BioOne.org will be down briefly for maintenance on 14 May 2025 between 18:00-22:00 Pacific Time US. We apologize for any inconvenience.
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 helpdesk@bioone.org with any questions.
Although cereal grains are the preferred food plants of the cereal leaf beetle, Oulema melanopus (L.), several other graminoid species are acceptable feeding hosts of larvae and adults of this chrysomelid beetle. In view of the potential for expanding the use of diverse endophytic fungi (Neotyphodium Glenn, Bacon and Hanlin) to protect forage and cereal grasses from insect pests, more information on the effect of Neotyphodium-infected (E ) grasses on the behavior and performance of the most important graminoid pests, including O. melanopus, is required. In feeding and oviposition choice experiments, adult O. melanopus fed readily on E and uninfected (E−) plants of wild tall fescue (Lolium arundinaceum (Schreb.) S.J. Darbyshire) and alpine timothy (Phleum alpinum L.), while exhibiting a feeding preference for E− over E plants of one tall fescue accession. In larval survival and development experiments, low survival on E plants of alpine timothy and one tall fescue accession (averaged 3.75 - 12.5%) was not linked to slow development of surviving larvae because developmental periods were similar on E− (averaged 11.31 - 12.73 days) and E (11.33 - 11.7 days) plants. Larval mortality was 100% on E plants of tall fescue from Morocco. Thus, O. melanopus feeding and survival is significantly reduced on some E wild grasses. Our results also expand our knowledge of the antiinsect properties of fungal endophytes in diverse grasses for possible use in protecting forage and cereal grass cultivars from O. melanopus and other important pests.
The standard method for assessing cotton fleahopper, Pseudatomoscelis seriatus (Reuter), abundance in cotton, Gossypium hirsutum L., involves direct counts of adults and nymphs on main stem terminals. Although this practice appears to provide adequate estimates for pest management programs, the accuracy and precision of population estimates obtained from terminal sampling, relative to whole plant examinations and potential time-of-day sampling effects, have not been investigated. We examined the distribution of cotton fleahopper adults and nymphs within cotton plants twice a day (0800 - 1130 h and 1300 - 1630 h) in 2007 and 2008 to determine whether the numbers of fleahoppers in the terminal of plants accurately and reliably reflect the numbers of fleahoppers on those plants. Overall, the mean numbers and distribution patterns of fleahoppers observed during the morning and afternoon sampling periods were statistically similar. Consequently, time-of-day sampling effects were not observed. When the numbers of fleahoppers found on plants were regressed on the numbers of fleahoppers observed in the terminal of those plants, the r2 and coefficient of variation (CV) values for adults were 0.81 and 40, respectively. Corresponding values for nymphs were 0.97 and 22. Based on regression slopes, the terminal accounted for 64% of the adults and 78% of the nymphs observed on plants. Our results suggest fleahopper counts obtained from terminal examinations accurately reflect the numbers of fleahoppers on those plants. However, this sampling practice may not provide the level of precision typically required in population research.
The western tarnished plant bug, Lygus hesperus Knight, is susceptible to the naturally-occurring pathogen, Beauveria bassiana (Balsamo) Vuillemin, in the San Joaquin Valley of California. Recent research efforts have focused on selection of Beauveria strains that were effective against Lygus under the high-temperature conditions typical of the cotton (Gossypium spp.) production season. However, the most appropriate use of this pathogen may not be as a rescue treatment. Alternatively, B. bassiana may be useful to efforts to target overwintering populations of Lygus if isolates are available that are highly virulent under the low temperature conditions typical of winter and early-spring in the San Joaquin Valley. One commercially-available isolate and 4 native isolates of B. bassiana were assayed against L. hesperus adults under constant temperatures of 12.8, 18.3, and 23.9°C. Although decreasing temperatures were associated with diminished Beauveria-induced mortality of Lygus and slower development of disease symptoms, no differences in efficacy were detected among the tested isolates. Differences in the patterns of occurrence of Beauveria disease symptoms were observed among isolates at some temperatures, but those differences were not substantial. Furthermore, results at some temperatures suggested potential influences of Lygus adult age or gender on susceptibility to B. bassiana. Those effects should be further investigated. Overall, the results did not indicate that any of the tested isolates of B. bassiana were superior to the commercially-available isolate under low temperature conditions.
