Insect damage impacts tremendously on the value of the Arizona cotton crop. As traditional pesticides become increasingly less useful, due to insect resistance and regulatory problems, new methods for insect control are needed. For these reasons, we engineered genes encoding protease inhibitors (PIs) from Manduca sexta (tobacco hornworm), for expression in cotton, with the hope that these inhibitors would have insecticidal activity. Transgenic plants containing PIs have been generated: 22 fertile lines of the duplicated 35S promoter anti-elastase, 4 fertile lines of the anti -chymotrypsin and 5 fertile lines of the anti -trypsin. Over 3,000 T-1 seeds have been collected and T-2 generation seeds are in production. Many crosses have been made into Delta Pine 16, 90 and 5415 respectively. No significant effect of the PIs on boll number or seed yield was observed. Insect tests have been conducted and the results indicate that plants expressing the protease inhibitors (PI's) have decreased emergence of whiteflies compared to control plants. We believe this research is a significant step towards a bio- pesticide producing Arizona cotton variety.

Article is abstract and references only / In 1992, a repeat of a trap -cropping experiment was conducted for the suppression of sweetpotato whiteflies in Pima (S-6) cotton (see Ellsworth et al. 1992). The 1991 experiment showed some promise, but was characterized by low to moderate and later infestations of whiteflies than was desired. The 1992 experimental design (land area = 9.5 acres) was modified to accomplish three improvements: 1) the cotton crop area was doubled in size to 8 rows by 50 ft to improve the ratio of crop to trap area, 2) a fourth treatment was added to form a Latin square design which consisted of cotton plots surrounded only by bareground (i.e., no trap crop): the other three were surrounded by Wright groundcherry that was untreated or treated with 1X or 2X rates of soil-applied aldicarb, and 3) melons (1 row X667') were late planted between blocks to ensure locally abundant whiteflies during the time of the test. The melons were watered regularly in order to retain whiteflies until the start of the test. Early groundcherry establishment was variable and later compromised by insufficient water. This prompted later than usual flushes of groundcherry growth and delayed canopy development. This fact coupled by the intense level of whitefly movement following melon dry -down effectively overwhelmed the insufficiently developed trap crop. Aldicarb was applied on two dates (7/29 & 8/15), and whiteflies were sampled from all plots five times through August. The sampling data are preliminary at this point, but several observations were apparent: 1) the groundcherry trap crop was insufficiently developed to protect the Pima crop, 2) the addition of melons to the system dramatically increased the ,cumbers of locally abundant whiteflies, 3) maintaining the melons in good condition (i.e., well- watered) effectively retained whiteflies in the melons until dry-down, 4) upon dry-down, the melons released overwhelming numbers of adult whiteflies which could not be suppressed on the groundcherry trap crop before reaching the adjacent cotton, 5) the groundcherry was still selectively attractive to the whiteflies (relative to cotton), but was insufficiently developed w trap and retain the huge numbers of dispersing whiteflies, 6) soil - applied aldicarb did accomplish some degree of control of whiteflies on the groundcherry plants, but was inadequate in the face of the tremendous immigration of whitefly adults, 7) the intense whitefly pressure ultimately killed the majority of immature groundcheny plants with the aldicarb-treated plants lasting somewhat longer than the untreated plants, and 8) the yield and quality of the adjacent, late -planted Pima crop was commercially unacceptable and judged to be virtually a total loss. The failure of this implementation of the trap -cropping concept does not preclude the possibility that a better implementation would have succeeded; however, the observation that melons in close proximity to the test area dramatically changed the number of locally dispersing adult whiteflies cannot be denied. It would seem unlikely that a suitable trap crop system could be developed where such an intense proximate source and near instantaneous release of thousands of whiteflies (i.e., at dry-down of melons) is occurring.

In conjunction with the 1992 cotton variety testing program (see Silvertooth 1993), 12 medium maturity varieties were evaluated for the presence of sweetpotato whitefli.es (SPWF). Three sites (Queen Creek, Maricopa, Coolidge) were selected for expression of a full range of infestation intensity. Total immatures per square inch ranged from less than 8 up to more than 8(X), depending on site, sample date and variety. The results indicated that there were significant effects of variety on SPWF numbers; however, the ranking of varieties was not always the same nor significant. Most varieties performed comparably, but one consistently had more SPWFs than the remaining varieties (chi 1 35). Comparative results from the three sites indicate that there may be separate preference and performance components which lead to the development of an infestation. Lea f hairiness was quantified front samples at one site, and the relationship of this factor to whitefly susceptibility is discussed. Two varieties, cb1135 and stv453, were found to be significantly more hairy than the remaining varieties. The results provided here represent a preliminary evaluation of the data. Further analyses will attempt to relate various crop production and agronomic factors to SPWF susceptibility (e.g., plant height, fruit retention, height:node ratio, canopy closure, growth habit, maturity, yield, crop protection regimen). One fact was clear, however. None of the varieties evaluated here demonstrated resistance to SPWFs and certainly not to the extent that a producer could eliminate substantial risk of infestation through variety selection.

