Ecology of the aphid pests of protected pepper crops and their parasitoids

Myzus persicae, Macrosiphum euphorbiae, Aphis gossypii and Aulacorthum solani (Homoptera: Aphididae) are principal pests of protected pepper crops in southeastern Spain. Our goal was to determine the incidence of aphids on pepper crops and the role of vegetation surrounding greenhouses as a source of aphids and their parasitoids. The population dynamics were followed in six commercial greenhouses during 3 years. Another 82 greenhouses and their surrounding vegetation were surveyed occasionally. Myzus persicae had the highest incidence in pepper greenhouses followed by M. euphorbiae and A. solani. Parasitism of all aphid species in greenhouses was low, Aphidius matricariae and Aphidius colemani being the most abundant parasitoids. Myzus persicae and Macrosiphum euphorbiae were the most abundant and polyphagous aphids, being present on 77 and 55% of the plants sampled outside greenhouses, respectively; species of Brassicaceae were the main hosts for both aphids. Aulacorthum solani was only present on Malva parviflora and at low numbers. Outside greenhouses, A. matricariae was the most common parasitoid of M. persicae, followed by Diaeretiella rapae and A. colemani. Aphidius matricariae was the most polyphagous, being present in 10 out of 22 aphid species. Macrosiphum euphorbiae and A. solani were both parasitised by A. ervi and Praon volucre. Aphelinus asychis was found on A. solani. Parasitoids were found in other aphids not attacking pepper. The role of natural vegetation as a reservoir of aphid pests of pepper and of parasitoids is discussed.     

Transmission of Zucchini yellow mosaic virus by Colonizing and Non-colonizing Aphids in Greece and New Aphid Species Vectors of the Virus

Nineteen aphid species were tested for their ability to transmit Zucchini yellow mosaic virus (ZYMV) from and to zucchini under laboratory conditions. Sixteen species were found to be new vectors of ZYMV (i.e. Aphis craccae, Aphis fabae, Aphis nerii, Aulacorthum solani, Brachycaudus cardui, Brevicoryne brassicae, Hyalopterus pruni complex, Hyperomyzus lactucae, Macrosiphoniella sanborni, Macrosiphum rosae, Metopolophium dirhodum, Myzus cerasi, Rhopalosiphum maidis, R. padi, Semiaphis dauci and Sipha maydis). Their transmission efficiency by a single aphid was low (0.1–4.2%). Myzus persicae was used as a control and was the most efficient vector (41.1%, one aphid per plant). Hayhurstia atriplicis, Myzus ascalonicus and Sitobion avenae did not transmit the virus. In four out of six new vectors assayed in arena tests for propensity estimation, propensity was higher than efficiency. Data from an experimental zucchini field in northern Greece revealed a high correlation between ZYMV spread and alatae of the vector species. The most abundant aphid vectors during 2 years experimentation were M. persicae, Aphis gossypii and Aphis spiraecola. The possible role of the 16 new and the previously known aphid vectors in the epidemiology of ZYMV was investigated using data of transmission efficiency combined with the captures of their alatae in the Greek net of a Rothamsted type suction trap.     

Host-range study about four aphid parasitoid species among 16 aphid species for constructing banker–plant systems

To provide fundamental information for the biological control of aphids in vegetable greenhouses, we compared the host ranges of four aphid parasitoid species, Aphidius colemani Viereck, Aphidius gifuensis Ashmead, Diaeretiella rapae (M’Intosh), and Ephedrus nacheri Quilis (Hymenoptera: Braconidae: Aphidiinae). The acceptability as host of 11 vegetable-pest aphids, Acyrthosiphon pisum (Harris), Aphis craccivora Koch, Aphis gossypii Glover, Aulacorthum solani (Kaltenbach), Brevicoryne brassicae (Linnaeus), Chaetosiphon fragaefolii (Cockerell), Lipaphis erysimi (Kaltenbach), Macrosiphoniella sanborni (Gillette), Macrosiphum euphorbiae (Thomas), Myzus persicae (Sulzer), and Uroleucon formosanum (Takahashi), in addition to five aphid species, Melanaphis sacchari (Zehntner), Rhopalosiphum maidis (Fitch), Rhopalosiphum padi (Linnaeus), Schizaphis graminum (Rondani), and Sitobion akebiae (Shinji) (Hemiptera: Aphididae) that serve as alternative hosts in banker–plant systems for the four aphid parasitoid species, were investigated. A newly emerged pair of parasitoid adults were provided to 100 aphids of each species on caged host plants in a 25 °C chamber for 24 h. The numbers of mummified aphids and emerged adults were counted in 10 trials for each aphid species. Aphidius colemani, A. gifuensis, D. rapae and E. nacheri parasitized four, two, three, and eight pest species, respectively, and four, three, three, and five alternative host species, respectively. Ephedrus nacheri had the broadest host range among the four species, and all the four species parasitized M. persicae, R. maidis, and S. graminum. This information will be useful for selecting candidate of biological control agents for aphids and for constructing banker–plant systems.

