Oviposition specificity and behavior of the watermilfoil specialist Euhrychiopsis lecontei

Eurasian watermilfoil (Myriophyllum spicatum L.) is a nuisance aquatic weed, exotic to North America. The freshwater weevil Euhrychiopsis lecontei (Dietz) is a potential control agent of Eurasian watermilfoil and is a fully submersed aquatic specialist herbivore. Its presumed original host is the native northern watermilfoil (Myriophyllum sibiricum Komarov). We conducted a set of oviposition experiments to reveal first and second oviposition preference of Euhrychiopsis lecontei when presented with seven macrophytes. We tested differences between source (lake) populations of weevils, differences in behavior between weevils reared on the exotic Eurasian watermilfoil and the native northern watermilfoil and between weevils in the presence and absence of their preferred hostplant. Oviposition assays confirmed that E. lecontei is a watermilfoil specialist. Out of the 207 females that laid eggs, only three oviposited on a non-watermilfoil plant, Megalodonta beckii. The weevils' degree of specificity was influenced by the watermilfoil species on which they were reared. Weevils reared on Eurasian watermilfoil tended to oviposit on Eurasian watermilfoil, spent more time on Eurasian watermilfoil than on other plants, and spent more time off plants and took longer to oviposit when Eurasian watermilfoil was removed. Weevils reared on northern watermilfoil did not exhibit a preference for either watermilfoil species in oviposition or in time allocation, although they oviposited on and spent significantly more time on watermilfoils than on other species. Rearing of the two populations on their complementary watermilfoil hostplant resulted in responses typical of the rearing plant, not the original host. These results show that although both weevil populations are watermilfoil specialists, Eurasian-reared weevils prefer Eurasian watermilfoil in general host attraction and oviposition, whereas northern-reared weevils do not. The results support the contention that E. lecontei may be a good biocontrol agent for Eurasian watermilfoil because of its high specificity. The results also suggest that the current host range expansion of the weevil to Eurasian watermilfoil has the potential to become a host shift due to the increased specificity. Herbivory in freshwater systems is not well studied, and the E. lecontei-M. spicatum relationship is a rare example of submersed freshwater specialist herbivore-host-plant interactions.     

Habitat distribution and habitat preference in Barbary macaques (Macaca sylvanus)

Barbary macaques (Macaca sylvanus,L.) occur at varying densities in a number of different habitat types in Morocco and Algeria. Taub (1977) has argued that the abundance of the species in cedar forests of the Moyen Atlas, Morocco, is an indication of a habitat preference. A reexamination of available data on the distribution and abundance of Barbary macaques suggests that monkey numbers reflect the distribution of habitat size rather than habitat types. Differences between populations relative to habitat types can be seen only between forest and scrub localities. Human factors are considered more important in determining the present status of this eclectic feeder. The modern distribution of the Barbary macaque is inadequate evidence for a habitat preference.     

Removal,early hand rearing,and successful reintroduction of an orangutan (Pongo pygmaeus pygmaeus/x abelii) to her mother

A newborn orangutan was removed from her mother 55 h after birth because no nursing had been observed. She was hand reared in a nursery for 3 d and then successfully reintroduced to her mother. Several factors that may have contributed to the successful reintroduction are discussed.     

Host race formation in the gall waspAndricus mukaigawae

Allochronic isolation between the two host races of the bisexual generation ofA. mukaigawae (Mukaigawa) (Hymenoptera: Cynipidae) was demonstrated in the field. Assortative mating seems to occur in the bisexual generation of each race. Genetic changes of ovipositional preference probably played an important role in the host race formation; it is likely that little or no genetic change in survival was required in this process. A difference in host phenology seems to have caused the allochronic isolation of the bisexual generation between the parent population on the original host tree species and its daughter population on the new host tree species. Gene flow between them may have been restricted ever since the initial host shift. The host race formation of this wasp probably represents an example of sequential evolution.

