bt cotton have been developed that provide high levels of control of the five lepidopteran key pests listed by Ridgway et al. (1984). The remaining key pest in the list, boll weevil, has been eradicated from much of US cotton and in North America is now only a problem in the Lower Rio Grande Valley and adjoining cotton production areas of Mexico (Allen, 2008). This dra-matic shift in the pest status of key pests reflects significant advances in insect control capabilities and an evolution of crop management practices over the past 30 yr. These changes have led to substantial economic and ecological ben-efits, including reductions in use of traditional broad-spectrum insecticides in many cotton production regions of the world (Naranjo, 2011), but also an ironic increase in other pests released from insecticide control originally targeting key pest species (Lu et al., 2010). In this update of Ridgway et al. (1984), we examine the suggested future management options envisioned in the previous review and provide an overview of additional changes not envisioned in 1984. Just as the original work of Ridgway et al. (1984) has become outdated, we recognize that adaptive insects as well as new technologies and evolving scientific capacity can impact dynamic production systems and will soon render the current review out

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of date. As a benchmark of current approaches, capacity, and concepts, we high-light key changes in the pest complexes, management approaches, and ecological influences that continue to evolve insect management capabilities.

Evolving Technology, Resistance Management, and Dynamic Pest Problems

A number of major insect control technologies were developed over the last three decades that provide superior levels of insect pest control as compared to those available when Ridgway et al. (1984) assessed cotton insect management options. Cotton yields have consistently increased during this period, at least in part because of the plant protection provided by insect management options that include the use of new insecticides and transgenic plants. Production costs also have risen, but to a large extent, increased yield has offset increasing production costs.

A comparison of 1983 and 2013 cotton insect loss data for the United States is provided in both Table 1 and Fig. 1 as an example of the changing status and influence of insect and mite management on cotton production. On the basis of calculations from these data, insect control costs were about US$0.02 per kilo-gram of lint produced for the United States in 1983, a year before the previous review. They were $0.04 in 2013. Adjusting for the US inflation rate of about 134% over this 30-yr period, average insect control costs across this time period are about the same or currently slightly lower, but regional differences illustrate the influence of changing insect pest problems and management options on cotton

Table 1. Comparative percent of crop loss, insect control costs, hectares harvested, and yield of US cotton in 1983 and 2013.†

StateCrop loss to insects Insect control costs Hectares harvested Yield

1983 2013 1983 2013 1983 2013 1983 2013––––––– % ––––––– –––– US$ ha−1 –––– ––––––– ha –––––––– –––– kg lint ha−1 ––––

AL 13.60 4.08 $24.28 $26.75 87,006 145,369 451 947AZ 7.40 5.61 $29.95 $52.99 128,485 66,885 1,193 1,707AR 5.30 7.34 $9.83 $54.94 125,450 128,688 555 1,255CA 3.30 0.32 $7.61 $36.56 390,514 112,501 1,104 1,773FL 15.70 6.43 $55.00 $29.80 3,844 50,585 696 841GA 9.10 3.10 $21.04 $24.72 46,538 540,245 562 947KS –‡ 0.43 – $6.47 – 10,522 – 704LA 9.40 5.34 $23.39 $42.53 165,918 51,799 708 1,513MS 6.50 8.10 $21.89 $63.59 273,158 129,497 717 1,222MO 2.30 5.00 $2.83 $45.22 37,635 105,216 423 1,054NM 20.00 6.92 $6.07 $13.77 24,281 17,101 655 1,401NC 11.50 3.59 $23.07 $27.69 23,876 203,148 410 807OK 17.10 0.87 $15.38 $10.15 121,403 69,645 251 673SC 12.40 3.52 $32.37 $21.81 27,923 103,193 428 785TN 5.60 8.03 $3.44 $27.23 87,006 95,099 375 984TX 7.80 0.74 $3.93 $12.84 1,344,664 1,335,438 377 687VA 9.00 1.25 $10.12 $18.59 121 33,791 359 1,121United States(all states)

7.67 2.68 $10.52 $24.93 2,887,823 3,198,721 574 902

† Calculated from survey data reported by Head (1984) and Williams (2014) unadjusted for inflation. The cumulative inflation rate during this 30-yr period was approximately +130%, making the United States (all states) insect control cost similar across this 30-yr period.

‡ No cotton production statistics were reported for Kansas in 1983 (Head, 1984).