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Chemical control strategies remain the primary IPM tactics to manage the cotton aphid, Aphis gossypii Glover, in Louisiana cotton. Historically, populations of this pest have demonstrated the ability to develop resistance to recommended insecticides. To monitor product efficacy, research and extension entomologists conduct field trials screening commercial and experimental insecticides against cotton aphid to validate performance. This report summarizes the results of those trials during the previous ten years. Currently, those products providing the most consistent levels of satisfactory control are generally included in the neonicotinoid class of chemistry (acetamiprid, imidacloprid, thiamethoxam). A novel product, flonicamid, was recently registered for use on cotton and currently is only the alternative to the neonicotinoids for cotton aphid management in cotton. [ABSTRACT FROM AUTHOR]

The article reports on the susceptibility of selected lepidopteran insect pests suscin Louisiana. The susceptibility levels of bollworm, Helicoverpa zea (Boddie), moths to a pyrethroid, cypermethrin, was made using the adult vial test (AVT). In 2006, adult survival at the cypermethrin discriminating dose of 5 immune globulin/vial was 24%, 57%, 48%, 33%, and 47%, respectively, with a mean annual survival of 42%. In 2007, survival at the 5 immune globulin/vial dose during was 13%, 29%, 33%, 28%, and 44%, respectively, with a mean annual survival of 30%. Additionally, in 2007, it concluded that bollworm survival was lower when compared to survival levels recorded during 2005 and 2006.

A series of field studies during 2005-2007 evaluated the performance of transgenic cotton expressing the Vip3A insecticidal protein against native and artificial infestations of bollworm, Helicoverpa zea (Boddie), and tobacco budworm, Heliothis virescens (F.). The conventional non-Bt cotton cultivar, 'Coker 312', and two Bacillus thuringiensis (Bt) cotton lines expressing either a single protein (Vip3A) or combination of proteins (Vip3A + Cry1Ab [VipCot™]) were sampled throughout the 2005-2007 production seasons for larval injury to fruiting forms and surviving larvae. Species composition and levels of native infestations varied within a season and across seasons, but both Bt cotton lines had significantly fewer damaged fruiting forms and surviving larvae compared to those found on Coker 312 plants. VipCot™ cotton plants had lower numbers damaged fruiting forms and fruiting forms infested with larvae compared to that on Vip3A plants. In addition, selected Coker 312, Vip3A, and VipCot™ plants in field plots were infested with either bollworm or tobacco budworm larvae. These plants were visually inspected at 3 d after infestation and every 2 d thereafter, until larvae were no longer detected. Lower levels of damaged fruiting forms and fewer larvae for both species were recorded on Vip3A, and VipCot™ plants compared to those on Coker 312 plants. A bollworm larva injured an average of 8.6, 4.6, and 1.0 fruiting forms on Coker 312, Vip3A, and VipCot™ plants, respectively. A tobacco budworm larva injured an average of 9.2, 5.9, and 0.9 fruiting forms on Coker 312, Vip3A, and VipCot™ plants, respectively. The patterns of seasonal efficacy generally showed the VipCot™ plants to be more durable with less fruiting form injury than that recorded on Coker 312 and Vip3A, especially during periods of peak heliothine infestations. The combination of two insecticidal proteins expressed in the VipCot™ cotton line improved efficacy levels against a complex of heliothines above that of the single protein in the Vip3A line. [ABSTRACT FROM AUTHOR]

A laboratory study quantified age-specific mortality of heliothines on flower buds of VipCot cotton lines. Heliothine larvae were allowed to feed on flower buds (squares) of conventional non-Bt, Vip 3A, and Vip 3A + Cry protein stacked cotton lines. Squares of the Vip 3A, and Vip 3A + Cry protein stacked cotton lines produced significant levels of cumulative mortality for bollworm, Helicoverpa zea (Boddie) and tobacco budworm, Heliothis virescens (F.). Larval mortality across age classes (both species) was similar and none of the larvae were capable of completing pupation on squares of the Vip 3A + Cry protein stacked cotton line. [ABSTRACT FROM AUTHOR]

A field study evaluated the influence of Southern green stink bug, Nezara viridula (L.), adults, (males and females), and fourth-fifth instar nymphs on cotton, Gossypium hirsutum L., physical fiber quality. Cotton bolls representing several age classes ranging from 0-600 heat units after anthesis were individually infested with a specific gender or life stage of Southern green stink bug. Feeding on bolls significantly affected the physical fiber properties of micronaire, strength, uniformity, and fiber length. Discoloration of cotton lint in the infested bolls was more common than in non-infested bolls. No significant differences in fiber quality properties were detected between Southern green stink bug genders and life stages. [ABSTRACT FROM AUTHOR]

