A 2-yr study was conducted to investigate the potential of using yellow sticky traps to survey lady beetles in cotton and to quantify seasonal activity patterns. The performance of sticky traps was compared with that of a 2-cycle vacuum sampler. The most common lady beetle species captured by sticky traps and vacuum sampler in cotton were Hippodamia convergens Guerin-Meneville and Scymnus loewii Mulsant. Sticky traps captured significantly more of both species of lady beetles, had greater capture efficiency, and more effectively detected lady beetles compared with the vacuum sampler. These data indicate that the sticky trap can be a valuable tool in monitoring lady beetle populations in cotton. In the second part of this study, a year-round survey of lady beetle populations in the periphery of a cotton farm using sticky traps showed that lady beetles remained active throughout the year in the Texas Rolling Plains, but the activity was influenced by winter severity. Over a 2-yr period, H. convergens, S. loewii, Coccinella septempunctata (L.), and Olla v-nigrum (Mulsant) comprised 89.6, 8.2, 1.9, and 0.3% of the specimens, respectively. Sticky trap captures were affected by year, trap height, and cropping season. Traps placed at 0.75 m above ground captured significantly more (80%) lady beetles than traps placed at 1.50 m (20%) above ground; traps at 0.75 m above ground also detected the rarer species while the traps at 1.50 m above ground detected only the abundant species. Trap captures were higher during the noncotton season (November to April) compared with the cotton season (May to October). A significant positive correlation between cotton aphid abundance during the growing season and H. convergens abundance during the following noncotton season was also detected, indicating a significant movement of H. convergens from cotton to the periphery of the farm to seek refuge after cotton termination.
Journal Article Influence of Constant Temperatures on Life History Parameters of the Cotton Aphid, Aphis gossypii, Infesting Cotton Get access Megha N. Parajulee Megha N. Parajulee 1 Texas Agricultural Experiment Station, 1102 E FM 1294, Lubbock, TX 79403 1Corresponding author, e-mail: m-parajulee@tamu.edu. Search for other works by this author on: Oxford Academic PubMed Google Scholar Environmental Entomology, Volume 36, Issue 4, 1 August 2007, Pages 666–672, https://doi.org/10.1093/ee/36.4.666 Published: 01 August 2007 Article history Received: 11 July 2006 Accepted: 27 March 2007 Published: 01 August 2007
Controlled field studies using clip cages were used to quantify development, reproduction, and survival, and generate life history characteristics and population growth parameters of the cotton aphid, Aphis gossypii Glover, on irrigated upland cotton, Gossypium hirsutum L. Newly born (<6-hour-old) aphid nymphs were individually placed on the underside of fifth mainstem cotton leaves (n = 30 plants). Aphids were monitored every 24 hours and the developmental stage, fecundity, and mortality recorded until the last aphid from the cohort died. Individual aphids were transferred to a new fifth leaf on the same plant when plants gained a newer leaf. Average daily temperature under the leaf surface was 28.1°C. Nymphal durations were 38, 48, 37, and 34 degree-days above a development threshold of 6.3°C for 1st, 2nd, 3rd, and 4th instars, respectively. Aphids began dying at 448 degree-days, and the last individual in the cohort died at 907 degree-days, with an average longevity of 674 degree-days. The gross reproductive rate and finite rate of increase were 62.24 and 1.43263, respectively. A complementary study was done by daily monitoring population dynamics and within-plant distribution of the aphid for two growing seasons. Cotton aphids were not typically in the field until mid-July or early August, and the population decreased after mid-September. A fifth mainstem leaf from the top of the plant canopy (T5) and a leaf from the mid-canopy (M) consistently tracked population activity with whole-plant densities, suggesting that either T5 or M should serve as a reliable indicator-leaf for monitoring cotton aphid population dynamics in the field.
A study was designed to examine the community composition of canopydwelling arthropods in adjacent fields of cotton, Gossypium hirsutum L., and alfalfa, Medicago sativum L., at Texas A&M University AgriLife Research and Extension Center farm near Lubbock, TX, during the cotton-growing seasons of 2008 and 2009. Samples were collected from 61 row-meter sections of cotton (1.02-m row spacing) and 61 row-meter sections of alfalfa (0.51-m spacing) via a “Keep It Simple Sampler” (KISS). Six samples were collected on each of 11 weekly sampling dates during the cotton-growing seasons of both years. We found that specimens in the canopy-dwelling arthropod community in cotton and alfalfa were from the orders Araneae, Coleoptera, Diptera, Hemiptera, Hymenoptera, Lepidoptera, Neuroptera, and Orthoptera, and in the orders, 41 families were identified. Members of Araneae, Coleoptera, and Hemiptera were most abundant in both crops. Overall, a greater number of arthropod taxa was found in alfalfa, but some arthropod taxa were unique to each crop. Analyses revealed a difference in temporal abundance of captured arthropods at the order (p ≤ 0.018) and family levels (p ≤ 0.021) during cotton squaring, flowering, and boll-development stages, with significantly greater abundance of arthropods at the order level in alfalfa compared to cotton in both years, except during the cotton-flowering period in 2008. Implications of arthropod community differences between alfalfa and cotton were discussed with respect to using alfalfa as a potential source of predators for adjacent cotton.
