Alien invaders in Hawaii: prospects for remediation using biological control.

In this short paper I will review both the positive and negative factors affecting the prospects for biological control in Hawaii, and will give some concrete recommendations for improving these prospects given intelligent prioritization of available funding

A Survey for Potential Biocontrol Agents of Bactrocera cucurbitae (Diptera: Tephritidae) in Thailand

Scientific note.Limited investigations on parasitoids of the melon fly, Bactrocera cucurbitae (Coquillett), infesting five species of Cucurbitaceae and seven species of Solanaceae were conducted in Thailand to determine natural occurrence of biological control agents. Fruit samples were collected during January-February 1996, and tephritid puparia were imported into the State of Hawaii Quarantine Facility for fly and parasitoid emergence. Cucumis sativus L., Luffa acutangula (L.), and Momordica charantia L. were commonly infested by B. cucurbitae. Bactrocera tau (Walker) was dominant only in L. acutangula. Infestation of ripe, cultivated fruit of M. charantia was 72.3 B. cucurbitae/kg fruit and parasitoids were pre-dominantly Psyttalia fletcheri (Silvestri) (Hymenoptera: Braconidae), with parasitization rates up to 12.4%. Bactrocera cucurbitae infesting M. charantia in northern Thailand yielded an unidentified Aceratoneuromyia species, (Hymenoptera: Eulophidae). Unlike other eulophids that attack B. cucurbitae, which require the presence of P. fletcheri in the same puparium to suppress host immunity, this parasitoid was able to develop alone. Average fecundity was 135 offspring/ female and mean parasitoids /host puparium was 21.1. It was also developed in the laboratory on the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), with an average life span of 23 d in both host species. Six species of solanaceous fruit were mainly infested by Bactrocera latifrons (Hendel), with infestation rates ranging from 4 to 17 flies/kg fruit. Psyttalia fletcheri and unidentified opiine, Bitomus species, eclosed from B. latifrons infested bird chili, Capsicum frustescens L. Only Lycopersicon esculentum Mill. produced B. cucurbitae, lightly parasitized by P. fletcheri

The biology of the predator complex of the filbert aphid, Myzocallis coryli (Goetze), in western Oregon

Commercial filbert orchards throughout the Willamette Valley were surveyed for natural enemies of the filbert aphid, Myzocallis coryli (Goetze). A large number of predaceous insects were found to prey upon M. coryli, particularly members of the families Coccinellidae, Miridae, Chrysopidae, Hemerobiidae, and Syrphidae. Also, a parasitic Hymenopteran (Mesidiopsis sp.) and a fungal pathogen (Triplosporium fresenii) were found to attack this aphid species. Populations of major predators were monitored closely during 1981 to determine phenology and synchrony with aphid populations and to determine their relative importance. Adalia bipunctata, Deraeocoris brevis, Chrysopa sp. and Hemerobius sp. were found to be extremely well synchronized with aphid population development cycles. Laboratory feeding trials demonstrated that all 4 predaceous insects tested (Deraeocoris brevis, Heterotoma meriopterum, Compsidolon salicellum and Adalia bipunctata) had a severe impact upon filbert aphid population growth. A. bipunctata was more voracious than the other 3 species, but could not live as long in the absence of aphid prey. Several insecticides were tested both in the laboratory and field to determine their relative toxicity to filbert aphids and the major natural enemies. Field tests showed Metasystox-R to be the most effective against filbert aphids, while Diazinon, Systox, Zolone, and Thiodan were moderately effective. Sevin was relatively ineffective. All insecticides tested in the field severely disrupted the predator complex. Laboratory tests showed all insecticides to be very toxic to Adalia bipunctata and Deraeocoris brevis, although Zolone caused a significantly lower mortality. Samples from a block of trees sprayed twice with Sevin showed higher aphid numbers late in the season than a comparable unsprayed block. This is interpreted as an indication that many aphid problems in commercial orchards are induced by insecticide disruption of natural biological control. Possible solutions to this problem are discussed

Oviposition of the invasive two-spotted leafhopper on an endemic tree: Effects of an alien weed, foliar pubescence, and habitat humidity

The two-spotted leafhopper, Sophonia rufofascia (Kuoh and Kuoh), is an exotic pest from South-East Asia that attacks a wide variety of plant species in Hawaii. Myrica faya Aiton is an aggressive exotic weed that displaces and excludes native plants in Hawaiian forests. It has been argued that because of the high nutritional quality of its foliage, M. faya might facilitate leafhopper invasion of native Hawaiian ecosystems that were originally dominated by the endemic tree Metrosideros polymorpha (Gaudichaud). In the present study, we quantified suitability of M. faya and M. polymorpha as ovipositional hosts for S. rufofascia. Overall, leafhoppers preferred to deposit their eggs into the foliage of M. faya. M. faya presence in the area did not affect leafhopper oviposition on M. polymorpha. Foliar pubescence provided good protection of hirsute morphotypes of M. polymorpha. At the same time, glabrous M. polymorpha morphotypes were quite suitable for leafhopper oviposition. There was no difference in the abundance of leafhopper eggs along a precipitation gradient. Our results confirm that invasion of native Hawaiian forests by the weed M. faya will facilitate their invasion by S. rufofascia. Because of the broad host range characteristic of the two-spotted leafhopper, this build-up may adversely affect a number of endemic plant species growing in native forests