The susceptibility of over 2,000 bollworm moths to pyrethroids was determined using the adult vial test (AVT) from May to Sep during 2004 and 2005. In 2004, survival at 5 μg/vial during May, Jun, Jul, Aug, and Sep was 9%, 16%, 30%, 21%, and 30%, respectively, with a mean survival of 23%. In 2005, survival at 5 μg/vial during May, Jun, Jul, Aug, and Sep was 23%, 34%, 43%, 43%, and 38%, respectively, with a mean survival of 38%. Bollworm survival during 2005 was at the highest level recorded in Louisiana. Mean annual survival of bollworm exposed to 10 μg/vial for 2004 and 2005 was 12% and 22%, respectively. In 2004, LD50's of bollworm larvae from field colonies collected at St. Joseph, Bossier, and Winnsboro in topical bioassays were 1.28, 3.24, and 6.12 μg/g, respectively. The Winnsboro colony tested in 2004 had a resistance ratio that was 7 to 22 fold higher than the pyrethroid-susceptible colonies tested during 1998. In 2005, LD50's of colonies from Somerset, St. Joseph, Sicily Island, St. Francisville, and Winnsboro were 0.68, 2.04, 2.04, 2.20, and 3.48 μg/g, respectively. Although these data clearly show bollworms are becoming less susceptible to pyrethroids in laboratory tests, no field control failures of bollworms with pyrethroids have been reported in Louisiana to date. [ABSTRACT FROM AUTHOR]

A 3-year study was conducted near Lamesa, Texas, to characterize the effect of irrigation water and nitrogen application on leaf moisture and leaf nitrogen content in cotton and the resulting influence on cotton aphid population dynamics. The treatments consisted of three irrigation levels and three nitrogen fertility treatments within each water level. Treatments were deployed in a randomized complete block design with nine replications, resulting in a total of 81 experimental units for the entire test. Each grid point was approximately 0.4 acre. Three nitrogen fertility treatments included blanket-rate-N, variable-rate-N, and no nitrogen. The three water levels (high, medium, and low) were 85, 75, and 65% ET replacement. Cotton aphid abundance, percentage leaf moisture, and percentage leaf nitrogen were measured per week from each plot during the entire growing season. The leaf water content did not vary among nitrogen treatments and various level of irrigation. Leaf nitrogen content did not vary with nitrogen application method (variable-N versus blanket-N), but both the blanket application and variable rate application resulted in significantly higher leaf nitrogen content than in zero nitrogen plots in 2003. The overall effect of irrigation level and nitrogen application method on insect, yield and plant quality related variables and the relationship among different variables were evaluated for 2003 data. The discriminant function analysis, MANOVA, and Mahalanobis analysis showed no significant difference between high and medium water level, but the low water level was significantly different from medium and high water levels. Similarly, multivariate data analysis suggested that the variable rate and blanket application of nitrogen were similar in overall cotton production. [ABSTRACT FROM AUTHOR]

A field study determined the influence of Southern green stink bug, Nezara viridula (L.) adults, (female and males), and nymphs (fourth-fifth) on boll abscission and yield loss. Cotton bolls of several age classes (0-50, 51-100, 101-150 through 451-500 heat units [HU]) were infested with one insect of each gender or life stage of Southern green stink bug for 72 h. Seed cotton yield of bolls infested with adults and late instar nymphs through ca. 500 HU beyond anthesis was significantly lowered compared to non-infested bolls. There were no significant differences in boll abscission and boll weights between adults and nymphs or between adult males and adult females compared to non-infested bolls. [ABSTRACT FROM AUTHOR]

COTMAN was used in insect management research projects as another means to measure the effects of differing planting dates, irrigation, row spacing, and tillage systems on cotton growth and development. Differences in plant growth and development can have a profound effect on the development of insect infestations. Planting date, row spacing and tillage practices had a significant effect on both early crop development and physiological cutout. The irrigation methods evaluated had little effect on plant development. Boll damage assessment based on heat unit-delineated maturity provided a boll safe cutoff value of 350 HU for the western tarnished plant bug (Lygus hesperus Knight), similar to that found for the tarnished plant bug in the Southeast. COTMAN was found to be a useful tool in evaluating the impact of various crop management practices on plant development and end-of-season management decisions. This information can be related to the development of insect infestations. [ABSTRACT FROM AUTHOR]