     

The potential host ranges in Australia of some imported aphid parasites [Hym: Ichneumonoidea: Aphidiidae]

Host selection trials on restricted populations of the aphidiid parasites,Lysiphlebus fabarum (Marshall) andL. testaceipes (Cresson), imported into Australia as biological control agents ofAphis craccivora Koch, the cowpea aphid, have shown that these imported parasites are not widely polyphagous, and thus support a view that the 2 species, as presently recognized, each represent a complex of host-restricted biotypes or of sibling species. Whereas both of the importedLysiphlebus readily oviposited in species ofAphis andToxoptera, and developed successfully to adulthood inA. craccivora, A. gossypii Glover andT. aurantii (Boyer de Fonscolombe), they failed to complete development inA. citricola van der Goot, one of the most common aphid species in Australia, and only a small number completed development inT. citricidus (Kirkaldy). Both of these hosts, then, act as “egg traps” for theLysiphlebus. A. nerii Boyer de Fonscolombe was a suitable host forL. testaceipes but not forL. fabarum. NeitherL. fabarum notL. testaceipes oviposited inCavariella aegopodii (Scopoli),Brevicoryne brassicae (L.),Brachycaudus helichrysi (Kaltenbach),B. persicae (Passerini),Hyperomyzus lactucae (L.),Acyrthosiphon kondoi Shinji,A. pisum (Harris),Macrosiphum euphorbiae (Thomas) orM. rosae (L.); andL. fabarum did not oviposit inRhopalosiphum padi (L.) orMyzus persicae (Sulzer). The prognosis for the effective establishment in Australia of these 2 parasites is therefore not good In contrast, another purportedly polyphagous aphidiid,Praon volucre (Haliday), imported into Australia to help effect control ofH. lactucae, the sowthistle aphid, successfully and effectively parasitizedMacrosiphum euphorbiae, M. rosae, Acyrthosiphon pisum, A. kondoi, Aulacorthum solani (Kaltenbach),Myzus persicae andAphis craccivora, in addition toH. lactucae.     

Effects of elevated CO2 on five plant-aphid interactions

We investigated interactions between five species of phloem-feeding aphids (Homoptera: Aphididae) and their host plants at elevated CO₂; Acyrthosiphon pisum (Harris) on Vicia faba L., Aphis nerii Boyer de Fonscolombe on Asclepias syriaca L., Aphis oenotherae Oestlund on Oenothera biennis L., Aulacorthum solani (Kaltenbach) on Nicotiana sylvestris Speg. & Comes and Myzus persicae (Sulzer) on Solanum dulcamara L. Host plants grown at elevated CO₂ generally had greater biomass, leaf area and C:N ratios than those grown at ambient CO₂, while plants with aphids had lower biomass and leaf area than those without aphids.The responses of aphid populations to elevated CO₂ were species-specific with one species increasing (M. persicae), one decreasing (A. pisum), and the other three being unaffected. CO₂ treatment did not affect the proportion of alate individuals produced. In general, aphid abundance was not significantly related to foliar nitrogen concentration.We performed separate analyses to test whether either aphid presence or aphid abundance modified the response of host plants to elevated CO₂. In terms of aphid presence, only three of the potential 15 interactions (five aphid species x three plant traits) were significant; A. solani slightly modified the response of the plant biomass to elevated CO₂ and M. persicae affected the response of leaf area and allocation. In terms of aphid abundance, only two of the potential 15 interactions were significant with A. nerii modifying the plant response to CO₂ in terms of total leaf area and allocation.We conclude that, in contrast to other insect groups such as leaf chewers, populations of most phloem-feeders may not be negatively affected by increased CO₂ concentrations in the future. The reasons for this difference include the possibility that aphids may be able to compensate for changes in host plant quality by altering feeding behaviour or by synthesizing amino acids. In addition, there is little evidence that aphid herbivory, even at high levels, will substantially modify the response of plants to elevated CO₂.     