Laboratory assays explored the potential of nitenpyram, a novel neonicotinoid insecticide developed by Takeda Chemical Industry Co., Ltd. against the brown planthopper, Nilaparvata lugens (Stål) (Homoptera: Delphacidae). All nymphal instars were sensitive to nitenpyram with the first and second instars being the most susceptible (median lethal concentrations [LC50] of 0.14 mg/L at 72 h after treatment). Fifth-instar nymphs were the least susceptible. Mortality of first - second instars treated with 2 mg/L peaked at 48 h after treatment. The five concentrations of nitenpyram tested (2, 1, 0.5, 0.25, 0.125 mg/L) decreased the weight of brown planthopper nymphs following treatment with the insecticide. These laboratory results indicate that nitenpyram may prove to be an effective alternative for the control of brown planthopper in rice culture.
The ant-loving crickets (Orthoptera: Myrmecophilidae) are obligate inquilines within ant colonies that obtain nourishment from ants in their nests. Recently, new morphological and genetic approaches have revealed more ant cricket species than had previously been recognized and have provided insights into their host specificity. In this study, we compare the degree of host specificity and behavior between 2 cryptic lineages of the ant cricket Myrmecophilus kubotai Maruyama that distinctly differ in their mtDNA sequences but are morphologically indistinguishable. In the field, crickets of lineage I (specialists) were found in nests of Tetramorium tsushimae Emery (Myrmicinae) at a high frequency (89%); whereas, crickets of lineage II (generalists) were found in nests of up to 12 ant species belonging to Formicinae and Myrmicinae. Behavioral observations in ant nests revealed that lineage I suffers few ant attacks and showed frequent intimate behavior with ants, i.e., grooming. In contrast, lineage II often suffers ant attacks and showed less frequent host grooming. In Japan's Nansei Islands, a “super-specialist” species of ant cricket that lives commensally with a single ant species has been reported to depend on mouth-to-mouth feeding from the worker ants; whereas, another “super-generalist” species that lives commensally with a variety of ant taxa feeds itself. Compared with these, the 2 lineages in the present study exhibited intermediate host specificity and behavioral specialization. These results suggest that there are various stages of specialization of commensalism in this genus.
Baseline surveys were conducted in Khartoum State, Sudan, during the rainy season (end of July to the beginning of September) in 2008, and female mosquitoes were sampled for arboviruses from November 2008 to January 2009 to predict outbreaks of Rift Valley Fever (RVF) in Khartoum State. Aedes vittatus (Bigot) and Ae. vexans (Meigen) vectors were found only at one of the study sites (Soba West). Under laboratory conditions, survival of these mosquitoes exceeded the mean incubation period of the arboviruses in these vectors (15 days). Field-collected blood-fed female mosquitoes were tested for the RVF virus using the real-time PCR technique. The virus was detected in populations of Ae. vexans and Culex quinquefasciatus (Say) for the first time in Sudan.
Bollworm, Helicoverpa zea (Boddie), larvae are known to move away from Bollgard™ (Monsanto Co., St. Louis, MO) cotton terminals. Bollworm larvae are also found more frequently on flower buds (squares) and bolls of Bollgard as compared with those of nontransgenic cotton. However, data are not available for bollworm behavior on commercially available transgenic cotton varieties expressing 2 Bacillus thuringiensis Berliner proteins. Thus, field studies were conducted in Stoneville, MS, during 2007 and 2008 to determine whether bollworm behavior differed among cotton expressing the Cry1Ac and Cry1F proteins (Widestrike®, Phytogen 485, PhytoGen Seed Co., LLC, Indianapolis, IN) and nonBt cotton (Phytogen 425, PhytoGen Seed Co., LLC, Indianapolis, IN). Two-day-old bollworm larvae were placed into terminals of either individual cotton plants or plants within 1-m plots during the flowering period. Comparison of larval movement away from cotton terminals between Widestrike and nonBt plants did not differ at 3, 6, 24, or 48 h after infestation. In addition, larval distribution on fruiting structures did not differ between Widestrike and nonBt cotton. These data indicate that different scouting methods for bollworm larvae should be used for the various Bt cotton technologies commercially available.
