Underside Of Branches Research Articles

Three-toed sloths walk differently from their cousins

Life is difficult when you live in the canopy, but even more so when you spend much of your day hanging suspended from the branches. Yet, there are a number of animals for which this is common, including tree sloths. Both two-toed and three-toed sloths spend nearly their entire lives hanging from branches and have therefore evolved some remarkable tricks for thriving in this unusual way of life, including their slow movements. But just how these sloths walk on the underside of branches is not fully understood. This led A. J. McKamy and Michael Butcher of Youngstown State University, USA, to ask how does the brown-throated three-toed tree sloth (Bradypus variegatus) move? And does it do so similarly to its previously studied cousin, Linnaeus's two-toed sloth (Choloepus didactylus)?Working alongside Melody Young and Michael Granatosky from New York Institute of Technology College of Osteopathic Medicine, USA, and Angela Mossor and Jesse Young of Kent State University USA, the team travelled to the Sloth Sanctuary in Costa Rica to meet up with Judy Avey-Arroyo. There, the researchers used a pressure sensor to measure how much force the sloths applied as they traversed a beam made of a local bamboo-like woody grass. They also videoed the movements to see how the sloths were gripping the woody beam and whether they were doing this differently from the two-toed sloths.Interestingly, the researchers found that as the three-toed sloths were walking, they were pulling down on the beam more strongly with their hindlimbs than with their front limbs. This is unique to the three-toed sloths, as their two-toed cousins pull down equally hard with their front and back limbs. This suggests that the three-toed sloths are actually using their back limbs to support more of their body weight than their front limbs, whereas the two-toed sloths spread their weight out evenly. McKamy suggests that this may be because three-toed sloths are very deliberate about where they place their front feet. They are frequently seen reaching out with their front limbs to test the branch for stability while most of their weight is on their hindlimbs.However, the back limbs are doing more than just supporting their body weight. These limbs are also used for slowing down while the animal is moving about, while the front limbs are used to propel the sloths forward. Additionally, the hindlimbs in three-toed sloths press inward on the beam with more pressure than the front limbs do, while their front limbs are pulling the beam out to the side. This pulling motion away from the beam is minimal in the two-toed sloths, but the researchers suggest that this is a result of how three-toed sloths grip tree branches. Instead of just hanging on with their claws from underneath, the three-toed sloths wrap their feet over the top of the branch, further gripping the branch with their claws to keep stable. So, although sloths may look similar and even live life in a similar way, at least two species have come up with different ways of moving in a life spent mostly hanging from the branches.

Biological traits and life history of Pagiophloeus tsushimanus (Coleoptera: Curculionidae), a weevil pest on camphor trees in China

Cinnamomum camphora (L.) J. Presl. (Laurales: Lauraceae) is widely cultivated as an important landscape tree species in many urban areas in South China, especially in Shanghai City. Pagiophloeus tsushimanus Morimoto has become a destructive insect pest of C. camphora plantations in Shanghai, but the biological and ecological traits of this pest remain largely unknown. In this study, we investigated the damage and life history and determined the larval instar of P. tsushimanus. The results indicated that P. tsushimanus is a monophagous weevil pest, and C. camphora is the unique host tree species. C. camphora plantations in all administrative districts of Shanghai have been seriously damaged by P. tsushimanus. Adults often aggregate for feeding on the tender bark of twigs and occasionally on newly emerged buds. After experiencing damage, the twigs shrink and crack and the buds will shrink. Adults tend to repeatedly mate and oviposit, and all females lay single eggs at a time. Eggs will be covered with a mixture of secretions and wood chips by female adults. Larvae (1st–2nd instar) feed on the phloem, while 3rd–5th instar can bore into the phloem and the cambium. Massive tunnels, including three shapes (inverted “L”, inverted “T”, and inverted “Z”), were observed in the trunk of each tree, and resulted in swelling of the outer bark. P. tsushimanus has one life cycle per year in Shanghai. Both adults and larvae (3rd–5th instar) overwinter from early November to early April. Adults overwinter in grooves on the underside of branches or at branch nodes, and larvae overwinter in tunnels. Five larval instars of P. tsushimanus were determined according to Dyar's and Crosby's rules. The biological traits and life history of P. tsushimanus have been identified and can provide guidance in terms of pest control and plantation management.