The resistance of three Solanum species to Myzus persicae, Macrosiphum euphorbiae and Aulacorthum solani (Aphididae: Homoptera)

A study was made of the resistance of three wild potato species, Solanum chacoense, S. stoloniferum and S. demissum, to three aphid species, namely Myzus persicae (Sulz.), Aulacorthum solani (Kalt.) and Macrosiphum euphorbiae (Thomas), which all commonly infest the cultivated potato, S. tuberosum. The resistance of each Solanum species differed with the species of aphid, with the part of the plant and with the physiological condition of the leaf. As a result, it may be difficult to utilize such resistance, since it is ineffective against some of the pest aphid species and may break down as the physiological condition of the plant changes.     

Virus-Vector Cell Interactions Regulating Transmission Specificity of Soybean Dwarf Luteoviruses

Transmission of soybean dwarf viruses (SbDV) indigenous to Japan (SbDV‐D) and to the eastern United States (SbDV‐Va19) were compared in vector and nonvector aphid species. Absolute vector‐specificity was maintained when Aulacorthum solani, Acyrthosiphon pisum, and Myzus persicae were allowed to feed on solutions of either virus (100 μg/ml) through Parafil© membranes. SbDVD was transmitted only by A. solani, and SbDV‐Va19 was transmitted only by A. pisum and M. persicae. Similar results were obtained when individual aphids were micro‐injected with 2 ng virus and subsequently allowed to feed on healthy plants. Ultrastructural studies of A. solani and M. persicae indicated that both SbDV‐D and SbDV‐Va20 were acquired specifically through the aphid hindgut. No difference in hindgut acquisition specificity was observed, and both A. solani and M. persicae were able to transport SbDV‐D and SbDV‐Va20 into the haemocoel by endocytotic/exocytotic pathways. When injected, SbDV was shown to be associated with only the accessory salivary glands (ASG) in aphids, indicating a high level of tissue specificity. Two different interactions with the ASG were observed for SbDV‐D and SbDV‐Va20 in A. solani and M. persicae. SbDV‐D penetrated the ASG basal lamina of A. solani, but was never observed in the basal lamina of M. persicae. The ASG basal lamina was a barrier to SbDV‐D transmission by M. persicae. SbDV‐Va19 penetrated the ASG basal lamina of both A. solani and M. persicae. However, SbDV‐Va20 was not observed in the ASG cytoplasm in A. solani, indicating that the basal plasmalemma functioned as the transmission barrier. Observations indicated that capsid protein structure, aphid basal lamina composition and cell membrane components influenced virus‐aphid interactions regulating SbDV transmission.     

Genetic, biochemical, and behavioral uniformity among populations of Myzus nicotianae and Myzus persicae

Prior to designation as distinct species, an appellation presently in question, the tobacco aphid, Myzus nicotianae Blackman (Homoptera: Aphididae), was classified as a tobacco-feeding form of the green peach aphid, Myzus persicae (Sulzer). In this study, RAPD polymorphisms distinguished members of the Myzus persicae complex (M. persicae and M. nicotianae) from three outgroup Myzus species (M. cerasi (F.), M. hemerocallis Takahashi, and M. varians Davidson). Polymorphisms within the complex did not separate populations on the basis of host association (tobacco versus other host plants) or geographic origin (collections from the United States, Europe, and Japan). Similarly, while GC-MS analysis of cuticular hydrocarbon profiles revealed both developmental and inter-populational differences within the M. persicae complex, it did not separate populations of tobacco feeding aphids from those collected off non-tobacco hosts. Finally, with the exception of their responses to a choice between lettuce and collards, the host preference behavior of a green peach aphid population, a red tobacco aphid population, and a green tobacco aphid population was indistinguishable in host preference experiments. These results add to a growing body of evidence suggesting M. nicotianae and M. persicae are conspecific.     