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Résumé L'isolement allochronique de 2 races spécifiques aux hôtes différents a été prouvé dans la nature pour la génération bisexuée deA. mulaigawae (Hymen., Cynip.). Des accouplements assortis semblent exister à l'intérieur de la génération bisexuée de chaque race. Des différences génétiques dans le choix du lieu de ponte doivent jouer un rôle important dans la formation de ces races; il n'est probablement pas nécessaire qu'il y ait des changements génétiques dans la survie, pour obtenir cette genèse. Une différence dans la phénologie des hôtes semble avoir entraîné l'isolement allochronique dans la génération bisexuée entre les populations parentales suivant l'espèce originelle d'arbre hôte, et dans ses populations filles suivant les nouvelles espèces d'arbres hôtes. Le flux génique entre ces populations peut avoir été limité depuis le changement initial d'hôtes. Chez ce cynipide la formation de races, en fonction de l'hôte, représente probablement un exemple d'évolution séquentielle.

     

Host stress influences oviposition preference and performance of a pine sawfly

Abstract.

• 1 The effect of ponderosa pine (Pinus ponderosa Doug]. ex Laws) water stress, measured by xylem water potential, on oviposition preference and egg development of Neodiprion fulviceps was determined by two laboratory experiments in 1987 and 1988.
• 2 In the first experiment, adult females were allowed to choose between foliage from water-stressed, watered, and untreated control trees.
• 3 Significant differences were found between treatments in xylem water potential in 1987 but not in 1988.
• 4 Females chose water-stressed trees and a positive correlation was found between female preference and xylem water potential in 1987 but not in 1988.
• 5 In the second experiment, females were placed in globe cages with a single branch from each treatment and allowed to oviposit.
• 6 Significant differences were found among treatments in egg survival in 1987 but not in 1988.
• 7 These results indicate that sawflies can distinguish between stressed and non-stressed trees and that this behaviour is adaptive in that egg survival was greatest on the preferred treatment.

     

The functional response and preference ofMacrolophus caliginosus [Heteroptera: Miridae] for two of its prey:Myzus persicae andTetranychus urticae

Functional response studies of females ofMacrolophus caliginosus Wagner for 2 prey speciesMyzus persicae Sulzer andTetranychus urticae Koch showedHolling's type II response (1959). Estimations of handling time (Th) and attack rate (a) obtained for the aphid (Th=.055 day; a=1.035) and for the mite (Th=.025 day; a=.947) enabled the development of a mathematical model which describes the predation rate on the 2 prey simultaneously. This mirid shows a sharp preference for aphids over mites.

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Résumé L'étude en laboratoire des réponses fonctionnelles des femelles adultes deMacrolophus caliginosus Wagner vis-à-vis des deux proiesMyzus persicae Sulzer etTetranychus urticae Koch montre dans les 2 cas une réponse de type II deHolling (1959). L'estimation du temps de manipulation (Th) et du taux d'attaque instantané (a) pour l'aphide (Th=.055 jour; a=1.035) et pour l'acarien (Th=.025 jour; a=.947) permet d'établir un modèle mathématique décrivant la prédation sur les 2 proies présentes simultanément et de préciser ainsi, au regard des résultats expérimentaux, l'existence d'une préférence du miride pour le puceronM. persicae.

     

Preservatives influence induction of feeding tolerance in Papilio demoleus larvae

The feeding responses of newly hatched larvae of Papilio demoleus on the diet with preservatives were as high as on the diet without preservatives though less than those on the host lime leaves. However, when the larvae were reared upto the 5th instar on the host lime leaves or the diet with or without preservatives, their feeding responses towards host lime leaves and the diet without preservatives were equally high. The diet with preservatives reared larvae showed 100% response when tested on the same diet. But their response towards diet with preservatives declined to 80% when the larvae were reared on the diet without preservatives and to 10% when they were reared on the host lime leaves. The larvae seem to have an aversion against the preservatives if reared in their absence which was enhanced by their experience of feeding on the host leaves during their ontogeny.

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Influence des agents de conservation sur la prise de nourriture par les chenilles de Papilio demoleus

Résumé La prise de nourriture par des chenilles néonates de P. demoleus est aussi élevée sur régime avec agents de conservation qu'en leur absence, bien qu'elle soit inférieure à celle qui est observée sur les feuilles de son hôte Citrus limettioides. Cependant, quand les chenilles ont été élevées jusqu'au 5ème stade sur des feuilles de C. limettioides, ou sur des régimes avec ou sans conservateurs, leur prise de nourriture sur feuilles de C. limettioides, et régime sans conservateur est aussi importante. Toutes les chenilles élevées sur régime avec conservateur ont consommé lorsqu'elles avaient été maintenues sur le même régime. Par contre, leurs réactions face à un régime contenant des conservateurs a entraîné une diminution de près de 20% après élevage sur un régime sans conservateur, et de près de 90% après élevage sur feuilles de C. limettioides. Les chenilles semblent manifester de l'aversion envers les conservteurs si elles ont été élevées en leur absence, aversion renforcée lorsqu'il y avait eu préalablement alimentation sur feuilles de C. limettioides.

