The Meaning of Percentage Parasitism Revisited: Solutions to the Problem of Accurately Estimating Total Losses from Parasitism

1991 ◽  
Vol 20 (1) ◽  
pp. 1-7 ◽  
Author(s):  
R. G. Van Driesche ◽  
T. S. Bellows ◽  
J. S. Elkinton ◽  
J. R. Gould ◽  
D. N. Ferro
1976 ◽  
Vol 108 (6) ◽  
pp. 649-654
Author(s):  
G. A. Surgeoner ◽  
C. R. Ellis

AbstractCarbofuran at 2 oz AI/acre caused a 94% reduction in 3rd- and 4th-instar larvae of alfalfa weevil. There was a 67% reduction in 1st- and 2nd-instar larvae which were protected within the buds. Carbofuran did not reduce the percentage parasitism by Bathyplectes curculionis (Thomson) although the total parasitoids that developed per unit area was less.


1988 ◽  
Vol 78 (1) ◽  
pp. 135-142 ◽  
Author(s):  
C. C. D. Tingle ◽  
M. J. W. Copland

AbstractIntroduction of parasitoids gave improved biological control of Planococcus citri (Risso) in a large glasshouse stocked with a variety of ornamental plants, supplementing that achieved by the predator Cryptolaemus montrouzieri Mulsant. Following parasitoid release, there was evidence of pest population regulation on guava and coffee bushes with reduced and stabilized mealybug numbers and stable percentage parasitism. The mean temperature during one sampling period was significantly correlated with the percentage parasitism two months later, indicating that temperature has a major impact on parasitoid efficiency. Leptomastidea abnormis (Girault) was responsible for about 90% of the parasitism observed; the remainder was by Leptomastix dactylopii Howard. The effects of supplementary inoculative releases of Leptomastidea abnormis were variable, but resulted in increased percentage parasitism only when the number released contributed significantly to those already established. No evidence of pest population regulation was found on Aristolochia or Passiflora vines nor on potted Gesneriaceae plants of the genera Streptocarpus and Saintpaulia. Peak mealybug populations on these last plants coincided with periods of new growth, fruiting or flowering. Host-plant quality thus seems to be a major factor inducing mealybug outbreaks.


1989 ◽  
Vol 121 (9) ◽  
pp. 745-756 ◽  
Author(s):  
J. Maltais ◽  
J. Régnière ◽  
C. Cloutier ◽  
C. Hébert ◽  
D.F. Perry

AbstractThe braconid parasitoid Meteorus trachynotus Vier. was found in overwintered larvae of the obliquebanded leafroller, Choristoneura rosaceana (Harr.), on foliage of a variety of deciduous species, well before the parasitoid’s attack on the spruce budworm, Choristoneura fumiferana (Clem.). In the spring, percentage parasitism of C. rosaceana by M. trachynotus was 8.0 and 18.8% in 1986 and 1987, respectively. Maximum parasitism on C. fumiferana (35 and 4% in 1986 and 1987, respectively) was reached in late June, at a time when over 50% of M. trachynotus cocoons found on deciduous vegetation had emerged. Twenty days later, parasitoids produced on C. fumiferana reached 50% adult emergence. The catches of adult parasitoids on sticky traps placed on deciduous trees and on conifers showed two periods of adult activity. Based on the sex ratio of captured parasitoids, male M. trachynotus were active at emergence sites, whereas females were found mostly in the habitats of available hosts. The phenology of C. rosaceana was observed in 1987. As indicated by light-trap captures, males fly sooner than females. Eggs were laid in July, and so the early larval stages were available to female M. trachynotus as overwintering hosts. Several parasitoids common to C. rosaceana and C. fumiferana were identified.


1981 ◽  
Vol 113 (9) ◽  
pp. 867-870 ◽  
Author(s):  
Chris T. Maier

AbstractBiosteres melleus (Gahan), Diachasma alloeum (Muesebeck), D. ferrugineum (Gahan), Opius canaliculatus Gahan, O. downesi Gahan (all Braconidae), and an undescribed Psilus sp. (Diapriidae) emerged from puparia of Rhagoletis pomonella (Walsh) collected in Connecticut during 1977 and 1978. Percentage parasitism ranged from 7.9 to 36.8% in flies on hawthorn and from 0.0 to 23.9% in flies on apple. It exceeded 5.0% in only 5 (22.7%) of 22 samples from apple. Higher rates of parasitism usually occurred at sites where other hosts of apple maggot parasitoids probably infested fruits on nearby plants.


