Phoracantha Semipunctata Research Articles

Insect pests affecting Eucalypts in Portugal: Current situation and future prospects

Eucalypts (Eucalyptus spp.) early established outside their native range have typically benefited from a pest-free environment. However, over time, due to the circulation of people and goods, several Australian insects that attack eucalypts reached the regions where these trees are commercially planted. In Europe, Portugal is the country with the largest area planted with eucalypts (mostly Eucalyptus globulus), covering almost 850,000 hectares. Thirteen insect species native from Australia have already been found in Portugal affecting eucalypts. From these, the snout beetle (Gonipterus platensis), the bronze bug (Thaumastocoris peregrinus), the longhorned borers (Phoracantha semipunctata and P. recurva), and the tortoise beetle (Trachymela sloanei) are the most important pests. This work aims to review the status of these pests, their impacts, and the success of the management strategies that have been employed. Future challenges are also discussed.

Constructing an Ensemble Model and Niche Comparison for the Management Planning of Eucalyptus Longhorned Borer Phoracantha semipunctata under Climate Change.

Phoracantha semipunctata is a destructive invasive alien forest pest worldwide. It primarily damages the eucalyptus via adults, affecting almost all parts of the eucalyptus. Its larvae develop in almost all major tissues of the plant. Phoracantha semipunctata spreads both via the migration of adults and global trade in intercontinental translocation. Currently, this pest has spread to six continents worldwide, except Antarctica, resulting in substantial economic losses. Based on global occurrence data and environmental variables, the potential global geographical distribution of P. semipunctata was predicted using an ensemble model. The centroid shift, overlap, unfilling, and expansion scheme were selected to assess niche dynamics during the global invasion process. Our results indicated that the AUC and TSS values of the ensemble model were 0.993 and 0.917, respectively, indicating the high prediction accuracy of the model. The distribution pattern of P. semipunctata is primarily attributed to the temperature seasonality (bio4), mean temperature of the warmest quarter (bio10), and human influence index variables. The potential geographical distribution of P. semipunctata is primarily in western and southwestern Asia, western Europe, western and southern North America, southern South America, southern Africa, and eastern and southern Oceania. The potential geographical distribution of P. semipunctata showed a downward trend in the 2030s and the 2050s. The distribution centroid showed a general tendency to shift southward from the near-current to future climate. Phoracantha semipunctata has largely conserved its niche during the global invasion process. More attention should be paid to the early warning, prevention, and control of P. semipunctata in the countries and regions where it has not yet become invasive.

Within-tree Distribution and Survival of the Eucalyptus Longhorned Borer Phoracantha semipunctata (Coleoptera: Cerambycidae) in a Mediterranean-Type Ecosystem.

The attack patterns, infestation success and larval development of woodborers within living trees are complex and are largely shaped by host tree characteristics. Following a severe drought in a native eucalypt forest where outbreak densities of a native Australian beetle, the eucalyptus longhorned borer (Phoracantha semipunctata), occurred, a tree dissection study was conducted in Australia. This involved felling 40 trees each of jarrah (Eucalyptus marginata) and marri (Corymbia calophylla) that were cut into 1-m sections and neonate larval galleries, larvae in pupal cells and adult borer emergence were measured and added to give total numbers per tree to determine the within-tree distribution and survival of P. semipunctata. There was a significant impact on larval survival in both species, in contrast, pupal survival remained high. Within-tree distribution of P. semipunctata was directional with borer emergence and incidence of larval galleries both negatively associated with tree section height above the ground and positively associated with section diameter and bark thickness, reaching a maximum towards the base of trees. High incidence and survival in lower thicker tree sections indicate a more conducive environment for larval development, in contrast to poor larval survival in smaller thinner sections at the top of trees. The dependence of larval survival on tree characteristics controlling the within-tree distribution of borer emergence is emphasized, and needs to be considered when estimating the spread of borer populations during outbreaks.

