Number Of Alate Aphids Research Articles

Population Dynamics of Aphid Vectors and Effect on Abaca Mosaic Epidemics

Trapped aphids in abaca plantations in Baybay, Leyte were: Aphis gossypii Glover, Aphis spiraecola Patch, Ceratovacuna /anigera Zehntner, Greenidea formosana (Maki), Pentalonia nigronervosa Coquerel, and Toxoptera odinae (van der Goot). Both alates and apterae of P. nigronervosa were found infesting abaca plants in the sites. Abaca mosaic incidence was not correlated with the total number of aphids and number of alate aphids per plant but highly correlated with the number of trapped aphids in the area. Abaca mosaic disease incidence continued to increase progressively as the number of trapped aphids increased. Temperature and relative humidity showed a profound effect on the number of alate aphids per plant and number of trapped aphids, respectively. Temperature appeared to enhance multiplication and wing bud formation of aphids while winri velocity favored aphid take-off and enhanced movements of alate aphids in the abaca plantations. These effects significantly influenced the level of abaca mosaic incidence

Some observations in west Wales on the relationships between numbers of alate aphids and weather

SUMMARYSome preliminary associations are reported between monthly totals of cereal aphids (Metopolophium dirhodum, Rhopalosiphum insertum, R. padi and Sitobion avenae) caught in suction traps and weather data. Catches at 1.2 and 12.2 m during the summer and autumn flight peaks from 1969 to 1979 were compared with combinations of prior monthly totals of rainfall and accumulated day‐degree temperatures. The best models fitting these results are reported and proposed for testing against future data. The possible relevance of these models, for forecasting whether measures for the control of barley yellow dwarf virus in autumn‐sown cereals are necessary in any year, are discussed.

Barley yellow dwarf virus in aphids caught in suction traps, 1969-73.

SUMMARYSuction traps operating at low level (1 5 m) were used to catch live alate Rhopalosiphum padi, Macrosiphum (Sitobion) avenae and Metopolophium dirhodum which were tested for transmission of barley yellow dwarf virus (BYDV). The first species caught and infective was R. padi, followed by M. (S.) avenae infective some 2–3 wk later and M. dirhodum 3–4 wk later still. Never more than 11‐5% of the annual catch of any species transmitted BYDV and the proportion fluctuated from week to week and between seasons in different years.The relative abundance of infective vectors of ths three species varied; annual numbers of infective M. (S.) avenae and M. dirhodum varied inversely with infective R. padi, the latter also usually transmitted severer virus. The results of the infectivity tests have been compared with the catches of these aphids by the Rothamsted Insect Survey and show that numbers of alate aphids do not necessarily indicate the likely incidence of BYDV.

Evaluation of Some Insecticides in Controlling Aphids and Reducing Flower Losses from Virus Disease in Gladiolus Plantings1

Several insecticides were tested to evaluate aphid control in Connecticut Valley gladiolus plantings. In 1971, no treatment had significantly fewer alate or a significantly lower total number aphids than the untreated control. In 1972, the number of alate aphids recorded on plants treated with either carbofuran 4 F or oxydemetonmethyl was significantly less than the untreated control. Overall, aldicarb-treated plants had a significantly lower total number of aphids per plant than the untreated control. Irrespective of reductions in aphid numbers, no significant differences were detected in the percentages of plants showing floral symptoms of cucumber mosaic virus disease. Little or no aphid colonization occurred on treated or untreated gladiolus plants. The majority of aphids observed on gladiolus was alates. The following species were collected in the experimental plantings: Aphis fabae Scopoli, A. gossypii Glover, A. craccivora Koch, A. maidiradicis Forbes, Capitophorus hippophaes (Walker), C. elaeagni (DelGuercio), Myzus persicae (Sulzer), Rhopalosiphum Maidis (Fitch), R. fitchii (Sanderson), Myzocallis Punctata (Monell), M. walshii (Monell), M. alnifoliae (Fitch), Macrosiphum venaefuscae (Davis), M. euphorbiae (Thomas), Macrosiphum sp., Nasonovia ribisnigri (Mosley), Therioaphis trifolii (Monell), Acrythosiphum pisum (Harris), Calaphis betulaecolens (Fitch), Monellia sp., Tinocallis ulmifolii (Monell), and Pemphigus populitransversus Riley.

Spring Populations of the Green Peach Aphid 1 on Peach Trees and the Role of Natural Enemies in Their Control 23

A 2-year study of the spring population of Myzus persicae (Sulzer) on peach trees showed that the number of surviving fundatrices reaching reproductive maturity represented less than 2% of the overwintering eggs. Colonies established from surviving fundatrices protected from natural enemies by slecve cages displayed a tremendous numerical recovery. For example, in a protected environment (cage) the average number of alate aphids per stem mother was 3596 in 1970, and 1080 in 1971. In contrast, on unprotected twigs the natural enemies, primarily coccinellid and syrphid predators, played a major role in reducing the production of alate aphids by an estimated 95% in both years (based on counts of immature aphids).

THE APPLE APHID APHIS POMI (HOMOPTERA: APHIDIDAE) ON APPLE UNDER SUMMER CONDITIONS IN A CONTROLLED ENVIRONMENT CABINET

AbstractThe apple aphid was reared on 1-year-old trees in a controlled environment cabinet with simulated mid-June through October 1968 daylengths and temperatures. Maximum rates of increase (ca. 2.7-fold per week) were observed during the first 5 weeks of the experiment and maximum populations were obtained in 7 weeks at the time the trees stopped growth when the diel photoperiod was 14.8 hr, and light/dark temperature was 20.5°/15.5 °C. The ratio of nymphs to adults increased from 5:1 to 10:1 from week 2 to week 8, followed by a rapid decline. At week 12 there were more adults than nymphs and the nymph:adult ratio remained 1:3 through the remainder of the experiment. Alate aphids appeared 2 weeks following infestation, increased very rapidly, ca. 6-fold per week, and maximum abundance was noted at the end of 6 weeks. Their numbers declined nearly as rapidly at ca. 0.35-fold per week and they were not seen after week 11. As the numbers of alate aphids decreased, apterous adults increased to week 12, remained constant to week 15, and slowly decreased in an environment of shorter daylengths and lower temperatures. The rate of apterous adult aphid increase was similar to the rate of accumulated degree days during the first 8 weeks and again in the 10- to 15-week period.Aphids were concentrated on the tree tops during the first 6 weeks of the experiment. A gradual migration followed and the aphids became dispersed over the trees with minor concentrations near the centers of the trees.

Preference of Green Peach Aphids for Virus-Infected Sugar beet Leaves12

In detached-leaf experiments, apterous Myzus persicae (Sulzer) preferred yellows-infected leaves to symptom less, mosaic-infected, or curly-top-infected leaves. However, apterous aphids appeared to move at random to healthy, mosaic-infected, or yellows-infected whole plants. Twice as many alate aphids were found on yellows-infected whole plants 24 hours after release as on healthy or mosaic-infected plants, but no marked differences were found in numbers of alate aphids on healthy, mosaic-infected, and yellows-infected whole plants 48–96 hours after release. In all tests aphids appeared to avoid curly top-infected leaves or plants.