Ailanthus altissima (Mill.) Swingle, tree-of-heaven, is an invasive species native to Asia. It first was introduced into the United States in the 1700 s and now is distributed throughout much of North America. Mechanical and chemical controls are current suppression tactics, however, implementation is costly. A weevil, Eucryptorrhynchus brandti (Harold), was identified in China and imported for quarantine testing in 2004 as a potential biological control agent. Host specificity tests on adult feeding, larval development, and oviposition of this weevil were conducted from 2007 to 2011 on A. altissima and 29 nontarget species. Eucryptorrhynchus brandti adults fed significantly more on A. altissima foliage when compared with all test species. Range of means for feeding on A. altissima was 32.5-106.5 mm(2)/adult/d. In no-choice tests, Simarouba glauca DC, Leitneria floridana Chapm., and Citrus limon (L.) Burm. F., had feeding rates of only 10, 49, and 10%, respectively, compared with the level of feeding on A. altissima. The mean range of adult feeding by E. brandti on all other test species was <7% of feeding on A. altissima (0.0-3.3 ± 5.0 mm(2)/adult/d). In the no-choice larval inoculation tests, larval development only occurred in two of 10 L. floridana seedlings compared with seven of 10 A. altissima seedlings. In the no-choice oviposition tests, oviposition and subsequent larval development did not occur in L. floridiana, whereas all seven A. altissima seedlings supported oviposition and subsequent larval development. The weevil did not appear to be a threat to L. floridana or any other nontarget species tested. Therefore, we conclude that Eucryptorrhynchus brandti is highly host specific to A. altissima.
The red palm weevil (RPW), Rhynchophorus ferrugineus (Olivier), recently found in Curaçao and Aruba, has become an economically significant palm tree pest in many tropical and subtropical regions. By the time a palm infested with RPW displays visible damage, larvae have destroyed much of the trunk internal structure, typically resulting in tree mortality. Acoustic technology may enable pest managers to detect and treat early RPW infestations before tree mortality, and to reduce unwanted importation and/or exportation of infested palms. Experiments were conducted in Aruba to determine the detectability of sounds produced by early instars in open, urban environments and in enclosures with ca. 10 dB acoustical shielding. To distinguish RPW signals from background noise, recordings first were analyzed to identify larval sound impulse bursts, trains of 7-199 impulses, 3-30-ms in duration, where impulses within the train were separated by less than 0.25 s. For a burst to be considered a larval sound, it was specified that a majority of its impulses must have spectra that match mean spectra (profiles) of known larval sound impulses more closely than profiles of background noise or known nontargeted sound sources. Based on these analyses, RPW larval bursts were detected in > 80% of palm fronds inoculated with neonates the previous day. There were no significant differences between burst rates in enclosed and open environments, but the shielding provided by the enclosure enabled detection of early instars from greater distances. Thus, there is potential to use acoustic technology to detect early RPW infestation in either minimally shielded or open environments. In addition, because late-instar impulses ranged to higher amplitude and had greater diversity of spectral features than with early instars, it may be possible to identify late-instar infestations based on the amplitudes and the diversity of sound features detected.
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Eucryptorrhynchus hrandti (Harold) (Coleóptera; Curculionidae) was identified in China and studied in quarantine in tbe United States as a potential biological control agent for the invasive weed, tree of heaven, Ailanthus altissima (Mill.) Swingle (Sapindales: Simaroubaceae). Studies on its general biology and development, and the most efficacious rearing method were conducted. E. brandti is univoltine. The metathoracic sternite and first abdominal segment are convex in females and concave or flat in males. Females are larger than males. Female and male sagittal measurements averaged 11.50 ± 0.14 (± SEM) and 10.35 ± 0.09 mm, respectively. Transversal measurements averaged 4.22 ± 0.06 and 3.73 ± 0.05 mm for females and males, respectively. Mean weight of females and males were 0.10 ± 0.003 and 0.07 ± 0.002 g, respectively. Females lived longer than males, averaging 66.3 ± 6.8 d and 46.5 ± 7.3 d, respectively. The egg stage averaged 5.0 ± 0.9 d, and the larval stage had six stadia and developed in 110 ± 15.0 d; the pupal stage was 16 ± 7.0 d at 25°C. A method for rearing E. brandti on cut A. altissima billets under quarantine conditions was developed. The most efficient egg-to-adult rearing method involved caging 12 males and 12 females or 24 males and 24 females for 7 d on 23-92-cm-long biUets. Duration up to 3 wk after cutting did not affect adult emergence. This information will facilitate laboratory rearing and conducting host specificity tests to determine agent impact on nontarget species.
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