DISTRIBUTION, PREFERENCE AND PERFORMANCE OF PHORACANTHA RECURVA AND PHORACANTHA SEMIPUNCTATA (COLEOPTERA CERAMBYCIDAE) ON VARIOUS EUCALYPTUS SPECIES IN TUNISIA

The two eucalyptus borers Phoracantha semipunctata and P. recurva were accidently introduced in Tunisia in 1962 and 1999, respectively. Their relative distribution is still unknown and very little is known about their preferences and performances in various host species under different Tunisian climates. We combined field data and laboratory follow-up, in order to define their present distribution, their relative abundance and to test the effects of sites and Eucalyptus species on attack density, reproductive and developmental performances and productivity of insects. The study was carried out in Eucalyptus plantations of ten localities ranging from humid to arid. Choice preference and colonization of various selected Eucalyptus species by the two borers were studied with standing trap trees and trap logs. Tree species differed among localities, but all localities contained at least one of the two species E. gomphocephala and E. camaldulensis, both being well appreciated by the two Phoracantha species. It appeared that both beetle species were present in all localities but P recurva was dominant over P semipunctata everywhere. Insect characteristics depended on attack localization on tree stem; attack densities were higher on the lowest than on the upper parts. It is perfectly coherent that the density of emerging beetles correlated positively with attack density, number of young larval galleries, larval survival and adult success in the trap tree experiment. High larval survival and adult success resulted in high offspring productivity. Insect parameters, especially the intensity of infestation, depended on locality but without relation with the climatic areas.

LEVANTAMENTO DA ENTOMOFAUNA EM PLANTIOS DE <i>Eucalyptus</i> spp. POR MEIO DE ARMADILHA LUMINOSA EM SÃO FRANCISCO DE ASSIS - RS

A cultura do eucalipto tornou-se uma importante atividade econômica no Brasil, no entanto, com o aumento das áreas de plantio, os problemas entomológicos tendem a aumentar nas mesmas proporções. Neste sentido, torna-se necessário o constante monitoramento dos insetos associados a esses sistemas de plantio homogêneos, buscando o desenvolvimento de programas de manejo integrado de pragas. Assim, o objetivo deste trabalho foi o levantamento populacional da entomofauna associada a plantios de Eucalyptus spp., em São Francisco de Assis - RS. As coletas foram realizadas por meio de armadilhas luminosas no período de julho de 2008 a agosto de 2009, em talhões de três anos de idade, com as espécies: Eucalyptus dunnii, Eucalyptus grandis e Eucalyptus grandis x Eucalyptus urophylla. Os insetos coletados foram analisados através dos índices de frequência, abundância, constância e diversidade. Realizou-se ainda a correlação entre as espécies-praga identificadas e as variáveis meteorológicas do período. Foram coletados 3.623 indivíduos distribuídos em oito ordens (Blattodea, Coleoptera, Dermaptera, Hemiptera, Hymenoptera, Lepidoptera, Mantodea e Odonata), identificando-se três espécies e três gêneros de lepidópteros desfolhadores considerados de importância econômica: Automeris illustris, Eupseudosoma sp., Sabulodes sp., Sarsina sp., Thyrinteina arnobia e Agrotis ipsilon. e a coleobroca Phoracantha semipunctata. Pelos resultados obtidos, pode-se concluir que existem espécies-praga importantes da cultura de Eucalyptus já estabelecidas na região, necessitando, portanto, de monitoramento constante para que estas espécies não ocasionem danos aos plantios.

Outbreak of Phoracantha semipunctata in Response to Severe Drought in a Mediterranean Eucalyptus Forest

Extreme climatic events, including droughts and heatwaves, can trigger outbreaks of woodboring beetles by compromising host defenses and creating habitat conducive for beetle development. As the frequency, intensity, and duration of droughts are likely to increase in the future, beetle outbreaks are expected to become more common. The combination of drought and beetle outbreaks has the potential to alter ecosystem structure, composition, and function. Our aim was to investigate a potential outbreak of the native Eucalyptus longhorned borer, Phoracantha semipunctata (P. semipunctata), following one of the most severe droughts on record in the Northern Jarrah Forest of Southwestern Australia. Beetle damage and tissue moisture were examined in trees ranging from healthy to recently killed. Additionally, beetle population levels were examined in adjacent forest areas exhibiting severe and minimal canopy dieback. Severely drought-affected forest was associated with an unprecedented outbreak of P. semipunctata, with densities 80 times higher than those observed in surrounding healthier forest. Trees recently killed by drought had significantly lower tissue moisture and higher feeding damage and infestation levels than those trees considered healthy or in the process of dying. These results confirm the outbreak potential of P. semipunctata in its native Mediterranean-climate Eucalyptus forest under severe water stress, and indicate that continued drying will increase the likelihood of outbreaks.