Transmission Comparisons of Cucumber Mosaic Virus Subgroup I and II Isolates by Different Aphid Species

To investigate the transmission differences between Cucumber mosaic virus (CMV) subgroup isolates, we carried out a comparative study with five aphid species Myzus persicae, Aphis gossypii, Lipaphis erysimi, Aphis craccivora and Megoura viciae in laboratory and field experiments to evaluate spread of CMV Subgroup I NX and subgroup II AG isolates in tobacco. Both NX and AG varied in transmission efficiency by the five aphids, and our transmission results revealed important differences in transmission efficiency of two isolates by Myzus persicae and Aphis gossypii. In contrast, significant transmission differences were not detected with Lipaphis erysimi, Aphis craccivora or Megoura viciae. Interestingly, the overall transmission efficiencies of the two different subgroup strains were almost equal when field transmissions were tested with mixed populations of the five aphid species. Our results together with our previously reported experiments on competition of CMV subgroup isolates in tobacco suggest that variations in aphid vector populations contribute substantially to the epidemic potential of CMV subgroup isolates.     

Population dynamics of aphid species in Korean seed potato cultivation area over four decades

The world's climate is changing. This can affect agricultural insects and the damage they cause by altering their ecology, behavior and habitats. Aphids are emerging as an indicator of climate change, and they are a good model for understanding these environmental changes, especially based on their migratory behavior. In this study, the occurrence of aphids in a seed potato field in Pyeongchang, Korea, was monitored daily using a yellow water pan trap from 1977 to 2017. During these 40 years, the annual migration fluctuations of the aphids were analyzed, with particular focus on four species known to vector potato viruses, Aphis gossypii, Aulacorthum solani, Macrosiphum euphorbiae, and Myzus persicae. It was found that, as time goes by, the start point of spring migration in these aphid species was getting earlier while the peak in autumn migration gradually moved to the winter season. Moreover, the annual total number of collected aphids increased by 3.74 times during the 40 years. Together with a mean annual temperature increase of 1.03°C in Pyeongchang over the past four decades, there is a potential threat of expansion in the distribution of aphid species. Therefore, we carefully hypothesized that this temperature change could influence the aphid's population changes in the Korean peninsula. This information can be used in an integrated aphid management program in seed potato cultivation.     

Einfluß von Sinigrin auf die Nahrungsaufnahme polyphager und oligophager Blattlausarten (Aphididae)

Zusammenfassung Bei einigen polyphagen und oligophagen Blattlausarten wurde die Nahrungsaufnahme an einer 20% igen wäßrigen Saccharose-Lösung ohne bzw. mit Zusatz von 0,1% Sinigrin mit Hilfe der Tracer-Methode verglichen. Die Anwesenheit von Sinigrin förderte die Nahrungsaufnahme bei Brevicoryne brassicae, Myzus persicae und Megoura viciae, sie hemmte sie stark bei Rhopalosiphum padi und schwächte sie bei Aphis fabae und Acyrhosiphon pisum. Aulacorthum circumflexum reagierte in einigen Versuchen positiv, in anderen aber negativ auf das Glycosid. Bei der Mehrzahl der untersuchten Arten entspricht demnach Annahme bzw. Ablehnung von Cruciferen als Wirte der Reaktion auf Sinigrin. Im Gegensatz dazu stehen die Befunde bei M. viciae, die keine Cruciferen besiedelt, an Lösungen mit Sinigrin jedoch höhere Werte erreichte, so daß vermutlich andere physikalische oder chemische Eigenschaften von Cruciferen deren Ansiedlung verhindern.

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Effect of sinigrin on sucrose uptake by some polyphagous and oligophagous aphids (Aphididae)

Summary The effect of 0.1% sinigrin on sucrose uptake (20% aqueous solution) by some polyphagous and oligophagous aphid species was tested using the tracer method. In the presence of sinigrin the sucrose ingestion of Brevicoryne brassicae, Myzus persicae and Megoura viciae was promoted. With Rhopalosiphum padi there was a strong, and with Aphis fabae and Acyrthosiphon pisum only a slight inhibition of sucrose uptake. Aulacorthum circumflexum reacted positively in some experiments, but negatively in others. Thus the acceptance or refusal of cruciferous plants as a host by the majority of the species examined corresponded to their reaction to sinigrin. Contrasting results were obtained with M. viciae. Although cruciferous plants are non hosts for this species, it ingested more sucrose when sinigrin was present. Therefore other physical or chemical properties must be considered for the refusal of cruciferous plants as a host.

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Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.     

