The susceptibility of late instar pink bollworm (PBW), Pectinophora gosspiella (Saunders), larvae to two species of Steinemema was evaluated in small scale field tests in spring and summer of 1993. In the spring PBW mortality at 15 infective juveniles /cm² for S. carpocapsae and S. riobravis was 87 and 89 %, respectively. In midsummer, mortalities with S. riobravis were significantly greater than with S. carpocapsae at the four concentrations tested. A simple method was developed for small scale field testing and efficacy monitoring for PBW and other soil associated insects.

A large scale for the control of sweetpotato (silverleaf) whitefly, Bemisia tabaci, (SPW) was carried out in Paloma and Painted Rock near Gila Bend, Arizona, on approximately 6,156 ha of cotton during the 1993 season. Within the program area 40 fields were randomly selected for comparison with 15 fields in each of 2 locations outside the program. They were identified as check east (approximately 11 k northeast of the program) and check west (approximately 3 k west of the program). Whitefly populations in both check areas were controlled according to individual grower protocol. On a weekly basis, adult counts were taken from all 4 edges and the centers of each field using the oil pan technique. Insecticides were applied aerially in the program area on the full field or edges based on population density recorded from pan samples. Insecticide combinations were rotated weekly in an attempt to reduce the potential for the development of pesticide resistance. During the 16 -week evaluation period SPW adults were significantly higher in check east and check west than the program area by 2- and 6-fold respectively; eggs were higher by 3- and 39 fold, respectively; and nymphs were also significantly higher in check east and check west by 3- and 60-fold respectively. Ginning records for 1993 indicate approximately a 20% increase in yield in the program area a 5% increase in check east and a 40% decrease in check west as compared to 1992. These results demonstrate that an area -wide approach, utilizing edge treatment where possible, based on extensive field sampling regimens represent an important integrated strategy in a successful whitefly control program.

An extension supported, grower controlled, community pest management group was initiated in the Laveen and Tolleson communities of Arizona with the management of sweetpotato whitefly (SPWF) as its initial focus. The three functions of this group were awareness, communication, and cooperation. Increased awareness and communication of pest management problems and solutions were achieved through regular meetings and newsletters. Community cooperation took the form of a community-based overwintering survey and a sticky trap network. These two cooperative activities served both an educational and a research function. From the overwintering survey and the sticky trap network, growers learned about the overwintering habits and movement dynamics of whiteflies in their area, the limits of sticky traps for SPWF detection, the need for the reduction of SPWF populations before they move onto cotton. and the need for careful infield sampling of SPWF populations.

Fixed-precision numerical and binomial sequential sampling plans are reported for adults of Bemisia tabaci (Strain B) on cotton. Both plans are based on whole leaf sample units from the fifth mainstem node (counted from the terminal). Numerical sampling plans allow for the efficient estimation of adult population density. Numerical sampling stop lines are presented relating the cumulative number of adults counted to the number of leaves examined for two levels of statistical precision. Binomial plans were developed to allow classification of adult population density for pest management decision -making application. These plans were devised for three action threshold levels; 5, 10 or 15 adults per leaf Binomial sampling stop lines are presented relating the cumulative number of infested leaves to the number of leaves examined as an aid for determining the need for population suppression.

Three field tests were set -up for evaluation of action threshold levels for sweetpotato whitefly control with two different chemical combinations. The thresholds used to initiate treatments were ca. 1, 10, and 25 adult whiteflies per leaf designated as "early ", "moderate ", or "late ". Immatures were present during these treatment initiation points at the rate of ca. 5 nymphs and ca. 10 eggs per sq.in. in the 'early' plots, 15.3 nymphs and 39.1 eggs per sq.in. in the 'moderate' plots, and 52.1 nymphs and 299.3 eggs per sq.in. in the 'late' plots. The insecticides used included a pyrethroid combination [Danitol® (.1 lb a.i/A) + Orthene® (.5)] and a non-pyrethroid combination [endosulfan(.75) + Ovasyn® (.25)1 Applications were by ground, broadcast, over-the-top, at 20 GPA. Populations were monitored as whitefly adults (leaf turns & net sweeps) and nymphs and eggs (leaf counts). Once applications were triggered, they continued ca. weekly. The early threshold required seven applications, starting 10 July, and produced yields (4038.8 lbs seed cotton/A) which were 2 or 3 times larger than the untreated check (1589.3 lbs seed cotton/A). Lint or leaf stickiness was not apparent; however, 2 or 3 sprays were required before any significant differences in whitefly populations could be found. Whitefly numbers were lowered significantly in both insecticide regimens, with somewhat lower numbers present in the pyrethroid treated plots. The late threshold was sprayed only twice, starting 12 August, and yielded no more cotton (1719.2 lbs seed cotton/A) than the untreated check (1395.0 lbs seed cotton/A). Lint and leaf surfaces were covered in stickiness and sooty mold. Whitefly populations were excessive and led to premature cut -out and poor fruit retention. The moderate threshold (10 adults per leaf) received five applications, starting 22 July, and produced high yielding and high quality cotton (3462.2 lbs seed cotton/A). Some stickiness and sooty mold growth was observable only on the lowest leaves. This was a result of limited honeydew production prior to the threshold and well before any boll opening. Lygus populations were extremely high and caused large differences in yields which favored the pyrethroid combination slightly and the earliest threshold significantly. Given commercial farm control realities (e.g., delays in sampling or application, differences in coverage or application, variable efficacy), the ideal threshold for initiation of treatments is likely between 1 and 10 adults per leaf.