Abstract Evolution of insect resistance is the primary threat to the long‐term efficacy of Bacillus thuringiensis (Bt) transgene technologies. Plants have a deeply conserved defence response to pests: Jasmonic acid (JA) hormone signalling mediated by transcriptional repressors called JASMONATE‐ZIM‐DOMAIN/JAZ. JAZs normally limit expression of plant defence pathways, promoting assimilate partitioning towards growth and reproduction, by their carboxyl terminal Jas motif that antagonises MYeloCytomatosis (MYC) master transcription factor activities. Deletion, alternative splicing/intron retention, or disruption of the Jas motif results in JA insensitivity and increased resistance to pathogens including arthropod herbivores, for example by production of secondary metabolites and new leaves with higher trichome density. JA‐mediated trichome initiation and elongation also impact cotton fibre production. Since its release in 2017, the third‐generation stacked commercial Bt insecticidal Vip3A protein traits are increasingly under severe pressure for evolution of Helicoverpa zea (bollworm) resistance. Regional differences in efficacy of Bollgard ® 3 and WideStrike ® 3 against lepidopteran pests and increasing pesticide use are emerging issues. Future transgenic field control failures from bollworm infestations and incursions of Helicoverpa armigera from Central America are likely in the U.S. Cotton Belt. In this systematic primer on the problem, we take a conceptual approach to consider JAZ genes as means to leverage ‘internal’ host‐derived herbivore resistance in cotton. We consider the genetic redundancy and pleiotropic nature of JAZ master regulators on tissue‐specific growth, development, crosstalk with hormonal and small RNA pathways as nodes in networks, and limitations of JAZ efficacy due to fitness costs/growth trade‐offs versus prospects for enhancing resistance networks to orchestrate transgressive segregation (generation of extreme phenotypes in breeding progeny not seen in parental lines).
Life history of immature Lyctocoris campestris (F.), a predator of stored-product insects, was investigated at 17, 21, 25, and 29°C and ≍43, ≍58, and ≍75% RH in the laboratory. Most life history traits of L. campestris were influenced by temperature, but none of the traits was influenced by relative humidity. The egg incubation period was ≍7 d at 25-29°C, but increased sharply at temperatures <25°C. An equation was developed to predict egg incubation period over a range of temperatures. Egg hatch rate did not vary with temperatures nor with the relative humidities. The mean hatch rate ranged from 78 to 86% across different temperatures summed across 3 relative humidities. The instar-specific nymphal development also varied with temperature. The 2nd stadium was the shortest followed by the 3rd, 1st, and the 4th, and the 5th stadium was the longest across all 4 temperatures. However, the ratios of duration of nymphal stadia remained constant across all 4 temperatures tested. Total nymphal durations were 20.5, 27.6, 40.1, and 66.2 d at 29,25,21, and 17°C, respectively; all 4 were significantly different from one another. The relationships between temperature and instar-specific nymphal durations and total nymphal durations were described by the same equation for both females and males; total nymphal durations did not vary with sex. Nymphal survival rates ranged from 0.60 to 1.00 and did not vary significantly with temperature or relative humidity. Sex ratio (proportion of males) of emerging adults ranged from 0.40 to 0.70, but did not differ from 1:1. These life history data are reported in a manner useful for developing a computer model for simulating L. campestris population dynamics.
Neonicotinoids are one of the most widely used classes of insecticides in agriculture. They are systemic insecticides mainly used as seed treatments to manage sucking insect pests in a wide range of field crops. Environment and growing conditions can impact the efficacy of neonicotinoid seed treatments. To evaluate this, an experiment was conducted to study the interactive effect of soil, water levels on the neonicotinoid concentration and plant growth in cotton. The experiment was laid out in a split-plot design, with three water levels, 30%, 60%, and 100% (control) of recommended irrigation and four seed treatments, including clothianidin, thiamethoxam, imidacloprid and an untreated control. Cotton seedlings were collected and analyzed for physiological changes and neonicotinoid concentrations at 15, 30 and 45 days after germination (DAG). Data were collected on plant height, fresh biomass and leaf area. The neonicotinoid concentrations were analyzed in leaf tissues using LC-MS/MS. The 30% and 60% of recommended irrigation treatments resulted in significantly taller seedlings with greater biomass and leaf area compared to the 100% water saturation (control) treatment. Thiamethoxam-treated seedlings had greater plant height and shoot fresh mass compared to clothianidin and the untreated control, whereas imidacloprid-treated seedlings had greater leaf area than thiamethoxam, clothianidin, and control at all water levels. 30% recommended irrigation increased neonicotinoid concentrations in leaf tissues, with clothianidin showing higher levels compared to other neonicotinoids at 45 DAG. Neonicotinoid seed treatment efficacy may vary with environmental factors, impacting sustainable pest control.
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