Analysis of data from a 15-yr study, coniposeetl of 117 1)oll \vee\-il cohorts from ovenvintering hahitiits in the Rolling Plains of Texas, sho\vetl tliiit o\wvintering sitnii.orsliip and spring/s~~ninier emergence were inRi,mced by tlie daiy of tlie !.ear (Dol') wlien tlle wveekils entered oveniintering habitat the nniount of rainfiill, and 1ial)it;it trniperiitiires experienced by the weevils during cliupaiise. The e d i e r tlie date that IveeLils entered oveiwin
There is concern that cotton gins located in boll weevil, Anthonomus grandis grandisBoheman, eradication zones serving customers in adjacent infested zones may serve as a site for boll weevil reintroductions if weevils are transported alive inside cotton modules. We surveyed fields in three distinct areas of Texas and found that weevils can be present in large numbers in cotton fields that have been defoliated and desiccated in preparation for harvest, both as free adults and as immatures inside unopened bolls. Harvested cotton taken from module builders indicated that ≈100-3,700 adult boll weevils were packed inside modules constructed at the sampled fields. Marked weevils were forced through a laboratory field cleaner (bur extractor) commonly mounted on stripper-harvesters, and 14% were recovered alive in the seed cotton fraction and lived at least to 24 h. Survival of weevils placed inside modules declined over time up to 7 d, but the magnitude of the decline varied with experimental conditions. In one experiment, 91% of the weevils survived to 7 d, whereas under harsher environmental conditions, only 11% survived that long. Together, our results indicate that when cotton is harvested in an infested area, boll weevils likely will be packed alive into cotton modules, and many will still be alive by the time the module is fed into the gin, at least up to 7 d after the module's construction. KeywordsAnthonomus grandis grandis, boll weevil, cotton gin, cotton module, eradication RightsWorks produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted. ABSTRACT There is concern that cotton gins located in boll weevil, Anthonomus grandis grandis Boheman, eradication zones serving customers in adjacent infested zones may serve as a site for boll weevil reintroductions if weevils are transported alive inside cotton modules. We surveyed Þelds in three distinct areas of Texas and found that weevils can be present in large numbers in cotton Þelds that have been defoliated and desiccated in preparation for harvest, both as free adults and as immatures inside unopened bolls. Harvested cotton taken from module builders indicated that Ϸ100 Ð3,700 adult boll weevils were packed inside modules constructed at the sampled Þelds. Marked weevils were forced through a laboratory Þeld cleaner (bur extractor) commonly mounted on stripper-harvesters, and 14% were recovered alive in the seed cotton fraction and lived at least to 24 h. Survival of weevils placed inside modules declined over time up to 7 d, but the magnitude of the decline varied with experimental conditions. In one experiment, 91% of the weevils survived to 7 d, whereas under harsher environmental conditions, only 11% survived that long. Together, our results indicate that when cotton is harvested in an infested area, boll weevils likely will be packed alive into cotton modules, and many will still be alive by the time the module is fed into the gin, at least u...
Bollworm, Helicoverpa zea (Boddie), and tobacco budworm, Heliothis virescens (F.), male adult (moth) activities were monitored between 1982 and 1995 by using sex pheromone traps in the Texas High Plains. Moths were monitored weekly from early March to mid-November near Lubbock and Halfway, two prominent cotton production areas in the Texas High Plains region. Based on trap captures, the bollworm-budworm complex consisted of approximately 98% bollworms and approximately 2% tobacco budworms. Seasonal activity patterns varied between location for bollworm but not for tobacco budworm. The 14-yr average (+/- SE) bollworm moth abundance (moths per trap per week) at Lubbock was significantly higher (226.5 +/- 10.4) compared with that at Halfway (153.7 +/- 8.1). Correlation analyses showed a significant positive relationship between moth abundance and average weekly temperatures, whereas a significant negative relationship was observed between moth abundance and average weekly wind velocity for both species. Analyses also showed a positive correlation between moth abundance and cumulative degree-days (> 0.0 degrees C) from 1 January. A strong positive relationship was observed between moth abundance and weekly average precipitation for both species. Average weekly abundances were positively correlated between adjacent months during most of the active cotton fruiting season (June-September). However, the relationship between populations that contributed to the overwintering generation and the following spring populations varied between species and study sites. Nevertheless, data from this study indicated that late-season moth catches could be indicative of the dynamics of the early-season moth catches the following year in the High Plains. The mean population abundance curve based on 14-yr averages showed two bollworm population peaks at Lubbock, but only one peak at Halfway. Separate degree-day-based models were developed to describe long-term seasonal abundance patterns of bollworm moths for the Lubbock and Halfway sites.
Temperature data are unavailable for most boll weevil overwintering habitats. As a result, ambient data often are used to estimate overwintering survival and emergence. In this study, relationship of ambient and overwintering habitat temperatures was determined for 6 habitats in the Rolling Plains of Texas. The amplitude of the daily temperature cycle in the leaf litter of each habitat was dampened compared with that recorded for ambient. Average minimum daily leaf litter temperature was 3.19"C higher in the shelterbelt habitat, followed by mesquite-grass pasture (3.54"C), tall shinnery motte (3.64"C), low shinnery brush (3.81°C), lovegrass (4.Ol0C), and pecan (6.01"C). Likewise, the average maximum daily leaf litter temperature was 3.77% lower in shelterbelt, followed by pecan (3.SSoC), lovegrass (3.87"C). mesquite-grass pasture (4.07"C), low shinnery brush (5.5loC), and tall shinnery motte (6.12"C). Stepwise multiple regression of hourly leaf litter temperatures explained 93% of the variability, with hourly ambient temperature and week of year being significant variables. Similarly, multiple regressions of daily leaf litter minimum temperatures and daily leaf litter maximum temperatures explained 96 and 90% of the variability, respectively, with ambient temperatures and week of year being significant variables for both regressions. The effect of temperature quality (ambient versus leaf litter) and sampling frequency (hourly versus daily) on positive (>6.1°C) and negative (
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