Cerambycid Communities and Their Associated Hymenopteran Parasitoids From Major Hardwood Trees in Delaware: Implications for Biocontrol of Invasive Longhorned Beetles.

Cerambycidae provide important ecological services in forests yet cause economic damage when they infest living trees. Parasitoids can regulate woodborer populations, providing considerable control of pest cerambycids. Identifying parasitoids of native cerambycids may be useful in managing cerambycid outbreaks and aid in new-association biocontrol of exotic invasive cerambycids. We investigated Cerambycidae and associated hymenopteran parasitoid communities infesting Acer rubrum, Pinus virginiana, and Carya tomentosa from a forest in Delaware from 2005 to 2012. Cerambycid abundance, diversity, and richness, as well as parasitoid abundance, were measured by collecting trees in different conditions: felled, girdled, and naturally infested. Effect of edge or interior red maple on cerambycid abundance, diversity, and richness was examined. Over 14,500 cerambycids of 56 species and 38 genera were collected during the 7-yr period. Eleven species represented 95% of all cerambycids collected. Treatment only affected red maple, showing increased cerambycid richness and diversity from naturally infested trees. Cerambycid richness and diversity were two times greater on hickory than other species when combining girdled and felled treatments. Over 19,000 parasitic Hymenoptera of 12 families emerged from woodborer-infested wood with >70% of individuals belonging to Braconidae. Thirteen known species, and two unknown species, of Braconidae were identified from a subsample of 495 specimens; Ontsira mellipes (Ashmead) (Hymenoptera: Braconidae) and Rhoptrocentrus piceus Marshall (Hymenoptera: Braconidae) were the most abundant. This study provides fundamental information on native parasitoids associated with Cerambycidae, including cerambycid larval host associations. Parasitoids identified herein should be investigated for potential adaptation to invasive Cerambycidae to benefit invasive woodborer management.

Biology and life history of Balcha indica, an ectoparasitoid attacking the emerald ash borer, Agrilus planipennis, in North America.

Balcha indica Mani and Kaul (Hymenoptera: Eupelmidae) is a solitary ectoparasitoid attacking larvae, prepupae, and pupae of the emerald ash borer, Agrilus planipennis Fairmaire (Hymenoptera: Eupelmidae). Its fecundity, oviposition rate, longevity, and development time were determined in the laboratory under standard rearing conditions (25 ± 2° C, 65 ± 10% relative humidity, and 14:10 L:D). Adults lived a mean of 59 days with a maximum of 117 days. Lifetime adult fecundity averaged 36 eggs with a maximum 94 eggs per female. The egg stage lasted for a maximum of four days with ~ 50% eggs hatched within two days. The development time of the first instars lasted for a maximum of nine days; 50% of the first instars completed their development (i.e., molted to the next instar) within five days. Instars of the intermediate and final stage larvae (after molting of the first instars occurred) could not be distinguished until they reached the pupal stage, and 50% of those larvae pupated ~ 62 days after adult oviposition. Under the standard rearing conditions, 50% of B. indica took ~ 83 days to complete the life cycle (from egg to adult emergence) ranging from 47 to 129 days. These results suggest that B. indica may not have more than two generations in the mid-Atlantic and Midwest regions of United States, where normal growing seasons--with average temperature above 25° C--are normally less than six months (May-October). Because of the long life span and oviposition period of adults, however, B. indica is likely to have overlapping generations.

Comparative genomics of mutualistic viruses of Glyptapanteles parasitic wasps.