Parasitoid Discrimination between Suitable and Unsuitable Congener Hosts

The eucalyptus longhorned borer, Phoracantha semipunctata (F.) (Coleoptera: Cerambycidae), is under complete biological control in California following introduction of the encyrtid egg parasitoid, Avetianella longoi Siscaro. The cerambycid congener, Phoracantha recurva Newman¸ subsequently established in the state and has been subject to limited parasitization by the wasp. Behavioral analysis demonstrated that female parasitoids follow the same sequence of ovipositional behaviors when encountering eggs of both beetle species, but discriminate between the species and make a decision to lay an egg only after inserting the ovipositor into an egg. Previous research has demonstrated that the eggs of P. recurva are capable of encapsulating and killing eggs of A. longoi. Eggs of P. semipunctata do not produce a host defense to parasitization. Consequently, the ability of a female to distinguish between the congeneric species has critical fitness consequences.

Evidence of a Genetic Basis for Differences in Parasitization Success between Strains of Avetianella longoi (Siscaro).

When the cerambycid, Phoracantha recurva, invaded California in the mid 1990’s a parasitoid wasp was imported from its native range in Australia as part of a biological control program. The wasp was later identified to be Avetianella longoi, which had already been released years earlier to control the congener longhorned beetle, Phoracantha semipunctata. Despite being recognized as the same species, the two wasps exhibited differential success on P. recurva eggs, indicating the presence of two separate strains. Here we determine if the differentiating factor between the two strains of A. longoi is a heritable genetic trait. All four pairings between the two strains were conducted, resulting in two homogenous and two heterogeneous crosses. All crosses except one produced viable F1 female offspring. F1 females were allowed to oviposit on P. recurva eggs and the survival of their offspring was compared to determine if survival can be affected by paternal contributions. The result was that the offspring of females with fathers from the second introduced strain showed significantly increased survival compared to F1 females with parents from the first introduced strain. This increased survival demonstrated that there is a heritable dominant trait that is associated with increased survival on P. recurva host eggs.

Potential for Interspecific Competition Between Congeneric Longhorned Beetle Species (Coleoptera: Cerambycidae) in an Adventive Environment.

The cerambycid beetle, Phoracantha semipunctata F., was introduced into California in the mid-1980s and killed large numbers of Eucalyptus host trees. The populations of the borer declined to very low levels in the mid-1990s following the establishment of the congener, Phoracantha recurva Newman, and the intentional introduction of the egg parasitoid, Avetianella longoi Siscaro. The distributions of the beetles overlap in the Australian native range, but one species has replaced the other in the adventive range in California. One possible explanation is differential susceptibility to natural enemies introduced for biological control. An alternative explanation for the reduced abundance of P. semipunctata is asymmetric interspecific competition between the two species. To test this hypothesis, equal larval densities of each species were introduced into host logs. In all cases, more P. recurva adults emerged than P. semipunctata adults, but the presence of congeners did not have a different effect than the presence of an equal density of conspecific individuals. Neither the temporal order of introduction or bark thickness altered the outcome of potential competitive interactions. Consequently, it appears that the ecological replacement of one borer with another in the adventive environment in southern California may not be a result of bottom-up intraguild competitive interactions. The top-down effects of natural enemies on P. semipunctata have most likely led to its decline.

A diverse assemblage of Ophiostoma species, including two new taxa on eucalypt trees in South Africa

Fungi in the Ophiostomatales include important pathogens of trees as well as agents of wood stain, reducing the economic value of timber. They rely on insects, such as bark beetles, for dispersal and are commonly associated with wounds on trees. Although Ophiostoma spp. have been reported from eucalypt wood chips in South Africa, very little is known about the diversity of the Ophiostomatales, or their insect associates, on plantation-grown Eucalyptus spp. The aim of this study was to consider the diversity and distribution of the Ophiostomatales infecting fresh wounds on Eucalyptus trees in the country. Additionally, knowledge regarding their association with nitidulid beetles, which have previously been shown to carry Ophiostoma spp., was sought. Surveys were conducted in five provinces where Eucalyptus spp. are commonly grown, and the fungi collected were identified using morphological comparisons and multigene sequence phylogenies. Of the 139 isolates collected, five Ophiostoma spp. were identified including O. quercus, O. tsotsi and O. tasmaniense. These were from cut stumps as well as from the nitidulid beetles Brachypeplus depressus and Carpophilus spp. In addition, two new taxa in the O. stenoceras–Sporothrix schenckii complex were identified from Eucalyptus trees infested by Phoracantha semipunctata. The two new taxa are described as O. candidum sp. nov., and O. fumeum sp. nov., respectively. The results of this study clearly show that the diversity and ecology of Ophiostoma spp. on Eucalyptus trees in South Africa is poorly understood and that further studies are required to determine the possible economic relevance of these fungi.

