Shoot Feeding Research Articles

Effect of maturation feeding period on survival of Tomicus piniperda (Coleoptera: Scolytidae)

AbstractCallow adults of the pine shoot beetle, Tomicus piniperda L., were fed shoots of Scots pine, Pinus sylvestris L. (Pinaceae), to investigate the influences of shoot age and feeding duration on survival and weight of callow adults and to characterize the relationship between the volume of shoot tissue excavated and weight gain. Heavier callow adults had better survival than lighter ones, and survival was higher on current-year shoots than on 1-year-old shoots. A significant relationship was observed between the amount of tissue excavated by callow females on current-year shoots and their body weight gain, a trend not observed in callow males. These results suggest that beetle weight and survival may be reduced when availability of current-year shoots during maturation feeding is limited because of competition (i.e., during population outbreaks), thus negatively affecting the production of future generations.

BROOD PRODUCTION AND SHOOT FEEDING BY TOMICUS PINIPERDA (COLEOPTERA: SCOLYTIDAE)

AbstractBrood production and shoot feeding by the pine shoot beetle, Tomicus piniperda (L.), were studied over 3 years in naturally infested plantations of Scots pine, Pinus sylvestris L. (Pinaceae), near Guelph and Waterloo, Ontario, using trap-logs. Adult beetles produced a single brood in 1996 and 1997 and two broods in 1999. Galleries for the first brood were all initiated under the bark over a 2- to 3-week period from mid-April to early May. The lone second brood occurred in early June. In all years, eggs were present by late April, larvae by mid-May, pupae by late June, and new adults by mid-July. Complete development (egg–pupa) required 12–13 weeks for the first brood and 8 weeks for the second brood. First-brood adults emerged over a 2- to 3-week period from early to mid-July in all years, with second-brood adults emerging in late July. The effective heat sums (degree-days (°d) > developmental-threshold temperature) were 77–79 °d for eggs, 267–293 °d for the larval stage, 139–152 °d for the pupal stage, and 43.2 °d for the pre-emergence stage, depending on the developmental-threshold temperature used. The total heat sums for the first brood (1249.8 ± 73.3 °d > 0 °C) were larger that those required for the second brood (856.4 ± 124 °d > 0 °C). Overall, values for first-brood development were similar to those calculated for European and Asian populations. Pine shoots in the upper tree crowns were used by adult beetles for maturation feeding between late July and late September in both 1995 and 1996. The re-emerging parental adults fed upon 1-year-old shoots, whereas newly emerging adults fed primarily upon current-year shoots. The beetles appeared to move to overwintering sites in late October to November, and no adults were found overwintering in shoots on the trees or the ground. Our results parallel those obtained by others under similar climatic conditions in Europe, and can be used to improve the management and regulation of this species as it becomes established in our native pine forests.

Shoot feeding and overwintering in the lesser pine shoot beetle Tomicus minor (Col., Scolytidae) in north‐west Spain

During 1991, 1992, &, 1993 a study on shoot feeding, overwintering and the presence of Tomicus minor inside pine shoots was carried out in the province of León (NW Spain). This paper deals with the duration of these processes, overwintering sites and pine shoot feeding characteristics: age, diameter, length, occurrence of exit holes, multiple attacks and length of the burrowed tunnels. It also refers to the degree of shoot occupation, sex‐ratio and detected adult mortality.

Shoot‐feeding Aphids Promote Development of Gremmeniella abietina, the Fungal Pathogen Causing Scleroderris Canker Disease in Conifers

AbstractWe tested experimentally whether shoot feeding aphids Cinara pinea (Mordv.) can promote the development of Gremmeniella abietina (Lagerb.) Morelet, a fungus which causes Scleroderris canker disease in conifers. Pine seedlings were infested with aphids at two different times, and subsequently inoculated with conidia of G. abietina at two different times. The degree of infestation was classified into three groups based on the number of aphids/seedling: none, one (low level), and three (high level). Because of parthenogenetic reproduction, the number of aphids increased during the summer, so we also used aphid numbers to explain the development of the symptoms. Necrosis caused by G. abietina was more prevalent in seedlings infested by aphids in June, and inoculated with fungus in July. Expressed as percents of the total length of the shoots, the necrosis had advanced 50%, 70%, and 95% with no, low, and high aphid levels, respectively. Canker formation was significantly greater when G. abietina conidia were inoculated in July, compared to August. In August, there were no statistically significant differences in the intensity of disease between aphid infestation levels, but the mean number of aphids was related to disease intensity. In the spring following infection, seedlings with aphids had more dead and fewer healthy terminal buds compared to seedlings without aphids.

Patterns of hand and mouth lateral biases in bamboo leaf shoot feeding and simple food reaching in the gentle lemur (Hapalemur griseus).