Determination of aphid transmission efficiencies for N, NTN and Wilga strains of Potato virus Y

Potato virus Y (PVY, genus Potyvirus, family Potyviridae) causes high economic losses worldwide, especially in the production of seed potatoes (Solanum tuberosum). PVY control systems rely on measuring virus pressure and vector pressure in the field. Calculation of the vector pressure is based on the relative efficiency factors (REFs) of aphid species. These REFs express the transmission efficiency of aphid species in relation to the transmission efficiency of Myzus persicae, the most efficient vector of PVY. In this paper, we report on the determination of aphids' relative transmission efficiency factors (REFs) for isolates of the PVY strains PVY^N, PVY^NTN and PVY^N-Wi. Biotype Mp2 of M. persicae was tested for its transmission efficiency for six PVY isolates (one PVY^N, three PVY^NTN and two PVY^N-Wi isolates) and showed comparable average transmission efficiencies for all isolates. The transmission rate of this biotype for the six PVY isolates was set to 1 and Mp2 was used as an internal control in transmission experiments to determine the REFs of three other biotypes of M. persicae and 16 other aphid species (three biotypes per species when available) for the six PVY isolates. Comparing the calculated REFs for PVY^N with the REFs reported in the previous century for PVY^N, we observe overall comparable REFs, except for Aphis fabae, Aphis spp., Hyperomyzus lactucae, Macrosiphum euphorbiae and Rhopalosiphum padi, which have a lower REF in our experiments, and Aphis frangulae and Phorodon humuli, which have now a higher REF. Comparing the new REFs found for the PVY^NTN strains with the new REFs for PVY^N, we observe that they are overall comparable, except for A. frangulae (0.17 compared with 0.53) and Schizaphis graminum (0.05 compared with 0.00). Comparing the REFs calculated for PVY^N-Wi with those calculated for PVY^N, we can observe six aphid species with higher REFs (Acyrthosiphon pisum, A. fabae, Aphis nasturtii, Aphis spp., P. humuli and R. padi). Only the species A. frangulae shows a lower REF for PVY^N-Wi compared with the transmission efficiency of PVY^N. Three aphid species (Aulacorthum solani, Myzus ascalonicus and S. graminum) for which no REF was determined earlier were found to be capable to transmit PVY and their REFs were determined.     

The effect of insecticides and a plant barrier row on aphid populations and the spread of bean yellow mosaic potyvirus and subterranean clover red leaf luteovirus in Vicia faba in South Australia

The effect of the insecticides malathion, demeton-S-methyl and disulfoton, and a barley barrier row on the rate and pattern of spread of bean yellow mosaic potyvirus (BYMV) and subterranean clover red leaf luteovirus (SCRLV) in Vicia faba was investigated in field plots with artificially introduced sources of viruses and vectors. The systemic insecticide treatments reduced aphid populations in the plots and this was associated with reduced spread of SCRLV, but not of BYMV. The barley barrier did not affect aphid populations in plots; however, it reduced the spread of BYMV to rows 1 · 1 m from the source but had only a minor effect on the spread of SCRLV. Apterae rather than alates of Aulacorthum solani were implicated in the spread of SCRLV. Spread of BYMV was attributed mainly to alate migrants of Myzus persicae and Macrosiphum euphorbiae, but other aphid species and morphs which occurred in high populations at the times of most rapid virus spread may also have had an active role as vectors of BYMV.     

Suitability of three aphid species for Aphidius gifuensis (Hymenoptera: Braconidae): Parasitoid performance varies with hosts of origin

Oviposition behavior and offspring fitness of the parasitoid Aphidius gifuensis (Ashmead) were compared on three aphid species, Sitobion avenae F., Myzus persicae (Sulzer), and Aphis gossypii Glover using wasps collected from both S. avenae and M. persicae. A. gifuensis produced more mummies and adults on S. avenae and M. persicae than on A. gossypii regardless of the host of origin. Mummy production was influenced by attack rate and percentage of aphids superparasitized. The F₁ generations from S. avenae and M. persicae were more female-biased and wasps were larger than those from A. gossypii. Although there were significant differences in development time of A. gifuensis in the three aphid species, the difference was generally shorter than one day. Fewer mummies were produced when A. gifuensis was transferred between S. avenae and M. persicae, but no significant difference was observed in emergence rate, percentage of female offspring, or body size. The effects of host species on A. gifuensis female performance and offspring fitness are discussed, along with the potential for using A. gifuensis to control M. persicae and A. gossypii.     