Integration of tactics for management of Eucalyptus herbivores: influence of moisture and nitrogen fertilization on red gum lerp psyllid colonization

AbstractMoisture stress and fertilization have been reported to both increase or decrease susceptibility of plants to herbivory. In the Eucalyptus (Myrtaceae) system in California, cultural practices that maintain sufficient moisture levels in the living outer bark contribute to the resistance of the trees to the invasive eucalyptus longhorned borer, Phoracantha semipunctata (Fabricius) (Coleoptera: Cerambycidae). However, a community of fluid‐feeding psyllids has also been introduced into the state and it was unclear if water management practices that reduce susceptibility to the borer enhanced susceptibility to the psyllids. The results of irrigation and fertilization field trials demonstrated that low water applications and high levels of fertilization resulted in higher levels of red gum lerp psyllid, Glycaspis brimblecombei Moore (Hemiptera: Psyllidae), populations on the foliage than on trees treated with higher levels of irrigation and no fertilization. There were no differences in levels of parasitization of the psyllids by Psyllaephagus bliteus Riek (Hymenoptera: Encyrtidae) under the various treatment regimes. Consequently, it is possible to integrate compatible cultural practices and the use of natural enemies to manage populations of both the borer and the psyllid.

Do acoustic cues mediate host finding by Syngaster lepidus (Hymenoptera: Braconidae)?

Syngaster lepidus Brulle is a braconid solitary ectoparasitoid that attacks the larvae of the cerambycid beetles Phoracantha semipunctata and Phoracantha recurva. The beetle larvae are concealed under the bark of their Eucalyptus host trees feeding at the interface of the inner bark and the wood. Ovipositing female parasitoids search the bark surface and must first locate a host larva accurately, drill through as much as 1 cm of the bark in order to paralyze the larva beneath, and lay a single egg on the paralyzed larva. Female wasps were provided with logs infested with host larvae, in which the positions of the host larvae had been determined by X-ray imaging. The sequence of behaviors following the landing of a female wasp on an infested log was recorded on videotape and subsequently analyzed to provide a detailed description of the processes of host location and oviposition. Female wasps searched significantly more on log sections with active host larvae than inactive larvae. They also turned toward and moved in the direction of active larvae in response to sounds produced by feeding. While searching for hosts, female wasps stand on the log surface and walk towards the location of the larvae; while it is possible that they perceive both airborne sound and associated surface vibration, the vibration signals are probably more important in indicating direction and possibly distance to the host.

Trichoferus campestris(Faldermann) (Coleoptera: Cerambycidae), An Asian Wood-Boring Beetle Recorded in North America

ABSTRACT Two adult specimens of Trichoferus campestris (Faldermann, 1835), a newly detected alien wood-boring beetle native to Asia (Coleoptera: Cerambycidae), were collected in Repentigny, Quebec, Canada in 2002 and 2006. Adults, pupae, and mature larvae of this species are described, illustrated and diagnosed to facilitate its recognition among other North American Cerambycidae. The mtDNA sequence of the COI “barcoding” region of a Canadian specimen was obtained and analyzed. We discuss taxonomic affinities of T. campestris, its native distribution, host plants, and significance as a quarantine pest in North America. The importance of solid wood-packaging material as a potential pathway for invasive wood-boring species is highlighted. Seven other non-native Cerambycidae species first recorded in North America since 1980 [Tetropium fuscum (Fabricius, 1787), Anoplophora glabripennis (Motschulsky, 1853), Tetrops praeusta (Linnaeus, 1758), Callidiellum rufipenne (Motschulsky, 1860), Phoracantha semipunctata...

Development of a Strategy for Selective Collection of a Parasitoid Attacking One Member of a Large Herbivore Guild

Selectively collecting a single natural enemy species that parasitizes one member of a guild of herbivores that attack the same host plants can be a challenging problem during development of biological control programs. We present here a successful strategy for the collection of a strain of the egg parasitoid Avetianella longoi Siscaro (Hymenoptera: Encyrtidae), that parasitizes eggs of the longhorned borer Phoracantha recurva Newman (Coleoptera: Cerambycidae). This cerambycid is one member of a large guild of woodborers that simultaneously infest dying and fallen Eucalyptus in Australia, and it has become a major pest of Eucalyptus in many areas of the world where Eucalyptus has been introduced. Adult P. recurva of both sexes were caged on freshly cut Eucalyptus logs, and the resulting egg masses were marked and then left exposed to natural parasitization in the field. Parasitized egg masses were then harvested and held in the laboratory until adult parasitoids emerged. Parasitoids were identified as A. longoi by morphological comparisons with reference specimens, and with molecular markers. This strain of A. longoi readily accepted and had high survival rates in eggs of P. recurva. In contrast, the strain of A. longoi that has been used for biological control of P. semipunctata in California since the 1990s strongly prefers eggs of eucalyptus longhorned borer, Phoracantha semipunctata (F.) (Coleoptera: Cerambycidae), and has relatively low rates of survival to adulthood in eggs of P. recurva. The causes of these behavioral and physiological differences between the two strains are not yet known.