BACKGROUND: Polydnaviruses, double-stranded DNA viruses with segmented genomes, have evolved as obligate endosymbionts of parasitoid wasps. Virus particles are replication deficient and produced by female wasps from proviral sequences integrated into the wasp genome. These particles are co-injected with eggs into caterpillar hosts, where viral gene expression facilitates parasitoid survival and, thereby, survival of proviral DNA. Here we characterize and compare the encapsidated viral genome sequences of bracoviruses in the family Polydnaviridae associated with Glyptapanteles gypsy moth parasitoids, along with near complete proviral sequences from which both viral genomes are derived. RESULTS: The encapsidated Glyptapanteles indiensis and Glyptapanteles flavicoxis bracoviral genomes, each composed of 29 different size segments, total approximately 517 and 594 kbp, respectively. They are generated from a minimum of seven distinct loci in the wasp genome. Annotation of these sequences revealed numerous novel features for polydnaviruses, including insect-like sugar transporter genes and transposable elements. Evolutionary analyses suggest that positive selection is widespread among bracoviral genes. CONCLUSIONS: The structure and organization of G. indiensis and G. flavicoxis bracovirus proviral segments as multiple loci containing one to many viral segments, flanked and separated by wasp gene-encoding DNA, is confirmed. Rapid evolution of bracovirus genes supports the hypothesis of bracovirus genes in an 'arms race' between bracovirus and caterpillar. Phylogenetic analyses of the bracoviral genes encoding sugar transporters provides the first robust evidence of a wasp origin for some polydnavirus genes. We hypothesize transposable elements, such as those described here, could facilitate transfer of genes between proviral segments and host DNA.

Structure and evolution of a proviral locus of Glyptapanteles indiensis bracovirus.

BACKGROUND: Bracoviruses (BVs), a group of double-stranded DNA viruses with segmented genomes, are mutualistic endosymbionts of parasitoid wasps. Virus particles are replication deficient and are produced only by female wasps from proviral sequences integrated into the wasp genome. Virus particles are injected along with eggs into caterpillar hosts, where viral gene expression facilitates parasitoid survival and therefore perpetuation of proviral DNA. Here we describe a 223 kbp region of Glyptapanteles indiensis genomic DNA which contains a part of the G. indiensis bracovirus (GiBV) proviral genome. RESULTS: Eighteen of ~24 GiBV viral segment sequences are encoded by 7 non-overlapping sets of BAC clones, revealing that some proviral segment sequences are separated by long stretches of intervening DNA. Two overlapping BACs, which contain a locus of 8 tandemly arrayed proviral segments flanked on either side by ~35 kbp of non-packaged DNA, were sequenced and annotated. Structural and compositional analyses of this cluster revealed it exhibits a G+C and nucleotide composition distinct from the flanking DNA. By analyzing sequence polymorphisms in the 8 GiBV viral segment sequences, we found evidence for widespread selection acting on both protein-coding and non-coding DNA. Comparative analysis of viral and proviral segment sequences revealed a sequence motif involved in the excision of proviral genome segments which is highly conserved in two other bracoviruses. CONCLUSION: Contrary to current concepts of bracovirus proviral genome organization our results demonstrate that some but not all GiBV proviral segment sequences exist in a tandem array. Unexpectedly, non-coding DNA in the 8 proviral genome segments which typically occupies ~70% of BV viral genomes is under selection pressure suggesting it serves some function(s). We hypothesize that selection acting on GiBV proviral sequences maintains the genetic island-like nature of the cluster of proviral genome segments described herein. In contrast to large differences in the predicted gene composition of BV genomes, sequences that appear to mediate processes of viral segment formation, such as proviral segment excision and circularization, appear to be highly conserved, supporting the hypothesis of a single origin for BVs.

A novel nonchemical method for quarantine treatment of fruits: California red scale on citrus.

A process for removing or killing California red scale, Aonidiella aurantii (Maskell), from citrus fruit as a postharvest treatment was evaluated. The process subjects the fruit to vacuum, steam, and vacuum that physically removes red scale from the fruit and kills those scales that are not removed from the fruit. Different numbers of cycles and steam temperatures were compared for efficacy in removing scale from lemons or killing those that remained. Multiple (two to three) cycles removed up to 96% of first molt scales on the fruit, but they were much less effective in removing other stages, especially those that had advanced beyond the second instar. However, it was extremely effective in killing the scales remaining on the fruit. Although this process does not eliminate cosmetic damage caused by scale presence, it might be used in combination with high-pressure washers currently used in packing houses to allow importers and exporters to meet the most stringent quarantine requirements. Because of its killing power, this technique should be tried on other insects and commodities to see whether it can be substituted for certain uses of methyl bromide.