Jack T. Reed

Biology, Crop Injury, and Management of Thrips (Thysanoptera: Thripidae) Infesting Cotton Seedlings in the United States

Several species of thrips are known to infest cotton seedlings in the United States and constitute one of the most common insect pest challenges for growers. The species complex, species abundance, extent of crop injury, and impact on lint yield varies widely across the cotton states. Cotton seedlings are most susceptible to thrips injury during the first 4 to 5 weeks after plant emergence. Feeding by thrips results in distortion, malformation and tearing of seedling leaves, reduced leaf area and plant height, reduced root growth, and injury to or death of the apical meristem, the latter of which leads to excessive vegetative branching. Plant maturity (i.e., fruit production) can be delayed and in extreme cases, losses of as much a 30-50% of lint yield potential have been reported. To date, no varieties of cotton have resistance to thrips, so controls are based solely on insecticide applications. Treatment thresholds and control practices (e.g., insecticide seed treatments, in-furrow or foliar applied insecticides) vary widely across cotton states. This article provides a brief summary of the various species of thrips present in U.S. cotton, their plant host range and injury to cotton, a general description of thrips biology, and management practices currently available to growers.

A survey of thrips (Thysanoptera) species infesting cotton seedlings in Alabama, Arkansas, Georgia, Louisiana, Mississippi, and Tennessee.

The common species of thrips that are considered pests of cotton, Gossypium hirsutum (L.), include flower thrips, Frankliniella tritici (Fitch); tobacco thrips, Frankliniella fusca (Hinds); western flower thrips, Frankliniella occidentalis (Pergande); onion thrips, Thrips tabaci (Lindeman); and soybean thrips, Neohydatothrips variabilis (Beach). Thrips feeding on cotton seedlings can inhibit plant growth, reduce plant stand, delay crop maturity, and reduce seed-cotton yield. Surveys were conducted in Alabama, Arkansas, Georgia, Louisiana, Mississippi, and Tennessee to determine the thrips species infesting cotton seedlings during 1996 to 1999. Cotton seedlings were sampled weekly between 7 and 48 days after plant emergence at one to four field sites in each state. Over 12,000 thrips adults were collected using plant washing procedures with 9,005 individuals mounted on slides, and identified to species. The tobacco thrips was the most common species collected in all states, except Georgia, and comprised at...

Timing bait applications for control of imported fire ants (Hymenoptera: Formicidae) in Mississippi: Efficacy and effects on non-target ants

An experiment was conducted to assess the efficacy of mid-day (11:00 – 13:00 h) and late evening (18:00 – 20:00 h) broadcast bait (Seige Pro®, 0.73% hydramethylnon) applications against black and hybrid imported fire ants (Solenopsis richteri Forel and S. richteri × invicta, respectively) and their impact on native ant species. It was hypothesized that evening bait applications would have less impact on native ant species that slow or cease foraging at night relative to mid-day applications. Bait was applied to a series of plots in northeastern Mississippi, USA, in summer of 2002 and 2003. Population densities and foraging activity of imported fire ants and native ants were compared between treated and control plots. Population density and foraging activity of imported fire ants were equally suppressed in plots receiving mid-day and evening broadcast bait applications. Population density of Monomorium minimum (Buckley), the little black ant, approached zero in treated plots during 2003 but remained relatively high in untreated control plots. Species richness declined in treated plots with no difference between mid-day and evening bait application. These data indicate that evening bait application offers no advantage over mid-day application in terms of preserving some native ant species.

Thrips and Tomato Spotted Wilt Virus in a Mississippi Peanut Field

Two species of thrips, Frankliniella fusca, the tobacco thrips, and western flower thrips (WFT), capable of vectoring tomato spotted wilt virus (TSWV), were collected from a peanut field in Coahoma County, Mississippi in 1992. Results of repeated sampling indicated that the numbers of tobacco thrips were high in the spring and very low late in the growing season. Numbers of WFT were low in the spring and higher late in the season. The percentage of plants developing symptoms of TSWV peaked at 11% early in the season and rose sharply to 75% in late August. The seasonal distribution of the two thrips vectors and the incidence of symptomatic plants indicates that the disease may have been vectored by tobacco thrips early in the summer and by WFT late at the end of August.

Temporal Foraging Activity of Selected Ant Species in Northern Mississippi During Summer Months1

A study was conducted in northeastern Mississippi to examine temporal foraging activity of imported fire ants (Solenopsis spp.) and other common ant species that inhabit pasture and meadow. Baited vials were placed horizontally on the ground along straight-line transects (n = 21) every 3 h for 24 h periods during June–August. Vials remained on the ground for 30 min, then were quickly plugged with cotton and collected. Principal species captured in baited vials included Solenopsis spp. (black and hybrid imported fire ant) (90.6%), Solenopsis molesta (Say) (5.9%), Monomorium minumum (Buckley) (2.5%), Tapinoma sessile (Say) (0.7%), and Paratrechina vividula (Nylander) (0.3%). Imported fire ants foraged during all time periods, as did S. molesta and P. vividula. Tapinoma sessile and M. minimum slowed or ceased foraging at night. Forelius pruinosus (Roger) was captured on a single date while sampling at 1800 h. Implications for timing of bait applications against imported fire ants are discussed.