DEVELOPMENTAL TIME AND HOST SELECTION BY THE APHID PARASITOID APHELINUS SP. NR. VARIPES (FOERSTER) (HYMENOPTERA: APHELINIDAE)

1992 ◽  
Vol 124 (4) ◽  
pp. 565-575 ◽  
Author(s):  
S.E. Lajeunesse ◽  
G.D. Johnson
Keyword(s):  
Host Selection ◽  
Native Species ◽  
Head Capsule ◽  
Russian Wheat Aphid ◽  
Primary Host ◽  
Aphid Parasitoid ◽  
Developmental Threshold ◽  
Head Capsule Width ◽  
Corn Leaf Aphid ◽  
Lower Developmental Threshold

AbstractDevelopmental rates, lower developmental threshold, host selection among three species of aphid, and head capsule width were determined for the parasitoid Aphelinus sp. nr. varipes (Foerster) (Hymenoptera: Aphelinidae). Aphid species used were Russian wheat aphid, Diuraphis noxia (Mordvilko), western wheat aphid, Diuraphis tritici (Gillette), and corn leaf aphid, Rhopalosiphum maidis Fitch. Developmental rate was determined at five constant temperatures, 11.3, 14.7, 19.0, 25.7, and 30.3°C. Developmental times of the wasp were similar in Russian and western wheal aphids, ranging from 88.7 days al 11,3°C to 11.3 days at 30.3°C. Lower developmental threshold was similar in both species, 9.7°C in Russian wheat aphid and 9.4°C in western wheat aphid. Because of the low number of corn leaf aphid s parasitized, it was not possible to compute a parasitoid development threshold in that host. In the host selection test, there were no significant differences in numbers of Russian and western wheat aphids attacked; corn leaf aphid was seldom attacked. The western wheat aphid is a native species that also causes leaf-rolling; we believe it was the primary host of the parasitoid before the arrival of the Russian wheat aphid. Wasps emerging from Russian wheat aphid were consistently larger than those emerging from western wheat aphid. Mean head capsule width for 30 female wasps from Russian wheat aphid was 0.33 mm; from 30 female wasps from western wheat aphid mean head capsule width was 0.20 mm.

Seasonal trends in the rate of population increase of Frankliniella occidentalis (Thysanoptera: Thripidae) on cucumber

1997 ◽  
Vol 87 (5) ◽  
pp. 487-495 ◽  
Author(s):  
V. Jarošík ◽  
M. Koliáš ◽  
L. Lapchin ◽  
J. Rochat ◽  
A.F.G. Dixon
Keyword(s):  
Population Growth ◽  
Frankliniella Occidentalis ◽  
First Generation ◽  
Developmental Rate ◽  
Exponential Phase ◽  
Population Increase ◽  
Developmental Threshold ◽  
Sum Of Effective Temperatures ◽  
Lower Developmental Threshold ◽  
Effective Temperatures

AbstractThe developmental rate of Frankliniella occidentalis (Pergande) was determined on cucumber Cucumis sativus cv. Sandra over a range of constant temperatures. The lower developmental threshold (LDT) and the sum of effective temperatures (SET) for the pre-imaginal development were 10.7°C and 231.1°C, respectively. The rate of population increase was assessed as the sum of effective temperatures above the lower developmental threshold by monitoring the numbers of thrips on individual leaves of cucumber under commercial greenhouse conditions. Population growth was characterized by an early stochastic phase, corresponding to pre-imaginal development of the first generation, and followed by an exponential phase starting with the second generation, the rate of which did not vary between plants. Throughout the exponential phase, the rate of population growth increased with time/age of plant. As significant damage to cucumber may occur during the exponential phase of population increase, the sum of effective temperatures of 231°C can be used to predict when damage is likely to start to occur.

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.

Survival and development of different life stages of three Ceratitis spp. (Diptera: Tephritidae) reared at five constant temperatures

2002 ◽  
Vol 92 (6) ◽  
pp. 461-469 ◽  
Author(s):  
P.F. Duyck ◽  
S. Quilici
Keyword(s):  
Simulation Models ◽  
Fruit Fly ◽  
Thermal Constant ◽  
Immature Stages ◽  
Developmental Threshold ◽  
Laboratory Rearing ◽  
Larval Stages ◽  
Survival And Development ◽  
Lower Developmental Threshold ◽  
Computer Simulation Models

AbstractFruit flies (Diptera: Tephritidae) are the most damaging pests on fruit crops on Réunion Island, near Madagascar. Survival and development of the Mediterranean fruit fly, Ceratitiscapitata (Wiedemann), the Natal fruit fly, C. rosa Karsch and the Mascarenes fruit fly, C. catoirii Guérin-Mèneville were compared at five constant temperatures spanning 15 to 35°C. Durations of the immature stages of C. capitata, C. rosa and C catoirii ranged from 14.5–63.8, 18.8–65.7 and 16.8–65.8 days, respectively, at 30–15°C. The lower developmental threshold and thermal constant were calculated using the temperature summation model. The thermal constant for total development of the immature stages of C. capitata, C. rosa and C. catoirii were 260, 405 and 356 DD, respectively. Species differed mainly during the larval stages and ovarian maturation period, with smaller differences in the egg stage. Ceratitis rosa appeared to be better adapted to low temperatures than the two other species as it showed a lower larval developmental threshold of 3.1°C compared to 10.2°C for C. capitata and 8.9°C for C. catoirii. Overall, C. catoirii had a low survival rate within the range of temperatures studied. The different responses of the three Ceratitis species to various temperatures explain to some extent their distribution on the island. The results obtained will be used for optimizing laboratory rearing procedures and for constructing computer simulation models to predict fruit fly population dynamics.

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.

Responses to Crude Oil Contamination by Cricotopus (Cricotopus) bicinctus and C. (C.) mackenziensis (Diptera: Chironomidae) in the Fort Simpson Area, Northwest Territories

1977 ◽  
Vol 34 (2) ◽  
pp. 254-261 ◽  
Author(s):  
David M. Rosenberg ◽  
Allen P. Wiens ◽  
Ole A. Sæther
Keyword(s):  
Crude Oil ◽  
Northwest Territories ◽  
Food Supply ◽  
Algal Biomass ◽  
Head Capsule ◽  
Common Species ◽  
Artificial Substrates ◽  
Oil Contamination ◽  
Field Exposure ◽  
Head Capsule Width

Cricotopus (Cricotopus) bicinctus (Meigen) and C. (C.) mackenziensis Oliver, two common species of Chironomidae in the Fort Simpson area, N.W.T., were examined for changes resulting from experimental field exposure to Norman Wells crude oil. Larvae of both species were always present in higher numbers on oiled than unoiled artificial substrates but numbers of C. bicinctus increased more quickly than C. mackenziensis in response to the oil. Cricotopus mackenziensis larvae occurred in higher numbers than C. bicinctus larvae on unoiled artificial substrates. Cricotopus bicinctus tended to dominate C. mackenziensis on oiled artificial substrates. Size of larvae, as measured by head capsule width, was unaffected by increased food supply during periods of maximum algal biomass on oiled artificial substrates. Larvae on oiled artificial substrates apparently produced part of another generation when compared to larvae on unoiled artificial substrates.

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