NUMBER OF INSTARS OF LARVAE OF THE ALFALFA LEAFCUTTER BEE, MEGACHILE ROTUNDATA (F.) (HYMENOPTERA: MEGACHILIDAE)

1987 ◽  
Vol 119 (10) ◽  
pp. 859-865 ◽  
Author(s):  
G.H. Whitfield ◽  
K.W. Richards ◽  
T.M. Kveder
Keyword(s):  
Linear Regression ◽  
Frequency Distribution ◽  
Direct Observation ◽  
Field Studies ◽  
Accurate Method ◽  
Head Capsule ◽  
Physical Injury ◽  
Megachile Rotundata ◽  
Head Capsule Width ◽  
Leafcutter Bee

AbstractThe number of instars of larvae of the alfalfa leafcutter bee, Megachile rotundata (F.), was determined by direct observation, frequency distribution plots, and linear regression of head-capsule measurements. For all three methods, developmental polymorphism was observed; larvae were grouped according to the number of instars. The majority of larvae (77%) had four larval instars and the remainder had five. Mortality of bee larvae, apparently a result of physical injury during measurement of head-capsule width, was high but results were based on data for 259 individuals that completed development to the prepupal (= pharate pupa) stage. Direct observation of larval moults was found to be the only accurate method for determining instar designation but analysis of head-capsule width did describe the number of instars present in a population and provided estimates of head-capsule width for each instar. A morphological key for separation among four instars is presented as a practical alternative for instar determination in field studies.

Nectar sugar production in alfalfa fields treated with several herbicides

1995 ◽  
Vol 75 (2) ◽  
pp. 521-524
Author(s):  
P. S. Curry ◽  
J. Waddington ◽  
N. Malik ◽  
G. G. Bowes
Keyword(s):  
Field Studies ◽  
Early Spring ◽  
Sugar Production ◽  
Winter Dormancy ◽  
Megachile Rotundata ◽  
Cocoon Production ◽  
Leafcutter Bee ◽  
Nectar Sugar ◽  
Medicago Sativa L ◽  
Herbicide Effects

Field studies were conducted at three sites in northeastern Saskatchewan to determine the effects of several herbicides applied in late fall or early spring on nectar sugar production in alfalfa (Medicago sativa L.) grown for seed. In general, sugar production was not affected detrimentally by the herbicides, but at one site alfalfa treated annually with metribuzin for 4 yr at the break of winter dormancy produced flowers in early July containing significantly less nectar sugar than flowers of plants not treated with herbicide. Increases in nectar sugar production sometimes occurred. At one site, chlorsulfuron at 0.11 kg ha−1 or more, hexazinone at 1.0 kg ha−1 and dichlobenil at 2.4 kg ha−1 increased nectar sugar production in early August. Herbicide effects were not consistent among sites, and it seems unlikely that leafcutter bee (Megachile rotundata Fabr.) cocoon production will be affected significantly by these weed control practices. Key words: Metribuzin, hexazinone, chlorsulfuron, terbacil, dichlobenil, imazethapyr

TOXICITY OF INSECTICIDES TO THE ALFALFA LEAFCUTTER BEE, MEGACHILE ROTUNDATA F. (HYMENOPTERA: MEGACHILIDAE), ESTABLISHED BY THREE EVALUATION METHODS

1988 ◽  
Vol 120 (4) ◽  
pp. 297-305 ◽  
Author(s):  
W. A. Charnetski
Keyword(s):  
Petri Dish ◽  
Evaluation Methods ◽  
Laboratory Evaluation ◽  
Evaluation Procedure ◽  
Megachile Rotundata ◽  
Field Cage ◽  
Male And Female ◽  
Significant Difference ◽  
Leafcutter Bee ◽  
Significant Mortality

AbstractThree methods—tube chambers (ventilated and unventilated), petri dish chambers, and field cages—were used to evaluate the toxicity of deltamethrin, trichlorfon, and methoxychlor deposits on alfalfa, Medicago sativa L., to 1- to 7-day-old alfalfa leafcutter bees, Megachile rotundata (F.), 24 and 48 h after exposure. In unventilated tube chambers, all three insecticides were significantly toxic to male bees after 24 and 48 h, but only deltamethrin and trichlorfon were significantly toxic to female bees after 24 h. In ventilated tube chambers, only deltamethrin was significantly toxic by contact and then only to male bees at 24 h. Significant vapor action was observed only for trichlorfon and only in unventilated tube chambers. By the petri dish method, only deltamethrin caused significant mortality to male and female bees. However, bee mortality increased significantly between 24 and 48 h. By the field cage method, there was no significant difference in mortality among treatments and controls within the 24- and 48-h evaluations. Bee mortality in the controls was much higher in the petri dish and field cage methods than in either of the two variations of the tube chamber method. The three evaluation methods are compared and the need for a standardized laboratory evaluation procedure is discussed.

