Registered users receive a variety of benefits including the ability to customize email alerts, create favorite journals list, and save searches.
Please note that a BioOne web account does not automatically grant access to full-text content. An institutional or society member subscription is required to view non-Open Access content.
Contact firstname.lastname@example.org with any questions.
Population dynamics of Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), were studied using yellow sticky traps in citrus groves in Florida, Texas, and Puerto Rico. Four groves were studied in Florida (three sweet orange groves and one grove of mixed Citrus spp.) and Texas (four grapefruit groves), and three groves were studied in Puerto Rico (one grove of mandarin oranges and two sweet orange groves). Abundance of Asian citrus psyllid based on trap captures of adults at two groves in Puerto Rico were similar to those in Florida, although several peaks in numbers trapped at one Florida grove far exceeded those at any other grove. Few adults were captured on traps at one of the Puerto Rico groves and at each of the four Texas groves. Less abundance of the psyllid was attributed to the grove in Puerto Rico being higher altitude and cooler. Fewer psyllids captured at two of the four Texas groves during some trapping periods were attributed to applications of insecticides but, overall, fewer adults captured on traps at the Texas groves seemed to be a consequence of differences in abundance of the psyllid. Environmental, biological control, or host plant factors may be less favorable for increases in abundance of Asian citrus psyllid in Texas than in Florida.
Iris yellow spot virus and its vector the onion thrips, Thrips tabaci Lindeman, are yield-limiting pests of onion, Allium cepa L., throughout the western U.S. In experiments in Colorado during 2005 to 2007, straw mulch applied to the center of onion beds at the early to mid-bulb growth stage reduced abundance of thrips as much as 33% when compared to nontreated plots of transplanted onions. Cumulative thrips-days indicated that straw mulch significantly reduced season-long abundance by 10 to 20% compared with check plots in bare soil. The addition of conventional insecticides (methomyl alternated with lambda-cyhalothrin) was associated with 12 to 27% greater cumulative thrips-days compared to the nontreated check in two experiments. In contrast, a reduced-risk insecticide program (spinosad alternated with azadirachtin) had fewer cumulative thrips-days on both bare soil (15%) and straw mulch (36%) compared to nontreated checks. Enhanced thrips control generally persisted during mid-season and may have contributed to reduced stress from damage by thrips feeding and reduced incidence and/or severity by Iris yellow spot virus during the early to mid-bulb stages of plant growth. Total yield and yield of jumbo-sized onions were increased as much as 13 and 18% by straw mulch compared to bare soil treatments among the individual experiments. Peak abundance of thrips on commercial red onion plants evaluated during 2004 was positively correlated with the incidence of iris yellow spot 40 days (R2 = 0.5864, P = 0.0060) and 54 days (R2 = 0.6086, P = 0.0046) later, indicating that suppressing thrips might provide some control of the disease. Effective long-term management of thrips and iris yellow spot in onion crop systems will depend on a multi-faceted approach that integrates host resistance, modified cultural practices such as straw mulching and irrigation scheduling, and judicious use of reduced-risk insecticides.
Hexaflumuron was evaluated for effects on gustatory response and reproduction of boll weevil, Anthonomus grandis grandis Boheman, captured in pheromone-baited traps. Hexaflumuron is an insect-growth regulator that inhibits chitin synthesis and disrupts insect cuticle formation during molting. The intent was to determine the effect of hexaflumuron mixed in ppm active ingredient (weight:volume) with 10% sucrose as a feeding stimulant on gustation and reproduction of boll weevil. Regardless of concentrations, weevils captured in pheromone-baited traps in the fall ingested significantly more hexaflumuron than those captured in the spring. Seasonal mean amount of hexaflumuron ingested by the weevil decreased significantly with greater concentrations (adjusted R2 = 0.82). At 5 and 25 ppm, hexaflumuron significantly depressed gustatory response for falland spring-captured boll weevils, respectively. Hexaflumuron at 5 and 25 ppm significantly depressed oviposition and larval hatch, respectively, for both springand fall-captured weevils. However, reduction in larval hatch was minimal. Data suggest that the use of hexaflumuron as a toxicant for suppression of boll weevil when ingested is limited because of inhibitory gustatory response and minimal reduction in larval hatch. However, this method of application used for hexaflumuron may be important for other insecticides to determine effectiveness on mortality and reproduction of weevils.