Host defensive response against an egg parasitoid involves cellular encapsulation and melanization

The egg parasitoid Avetianella longoi Siscaro attacks two species of eucalyptus longhorned borers (Phoracantha semipunctata F. and P. recurva Newman) in southern California. During the past decade, P. recurva has replaced P. semipunctata as the dominant borer species, apparently due to differential rates of parasitism. The present study reveals that this replacement is due in part to a physiological defensive response mounted by one species (P. recurva) against parasitoid eggs and larvae, similar to the encapsulation/melanization immune response observed in larval host/parasitoid systems. Fluorescence microscopy and vital dyes confirmed that the defensive response was cellular in nature. Both Phoracantha species exhibited a cellular wound-healing response around the wasp egg pedicel, but the encapsulation of the wasp eggs/larvae was elicited only in eggs of P. recurva. This is the first conclusive evidence that hosts in the egg stage can mount a cellular immune response against a metazoan parasitoid, and may provide insight into the mechanisms underlying the host specificity of many egg parasitoids.

Effects of Single Versus Multiple Mates: Monogamy Results in Increased Fecundity for the Beetle Phoracantha semipunctata

Effects of polyandry versus monogamy were assessed for the beetle Phoracantha semipunctata (Coleoptera: Cerambycidae) by comparing measures of female reproductive success, including fecundity, egg viability, time until eclosion, and clutch size. The effect of intermittent presence or absence of a male was also evaluated. Polyandry was detrimental to female reproductive success in comparison to monogamy. Fecundity, egg viability, and clutch size were lower, and time to eclosion were increased for eggs from females with multiple mates compared with monogamous females. Intermittent presence of males had no effect on female reproductive success. Possible explanations for the decreased fecundity experienced by females with multiple mates include sperm competition intensity, costs of male harassment, and exceeding the optimal mating frequency. Females may reduce costs associated with polyandry by spending less time on host logs where mating occurs.

Influence of the larval environment on performance and adult body size of the wood‐boring beetle Phoracantha semipunctata

AbstractLarge body size confers a reproductive advantage to adults of the wood‐boring beetle Phoracantha semipunctata (F.) (Cerambycidae: Cerambycinae: Phoracanthini). Larvae of this species feed subcortically in stressed and dying eucalypt trees and logs. We evaluated the influence of the larval environment on larval performance and adult body size by manipulating the post‐felling age of host logs (from freshly cut to 2‐weeks‐old) and the density of colonizing neonates (low density with minimal competition for resources vs. high density with intense competition). Adult beetles emerged in greater numbers from logs that had been subjected to the aging treatment which reduced bark moisture content and favored colonization by neonates. Survival was greatest in larger logs having lower densities of neonates, but was greatly diminished in all treatments by mortality during pupation. Development time varied from 2 months to more than a year and was shortest in smaller logs having high densities of larvae. The size of adult beetles emerging from a log was not influenced by larval density, but was positively correlated with the age of logs when the neonates colonized, and log size. These findings suggest that the optimal developmental conditions for P. semipunctata larvae, in terms of larval performance and adult body size, are available in large, aged host logs having low densities of larvae. Manipulation of the larval environment in this study resulted in a considerable variation in adult body size, but large individuals were relatively more common in the wild population that was the source of neonates for the experiment. Potential body size may have been constrained by our use of only one host species and a narrow range of log dimensions.