The mark–recapture method applied to population estimates of a freshwater crab on an alluvial plain

2013 ◽  
Vol 64 (4) ◽  
pp. 317 ◽  
Author(s):  
Débora de Azevedo Carvalho ◽  
Pablo Agustín Collins ◽  
Cristian Javier De Bonis
Keyword(s):  
Hydrological Cycle ◽  
Field Studies ◽  
Accurate Method ◽  
Alluvial Plain ◽  
Short Term ◽  
Chi Square ◽  
Mark Recapture ◽  
Closed Population ◽  
Short Term Study ◽  
Chi Square Test

Mark–recapture methods are a useful population estimation tool, although with many assumptions that cannot always be satisfied for all types of organisms and environments. In the present study, three mark–recapture methods (Petersen, Schnabel and Schumacher–Eschmeyer) were applied in a preliminary trial to estimate the population size of the crab Trichodactylus borellianus and to gain information that would support the use of the methods in the field. The accuracy of these estimates was verified by analysing the percentage of bias, the width of the confidence intervals, and by a chi-square test. The assumptions of equal catchability and closed population were verified, along with assumptions related to the efficiency of marking. The adjusted methodology was applied in a short-term study of a pond on the Paraná floodplain. The results showed that the assumptions were satisfied for both the experimental and field studies. The Schnabel was the most accurate method evaluated in both studies. Although the Schumacher–Eschmeyer method also provided accurate results in the field study, it needed large samples to give reliable estimates. The applicability of these methods depends on the stage of the hydrological cycle. The choice of a short-term research design will ensure that the assumption of a closed population is valid for research of this type on an alluvial plain.

The Phenologies of Cotesia-Urabae, Dolichogenidea-Eucalypti (Hymenoptera, Braconidae) and Their Host Uraba-Lugens (Lepidoptera, Noctuidae) in the Adelaide Region

1990 ◽  
Vol 38 (4) ◽  
pp. 347 ◽  
Author(s):  
GR Allen
Keyword(s):  
Field Study ◽  
Larval Stage ◽  
First Generation ◽  
Dry Weight ◽  
Head Capsule ◽  
Head Capsule Width ◽  
Two Generations ◽  
High Level ◽  
Lepidoptera Noctuidae ◽  
Host Generation

A field study was undertaken to determine the phenologies of the solitary larval endoparasitoids Cotesia urabae and Dolichogenidea eucalypti in relation to that of their bivoltine host Uraba lugens. C. urabae had two generations within both the summer and the winter generation of U. lugens, and D. eucalypti had two generations in the summer but only one generation in the winter. D. eucalypti parasitised a narrower range of host sizes in the field. Both parasitoids attacked recently hatched (typically 1st instar) or 'small hosts' at the beginning at each host generation. In summer D. eucalypti was the first to emerge from hosts, but both D. eucalypti and C. urabae, emerged from hosts which had modes of 0.85-1.05 mm in head capsule width and 0.9-1.5 mg in dry weight (mid hosts). In winter, C. urabae emerged from hosts which had modes of 1.15 mm in head capsule width and 2.7 mg in dry weight (large hosts). Both species in summer, and C. urabae in winter, then proceeded to parasitise hosts of around these sizes to commence second parasitoid generations. In its second generation in summer and its first generation in winter, D. eucalypti typically emerged after most unparasitised hosts had pupated. Both species of parasitoid overwintered within the larval stage of their host. Levels of parasitisation appeared to be low, and dropped between first and second generations within each host generation. It was concluded that C. urabae and D. eucalypti displayed continuity of generations and a high level of synchronisation with U. lugens in the Adelaide region.

EFFECT OF ENVIRONMENT AND EQUIPMENT ON PRODUCTIVITY OF ALFALFA LEAFCUTTER BEES (HYMENOPTERA: MEGACHILIDAE) IN SOUTHERN ALBERTA, CANADA

1996 ◽  
Vol 128 (1) ◽  
pp. 47-56 ◽  
Author(s):  
K.W. Richards
Keyword(s):  
Environmental Variables ◽  
Total Cell ◽  
Significant Positive Effect ◽  
Megachile Rotundata ◽  
Southern Alberta ◽  
Temperature Heat ◽  
Leafcutter Bee ◽  
Nesting Material ◽  
Higher Temperature ◽  
Positive Effect

