EJE, vol. 91 (1994), issue 1

Critical Issues in Aphid Biology. Proceedings of the Fourth International Symposium on Aphids.


Eur. J. Entomol. 91 (1): 1994


The effects of temperature on aphid morphology, using a multivariate approach


Eur. J. Entomol. 91 (1): 7-22, 1994

Clonal samples of aphids were used as the groups in canonical variate (CV) analysis, in order to compare the temperature responses of single genotypes, and thus to distinguish genotypic and environmental contributions to the phenotypic response pattern. The analysis was based on a large data set obtained by measuring 19 linear variables on adult apterae reared at four temperatures (10, 15, 20 and 26.5C). The species used were Myzus persicae (Sulzer) and its close relative, M. antirrhinii (Macchiati). Two vectors - the scores on the first two CV's - were invariably needed to describe the temperature response. In each of three M. persicae...

Environmental factors and morphological discrimination between spring and summer migrants of the grain aphid, Sitobion avenae (Homoptera: Aphididae)


Eur. J. Entomol. 91 (1): 23-28, 1994

The morphology of spring and summer migrants of Sitobion avenae (F.) from several different environmental conditions were compared using analysis of variance and canonical variate analysis. Both between morph and within morph differences were found for a range of morphometric features and ratios. When aphids of both morphs and from a range of conditions were considered together any morph differences were obscured by phenotypic variability. SimilarIy canonical variate analysis indicated that differences due to environmental variability were greater than those due to morph.

Deadlines and delays as factors in aphid sex allocation


Eur. J. Entomol. 91 (1): 29-36, 1994

In this paper we use the concept of the evolutionary individual as the basis for an attempt to characterise sex-allocation patterns in aphids. We then examine the various selection pressures involved in the evolution of aphids' sex ratios, and propose a novel explanation for biased sex allocation in host-alternating aphidines, in which inbreeding is impossible. Their production of gynoparae (females that migrate from secondary to primary hosts to produce the sexual females) before males is the clonal equivalent of sex reversal - sequential hermaphroditism. Selection on the timing of the reversal, and thus the overall sex-allocation ratio, should depend...

Birth weight and the rate of increase in the cowpea aphid Aphis craccivora (Homoptera: Aphididae)


Eur. J. Entomol. 91 (1): 37-46, 1994

Consequences of birth weight for development, survival and fecundity were studied in the offspring of the alate morph Aphis craccivora (Koch), with the aim of testing the hypothesis that birth weight is near optimal. Aphids large at birth were found to mature sooner and achieve higher total reproduction than those born smaller.

A bootstrapping procedure was used to estimate the correlation between birth weight and two measures of fitness (rm): one calculated from unadjusted life-table data, the other from life tables adjusted to correct for the trade-off between offspring weight and offspring number. The unadjusted data...

Sieve element acceptance by aphids


Eur. J. Entomol. 91 (1): 47-52, 1994

Aphis fabae took 3 to 4 hours, after access to a plant, to show the first puncture of a sieve element. A further hour was needed before sustained ingestion started. Early probes did not show sieve element punctures, in general. Within later probes, showing these punctures, the average time needed to reach them was 30 min. Early sieve element punctures were mainly accompanied by the secretion of a watery saliva. The composition of this saliva and the function of its secretion is unknown. It is speculated that this saliva secretion makes the phloem sap more readily available and/or improves its quality for aphids. Further research is needed to...

Resource deprival as an anti-herbivore strategy in plants, with particular reference to aphids


Eur. J. Entomol. 91 (1): 53-56, 1994

It is generally considered that many specialist insects, such as aphids, have overcome chemical barriers to successful feeding and turned them to their own advantage as host recognition cues and phagostimulants. It is suggested that plants may counter-respond to the presence of specialised insect herbivores by manipulating recognition cues and phagostimulants to the detriment of the insect. One might expect this to involve the plant depriving the insect of access to these chemicals at critical periods in the insect's life cycle. Evidence in support of the 'resource deprival' hypothesis is presented from work carried out on the large pine aphid, Cinara...