1985 ◽  
Vol 117 (4) ◽  
pp. 409-421 ◽  
Author(s):  
Ann E. Hajek ◽  
Donald L. Dahlsten

AbstractThirty-four species of insects associated withScolytus multistriatus(Marsham) were reared or collected from several species of elm collected throughout California. Few of these species occurred in large numbers and many of their ecological roles in this subcortical habitat are unknown. Predators were uncommon; only 6 species of parasitic Hymenoptera were reared, 3 of which were not previously known from California. One,Dendrosoter protuberans(Nees), had previously been released for biological control ofS. multistriatusonly as far west as Colorado. The most abundant insect associate reared from northern California,Cheiropachus quadrum(F.), exhibited a maximum percentage parasitism of 2%. Seven species of mites, including 2 new species, were also collected in association withS. multistriatus.


1980 ◽  
Vol 70 (2) ◽  
pp. 213-219 ◽  
Author(s):  
D. Gerling ◽  
U. Motro ◽  
R. Horowitz

AbstractThe dynamics of Bemisia tabaci (Gennadius) were followed during two years in treated and untreated cotton fields in three locations in Israel. Two parasite species, Encarsia lutea (Masi) and Eretmocerus mundus Merc., were the only important natural enemies, but percentage parasitism did not rise with increase in the host population. The whiteflies reached peak populations at the end of the summer. Their distribution upon the plants was not uniform, rather, they tended to concentrate on a few leaves. The leaf bearing the maximal population was the sixth or seventh until mid-July. From then on, its location was variable according to the growth pattern of the foliage. Insecticide treatments, in particular with aldicarb, resulted in depression of both whitefly and parasite populations, but neither was exterminated.


1979 ◽  
Vol 59 (2) ◽  
pp. 399-410 ◽  
Author(s):  
D. G. FINLAYSON

In a 4-yr study (1974–1977), combinations of selected soil-incorporated insecticides (carbofuran, chlorfenvinphos, disulfoton, fensulfothion, terbufos and isofenphos) and foliar-applied insecticides (Dipel®, methomyl, ethiofencarb/Thuricide®, methamidophos and permethrin) were studied to determine their effects on occurrence of cabbage maggot (Hylemya brassicae [Bouché]) and its parasites, and of various leaf-feeding lepidopterous larvae and aphids during bed-system production of broccoli (Brassica oleracea var. italica Plenck), Brussels sprouts (Brassica oleracea var. gemmifera Zenker), cabbage (Brassica oleracea var. capitata L.) and cauliflower (Brassica oleracea var. botrytis L.). Several soil-incorporated insecticides reduced the numbers of emergent seedlings. Plants treated with carbofuran and chlorfenvinphos had least maggot damage in their roots. Disulfoton was ineffective. The best aphicide was ethiofencarb closely followed by methamidophos. Permethrin was ineffective as an aphicide but very effective against lepidopterous larvae. Numbers of overwintering puparia of H. brassicae were greatest from untreated plants and least from plants treated with chlorfenvinphos. Percentage parasitism by the staphylinid beetle Aleochara bilineata Gyll. averaged 32% in puparia from untreated plots, but only 5.5% in those from treated plots.


2003 ◽  
Vol 3 (1) ◽  
pp. 13-16
Author(s):  
Purnomo Purnomo ◽  
Aunu Rauf ◽  
Soemartono Sosromarsono

Parasitism of Hemiptarsenus varicornis (Girault) (Hymenoptera: Eulophidae) on leafminer fly Liriomyza huidobrensis  (Blanchard) (Diptera: Agromyzidae) on  kacang endul  (Phaseolus vulgaris L.)  in Ciloto, West Java.  The objective of this research was to elucidate the  relationship between leafminer and its parasitoid abundants. The research was conducted in Ciloto (Cianjur), West Java in 1999. The miner infested leaves of kacang endul were collected and placed in plastic  bowls.  The emerged parasitoids from those leaves were counted.  The result indicated that the level of parasitism of H. varicornis during the plant growth stage ranged from 39 to 50%.  The  perfect density dependent between percentage parasitism and the leafminer abundance was experimentally proved.


1987 ◽  
Vol 119 (2) ◽  
pp. 147-151 ◽  
Author(s):  
M.K. Mukerji

AbstractParasitism by Scelio calopteni Riley in eggs of Melanoplus bivittatus (Say) and M. sanguinipes (Fabr.) in Saskatchewan during 1967–1980 was highly aggregated. There was no evidence of any numerical response of the parasites to adult grasshopper density and, furthermore, change in grasshopper population density was independent of percentage parasitism. Thus, it is concluded that parasitism by S. calopteni does not play a significant role in the population dynamics of the two grasshopper species. The relationship between parasitism and wetness in August was highly significant in both grasshopper species and showed that percentage parasitism increased, but at a decreasing rate, up to a certain wetness and levelled off thereafter.


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