Species Composition Of Aphids Research Articles

Facultative endosymbionts of aphids on strawberry crops affect aphid-parasitoid interactions

Aphids are major agricultural pests and laboratory studies have shown that heritable bacterial endosymbionts can protect aphids against biocontrol parasitoids, but results from agricultural crop systems are lacking. Here we assess (1) which aphid species are present in Dutch strawberry crops, (2) which facultative endosymbionts they carry, and (3) how such facultative endosymbionts affect parasitism success of the biocontrol parasitoid wasps Aphidius ervi and Praon volucre on the most prevalent aphid species Acyrthosiphon malvae. By curing endosymbiont infections, we were able to determine the effects of endosymbionts and aphid genotypes on the parasitism success of both parasitoid species.We show that aphid species composition on strawberry crops is dynamic across the season and that facultative endosymbiont (co-)infections are common. Infection with facultative endosymbionts protected A. malvae against A. ervi, but not against P. volucre. Finally, we also found variation in levels of endogenous resistance among A. malvae lines against A. ervi. Our study is the first to show that a common aphid pest on agricultural farms can be protected against biocontrol parasitoids by both facultative endosymbionts and endogenous resistance.

Aphid Species Composition in Three Parks of Saint-Petersburg and Leningrad Region in 2021

Due to the high harmfulness of aphids inhabiting trees and shrubs in the St. Petersburg’s and the Leningrad Region’s park areas, it becomes necessary to monitor the dynamics of the numbers and species composition of this group of insects. During the vegetation season of 2021, the species composition of aphids was determined in three parks in St. Petersburg and the Leningrad Region: Sosnovsky forest park, Pavlovsky and Gatchina parks. The material was taken directly from plants and caught using an entomological net. A total of 16 species were identified. In the Sosnovsky forest park, 10 species were identified, in the Pavlovsky park – 12, in the Gatchinsky park – 9 species. Two species were found on coniferous trees, the rest – on the deciduous ones. Species such as dogwood aphid (Anoecia corni F.), bird cherry-oat aphid (Rhopalosiphum padi L.), silver birch aphid (E-uceraphis betulae gr. sp.), common oak aphid (Tuberculatus annulatus Hart.), black bean aphid (Aphis fabae Scop.), rose aphid (Macrosiphum rosae L.) were found in all three parks, the rest – in one or two parks. Dogwood aphid, bird cherry-oat aphid, silver birch aphid, black bean aphid and rose aphid were observed in massively large colonies on a significant number of host trees. In other species, small colonies were found on separate trees; finally, for some species only single individuals were caught. In the first half of September, the number of aphids was relatively low.

Assessment of dynamics of density and species composition of aphids with suction trap in the North-West of Russia

Assessment of dynamics of density and species composition of aphids with suction trap in the North-West of Russia

The results of catching winged aphids with water traps on potato plantings in the southern part of the Arkhangelsk region

Dynamics of the number and species composition of aphids were studied on seed potatoes using yellow water traps in the southern part of the Arkhangelsk region in 2018-2019. 12 species of winged aphids (165 insects) were identified in 2018, and 16 species (115 insects) - in 2019. The following types dominated: black bean aphid A. fabae Scop., bird cherry-oat aphid R. padi L., blackcurrant-sowthistle aphid H. lactucae L., glasshouse-potato aphid A. solani Kalt. The share of aphids as direct and indirect vectors of viral diseases was 91 % of the total number in 2018, and 79.1 % in 2019. The pest population of potato plants depended directly on weather conditions of the growing season. The sum of the average daily temperatures during the period of catching aphids was 1273.3 C in 2018, and 983.3 C - in 2019. During the experimental period, 131.6 mm of precipitation fell in 2018, and 280.4 mm - in 2019. Due to the constant presence of aphids on seed potato crops, annual monitoring of pest population and, in case of necessity, protective measures are required.

Variations in community assemblages and trophic networks of aphids and parasitoids in protected crops

AbstractGreenhouse crops are thought to be simplified ecosystems because they often consist of monocultures that are relatively isolated from their environment. However, insect pests are still able to colonize these protected crops, which threaten their yields. Similarly, natural enemies of pests may be able to colonize greenhouses, providing a form of natural biological pest control. Protected strawberry crops are grown in several types of greenhouses that vary in their degree of openness. Crops often suffer from aphid outbreaks, which can be partly controlled by insect parasitoids immigrating from the surrounding environment. We investigated variations over space and time in both the aphid and parasitoid community diversity and species assemblages associated with protected strawberry crops. We sampled aphids and parasitoids in five regions of France in the spring and summer of two successive years. Despite the relative isolation of these protected crops, we identified a high aphid species richness in them, even at the greenhouse scale. Aphid community composition varied with spatial and temporal factors, but the species assemblages present were mostly determined by local factors. Parasitoid communities were mostly similar among the studied regions, but varied between seasons, with this temporal variation being related to changes in aphid species composition. The study of trophic interactions occurring between aphids and parasitoids allowed the most prevalent and efficient parasitoid species to be identified. The structures of food webs strongly varied in time and space, compromising any prediction of “natural” biological control. We also highlighted ecological factors that can disrupt aphid biological control, such as the occurrence of hyperparasitism or the possibility of apparent mutualism between aphid species. Finally, we showed that the degree of openness of greenhouses influenced both the aphid communities and the hyperparasitism rates in them. These results provide valuable information to improve aphid biological control in protected crops.