Seasonal Development ofPhoracantha recurvaandP. semipunctata(Coleoptera: Cerambycidae) in Southern California

A seasonal development study of the cerambycid beetles Phoracantha recurva Newman and Phoracantha semipunctata (Fabricius) (Coleoptera: Cerambycidae) was conducted under field conditions to look for differences in the developmental parameters of these congeneric species in southern California. Neonate larvae were introduced into eucalyptus logs in February, May, July, and October, and the infested logs were held in field cages at two locations: an inland desert site and a more temperate coastal site. Development times from neonate larva to emerged adult and percent emergence were recorded for beetles from all log cohorts at both sites. Under southern California climatic conditions, P. semipunctata seems to complete only one generation per year. Adult P. semipunctata emerged from infested logs from June to October. In contrast, P. recurva seems to be able to complete one generation and begin a second generation within the same year. Adult P. recurva emerged from infested logs from February to October. Across all treatments, a greater percentage of P. recurva (70 ± 2.5%) completed development in host logs than P. semipunctata (64 ± 1.5%). The majority of P. recurva (74.9%) and P. semipunctata (99.4%) emerged during June, July, and August. Host quality was correlated with beetle size. Overall, the differences in the developmental parameters of the two species may be contributing to the replacement of P. semipunctata by P. recurva in their shared habitat niche in southern California.

Effects of Temperature on Fecundity and Longevity of <I>Phoracantha recurva</I> and <I>P. semipunctata</I> (Coleoptera: Cerambycidae)

The cerambycid beetles Phoracantha recurva Newman and Phoracantha semipunctata F. were accidentally introduced into southern California where they have caused significant mortality to eucalyptus trees. In recent years, P. recurva populations have increased rapidly with a concomitant decrease in P. semipunctata numbers in their shared habitat in southern California. P. recurva has been collected in field surveys earlier in the season, suggesting that this species may be active over a broader range of temperatures and consequently have a longer seasonal activity period. We conducted lifetime fecundity studies to examine egg production, egg hatch, and adult longevity of beetles of both species subjected to temperatures typical of late fall and late winter/early spring in southern California. Overall, there were no differences in lifetime fecundity between P. recurva and P. semipunctata. P. recurva did not seem to reproduce over a larger range of temperatures than P. semipunctata, and there did not seem to be any substantial differences in their reproductive biologies. P. recurva eclosed slightly faster and lived slightly longer at reproductive temperatures than P. semipunctata, suggesting that P. recurva may have a slight reproductive advantage over P. semipunctata. However, it seems unlikely that such an advantage can account for the rapid increase in P. recurva populations and the simultaneous decrease in P. semipunctata populations in southern California.

Ovipositional preferences and progeny development of the egg parasitoid Avetianella longoi: factors mediating replacement of one species by a congener in a shared habitat

Abstract Populations of Phoracantha recurva , a cerambycid beetle that appeared in California around 1995, have increased rapidly while populations of the congener Phoracantha semipunctata , that arrived in California before 1985, have dramatically declined in the southwestern part of the state where the two species occur together. Both species colonize stressed Eucalyptus trees and fallen branches in the shared habitat. The proportion of P. recurva in the mixed population increased rapidly from 0.1% in 1995, the first year this species was detected, to 4.7% the following year, and 74% in 1997. To determine whether differential parasitization of eggs of the two beetle species by an egg parasitoid may be a contributing factor in this apparent ecological replacement of one species with a congener, we evaluated oviposition preference and host suitability of eggs of the two congeneric beetle species using strains of the egg parasitoid Avetianella longoi reared on eggs of either P. semipunctata (S-strain wasps) or P. recurva (R-strain wasps) for multiple generations. In both choice and no-choice bioassays, female parasitoids of both strains preferred to oviposit in P. semipunctata eggs, and survival rates were much higher in P. semipunctata eggs than in P. recurva eggs, for host eggs of two age classes (0.5 and 2.5 days old). Preference and survival of progeny of R-strain or S-strain females on P. semipunctata eggs were not significantly different, indicating that the preference for P. semipunctata eggs as a host resource was innate and had not been affected by >15 generations of selection. A substantial fraction of P. recurva eggs parasitized by wasps of either strain survived parasitization and produced neonate larvae, whereas no P. semipunctata eggs survived parasitization. Furthermore, a significantly larger percentage of parasitized P. recurva eggs produced neither a parasitoid nor a neonate larva than parasitized P. semipunctata eggs. The size and sex ratio of progeny of either parasitoid strain were minimally affected by host egg species. Although P. recurva eggs were smaller in diameter and weight than P. semipunctata eggs, eggs of both species were large enough to support the development of several parasitoids, so it is unlikely that insufficient nutrition was a contributing factor to survival of parasitoids in eggs of either host species. Cumulatively, these results suggest that eggs of both species contain adequate nutrition for developing parasitoids, but that ovipositing A. longoi females and their developing progeny frequently are not able to terminate P. recurva egg development.