Behavior Of Weevils Research Articles

Budburst phenology of sitka spruce and its relationship to white pine weevil attack

Abstract Phenology of budburst development of Sitka spruce, Picea sitchensis Bong. Carr., measured at two sites on Vancouver Island, British Columbia, Canada, was under strong genetic control, with family heritability ( h 2 f ) ranging from 0.45 to 1.0, depending on phenology stage. On average, families with resistance to the white pine weevil, Pissodes strobi (Peck), initiated and maintained a faster rate of bud development than families from susceptible parents, requiring lower heat accumulation to reach particular stages of bud development. However, a large overlap occurred, with one resistant family having a budburst phenology not significantly different from the susceptible families and some susceptible families having phenology as early as that of resistant families. It is postulated that resistance is a multicomponent trait based on different resistance mechanisms, some of which may be correlated with phenology but not others. Close observation of weevil behaviour through the season indicated that resistant families experienced reduced weevil presence, copulation and oviposition rate with respect to susceptible families.

The influence of Shelterwood density on Hylobius abietis (L.) occurrence and feeding on planted conifers

Damage to planted conifer seedings was assessed and numbers of adult pine weevils (Hylobius abietis) were estimated after cutting of a mixed conifer stand to form shelterwoods of eight different densities. Untreated and insecticide treated seedlings of Picea abies and Pinus sylvestris were included in the experiments. Both seedling damage and pine weevil occurrence were considerably higher on clear‐cuttings and in shelterwoods of low densities ( < 80 stems ha‐1) than in shelterwoods with 320 or more stems ha‐1. In shelterwoods with 80–160 stems ha‐1 feeding damage was low despite of high catches of pine weevils. Pine weevil damage on seedlings in shelterwoods is discussed in relation to solar radiation, vegetation cover and weevil behaviour. The use of shelterwoods is suggested as a practical method for reducing pine weevil damage.

The Effect of Crop Microenvironment on the Pea Leaf Weevil's Behaviour: An Explanation for Weevil Departure from Diverse Cropping Systems

A study of the effect of microenvironment on the pea leaf weevil’s behaviour was made comparing a broad bean monoculture with a broad bean-oat crop mixture. It is observed that more weevils depart from the crop mixtures than from the monocultures. Microenvironment study in the two cropping systems show that temperature and wind speed are not significantly altered in the crop mixtures as compared to the monoculture, but beans growing in the mixtures were significantly more shaded than those in the monoculture. Evidence is given to show that this relative shading could be the main factor responsible for the observed increased weevil departure from the crop mixtures.

Effect ofLoliumendophyte fungus infections on behaviour of adult Argentine stem weevil

Abstract The effect of Lolium endophyte on feeding and oviposition by adult Argentine stem weevil (Listionotus bonariensis( (Kuschel)) was studied in the laboratory and screenhouse. The effects of endophyte on weevil behaviour were determined in choice and non-choice experiments. Feeding and oviposition were reduced in weevils confined on endophyte-infected plants compared to those confined on endophyte-free plants.

A Stochastic Model for Oviposition Tactics in the Bean Weevil

AbstractIn a recent paper, MITCHELL (1975) experimentally investigated the oviposition behavior of weevils on mung beans. In this paper, we develop a stochastic model to study the oviposition tactics of the female weevils on beans.

Humidity Preference of the Alfalfa Weevil, Hypera postica,1 as Affected by Microenvironmental and Physiological Conditions2

Humidity preference of adult Hypera postica (Gyllenhal) (Coleoptera: Curculionidae) was studied in the laboratory using modified petri dish and modified T-tube humidity chambers. Both chamber types offered 2 choices, with humidities being controlled by solutions of sulfuric acid and distilled water. Test results showed that sulfuric acid had no inherent effect upon alfalfa weevil behavior. The source of weevil, whether field collected or laboratory reared, had little effect on humidity behavior except under extreme conditions. Pretest starvation accentuated but did not change the direction of response to humidity gradients by the weevil. Both increasing age and increasing temperature resulted in increased selection of the higher of the 2 humidities. The higher of the 2 humidities was selected more frequently in the light than in the dark. Weevil response to moving and still-air gradients was similar. Weevil adults could distinguish humidity differences as small as 5% at 35°C. Discussion is presented to correlate results obtained and field behavior. It was felt that weevil presence on plants at night might be due in part to the low humidity preferred in decreasing light and temperature conditions. This lower humidity would be found near plant tips rather than in the duff. Decreasing weevil numbers on plants with increasing weevil age might similarly be correlated with a tendency to select higher humidities (as found in the duff) with increasing age. Correlation of experimental results and field conditions indicated that weevil humidity response would not differ significantly between the moving air at the tops of the plants and the still air of the duff.

Some Aspects of Weevil Behaviour affecting Population Establishment

IT has been recognized for some time that it is necessary to assess the significance of low-density pest populations in stored grain. These may be survivors from a treatment (probably pre-adult stages) or migrants entering hitherto uninfested material; either may give rise to larger populations. On the other hand, ‘tolerable levels’ of infestation may exist, below which a population would fail to establish itself.

THE RESPONSE OF THE WHITE-PINE WEEVIL TO NATURALLY OCCURRING REPELLENTS

The reactions of the white-pine weevil to air-borne repellents was studied in an olfactometer which, unlike other types, permitted a quantitative measure, capable of gradation, to be made of an individual's response. Different coniferous tree species supplied the odorous material in the form of essential oils extracted for use in these experiments by distillation from the bark. Degree of oil repellency and tree species were related. The response of any one individual tended to be consistent. Males and females responded equally to the repellents. The curve relating the response and the concentration of the repellent was similar to those generally describing the relation between stimulus strength and response. Adaptation to the repellent odors was clearly seen. From analysis of motion picture film it was apparent that repellent vapors affected weevil behavior so that the duration of activity periods was shortened although the rest periods remained constant.