Sink strength and clone size of sympatric, gall-forming aphids


Eur. J. Entomol. 91 (1): 57-61, 1994

The supply of carbohydrates to growing galls of four species of aphids (Pemphigidae: Fordinae) that co-exist on Pistacia palaestina trees was studied. Using 14C labelling we compared the sink strength of the gall of each species for its ability to manipulate the normal phloem transport from different sources. The results indicated that none of the galls had net photosynthetic ability and all of them imported assimilates according to their specific sink strength. The data also demonstrated a correspondence between the ability of galls to draw assimilates from wider sources (sink strength) and aphid reproductive performance. Furthermore,...

Ecology of host alternation in aphids


Eur. J. Entomol. 91 (1): 63-70, 1994

This paper reviews the evidence for the fundatrix specialization hypothesis and attempts to quantify the relative advantage of host alternation and define the conditions favouring the evolution of this way of life. Contrary to the predictions of the fundatrix specialization hypothesis there does not appear to be a barrier to some host alternating Aphidinae transferring their whole life cycle over to a secondary host plant. The coexistence of plants with asynchronous phenologies supplied the potential and the ability of aphids to produce a number of highly prolific generations in quick succession, which amplify the differences in performance on the...

Phenotypic plasticity and fitness in aphids


Eur. J. Entomol. 91 (1): 71-78, 1994

In holocylic aphid species many different morphs are produced during the phase of parthenogenetic reproduction. Because these morphs differ in their life-histories, research has been focused on how individual life-histories can be explained in the framework of maximizing the Malthusian parameter rm. All these different morphs are produced by the same genotype. Since it is the genotype that selection acts on it is questionable whether the intrinsic rates of increase of individual morphs can be used to make inferences about the fitness of the genotype. A simple model is developed to investigate the relationship between individual rm...

Use of DNA sequences to reconstruct the history of the association between members of the Sternorrhyncha (Homoptera) and their bacterial endosymbionts


Eur. J. Entomol. 91 (1): 79-83, 1994

The suborder Sternorrhyncba (Insecta: Homoptera) includes aphids, whiteflies, psyllids and scale insects; these are all large diverse groups of herbivorous insects that feed on plant sap and that include many of the most damaging agricultural pests. All of these insects are dependent on obligately intracellular procaryotic symbionts for their survival. In this collaborative project between Nancy Moran and Carol von Dohlen, both insect biologists, and Paul Baumann, a bacteriologist, molecular phylogenetic methods have been used to explore the evolutionary history of these mutualistic interactions. Using PCR amplification with procaryote-specific primers,...

Circadian rhythm of sex pheromone production and male activity of coexisting sibling species of Cryptomyzus aphids (Homoptera: Aphididae)


Eur. J. Entomol. 91 (1): 85-89, 1994

The aphid sibling species of Cryptomyzus live sympatrically on the same host plant and their sexual females appeared to be produced in the same period of the year. The circadian rhythm of the production of their sex pheromones, and the activity of the males, differed between the species. The origin of this divergence of mate recognition and the possibility of speciation by reinforcement are discussed.

Evolution of host fange in aphids


Eur. J. Entomol. 91 (1): 91-96, 1994

A simple model reveals one possible explanation of why aphids and organisms with a similar bionomy, i.e., have a high rate of population increase, a short adult life, and are time - limited dispersers, are so highly host specific. It indicates that small differences in host suitability amplified by the high rate of population increase over a number of generations could compensate for the losses incurred in searching for the best host plant.

Possible sound producing structures present in some Macrosiphini (Homoptera: Aphididae)


Eur. J. Entomol. 91 (1): 97-101, 1994

Some aphid species of the tribe Macrosiphini possess a row of peg-like hairs on the hind tibiae, which resemble the plectrum of the sound producing apparatus in Toxoptera (tribe Aphidini). In addition to the three earlier recorded cases in the genus Macrosiphoniella (M. jaroslavi Szelegiewicz, M. myohyangsani Szelegiewicz, M. spinipes Basu) and Macrosiphum (Sitobion) gravelii van der Goot, these hind tibial pegs were found in Macrosiphoniella millefolii (DeGeer) and 10 species of the genus Uroleucon. In the Aphidini the plectrum is a transformed posterior row of hairs (rastral setae),...