The study was conducted at the AG-CARES farm in Lamesa, Texas to quantify the seasonal activity patterns of the western flower thrips, Frankliniella occidentalis (Pergande), and cotton fleahoppers, Pseudatomoscelis senates (Reuter). Thrips infestation started from cotyledon stage. Thrips showed two distinct peak populations, one at 1-2 true leaf stage (20 DAP) and another at flowering stage (82-96 DAP). In the first peak, thrips numbers reached up to 6.1 total thrips per plant and the number slowly declined as the plant matured and began squaring. However, once cotton started flowering (75 DAP), thrips population began to grow and attained the second peak in the second week of August (96 DAP); the second peak was larger than the first peak. Fleahopper activity began 44 days after planting and showed only one peak in early square stage (103 DAP). Seasonal average fleahoppers were found significantly higher in late-planted cotton (2705 per acre) compared with that in timely planted cotton (1118 per acre). The tillage system and variety did not have a significant influence on abundance pattern of thrips or fleahoppers. Visual sampling method detected the highest abundance of fleahoppers (37,851 per acre) followed by beat bucket (17,086 per acre), drop cloth (8,378 per acre), vacuum (951 per acre), and sweepnet (798 per acre) sampling. [ABSTRACT FROM AUTHOR]

The tarnished plant bug, Lygus lineolaris, and western tarnished plant bug, L. hesperus, have been known to be key pests of cotton in several States in the Cotton Belt. In addition to these two species, a third species, Lygus elisus, has been identified to be an equally prevalent species of Lygus in the Texas High Plains. The objectives of this project were to identify the noncotton host plant sequence prior to cotton planting and to establish the relationship between noncotton host plants and Lygus migration to adjacent cotton. Lygus bugs were recorded from 26 noncotton host plants that were sampled along the roadside in the Texas High Plains. Lygus species identification has not been completed, but it appears that L. elisus and L. hesperus are the two dominant species in the Texas High Plains Lygus complex, with occasional occurrence of L. lineolaris. The mid- April survey showed that wild mustard, redstem filaree, and alfalfa were the dominant hosts that supported Lygus bugs. When mustard senesced and alfalfa began to bloom in mid-May, alfalfa, yellow sweetclover, woolyleaf bursage, prickly lettuce, curly dock, Russian thistle, field bindweed, broomweed, ragweed, pigweed, and gaura supported Lygus populations. The mid-June survey indicated that alfalfa and yellow sweetclover were still the dominant hosts prior to cotton squaring, while Russian thistle and wild sunflower supported a significant population in areas where alfalfa was not very lush. In late July, overall Lygus numbers in wild hosts declined, with alfalfa, pigweed, Russian thistle, and silverleaf nightshade supporting a small number of Lygus. In early September, alfalfa continued to be the most attractive host for Lygus. Lygus abundance in cotton was 0.5 adults per 100 sweeps compared with 2.5 per 100 sweeps in alfalfa in late July. Lygus abundance in cotton remained the same from late July to early September, when alfalfa became more attractive for Lygus. Preliminary data suggest that in the Texas High Plains a host sequence exists for Lygus to move from noncotton hosts to cotton and back to noncotton hosts. [ABSTRACT FROM AUTHOR]

A laboratory study quantified heliothine survivorship on selected reproductive structures of a VipCot cotton line. Heliothine larvae were allowed to feed on selected reproductive structures of a non-Bt variety or a VipCot line for 96 h. Heliothine mortality was nearly 100% on VipCot plant terminals and flower petals. Tobacco budworm, Heliothis virescens (F.), larval mortality was significantly lower on whole squares, square bracts, and bolls of VipCot compared to that for bollworm, Helicoverpa zea (Boddie) larvae. [ABSTRACT FROM AUTHOR]

Seasonal abundance of fleahoppers and Lygus varied with cotton cultivar as well as the planting date window. Paymaster 2326RR had the most fleahoppers and Lygus compared with Stoneville 2454R, Paymaster 2145RR, and Paymaster 2167RR. Late-planted cotton attracted significantly more of both species compared with the timely planted cotton. Sampling methods varied in their efficiency to capture fleahoppers and Lygus. The beat bucket method captured significantly more Lygus, while the visual method accounted for the most fleahoppers compared with other sampling methods. [ABSTRACT FROM AUTHOR]