AbstractFour indicators of productivity and quality for the alfalfa leafcutter bee, Megachile rotundata (Fab.), were examined over a 3-year period and the influence of different shelter designs, nesting materials, and 34 environmental variables evaluated. A higher percentage of cocoons per total cells was produced in polystyrene nesting material than in pinewood nesting material. Both nesting materials had similar percentages of tunnels capped or containing cells and total numbers of cells per hive. Shelters with conspicuous orientation patterns or silhouettes had more tunnels capped per hive, tunnels with cells, and greater total cell production per hive than did other shelter designs. The time of maximum bee production varied greatly among the 3 years. Many environmental variables, especially those associated with higher temperature, heat units, and mean actual temperature, had a significant positive effect on bee productivity and cell quality. The information contained in this study may help delineate those climatic areas where this valuable alfalfa pollinator can be most effective, and may assist beekeepers in making management decisions that will improve their operations.

IMPACT OF DAMAGE BY THE DRIEDFRUIT MOTH, VITULA EDMANDSAE SERRATILINEELLA (LEPIDOPTERA: PYRALIDAE), A PEST OF THE ALFALFA LEAFCUTTER BEE, MEGACHILE ROTUNDATA (HYMENOPTERA: MEGACHILIDAE)

1983 ◽  
Vol 115 (12) ◽  
pp. 1549-1553 ◽  
Author(s):  
K. W. Richards
Keyword(s):  
Positive Relationship ◽  
Megachile Rotundata ◽  
Wood Material ◽  
Significant Positive Relationship ◽  
Leafcutter Bee ◽  
Lepidoptera Pyralidae ◽  
Nesting Material

AbstractLarvae of the driedfruit moth, Vitula edmandsae serratilineella Ragonot, enter uncapped tunnels in hives of the alfalfa leafcutter bee, Megachile rotundata F., and eat the pollen and nectar provisions of incomplete cells. Significantly more cocoons are destroyed in hives made of pine nesting material than in those made of polystyrene nesting material. However, significantly more tunnel walls are chewed into and through in the polystyrene than in the wood material. A significant positive relationship exists between the number of moth larvae per hive and the number of bee cells produced in that hive. After hives are removed from the field and placed in storage for the winter, most mature larvae leave the tunnels upon completion of feeding and aggregate in spaces between hives.

RELATIONSHIPS BETWEEN THE PARASITOID HYPOSOTER EXIGUAE AND THE CABBAGE LOOPER, TRICHOPLUSIA NI: EFFECTS ON HEAD-CAPSULE WIDTH, LIVE AND DRY WEIGHTS, AND HEMOLYMPH SPECIFIC GRAVITY OF HOSTS AT DIFFERENT AGES

1975 ◽  
Vol 107 (9) ◽  
pp. 927-934 ◽  
Author(s):  
Gerard F. Iwantsch ◽  
Zane Smilowitz
Keyword(s):  
Specific Gravity ◽  
Trichoplusia Ni ◽  
Dry Weight ◽  
Head Capsule ◽  
Cabbage Looper ◽  
Host Age ◽  
Head Capsule Width ◽  
Growth Increments ◽  
Developmental Parameters

AbstractThe effects of parasitism by Hyposoter exiguae (Viereck) on certain developmental parameters of Trichoplusia ni (Hübner) were influenced by host age at parasitism.Head-capsule growth increments for parasitized Trichoplusia ni became smaller with each successive molt during parasitism so that determination of instar on the basis of head-capsule width became impossible.Parisitized T. ni showed a proportionately smaller gain in weight from time of stinging until parasitoid emergence the older they were when stung (6 times for 3rd instars; 2 times for 4th instars; and no gain for 5th instars). This retardation was evident 24 h after parasitism. Essentially the same results were obtained for dry weight.Percentage dry weight of parasitized larvae tended to increase over control values until the 5th stadium when controls abruptly increased. Values for parasitized 5ths remained below the controls. Values found on the last days reflected those of the parasitoid which composed most of the mass inside the host cuticle.Hemolymph specific gravity in controls and parasitized 3rd instars oscillated with a frequency of one stadium in the 3rd, 4th, and early 5th stadia. Specific gravity of controls then rose to a maximum of 1.0501 in the prespinning phase and dropped by the pharate–pupal phase. Values for parasitized larvae in the 5th stadium rose slightly before leveling off, and parasitized 5th instars rose to a maximum on the next-to-last day. Maximum values attained for hosts parasitized as 3rd and 5th instars never reached that for controls on day 11. This may be related to the complete unacceptability or unsuitability of T. ni larvae for parasitism from day 11 on.

Sign in / Sign up

Export Citation Format

Share Document