Dynamics of re-migration of sexuparae to their primary hosts in the gall-forming Fordinae (Homoptera: Aphidoidea: Pemphigidae)


Eur. J. Entomol. 91 (1): 103-108, 1994

Migratory flight of sexuparae of gall forming Fordinae to 3 species of Pistacia hosts was monitored using sticky traps. Sexuparae arrived from late March to July. Species arrival time distributions overlapped but modes did not coincide. Although the Fordinae are strictly host-specific, sexuparae landed and reproduced not infrequently on the wrong Pistacia host, a reproductive dead end. These results show that their host-selection ability is imperfect.

DNA fingerprinting of cereal aphids using (GATA)4


Eur. J. Entomol. 91 (1): 109-114, 1994

The role of DNA fingerprinting as a tool for studying cereal aphid populations along with the principals behind fingerprinting and the process of obtaining fingerprints using the multilocus probe, 32P labelled (GATA)4 are discussed. The successful application of this technique in obtaining fingerprints capable of distinguishing between different clones of Sitobion avenae (F.) is presented.

Variation in behavioural migration in aphids


Eur. J. Entomol. 91 (1): 115-120, 1994

The behaviour of Aphis fabae during maiden flight in an automated flight chamber was assessed by their response to the intermittent presentation of a plant-like visual target. As shown previously, alate virginoparae were much more responsive to the target, i.e. indicating foraging flight, during the initial part of maiden flight than were gynoparae. Virginoparae initiated foraging flight after a short behavioural migratory period, i.e. the initial period of flight when the aphid remains unresponsive to the target, (on average 8 ± 5 min) while gynoparae undertook a longer migratory flight (on average 102 ± 19 min). However, if starved...

How variable are rates colonisation?


Eur. J. Entomol. 91 (1): 121-125, 1994

The rates of spatial expansion of range following the introduction of animals to new areas are extremely variable between species. Data on a selection of species from a range of taxa show that these rates vary over about five orders of magnitude. The range expansion of a limited number of pest species of aphids have been mapped following colonisation. Studies on rates of colonisation are important as they are central to pest risk analysis. In addition, the observed variation in rates have significant implications for the development of realistic models of metapopulations.

Why are there so few aphid species in the temperate areas of the southern hemisphere?


Eur. J. Entomol. 91 (1): 127-133, 1994

An answer to this question is proposed on the basis of the assumed evolutionary history of aphids based on palaeontological studies, zoogeographical data and estimated origin of each aphid genus in the world. An adaptive radiation of Aphididae and Lachnidae occurred rather late in the Tertiary on the northern hemisphere, and the tropics acted as a barrier. Most aphid genera endemic to the temperate regions of the southern hemisphere belong to other groups. The life cycles of aphids are discussed, and it is concluded, that the life cycles characteristic to most aphids in the temperate regions of the northern hemisphere are developed as an adaptation...

The relationship between the regional number of aphid species and plant species diversity


Eur. J. Entomol. 91 (1): 135-138, 1994

The relationship between the regional number of aphid species to the number of plant species in the same area was assessed. A simple power model was statistically fitted to data from 35 countries, spanning six continents. The maximum aphid species diversity was found to occur at an intermediate plant species diversity.

The simplification of aphid terminology


Eur. J. Entomol. 91 (1): 139-141, 1994

A report is provided of a workshop at 4th International Symposium on Aphids, where the decision was reached to recommend a major simplification of the terms used in papers on aphid biology, in order to make aphid work more accessible. It was concluded that most of the specialist terms usually applied to aphid morphs anf life cycles could and should be avoided in papers that are intended to be of general interest to other biologists. Specific recommenadations are made for their replacement by terms that are simpler and more widely understood.