     

Effects of aluminium and mineral nutrition on growth and chemical composition of hydroponically grown seedlings of five different forest tree species

Forest die-back and impaired tree vitality have frequently been ascribed to Al-toxicity and Al-induced nutritional disorders due to increased acidification of forest soils. Therefore, in this experiment effects of Al were studied on growth and nutrient uptake with seedlings of five different forest tree species. During growth in culture solutions with and without Al all five species proved to be very Al-tolerant, despite high accumulation of Al in roots. In the coniferous evergreens Douglas-fir and Scots pine shoot as well as root Al concentrations were significantly higher than in the deciduous broad-leaved species oak and birch. Larch showed intermediate Al levels. In none of the five species did Al reduce nutrient concentrations or the Ca/Al ratio to values below the critical level. Besides differences in Al accumulation, coniferous and broad-leaved species also differed with respect to uptake and assimilation of nitrogen. Due to extra NH ₄ ⁺ uptake, oak and birch showed a much higher N uptake and higher NH ₄ ⁺ preference than the coniferous species. Especially with oak this high NH ₄ ⁺ preference in combination with a low specific root surface area resulted in a high root proton efflux density. In comparison to both broad-leaved trees and Scots pine the NO ₃ ⁻ reduction capacity of larch and Douglas-fir was extremely low. This may have important consequences for both species if grown in NO ₃ ⁻ -rich soils.     

A report of behavioral lateralization in an infant orang-utan (Pongo pygmaeus)

The limb used to perform seven common activities was recorded during weekly observations of an infant orang-utan. For five of these behaviors, preferences were found that remained consistent in their direction, although there were week to week fluctuations in magnitude. Most notably, a right hand preference was found for nonfood reaching and a right hindlimb preference appeared for initiating locomotion. Although initially, food reaching was predominantly with the right hand, a shift toward preferential left hand use occurred during the final weeks of the study. Additionally, a left hand preference appeared when the infant touched either its body or head.     

Estimating the susceptibility of tree species to attack by the gypsy moth, Lymantria dispar

ABSTRACT.

• 1 Numbers of gypsy moth larvae feeding on each of 922 randomly sampled trees in a Quercus—Acer—Fraxinus forest in southwestern Quebec, Canada were counted in 1979 and in 1980 to quantify the larval feeding preferences as observed in the field for eighteen deciduous and one coniferous tree species at the northern range limit of the gypsy moth.
• 2 Both the diameter at breast height (dbh) and the estimated foliage biomass of the sampled trees were used to calculate the relative proportions of foliage represented by each of the nineteen tree species in the forest canopy. With these data on availability and utilization of the tree species by the gypsy moth larvae an Ivlev-type electivity index was used to quantify the larval feeding preferences. These preferences observed in the field define the susceptibility of a tree species to attack by the gypsy moth.
• 3 The feeding preferences calculated using estimated foliage biomass were comparable to the simpler calculation based on dbh (Spearman's rho = 0.79; P= 0.0001). The dbh-based feeding preferences remained almost unchanged in 1979 and 1980 (Spearman's rho = 0.83; P= 0.0001).
• 4 The composite 1979—80, dbh-based feeding preferences show Quercus rubra, Populus grandidentata, Ostrya virginiana, Amelanchier spp. and Acer saccharum were preferentially attacked by gypsy moth. Prunus serotina, Betula lutea, Acer rubrum, A. pensylvanicum, Fraxinus americana, Ulmus rubra, P. pensylvanicum and B. papyrifera were avoided. All nineteen tree species were, however, utilized to at least some degree by gypsy moth larvae.
• 5 These results quantitatively affirm and clarify earlier reports of gypsy moth feeding preferences in North America and Eurasia. The advantages and limitations of using an electivity index to estimate the susceptibility of different tree species to attack by folivores like the gypsy moth are discussed.