Quantification of (1→4)-β-d-Galactans in Compression Wood Using an Immuno-Dot Assay.

Compression wood is a type of reaction wood formed on the underside of softwood stems when they are tilted from the vertical and on the underside of branches. Its quantification is still a matter of some scientific debate. We developed a new technique that has the potential to do this based on the higher proportions of (1→4)-β-d-galactans that occur in tracheid cell walls of compression wood. Wood was milled, partially delignified, and the non-cellulosic polysaccharides, including the (1→4)-β-d-galactans, extracted with 6 M sodium hydroxide. After neutralizing, the solution was serially diluted, and the (1→4)-β-d-galactans determined by an immuno-dot assay using the monoclonal antibody LM5, which specifically recognizes this polysaccharide. Spots were quantified using a dilution series of a commercially available (1→4)-β-d-galactan from lupin seeds. Using this method, compression and opposite woods from radiata pine (Pinus radiata) were easily distinguished based on the amounts of (1→4)-β-d-galactans extracted. The non-cellulosic polysaccharides in the milled wood samples were also hydrolysed using 2 M trifluoroacetic acid followed by the separation and quantification of the released neutral monosaccharides by high performance anion exchange chromatography. This confirmed that the compression woods contained higher proportions of galactose-containing polysaccharides than the opposite woods.

Characterization of a 1-aminocyclopropane-1-carboxylate synthase gene from loblolly pine ( Pinus taeda L.)

1-Aminocyclopropane-1-carboxylate (ACC) synthase catalyzes what is typically the rate-limiting step in the biosynthesis of ethylene, a gaseous plant growth regulator that plays numerous roles in the growth and development of higher plants. Although ACC synthase genes have been characterized from a wide variety of angiosperm plant species, no ACC synthase genes have been described previously for gymnosperms. Evidence suggests that ethylene helps to regulate wood formation in trees, and may also signal for the metabolic shifts that lead to compression wood formation on the undersides of branches and leaning stems in gymnosperm trees. Since compression wood is an inferior feedstock for the manufacturing of most wood products, a better understanding of the factors influencing its formation could lead to substantial economic benefits. This study describes the isolation and characterization of a putative ACC synthase gene, PtaACS1, from loblolly pine ( Pinus taeda L.), an important commercial forest tree species. Also described is an apparent splice variant of PtaACS1 ( PtaACS1s) that is missing 138 bp from the 5′ end of the transcript, including bases that encode a conserved amino acid residue considered critical for ACC synthase activity. The two sequences share interesting homologies with a group of plant aminotransferases, in addition to ACC synthases, but structural models and the conservation of critical catalytic amino acid residues strongly support PtaACS1 as encoding an active ACC synthase. The two transcripts were differentially expressed in various tissues of loblolly pine, as well as in response to perturbations of pine seedling stems. Transcript levels of this ACC synthase gene increased rapidly in response to bending stress but returned to near starting levels within 30 min. It remains unclear to what extent bending-induced expression of this gene product plays a role in compression wood formation.