АБІОТИЧНІ ТА БІОТИЧНІ ЧИННИКИ ВПЛИВУ НА ЩІЛЬНІСТЬ ПОПУЛЯЦІЇ ВЕЛИКОЇ ЗЛАКОВОЇ ПОПЕЛИЦІ (SITOBION AVENAE F.) У ПРАВОБЕРЕЖНОМУ ЛІСОСТЕПУ УКРАЇНИ


 
 
 Species composition of aphids on winter wheat was determined in the right- bank Forest Steppe of Ukraine during 2017–2018. Interspecies population was formed on wheat. It consisted of three species: S. avenae, Sch. graminum and D. noxia. S. avenae dominated and the other two species were found in small numbers. The abundance of S. avenae was determined by abiotic and biotic factors. The main factors influencing the density of the phytophage population were the meteorological conditions in April, May and June. Low spring temperatures and summer drought have hampered the development and spread of the pest. The influence of the genotype on the abundance of S. avenae is proved. Aphidophages effectively reduced the number of aphids during their active feeding. Aphidophages effectively reduced the number of aphids during their active feeding. Four species of Coccinellidae were identified, of which only one was dominated (Coccinella septempunctata L.).
 
 

Species Composition of Aphids (Hemiptera, Aphididae) on Seed Potato Plantings in Northwest Russia

Collections using yellow water traps revealed from 20 to 43 species of aphids on seed potato plantings in the farms of Northwest Russia in 2013–2017. Among them, from 2 to 5 species were vectors of potato viruses; aphids of these species together comprised 12.5–36% of the total number of captured aphids. The remaining 18–38 aphid species attracted to yellow traps were associated with vegetable, fruit and berry crops, weeds, trees, and shrubs surrounding potato plantings in the study areas. The species number and abundance of aphids depended on weather conditions, insecticide treatments, and the presence of home gardens near the traps. Up to 7 aphid species feeding on potatoes were recorded using the “100 leaves” sampling method; 6 of them are vectors of viral potato diseases: Aphis fabae Scop., A. nasturtii Kalt., A. frangulae Kalt., Aulacorthum solani Kalt., Macrosiphum euphorbiae Thomas, and Myzus persicae Sulz.

ИЗУЧЕНИЕ ВИДОВОГО СОСТАВА ТЛЕЙ НА ПОСАДКАХ ОРИГИНАЛЬНОГО КАРТОФЕЛЯ В УСЛОВИЯХ ЛЕНИНГРАДСКОЙ ОБЛАСТИ

ИЗУЧЕНИЕ ВИДОВОГО СОСТАВА ТЛЕЙ НА ПОСАДКАХ ОРИГИНАЛЬНОГО КАРТОФЕЛЯ В УСЛОВИЯХ ЛЕНИНГРАДСКОЙ ОБЛАСТИ

Landscape structure and agricultural intensification are weak predictors of host range and parasitism rate of cereal aphids

Proportions of specialist and generalist primary parasitoids have been described by the resource breadth and the trade-off hypothesis. These alternative hypotheses predict either decreased or increased, respectively, parasitism rate of shared aphid species by specialist parasitoids. We tested both hypotheses and the confounding effects of landscape structure and agricultural intensification (AI) using extensive samplings of aphids and their parasitoids in Polish agricultural landscapes. Abundances, species composition of aphids, primary parasitoids, and parasitism rate of aphids by specialists and generalist parasitoids were analysed. Contrary to our expectations we found equally decreased parasitism rates by both types of primary parasitoids at higher aphid densities and thus proportion of specialists to generalists did not change with increasing host density. In line with the resource breadth hypothesis, specialist parasitoids had always lower abundances and parasitism rates than generalist parasitoids. Landscape diversity and agricultural intensification did not influence the host-parasitoid population dynamics. We speculate that these contrasting results could be caused by the additional density effects of secondary parasitoids. We conclude that simplistic two-trophic-level population models are not able to fully describe the complex dynamics of trophic networks. We also argue that agricultural intensification has lower effects on abundance and effectiveness of parasitoids than predicted by respective predator–prey models and empirical studies performed in controlled and artificial conditions.