Lateralized feeding behaviors of 7 wild-born and 6 captive-born Hapalemur griseus sp. were evaluated in two conditions, simple food reaching and species-typical bamboo foraging. Gentle lemurs were found to have the strongest lateral hand preference in simple food reaching of any prosimian species yet studied. However in this small sample, population-level lateralization was not found: 5 preferred the right hand and 8 the left. The movement pattern used by hapalemurs when feeding on bamboo leaf shoots was categorized into four components: PULL IN, COUNTERFORCE, TURN, and FEED IN. Lateral hand bias was scored for all four components and lateral mouth preference was scored for the two components that involved the mouth (COUNTERFORCE and FEED IN). Strong positive correlations were found between hand preference in the most lateralized components of shoot eating (TURN and FEED IN) and simple food reaching. This suggests that the gentle lemurs' species-typical bamboo feeding behavior may contribute to the exceptionally strong hand preference for simple food reaching seen in this species. There were negative correlations between the component measure of shoot feeding that required strength (COUNTERFORCE) and the components that required manipulation (TURN and FEED IN). Within the COUNTERFORCE and FEED IN components, mouth preference and hand preference were positively associated in a manner that suggested one side of the mouth was preferred for removing the shoot and the other side for mastication. Asymmetrical dental wear may provide a means of dating behavioral lateralization in ancestral species. © 1993 Wiley-Liss, Inc.

Treating Scots pine seedlings with the herbicide atrazine does not affect shoot chemistry or feeding and oviposition by Lygusrugulipennis

Polyphagous Lygus (Heteroptera: Miridae) bugs, which have one of the widest documented host-plant ranges, have accepted nursery-grown conifer seedlings as host plants only recently. One explanation for this adaptation to the conifer nursery environment could be the increased attractiveness of conifer seedlings due to herbicide treatments. In three laboratory experiments, we tested whether atrazine treatments (2 or 4 kg•ha−1) affected shoot chemistry of pine seedlings and the feeding and oviposition behaviour of the European tarnished plant bug, Lygusrugulipennis Popp. Shoot growth of the pine seedlings was decreased by the atrazine treatment (2 kg•ha−1) in only one experiment. The number of feeding lesions caused by Lygus bugs and the number of eggs laid per seedling were not affected by herbicide treatments, nor was the proportion of seedlings damaged. Concentrations of total amino acids were not affected by the herbicide in any of the experiments. In one experiment, the level of lysine was increased in the atrazine treatment. Terpenes and resin acids were analysed only in one experiment, and total concentrations of these defence compounds were not affected by atrazine. Dominant monoterpenes were α-pinene and 3-carene, the latter varying strongly between individual seedlings. Abietic acid and neoabietic acid were the dominant abietane and pimarane resin acids. The results suggest that applications of atrazine are not likely to reduce the resistance of pine seedlings to Lygus bugs. Herbicides may have an indirect effect by reducing the availability of alternative host plants for bugs. Other potential causes for increased numbers of Lygus bugs on nursery-grown conifer seedlings are discussed.

Impact of the Red Pine Shoot Moth, Dioryctria resinosella (Lepidoptera: Pyralidae), on Height and Radial Growth in Wisconsin Red Pine Plantations

A newly described species, the red pine shoot moth, Dioryctria resinosella Mutuura, was found to be responsible for a decline in form of Pinus resinosa Ait. in central Wisconsin. Larval shoot feeding resulted in height and radial growth losses. Height growth losses were evaluated by comparison of growth in epidemic years with potential growth determined by a biological growth curve equation. Radial growth losses were evaluated by comparison of pre-outbreak growth to growth in outbreak years. Height growth loss estimates for various stands ranged from 38 to 65% over a 9-year epidemic period. Radial growth loss estimates ranged from 16 to 42% in the same stands over the same period.

BIONOMICS AND PATTERN OF ATTACK OF THE RED PINE SHOOT MOTH, DIORYCTRIA RESINOSELLA (LEPIDOPTERA: PYRALIDAE), IN WISCONSIN

AbstractThe bionomics of the red pine shoot moth, Dioryctria resinosella Mutuura, a newly described species of shoot borer in red pine, Pinus resinosa Ait., were investigated in Wisconsin sand plains plantations. The appearance of eggs, larvae, pupae, and adults are described. Head-capsule measurements indicated five larval instars. First-instar larvae overwintered in hibernacula. Shoot feeding was generally initiated by third-instar larvae in late May. Cones also were attacked. Pupation occurred in July. The flight period extended from mid-July to mid-September. The sex ratio was 0.53. Only red pine shoots and cones were attacked in a mixed pine stand. Infestation rates were highest along plantation edges, in the top half of the crown and in plantations greater than 20 years of age. Hyssopus rhyacioniae Gahan occurred most frequently among parasitoids reared from larvae and pupae.

Susceptibility of Loblolly and Slash Pines to Rhyacionia spp. Oviposition, Injury, and Damage

Oviposition and initial larval feeding (injury) by the Nantucket pine tip moth, Rhyacionia frustrana (Comstock), and the pitch-pine tip moth, R. rigidana (Fernald), were found on neighboring loblolly pine, Pinus taeda L.; shortleaf pine, P. echinata Mill.; longleaf pine, P. palustris Mill.; and slash pine, P. elliottii Engelm. Shoot and bud killing (damage) occurred mostly on shortleaf and loblolly pines. Studies on loblolly and slash pine showed that differential larval survival following oviposition and initial shoot feeding was responsible for differences in shoot and bud killing.