Hydraulic and anatomical properties of light bands in Norway spruce compression wood

Compression wood (CW), which is formed on the underside of conifer branches, exhibits a lower specific hydraulic conductivity (k(s)) compared with normal wood. However, the first-formed tracheids of an annual ring on the underside of a conifer branch often share several properties with normal tracheids, e.g., thin cell walls and angular cross sections. These first-formed tracheids appear bright when observed by the naked eye and are therefore called light bands (LB). In this study, hydraulic and related anatomical properties of LBs were characterized and compared with typical CW and opposite wood (OW). Measurements were made on branches of Norway spruce (Picea abies (L.) Karst.). Specific hydraulic conductivity was measured with fine cannulas connected to microlitre syringes. Micro- and ultrastructural analysis were performed on transverse and radial longitudinal sections by light and scanning electron microscopy. Xylem areas containing both typical CW and LBs had a k(s) 51.5% that of OW (7.95 +/- 0.97 m(2) s(-1) MPa(-1) x 10(-4)), whereas k(s) of pure CW was only 26.7% that of OW. The k(s) of LBs (6.38 +/- 0.97 m(2) s(-1) MPa(-1) x 10(-4); 80.3% of OW) was estimated from these k(s) values because the cannulas were too wide to measure the k(s) of LBs directly. Mean lumen area of first-formed tracheids on the underside of branches was 65.7% that of first-formed tracheids in OW and about three times that of CW. Light-band tracheids exhibited a bordered pit frequency of 42.7 +/- 1.3 pits mm(-1), which was three times that in CW and 1.6 times that in OW. Bordered pit apertures in LB tracheids (9.15 +/- 0.60 microm(2)) were 1.7 times wider than those in CW and similar in aperture to those in OW. The high k(s) of LBs was correlated with their wide tracheid lumina, high pit frequency and wide pit apertures. We therefore suggest that LBs have a primarily hydraulic function within the mechanically optimized CW region. This might be important for supplying water to living tissues on the underside of branches, as well as to other distal areas along water transport pathways following the spiral grain of wood.

Light interception in apple trees influenced by canopy architecture manipulation

Improvement of light penetration within tree canopies has been a constant objective of fruit tree architecture manipulation through the setting up of training systems. Recently, centrifugal training, i.e. the removal of fruiting shoots in the tree centre and on the underside of branches, has been proposed to improve fruit size and colour as well as return-bloom as compared to conventional solaxe-trained trees with equivalent crop loads. The present study was conducted to quantify the benefits of centrifugal training on light interception by the fruiting shoots via computer-assisted three-dimensional representations of foliage geometry. Data were collected on six 5-year-old apple trees cv.Galaxy, trained either with solaxe or centrifugal training systems, using an electromagnetic 3D digitiser. The 3D distribution of the foliage in the tree canopy was recreated by combining both the spatial locations of shoots (as measured from 3D digitising) and foliage reconstruction. Light interception efficiency properties of the trees were characterised by silhouette to total area ratio (STAR) values computed from images of the 3D mock-ups. Compared to the solaxe system, centrifugal training significantly improved the STAR of the whole tree by 20%. It also increased both leaf area and STAR of the fruiting shoots by approximately 15%, regardless of their position in the canopy. In this paper, we discuss the role of this enhanced light interception by the canopy in increasing the autonomy of the fruiting shoot, i.e. improved fruit size and colour, and return-bloom.

Adult resting sites as a target for chemical control of the cocoa pod borer, Conopomorpha cramerella (Lepidoptera: Gracillariidae), in Malaysia

AbstractThe daytime resting sites of adult Conopomorpha cramerella (Snellen), a serious pest of cocoa in south-east Asia, were identified as a possible target to which insecticide could be selectively applied. Field observations were made on 126 resting moths in a cocoa plantation in East Malaysia. All moths were found on the undersides of branches 45° or less from horizontal, and 1·5 cm or more in diameter; 90% were found in the lower half of trees. A field trial was conducted in which 25 ppm deltamethrin was applied with knapsack sprayers to these sites. Five applications were made at ten day intervals, each crop season (6 months), over a two year period. Mean estimated losses in the sprayed area were 12.1 to 33.7 percentage points lower than in the control area, giving an estimated net benefit of up to RM978 ha in one season, assuming a cocoa price of RM4000 per tonne. Losses in the sprayed area still ranged from 7.0% to 43·1% and did not decline over successive seasons. There was some evidence for immigration into the sprayed area, but it is suggested the rapid recovery of populations following spraying is also due to the high potential rate of increase of the insect in susceptible cocoa varieties. In susceptible cocoa varieties control is always likely to be difficult, but in less susceptible varieties, and with well maintained trees, chemical control by selective application to adult resting sites can be a practical component of integrated control.