A season long pesticide rotational system for cotton management of Bemisia tabaci (Gennadius) (SPWF) was put in place. The system tried to minimize pesticide impact on midseason build -up of beneficials against SPWF. SPWF thresholds were used to begin use of "potent, efficient" insecticides to stop exponential increase of SPWF in late season. Insecticide class rotation was a key element of the system to prevent insecticide resistance. Comparisons between test blocks and best agricultural practices for rest of field showed that SPWF eggs and large immature of September populations, yields (2.68 bales /Ac), and beneficials were about the same among the blocks. The cotton was free of stickiness in the entire field.

Four cotton varieties, each differing in leaf pubescence, and three nitrogen (N) levels were investigated for effects upon development of SPWF populations. The N treatments appeared to have no effect upon population development. However, there was a direct correlation of increased SPWF numbers with increased hairiness. Both DPL 5415 and SALCOTIO had significantly lower seasonal means of all stages than did the more hairy varieties of CB1135 and STV453.

The cotton leafperforator (CLP) Bucculatrix thurberiella Busck. is a sporadic pest in cotton fields of southwest desert area. The cotton leafperforator sex pheromone was identified and synthesized by Hall et al. (1992), thus providing a sensitive method for detecting CLP moths. Tests were conducted in 1992 and 1993 to determine the effective life of CLP polyethylene pheromone dispensers, correlate CLP male moth catches to cotton field infestations, determine the seasonal distribution, and effect of trap height on moth catches. The polyethylene pheromone dispensers were effective for about 4 weeks. The best correlation coefficients for 1993 data, were obtained by comparing CLP moth catches per night to main stem leaf damage at 6 node position from top of plants at field edges. Horseshoe stage CLP per leaf and trap catches had the highest correlation coefficient, r= 0.78. There was more than twice as much CLP damage to leaves at field edges when compared to leaves 10 m into the field. The first CLP moth capture occurred in early to late July and increased rapidly each year in August to 100 to 200 per trap night, but was variable in September, with a high of 300 and a low of 9 per trap night. CLP- baited delta traps placed 0.3 m above ground caught more moths than traps placed at greater heights from 11 to 21 August.

Two rates of buprofezin and a combination, buprofezin + endosulfan, were compared against Ovasyn® and the standard pyrethroid combination Danitol® + Orthene®. Targeted pests were all stages of the sweetpotato whitefly (SPWF). Danitol + Orthene was the most effective treatment against all SPWF stages. All buprofezin treatments, including the buprofezin + endosulfan combination, were moderately effective against all SPWF stages relative to the untreated check, while Ovasyn had control levels similar to the untreated check. Danitol + Orthene had the highest yield at 4030.2 lbs seed cotton/A, and buprofezin + endosulfan had the second highest yield, 2172 lbs/A. All other treatments yielded amounts similar to the untreated check, 863.0 lbs/A. Effects of these control practices on beneficial and other non- target arthropods have not yet been analyzed. Lygus populations were extreme in this test and favored the Danitol + Orthene treatment over the SPWF -specific buprofezin treatments.

Various registered and experimental insecticides were evaluated for sweetpotato whitefly (Bemisia tabaci Gennadius) control in several field experiments at Yuma, Arizona in 1994. Best controls were obtained with insecticide mixtures, particularly a pyrethroid and an organophosphate, rather than with individual materials. Results of these experiments indicate that severe population densities can be controlled using insecticide combinations, even though sustained use of these insecticides would probably lead quickly to the development of resistance.