Different pairs of plants planted in a single pot were tested in the greenhouse for oviposition preference by the silverleaf whitefly, Bemisia argentifolii Bellows & Perring (Hemiptera: Aleyrodidae). Treatments were: 2 giant red mustard plants (Brassica juncea (L.) Czern.), 2 collards (Brassica oleracea L. var. acephala), and 1 plant of each species in individual pots. Treatments were exposed to whitefly adults and numbers of eggs laid were counted 6 d later. Numbers of whitefly eggs were significantly lower on the mustard-mustard treatment. Average egg counts were lower on collard plants in the treatment where both host plants were presented simultaneously than in treatments where collards were presented alone. These results suggest the possibility of repellent volatiles in the giant red mustard. To test for repellent effects in the field, an experimental plot was planted with squash (Cucurbita pepo L.), cabbage (Brassica oleracea L. var. capitata), broccoli (Brassica oleracea L. var. italica), collards, and cantaloupe (Cucumis melo L. reticulatus). A central plot of mustard transected the experimental area. To measure any effects of distance from the mustard, weekly sampling was performed at 5 equidistant intervals of 2.4 m to a distance of 12.2 m from the central mustard plot. Results showed whitefly attraction to squash and cantaloupes and aversion to mustard, with other crops (including collards), hosting intermediate insect densities. Repellent properties of mustard at these sampling distances in the field did not affect attraction or oviposition on other crops. It is possible that the sampling distances were too large to detect any repellent effects, or any effects of volatiles were stronger within the confines of the laboratory test arena. In general, results presented in this study are preliminary. Further field research needs to be conducted to determine if intercropping giant red mustard can be a promising strategy. However, squash and cantaloupe may have potential as trap crops for whitefly, or giant red mustard may be planted as a resistant crop when heavy whitefly infestations are anticipated.
Chikungunya (CHIK) is an emerging or reemerging arboviral infectious disease transmitted to humans by the Asian tiger mosquito, Aedes albopictus (Skuse), and the yellow fever mosquito, Ae. aegypti (L.), particularly in Africa, India, Southeast Asia, and other parts of Europe where numerous outbreaks and epidemics were documented during recent decades. This viral disease is a potential threat to human health worldwide; thus, a quantitative one-step, real-time RT-PCR protocol was developed and assessed as a suitable assay for minimum detection of chikungunya virus (CHIKV) E1 (genus Alphavirus, family Togaviridae) in human serum (7.51 fg/μl) by using the QuantiTect® Probe RT-PCR kit with appropriate synthetic primer (CHIK E1 F and CHIK E1 R) and dual-labeled CHIK E1 probe. Unfortunately, we did not detect any CHIKV from 9 species, namely Ae. albopictus, Aedes (=Ochlerotatus) cantans (Meigen), Ae. cinereus Meigen, Ae. geminus Peus, Ae. vexans (Meigen), Anopheles claviger Meigen, An. maculipennis Meigen s.l., An. plumbeus Stephens, and Culex pipiens L., but some Kamiti River virus (KRV) were found in Ae. albopictus eggs, Ae. cinereus and Ae. vexans mosquitoes adults. Phylogenetic analyses revealed that these novel insect flaviviruses from Ae. albopictus eggs is closely related to Cell fusing agent virus (CFAV), which is different from the other group of arboviruses from extra Aedes spp. mosquitoes. These results suggest that Aedes spp. in the area of Ticino, Switzerland are likely to be highly infected with two distinct groups of insect flaviviruses, excluding the possibility of CHIKV in mosquito vectors.
Fall armyworm, Spodoptera frugiperda (J. E. Smith), and corn earworm, Helicoverpa zea Boddie, perennially cause leaf and ear damage to corn for silage production in the southeastern United States. Transgenic hybrids expressing the Cry1Ab (MON810 event) insecticidal endotoxin from Bacillus thuringiensis (Bt) were evaluated for management of fall armyworm and corn earworm in central Georgia during 2006 and 2007. Hybrids with a temperate or semitropical background were planted at the recommended time in mid-April and in late June to simulate a double-crop corn planting. Whorl infestation and damage by fall armyworm was significantly reduced in hybrids with the Bt trait when infestations were large. Fall armyworm infestation levels and damage were similar in both temperate and semitropical types. Hybrids with the Bt trait also had a small reduction in ear infestation and less kernel damage in ears infested by corn earworm than susceptible hybrids in most trials. Corn earworm infestation level were less in the semitropical than the temperate hybrids in 2006 but were not different in 2007. Silage yield was not significantly different among hybrids with and without the Bt trait in the first planting in both years. The Bt trait prevented significant yield loss of 17.1% during the second planting in 2006 when fall armyworm whorl infestations exceeded 39% in susceptible hybrids, but did not significantly affect silage yield in the late planting in 2007 when fall armyworm infestations were low. Temperate hybrids yielded more than semitropical hybrids in the early planting, but the semitropical type tended to perform better in the late planting. Corn silage quality as measured by neutral detergent fiber, acid detergent fiber and crude protein content did not differ among hybrids with or without the Bt trait indicating silage dry matter yield was the main silage component affected by the Bt trait and insect damage.
This article is only available to subscribers. It is not available for individual sale.
Access to the requested content is limited to institutions that have
purchased or subscribe to this BioOne eBook Collection. You are receiving
this notice because your organization may not have this eBook access.*
*Shibboleth/Open Athens users-please
sign in
to access your institution's subscriptions.
Additional information about institution subscriptions can be foundhere