Functional analysis of the sporulation-specific SPR6 gene of Saccharomyces cerevisiae

The SPR6 gene of Saccharomyces cerevisiae encodes a moderately abundant RNA that is present at high levels only during sporulation. The gene contains a long open reading frame that could encode a hydrophilic protein approximately 21 kDa in size. This protein is probably produced by the yeast, because the lacZ gene of Escherichia coli is expressed during sporulation when fused to SPR6 in the expected reading frame. SPR6 is inessential for sporulation; mutants that lack SPR6 activity sporulate normally and produce viable ascospores. Nonetheless, the SPR6 gene encodes a function that is relevant to sporulating cells; the wild-type allele can enhance sporulation in strains that are defective for several SPR functions. SPR6 is located on chromosome V, 14.4 centimorgans centromere-distal to MET6 .Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46973/1/294_2004_Article_BF00318210.pd

Contemporary Hawaiian Insect Fauna of a Lowland Agricultural Area on Kaua'i: Implications for Local and Island-wide Fruit Fly Eradication Programs

We sampled the insect fauna of a 900-ha, lowland agricultural area on the northeast shore of Kaua'i to identify native and beneficial species that could be potentially impacted by USDA fruit fly control measures. Of the 283 species currently identified, only 24 species (<10%) are endemic to Hawai'i, and most of these are common species occurring on all the major islands. Stream and riparian systems, more than any other habitat, appear to still harbor the greatest number of endemic species. Lack of adequate taxonomic and distributional information for some species presents a major obstacle in the development of safe eradication technologies in lowland agricultural areas. Twenty-five species represent biological control agents purposefully introduced to suppress noxious pests, and numerous other inadvertent immigrants functioning as predators, pollinators, and in nutrient recycling should also be considered in any impact assessment. This survey suggests that the expansion of control measures to other agricultural areas and different habitats should consider the likely presence and potential impact on endemic species

Annotated Insect Distribution Records for the Island of Kauai

Thirty five new distribution records are presented for the island of Kauai. Cardiastethus minutissimus Usinger (Heteroptera: Anthocoridae) is reported for the first time from the state of Hawaii

Response of the Egg-Larval Parasitoid, Fopius ceratitivorus Wharton (Hymenoptera: Braconidae) to the Gall-Forming Tephritid Fly, Eutreta xanthochaeta (Diptera: Tephritidae)

We investigated the potential impact of the imported biological control agent Fopius ceratitivorus Wharton, on the non-target beneficial tephritid, Eutreta xanthochaeta on the lantana weed, Lantana camara. In a no-choice test, where the wasp was offered nothing but infested lantana weed, and in a choice test, where the wasp was offered both the non-target fly and its normal host, Ceratitis capitata (Wiedemann), F. ceratitivorus showed no positive response and caused neither parasitism nor mortality to E. xanthochaeta eggs or larvae. Infested plants exposed to F. ceratitivorus were reared until all flies eclosed, over which time not a single wasp emerged, indicating that F. ceratitivorus is unable to recognize the microhabitat of this gall-forming tephritid. These results, in addition to previous work with two other non-target tephritids, suggest minimal risk of environmental impact from this new biological control agent

Parasitism of Hawaiian Non-Frugivorous Fruit Flies (Diptera: Tephritidae) by an Exotic Parasitoid, Eurytoma tephritidis Fullaway (Hymenoptera: Eurytomidae)

Eurytoma tephritidis Fullaway (Hymenoptera: Eurytomidae) is an exotic solitary larval endoparasitoid that has been recorded to parasitize gall-forming tephritids in Hawaii. We surveyed E. tephritidis parasitism of Tetreuaresta obscuriventris (Loew.), Ensina sonchi (L.), Acinia picturata (Snow), Procecidochares utilis Stone, P. alani Steyskal, Trupanea sp. nr. cratericola, and T. dubautiae (Bryan) (Diptera: Tephritidae) on four major Hawaiian islands. No wasps emerged from T. obscuriventris and E. sonchi. Among other species, percent parasitism ranged from less than 1% to over 67%, depending on fly species and sampling location. Overall, E. tephritidis showed higher affinity for gall-forming tephritids than flowerhead-feeders, although it parasitized substantial numbers of the native flower-infesting T. sp. nr. cratericola. The implications of our findings for a more accurate estimation of the risks posed by biological control programs to non-target fruit flies in Hawaii are discussed