This study examined how land management practices can affect the abundance of several arthropods commonly found in agriculture. This work was done in plots that had been subjected to three successive years of an agronomic experiment that evaluated the effects of a wheat, Triticum aestivum L., cover crop or no cover crop on weed and water management. After the third growing season, pitfall traps were installed and arthropods were collected and identified. At one location, carabids (Coleoptera: Carabidae) were identified to genus. Four of the genera (Amara, Anisodactylus, Harpalus, and Calathus) were more common under no-till conditions. Only one genus (Stenolophus) was more common in tilled plots. Five genera (Amara, Bradycellus, Scarites, Stenolophus, and Calathus) were more common in plots with a history of more weeds caused by less herbicide use. Carabids were not more abundant in plots with fewer weeds after herbicides had been applied. Past presence of a winter cover crop never reduced carabid numbers, but significantly increased members of two genera (Harpalus and Poecilus). As a group, carabids at one location were more common in plots without a history of a cover crop. At another location, more carabids were in tilled than nontilled plots. Crickets (Orthoptera: Gryllidae) were more common under no-till conditions. At all locations, wolf spiders (Araneae: Lycosidae) were more common in plots with no tillage and a previous cover crop. Results suggested that surface residues affected carabids, wolf spiders, and crickets.
The tobacco budworm, Heliothis virescens F., is one of the most important insect pests of cotton, Gossypium hirsutum L., and other crops. In recent years tobacco budworm has been successfully controlled with Bacillus thuringiensis-expressing cottons but might acquire resistance to this bacterium insecticide. To test its susceptibility to B. thuringiensis, a large number of tobacco budworms should be evaluated. However, obtaining large numbers of this pest has proven difficult in recent years. Varieties of garbanzo, Cicer arietinum L., one of the most preferred hosts were tested against tobacco budworm in the field. Sierra, C-104, and Annigeri varieties that can harbor ≥10 late-instar tobacco budworm larvae per meter of row and can withstand the biotic and abiotic conditions of northwestern Mississippi, were identified as good hosts for tobacco budworm. This information is of value for obtaining sufficient samples of tobacco budworms for multiple purposes and can serve as a baseline for evaluating varieties of garbanzo for commercial purposes.
Clover mite, Bryobia praetiosa Koch, is a widespread pest of coolseason turfgrasses and a frequent nuisance invader of homes. It has primarily been managed by use of pesticides applied to lawn areas, but all effective materials used for this purpose have recently had dramatically curtailed registered uses on turfgrass. Preliminary observations suggested that supplemental irrigation could negatively affect clover mite populations, and studies were conducted in 1997 and 1998 to better quantify the effect of twice weekly 2.5-cm spring irrigations on clover mites. During both study years, following irrigation, numbers of clover mites were about twice as low on irrigated turfgrass compared to that receiving natural precipitation alone. In the second year, effects on larvae seemed to be greater than on nymphs and adults. Abundance of thrips also was less on irrigated plots in 1997.
An experiment at Estación de Biología Chamela in western México addressed the consequences of social behavior on growth and survival of Hylesia lineata Druce caterpillars. Three of the primary hosts (Casearia corymbosa HBK, Thouinia paucidentata Radlk., and Erythroxylum havanense Jacq.) were used as experimental plants. Because caterpillars usually build shelters with leaves from their hosts, it was suspected that differences in leaf size, leaf form, and branching pattern among hosts could promote contrasting effects on larval performance. In addition, H. lineata caterpillar colonies usually are formed of dozens to hundreds of individuals, suggesting strong differences in larval performance because of group size and social interactions. During a period of 21 days, accumulation of larval biomass was greater on C. corymbosa than on T. paucidentata or E. havanense. Group size had a strong effect on growth of H. lineata larvae. Caterpillars accumulated more biomass when kept in larger groups than in small groups but the pattern was reversed as caterpillars grew older, apparently as a consequence of an increasing demand for food. This outcome was similar across hosts. Survival of larvae did not seem to be affected by either host or group size, suggesting that within the range of larval group sizes examined (46–233) the per-capita predation risk was constant, probably because of a large array of anti-predator traits that caterpillars display, and thus also balanced for host-related differences in the risk of predation.
Adults of the crane flies Tipula (Platytipula) ultima Alexander and Tipula (Platytipula) spenceriana Alexander appear in early autumn in western Michigan. This is the first report of T. spenceriana from the state and the first report of the association between drying ferns (Pteridium aquilinum (L.) Kuhn) of autumn and the two cryptically-protected tipulids that resemble browning fronds in color and in the shape of their wings at rest. Difficulty was encountered when identifying these species despite their large size, conspicuous flight, and abundance. Therefore, the literature of the 12 currently recognized Nearctic species of subgenus Platytipula was reviewed and illustrations are provided to assist in identification. New information about the biology of the two crane fly species is provided, including habitat and the egg stage.