Density and location of simulated signs of injury affect efficacy of ground surveys for Asian longhorned beetle

Surveys for signs of attack by Asian long-horned beetles, Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae), currently rely upon visual examination of trees to discover signs of attack. By embedding simulated A. glabripennis oviposition pits and exit holes on open-grown Norway maples, Acer platanoides L. (Aceraceae), we evaluated the effect of sign density, height (below or above 2.5m), and position (bole or branch) when foliage was present or absent on inspector ability to distinguish trees with or without signs. From this, we quantified detectability, or the proportion of trees correctly identified as infested, and determined the time taken to do so. Effectiveness in detecting trees with signs improved when sign density increased, when signs were below 2.5m, and when oviposition pits were located on boles and exit holes on branches. These main findings require some caveats, due to a number of significant interactions. Foliage presence/absence had no apparent influence on effectiveness; possible reasons are provided for this result. Time-to-find curves, which illustrated the proportion of inspectors who accurately identified an infested tree as a function of survey duration, revealed that for most treatment combinations, most infested trees were detected within the first 2 min of survey time. These findings provide baseline data to assist managers in designing effective protocols for ground surveys of A. glabripennis.

Frugivorous birds, host selection and the mistletoe Psittacanthus schiedeanus, in central Veracruz, Mexico

Frugivorous birds play an important role in parasitic mistletoe transmission among host species. The foraging behaviour and host selection of Psittacanthus schiedeanus mistletoe fruit-eating birds was studied in cloud forest remnants in Central Veracruz, México. Cedar waxwings, Bombycilla cedrorum, gray silky-flycatchers, Ptilogonys cinereus, and social flycatchers, Myiozetetes similis, eating ripe whole mistletoe fruits and defecating or regurgitating the seeds were observed. That variation in host species selection by frugivorous birds had a direct effect on mistletoe dispersion was hypothesized. To test whether mistletoe host species are visited in proportion to their abundance (total number of trees), or infested-tree abundance (total number of infested trees), or abundance of mistletoes (total number of individual mistletoe plants in each host species), the number of trees, infested trees and individual mistletoe plants were recorded. Tree abundance, infested-tree abundance and mistletoe abundance were different among host species. Frequency of birds' visits to host species varied depending on the tree, infested-tree, or mistletoe abundance. Liquidambar styraciflua was the most abundant host species with the highest number of infested trees and individual mistletoe plants, but Persea americana and Crataegus mexicana host species had the highest number of individual mistletoe plants in each tree. Our data suggest that L. styraciflua was the most selected host species by the three frugivorous birds. Host selection by birds is one behavioural factor in explaining differences in prevalence among host species, and variation in infection levels among individuals of one host species.RESUMEN. Las aves frugívoras juegan un importante papel en la transmisión de muérdagos parásitos hacia sus árboles hospederos. La conducta de forrajeo y selección de hospedero de aves consumidoras de frutos del muérdago Psittacanthus schiedeanus fueron estudiados en remanentes de bosque mesófilo de montaña del Centro de Veracruz, México. Bombycilla cedrorum, Ptilogonys cinereus and Myiozetetes similis fueron observados consumiendo frutos maduros enteros y defecando o regurgitando las semillas. Hipotetizamos que la variación en la selección de la especie hospedera por las aves frugívoras tiene un efecto directo en la dispersión del muérdago. Para probar si las especies de árboles hospederos son visitadas en proporción a su abundancia (número total de árboles), o la abundancia de hospederos infectados (número de árboles infectados) o la abundancia de muérdagos (número total de plantas individuales de muérdago en una sola especie de árbol); el número de árboles, árboles infestados y plantas de muérdago fueron registradas. La abundancia de árboles, de árboles infestados y de plantas de muérdago fue diferente entre las especies de árboles estudiadas. La frecuencia de visitas de las aves a las especies hospederas varió de acuerdo a la abundancia de árboles, de árboles infestados y de plantas de muérdago. Liquidambar styraciflua fue la especie hospedera más abundante con el mayor número de árboles infestados y abundancia de muérdagos, pero las especies Persea americana y Crataegus mexicana presentaron el mayor número de plantas de múerdago por árbol. Nuestros datos sugieren que L. styraciflua fue la especie hospedera más seleccionada por las aves frugívoras. La selección de hospederos por las aves es uno de los factores conductuales que explican las diferencias en prevalencia entre especies de hospedero, y la variación en los niveles de infestación entre individuos de una de las especies de hospedero.

RELATIVE ABUNDANCE AND SEASONAL OCCURRENCE OF CORTICEUS GLABER AND CORTICEUS PARALLELUS (COLEOPTERA: TENEBRIONIDAE), ASSOCIATES OF THE SOUTHERN PINE BEETLE, DENDROCTONUS FRONTALIS (COLEOPTERA: SCOLYTIDAE)

In southern Louisiana, Corticeus glaber (LeConte) outnumbered Corticeus parallelus (Melsheimer) 3.7:1 during 15-month study from October 1976 to December 1977. Corticeus spp. varied significantly (P < 0.01) among the 52 sample dates and three sample heights on infested tree boles. Corticeus spp. were significantly correlated with numbers of southern pine beetle eggs, Dendroctonus frontalis Zimmermann, in the bottom and middle samples but not in the top sample. Corticeus glaber peak arrival occurred from 14 days prior to 14 days following pine beetle mass attack, while C. parallelus peak arrival occurred from 7 days prior to 10 days following pine beetle mass attack.

SURVIVAL MODELS FOR WITHIN-TREE POPULATIONS OF DENDROCTONUS FRONTALIS (COLEOPTERA: SCOLYTIDAE)

Within-tree models of Dendroctonus frontalis generation survival from attacking adults to emerging adults and survivorship from eggs to emergence were developed for five regions of the infested tree bole of Pinus taeda L. The generation survival model (GS) describes the number of D. frontalis/attacking adult as a function of time at a specific height. The form of the model isYGS = 1.0 + C(1–e–20.0X)eA(1.0–X)B + ɛ.The survival model (S) describes the number of D. frontalis/100 eggs as a function of time at a specific height. The form of this model isYS = CeA(1.0–X)B + ɛ.The generation survival model indicated that the rate of survival was primarily a function of generation development time, rather than position on the infested tree bole. The rates also varied in different sections of the tree depending on the initial egg/attacking adult population of D. frontalis. The emergence/attack ratios for the tree sections were slightly greater at the top and bottom than in the middle of the infested bole.The survivorship curves, based on an initial cohort of 100 eggs, were similar for the various sections of the tree bole. Again, the rate of population change was primarily a function of developmental time, rather than position on the tree. The curves for the various tree sections were essentially the same.The combined action of the various biotic and abiotic mortality agents acting in the different sections of the tree resulted in essentially uniform survivorship throughout the infested portion of the tree bole.

ODOUR OF SAN JOSE SCALE, ASPIDIOTUS PERNICIOSUS

In the many accounts of this insect, I do not recall that attention has been called to the odour that is associated with insect, and which, in cases of excessive abundance, can be detected at a considerable distance away. Where the air is quiet it is often possible to detect the presence of a badly infested tree a yard away, and I presume that with more acute olfactories, such as insects are supposed by many to possess, even the presence of a more limited number of the scale might be detected at a much greater distance.