The understanding of industrial melanism in the peppered moth (Biston betularia) (Lepidoptera: Geometridae)

Melanic polymorphism in B. betularia has been extensively studied. Correlations between high melanic frequency and high levels of air pollution have been demonstrated. Kettlewell and others have shown that differential bird predation has an important effect on the maintenance of the polymorphism, and coefficients of visual selection have been obtained on the assumption that the moth habitually rests on tree trunks. Computer models based on these selective coefficients show that they are not sufficient accurately to explain observed melanic frequencies. Other non-visual selective factors and weak frequency-dependent selection have been invoked to improve fits. Analysis of the resting positions of moths recorded in the wild demonstrates that B. betularia does not usually rest in exposed positions on tree trunks, but rather rests on the underside of branches, on trunks in shaded positions just below major branch joints or on foliate twigs. The results of a pilot selection experiment, while agreeing qualitatively with Kettlewell's results, suggest that fitness estimates that assume trunk-resting are quantitively incorrect. The error is greatest for melanic moths in rural areas. It is suggested that visual selective coefficients based on a true assessment of the resting behaviour of the moths may considerably improve the fit between computer predictions and observed phenotype frequency distributions.

Influence of Elm Spanworm 1 Oviposition Sites on Parasitism by Ooencyrtus clisiocampae2 and Telenomus alsophilae3

The egg parasitoids Telenomus alsophilae Viereck and Ooencyrtus clisiocampae (Ashmead) suppress populations of Ennomos subsignarius (Hubner). O. clisiocampae parasitizes eggs during the foliated period of the year and T. alsophilae during the dormant afoliated season. Incidence of parasitism by these two parasitoids in host eggs deposited on boles was similar to that of eggs deposited on undersides of branches. O. clisiocampae was found to be most abundant in host eggs in the upper portions of the forest. In an area where O. clisiocampae was extremely abundant, almost all host eggs were parasitized at all levels of the forest. Parasitism by T. alsophilae was similar at all levels of a forest where O. clisiocampae was not abundant. In a forest where O. clisiocampae was moderately abundant, a significant negative correlation was obtained for relationship of eggs parasitized by this parasitoid to those parasitized by T. alsophilae . The immature stages of both parasitoids were highly overdispersed. It should also be noted that the mortality of host eggs by causes other than parasitism was more pervalent in smaller egg masses than in larger ones.

A study of the resting sites of Glossina swynnertoni Aust. in northern Tanganyika

Observations in three areas in northern Tanganyika on the day-time resting sites of adults of Glossina swynnertoni Aust. showed that the most important of these was the underside of branches of trees. The number of flies seen on this site represented about one-third of the total population as calculated from the apparent density, and about half of them were on branches 4–9 ft. above ground, 1–4 in. in diameter and at an angle of less than 35° from the horizontal. It is suggested that were an insecticide to be applied to branch sites within these limits, then, since any fly must make six or more flights in the first 18 days of its life, it would be expected to alight on a treated surface at least once in this period. Were a lethal deposit maintained for twice this period, plus the pupal period, control could be effected.

Effects of Solarization on Elm Spanworm Eggs (Lepidoptera: Geometridae)

The elm spanworm, Ennomos subsignarius (Hubner), oviposits almost exclusively on the undersides of branches. Experimentation showed that this habit benefits egg hatch. Mortality from overwinter solarization in cardinal directions increased clockwise from north through west. No hatch took place when eggs were exposed toward the zenith; normal eclosion occurred among eggs exposed toward the nadir.

ABNORMAL XYLEM RAYS IN CHAMAECYPARIS

ABNORMAL XYLEM RAYS IN CHAMAECYPARIS