Seven insecticides were evaluated in nine treatment combinations for efficacy against the sweetpotato whitefly (SPWF) and the cotton aphid (CA). Five different classes of chemistry were represented by these compounds, which were compared to an untreated check. The infestation was characterized as severe (> 300 SPWFs/sq. in.) and included a substantial number of CAs at the beginning of the evaluation ( >90 /leaf). Three applications were made in August after the onset of "stickiness." For SPWFs, three treatments compared favorably with the check, but only after three applications Orthene +Danitol, Capture alone, and Capture +Ovasyn. Intermediate control was achieved with Endosulfan +Ovasen. Rankingsfor CA control were dissimilar with Vvdate +Asana, Endosulfan +Ovasen, and Ovasen alone consistently performing better than the check. Vvdate alone, Endosulfan alone, and Orthene +Danitol were intermediate in CA control, but also significantly different from the check. Capture alone and Capture+Ovasyn which performed well for SPWF control was not efficacious against CAs. Indeed the two single pyrethroid treatments (Capture: Asana) failed to achieve any degree of CA control.

Sweetpotato whitefly (SPWF) Bemisia tabaci Gennadius strain B has been a devastating pest of cotton in Arizona and California in recent years. Management systems involving cultural procedures, SPWF population monitoring crop sanitation, crop sequencing chemical control and other technology are developing slowly. SPWF population information in relation to cotton yield and quality losses are urgently needed Preliminary studies with cotton insecticide treatments initiated each week from shortly after cotton seedling emergence to late in the cotton season were conducted at the Irrigated Desert Research Station, Brawley, CA in 1993. The results suggest significant correlations for numbers of SPWF per leaf disc from cotton leaves vs. cotton yield and lint stickiness. Cotton lint yield was negatively correlated to all stages of SPWF populations (-0.783 or higher). Lint stickiness was high positively correlated to SPWF populations (0.707 or higher) and cotton defoliation was positively correlated to SPWF populations (0.876 or higher).

Various registered and experimental insecticides were evaluated for sweetpotato whitefly (Bemisia tabaci Gennadius) control in several field experiments at Yuma, Arizona in 1993. 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.

Combinations of two insecticides, often a pyrethroid with an organophosphate, have been used more successfully in sweetpotato whitefly (SPWF) control programs rather than single insecticides when SPWF populations are chronically high. Ten combinations of various insecticides were compared for their effectiveness against all SPWF stages. Applications were by ground, broadcast over -the -top of plots 12 rows x 40 ft on five application dates. Three sampling methods were used: leaf turns and sweeps for adult counts, and microscopic leaf counts for immature stages. Danitol® +Orthene® emerged as the most consistently effective combination on all SPWF stages when compared to the untreated plots. Over all dates and SPWF life stages, the combinations were ranked according to the following order of descending efficacy: Danitol + Orthene 5 Danitol + Lorsban® Karate® + Penncap -M® = Scout Xtra® + Orthene = Asana® + Curacron® = Asana + Orthene < Asana + Phaser® = Scout + Phaser = Asana + Lorsban = Asana + Vydate® < untreated check. Yields were also affected by the combinations, but attributed to SPWF and Lygus suppression. Orthene treatment combinations yielded consistently greater than other entries and was likely due to superior Lygus control and at least average SPWF control. The Asana + Vydate was ranked among the best in Lygus control but low in SPWF control, while Karate + Penncap, Danitol + Lorsban, and Asana + Curacron were ranked high in SPWF control but low in Lygus control. The remaining treatments were more or less intermediate in SPWF and Lygus control. Rankings of these combinations for Lygus control were in the following order of descending efficacy: Asana + Vydate = Scout + Orthene = Asana + Orthene = Danitol + Orthene < Scout + Phaser = Danitol + Lorsban = Karate + Penncap < Asana + Curacron < Asana + Phaser = Asana + Lorsban < untreated check.

Cotton growers in Pima County, Arizona are working together to implement a community-wide Integrated Pest Management program. Participation is voluntary; and is unanimous in at least some components of the program. The IPM program employs many control components aimed at the pink bollworm, the principle cotton insect pest in the area. Growers time the deployment of the control components to act in unison throughout the community. Insecticide applications in the area have trended downward since the program began in 1991, indicating that we are making progress toward our goal of reducing the reliance on pesticides.

Trap crops were evaluated as a part of a community -wide pink bollworm (PBW) control program. We measured extraordinarily high numbers of PBW larvae in the trap crops in 1992, which indicated that the trap crops were attracting PBW moths from wide areas. However, we have no direct way of measuring any effect this would have on the main crop. Overall PBW populations were very low in 1993. While PBW numbers drastically declined in the community, this study offers no conclusive evidence as to whether trap crops are an effective component of a community-wide IPM program.

A limited chemical control tactic known as pinhead square treatment has gained recent Favor as a component of pink bollworm population management. The strategy has economic and ecologic goals of using reduced insecticides early in the season (to include lower rates, half the acreage, and less potent chemistry) in order to reduce later season risk of pink bollworm infestations. This strategy also depends in part on the cultural tactic which results in "suicidal emergence" of overwintering pink bollworms through optimal planting date management. The combination of these tactics has been used in the past to overcome boll weevil populations area-wide. This study is focused on the evaluation of this system as a basis for pink bollworm suppression. Though only preliminary is presented here, it is clear that there are numerous insects impacted by this practice which interact in complex ways to influence pest populations of all kinds. Furthermore, the fate of such a practice in any production system is also influenced by the specific chemical agent used. This experiment details the use of four different classes of insecticide chemistry as well as one bioinsecticide. The experiment has been duplicated in 1993; however, only 1992 data are shown here.