The effects of monitoring the abundance and species composition of aphids as virus vectors on seed potato production in Serbia

Aphids are the most important vectors of potato viruses during the crop?s growing season. The most widespread and damaging viruses, the potato virus Y and potato leaf roll virus, are transmitted by aphids in non-persistent and persistent manner, respectively. The two viruses cause the greatest concern of potato producers and a great constraint to seed potato production in Serbia, the region and across the world. Potato virus Y is particularly harmful, given its distribution and spreading rate. Seed potato production systems under well-managed conditions involve a series of virus control measures, including the monitoring of outbreaks of winged aphids, their abundance and species composition, in order to forecast virosis, i.e. potential plant and tuber infection periods. Monitoring the aphid vectors of potato viruses enables determination of optimum dates for haulm destruction when higher than normal numbers of winged aphids as vectors of economically harmful diseases have been observed. Haulm destruction in a potato crop reduces the risk of plant infection and virus translocation from the aboveground parts to tubers, thus keeping the proportion of infected tubers within tolerance limits allowed for certain categories of seed potatoes. This practice has positive effects if used in combination with other viral disease control measures; otherwise, it becomes ineffective. This paper provides an integral analysis of the effects and role of monitoring outbreaks of aphids, their abundance and species composition in timing haulm growth termination to prevent plant infection, virus translocation and tuber infestation in potato crops in Serbia and the wider region.

Infestation and natural parasitism of aphids in single and mixed pastures of black oats and ryegrass

Some species of aphids are major pests on cereal crops and grass pastures. Usually these pests are not adequately controlled in pasture lands that become sources of aphid infestations to cereal crops. The dynamics of aphids and the incidence of natural enemies are less known in pasture systems than in cereal fields. The objective of this work was to assess the aphid infestation and natural aphid parasitism in different pasture composition. Three hypotheses were tested: 1- the aphid species composition in pastures may vary according to the cereal species in the field; 2- the mixture of two plant species can modify the amount and diversity of aphids; 3- the plant species composition of pasture fields influences the parasitism of aphids. Empirical data were obtained from three Poaceae fields: black oats (Avena strigosa L.), ryegrass (Lolium multiflorum L.), and a mixed field of black oats and ryegrass. The most abundant aphid species was Rhopalosiphum padi followed by Sitobion avenae. Plant species composition increases the amount and the parasitism rates of aphids. The mixture of heavily infested black oats with a poorly infested ryegrass resulted in reduction of aphid infestation in comparison with heavily-infested single plant species field. This is possible because the conditions are favorable for the development of parasitoid populations. Aphidius colemani was the main parasitoid found in these areas.

Effect of Source Strength, Distance and Direction on the Spread of Maize Dwarf Mosaic Virus

AbstractSpread of maize dwarf mosaic virus (MDMV) from infected maize to trap plants was assessed at 8 successive weeks. During each week, 0, 9 or 81 infected plants were placed in the centre of a fallow area. Ten trap plants each were placed at each of eight compass directions at three distances (8, 16 and 24 m) from the source. Disease incidence varied with week, distance and source strength (number of infected plants at the source). Disease increased to a maximum by 27 August, and then decreased. There was a decline in disease with distance from the source but no change in disease with direction. There was little disease in the controls or at 24 m in the other plots. Number and species composition of aphids also varied with time, and a few species were highly related to disease incidence.

Seasonal Abundance and Species Composition of Aphids (Homoptera: Aphididae) in Virginia Small Grains

The seasonal abundance of aphids in winter wheat and barley was monitored in eastern Virginia during 1979–1980 and 1980–1981. Significantly more aphids were observed in barley than in wheat. Population densities were significantly higher in the fall of 1979 than in 1980; however, the reverse was noted in springtime population levels. The heavy fall population, approaching 240 aphids per 0.3 row m. rapidly dropped in December 1979 after 8 consecutive days of subfreezing temperatures. The 1980–1981 season had below-normal temperatures in the fall, and populations never exceeded 82 aphids per 0.3 row-m until spring. In both years, aphid populations rapidly fell in May after several days of 27°C temperature and low humidity. The corn leaf aphid. Rhopalosiphum maidis (Fitch), was usually the most abundant species in the complex in autumn. The English grain aphid, Macrosiphum Avenae (F.), was the most abundant species during the spring. Rhopalosiphum padi (L.), and the green bug, Schizaphis graminum (Rondani), were relatively abundant throughout the entire growing season. Corn leaf aphids were not present in the spring. Ovoviviparous reproduction was observed in most months of the season, even at temperatures as low as 9° C.