A strain of the bacterial symbiont Regiella insecticola protects aphids against parasitoids

Aphids commonly harbour facultative bacterial endosymbionts and may benefit from their presence through increased resistance to parasitoids. This has been demonstrated for Hamiltonella defensa and Serratia symbiotica, while a third common endosymbiont, Regiella insecticola, did not provide such protection. However, this symbiont was recently detected in a highly resistant clone of the peach-potato aphid, Myzus persicae, from Australia. To test if resistance was indeed conferred by the endosymbiont, we eliminated it from this clone with antibiotics, and we transferred it to two other clones of the same and one clone of a different aphid species (Aphis fabae). Exposing these lines to the parasitoid Aphidius colemani showed clearly that unlike other strains of this bacterium, this specific isolate of R. insecticola provides strong protection against parasitic wasps, suggesting that the ability to protect their host against natural enemies may evolve readily in multiple species of endosymbiotic bacteria.     

Host range limitation caused by incomplete host regulation in an aphid parasitoid

Defining host ranges in parasitoid insects is important both from a theoretical and an applied point of view. Based on the literature, some species seem able to use a wide range of hosts, while field studies indicate possible local host specialization. In koinobiont endoparasitoid species, such specialization could involve physiological processes. We tested the ability of two strains of the cosmopolitan and polyphagous parasitoid Diaeretiella rapae, to develop in three of its recorded aphid host species. Both strains produced high parasitism rates on the cabbage aphid Brevicoryne brassicae and the green peach aphid Myzus persicae but almost no progeny on the cherry-oat aphid Rhopalosiphum padi. This last species was less attacked by female parasitoids. Moreover, parasitoid eggs and larvae were smaller than in the two other host aphid species and their development was delayed. This abnormal development appeared to be due to an incomplete host regulation process, probably related to the low number and the size of teratocytes produced by D. rapae in R. padi individuals. Such a failure as far as gaining control of the host's metabolism is concerned could play an important role in shaping the host range of parasitoid insects, leading to local variation of the host spectrum in populations from various geographical areas.     

Suitability of Different Prey Aphids on the Growth,Development and Reproduction of <Emphasis Type="Italic">Chrysoperla zastrowi sillemi</Emphasis> (Esben-Petersen) (Chrysopidae: Neuroptera)

The prey preference of polyphagous predator, green lacewing (Chrysoperla zastrowi sillemi (Esben-Petersen)) was evaluated against five prey aphids viz., mustard aphid (Lipaphis erysimi), green peach aphid (Myzus persicae), cabbage aphid (Brevicorynebrassicae), black bean aphid (Aphis craccivora), spirea aphid (Aphis spiraecola) of agriculture importance and compared with eggs of Corcyracephalonica (Stainton). Lacewing larvae preferred Myzus persicae most followed by Brevicorynebrassicae. The highest growth index (8.31), larval survival (94.50 %), larval weight (10.45 mg), pupal weight (8.78 mg), faster multiplication rate (0.051) and fecundity (183.4 per gravid female) of the predator were recorded on M. persicae. However, the chrysopid reared on Corcyra eggs performed best in all biological parameters and fitness, than on aphid preys. This study explores the possibilities of selecting the most suitable prey aphid species for its exploitation as supplement for mass multiplication of chrysopid during off-season or unavailability of Corcyra eggs.     

Oviposition vs. offspring fitness in Aphidius colemani parasitizing different aphid species

We measured the acceptance and suitability of four aphid species [Aphis gossypii Glover, Myzus persicae (Sulzer), Rhopalosiphum padi (L.), and Schizaphis graminum (Rondani)] (Homoptera: Aphididae) for the parasitoid Aphidius colemani Viereck (Hymenoptera: Braconidae). Female parasitoids parasitized fewer R. padi than the other three aphid species, and fewer offspring successfully completed development in R. padi than in the other three host species. Sex ratios of emerging adults were more male‐biased from R. padi than from the other three aphid species, suggesting that R. padi is a poor quality host for this population of A. colemani. Ovipositing A. colemani encountered R. padi at a slower rate, spent more time handling R. padi, and parasitoid offspring died at a higher rate in R. padi compared to A. gossypii. Our results show that oviposition behavior and offspring performance are correlated. In each experiment, we tested the effect of the host species in which the parasitoids developed (parental host) on the number of hosts attacked, the proportion of each host species accepted for oviposition and the survival of progeny. Parental host affected maternal body size and, through its effect on body size, the rate of encounter with hosts. Other than this, parental host species did not affect parasitism.