Non-Chemical Control of Bollworm and Pink Bollworm in Cotton and Automated Insect, Plant and Profit Analysis

Non-Chemical Control of Bollworm and Pink Bollworm in Cotton and Automated Insect, Plant and Profit Analysis

Summary

Objectives
1.To integrate and test non-chemical insect control factors for cotton insect control.
2.Furnish growers with a immediate management information which can be used to predict future events.
3.To furnish ecological data which can be used to expand our understanding of community structure and function within the economic structure and time dictated by crop production

Abstract
The broad objective of this research was to test a portable pest management system which can be quickly integrate biological attributes of relevant plant and animal species in extensive agricultural ecosystems over large land masses. An overview of the important features of crop production (fertilizer, soil, moisture, pesticides, weather, plant phenology, migration, distribution and parasite/predator interactions) in relation to arthropod population dynamics in both relatively simple and complex agricultural ecosystems, can be obtained. This system offers a new approach to the management of pest populations.

Computer Vision software has been developed that is capable of classifying a variety of pests and beneficial insects from digital images of field samples. The software currently performs with an approximate average error rate of 12 percent in an open-world sense (actual operating conditions) and 0.5 percent in a closed-world sense but improvement is expected with careful selection and evaluation of new feature measurements. This software can greatly enhance the efficiency of field scouts, researchers and growers in making rapid management decisions.

Our research to reduce hard, environmentally less friendly insecticides involved testing four insecticides on Acala 1517-91 cotton to evaluate the toxicity on the beneficial complex. The insecticides used were Tracer, a biological insecticide, Regent, a new class of insecticides, Confirm, an ecdysome-mimic insect growth regulator, and Karate, used as a standard. Confirm, Regent, Tracer did not reduce the total density of the beneficial complex in cotton. Confirm was the softest insecticide on the beneficial complex. Tracer at higher dosages showed some efficacy on parasitoids. Nabids were sensitive to all treatments; however assassin bugs and collops beetles seemed to be unaffected by all treatments. Karate significantly reduced the density of 10 species of beneficials and promoted secondary outbreaks of cotton aphids.

Early season control of pink bollworm (PBW) with pheromones was demonstrated on 35 acres of upland cotton that in previous years had 40 to 75 percent infestation. Plant phenology was monitored weekly to evaluate the stage of the plant that was most susceptible to early season pink boll worm infestations. Emergence of PBW prior to first square are suicidal and reducing overwintering emergence with pheromones limited the initial early season infestations allowing fruiting structures to mature. Mature bolls are less attractive to PBW infestation. Eliminating insecticides early season also maintained a balance of beneficial insects, keeping secondary pests in check. Pheromone applications prior to first square decreased infestation to less than 4 percent. Late in the season (September) pheromone applications were less effective when higher densities of pink bollworm existed. Timing of one or two late season applications of insecticides reduced repeated insecticide applications and increased yield. Cotton that received only one (timed) application of insecticide with no early season pheromone and early termination with defoliant averaged 8 percent PBW infestation. Cotton left untreated (receiving only a defoliant for termination) averaged 35 to 45 percent PBW infestation. Cotton receiving repeated applications of insecticide sustained 8 percent PBW infestation but caused secondary aphid outbreaks which required additional treatments.

Timing of planting and harvesting plays a major role in the ability of pink bollworms to overwinter successfully. Cotton planted early and harvested late provides the best scenario for increased overwintering development. To determine which times are optimal for planting and termination of cotton pink bollworm larvae were collected from cotton bolls weekly late season and retained in cups and maintained at a constant temperature. Those that remained as larvae at the end of the season were considered to be in diapause and those that emerged as adults moths were not. Date of emergence, variety of cotton and sex of larvae were recorded. Adult PBW begin emerging around mid April, this population is suicidal until squares are available. Delayed planting delays squaring but not significantly. Delaying the first irrigation also aids in delaying squaring. This enhances the suicidal emergence of PBW. Moths begin an early diapause about mid-September, peaking mid to late October and diminishing in early November. Those moths that entered diapause in October were successful in completing development the following year when squares were present. Those that entered diapause earlier and later than that period were less successful, mostly the suicidal population. Maturing and terminating the cotton crop in early October could significantly reduce the overwintering population in successive years. Integrated with a pheromone program, PBW could be managed to reduce cost and environmental hazards.

Cotton interplanted with four varieties of refugia to maintain a reservoir of beneficial insects was evaluated. Refugia were alfalfa, canola, sanfoin and hairy vetch. Samples were taken frequently to evaluate the density of beneficial insects in the refugia. Sanfoin and canola had the highest density of beneficial insects. The refugia attracted parasitoids, some of which could be effective in controlling pink bollworm and bollworm. The hymenoptera families with the highest densities were: Mymaridae, Braconidae, Eulophidae and Pteromalidae. The more abundant groups of predators were Nabis spp, Geocoris spp, Orius spp, Collops spp and Coccinelids. The refugia planted next to cotton acted more as a sink for beneficial insects and may require additional management such as timely mowing to promote migration from the refugia to the cotton.

Two types of PBW pheromone traps (standard delta trap and oil trap) were evaluated for efficiency and effectiveness for use as a management decision making tool. Although trap catches cannot be correlated to infestation in the field, trap catches do characterize initiation and duration of effectiveness of pheromone applications.

Bt cotton plants were transplanted (six true leaf stage) into blocks of newly seeded upland cotton (20%:80%, respectively) to provide an attractive food source for overwintering PBW and bollworm. Our results with transgenic Bt cotton showed that cotton transplants did not impact PBW and bollworm infestations significantly. Damage to upland 1517 was apparent (8% to 24%), whereas the Bt cotton sustained incomplete infestation (penetration of larvae halted at the carpel wall, where mortality of first instar larvae occurred). Although there was some level of PBW and bollworm mortality, the effect of the interplanted crop on the general population was limited.

A pamphlet relating present and past results will be distributed to growers at local meetings by extension agents. This pamphlet will detail management strategies growers can use for pink bollworm and bollworm control in IPM systems.

Submitted to the Journal of Cotton Science: "Comparison of two pheromone traps, delta sticky trap and high capacity oil, for effectiveness and sensitivity in captures of pink bollworm Pectinophora gossypiella, (Sanders)"

Economic Analysis
Approximately 20,000 acres of cotton are grown in and around the Mesilla Valley. An average "hard" insecticide application may range from $12.00 to $15.00 per acre, excluding any long term health and environmental cost. A rigid non-chemical control program can save growers three to four applications of insecticides ($36.00 to $60.00/acre). Early season pheromone and "soft" insecticide applications minimize the impact of hard insecticide applications further reducing health and environmental risks.

Farmer Adoption and Direct Impact
Organic growers and progressive growers have adopted and implemented some IPM practices. Pink bollworm and bollworm control are expected to be confounded by a region wide boll weevil (BW) eradication program being proposed for this area. Incorporation of some of these results may be imperative for a successful eradication program. The eradication program as presently envisioned will involved intense repeated applications of insecticides. Providing growers with alternative methods of PBW control will substantially minimize insecticide applications, enhancing chances for total eradication.
Reported in 1998