Attraction of the potential biocontrol agent Altica cyanea by volatile compounds of three species of Ludwigia weeds from rice fields

Ludwigia adscendens (L.) Hara, Ludwigia parviflora Roxb., and Ludwigia octovalvis (Jacq.) Raven (Onagraceae) are abundant weeds in rice fields in India. These weeds compete with rice for resources in fields and this results in reduction of grain yield. Altica cyanea (Weber) (Coleoptera: Chrysomelidae) is a biocontrol agent of the three rice-field weeds. Hence, it is relevant to study host preference of A. cyanea using volatile cues of these three weeds. Therefore, we attempted to identify volatiles from leaves of the three Ludwigia species attracting A. cyanea, which could be used as an attractant during early emergence of the weeds in rice fields. In Y-tube olfactometer assays, A. cyanea females were more attracted to natural volatiles of plants after 48 h of feeding by adults than to volatiles of undamaged plants. The volatile organic compounds from undamaged plants, and plants after 6 and 48 h of feeding by A. cyanea were identified and quantified by gas chromatography and mass spectrometry (GC–MS) and GC-flame ionization detection (FID), respectively. In total, 25, 29, and 29 volatile compounds were detected in headspaces of undamaged L. adscendens, L. parviflora, and L. octovalvis, respectively, whereas 32, 35, and 34 compounds, respectively, were detected after 48 h of feeding by A. cyanea. Methyl jasmonate predominated among the volatile compounds in all treatments, but this compound was not attractive to A. cyanea. Females were attracted by synthetic blends of 3-hexanol, α-pinene, linalool oxide, and phytol in amounts mimicking those in each of the three Ludwigia species after 48 h of feeding by A. cyanea. The blends mimicking L. adscendens and L. parviflora included geraniol, whereas the blend mimicking L. parviflora also included 1-tridecanol. These synthetic blends may be helpful to monitor A. cyanea in biocontrol programmes.     

Comparative Prey Suitability ofOstrinia nubilalisEggs andAcyrthosiphon pisumforColeomegilla maculata

The effects ofOstrinia nubilalis(Hübner) (Lepidoptera: Pyralidae) eggs andAcyrthosiphon pisum(Harris) (Homoptera: Aphididae), when provided as single prey species and in combination, on life history characteristics ofColeomegilla maculataDeGeer (Coleoptera: Coccinellidae) larvae and adults were quantified. Preimaginal development was not influenced by the larval prey regime; development at 26 ± 1°C was completed in approximately 13.5 days onO. nubilaliseggs,A. pisum,orA. pisumalternated daily withO. nubilaliseggs. The resulting adults weighed 13.0, 10.7, and 12.5 mg when reared onO. nubilaliseggs,A. pisum,andA. pisumalternated daily withO. nubilaliseggs, respectively. Eighteen percent of the individuals died when reared onA. pisum,28% died when reared onO. nubilaliseggs, and 22% died when fedA. pisumalternated daily withO. nubilaliseggs. Seven adult diet combinations, based on diet regimes of larvae and adults, did not cause significant differences in preoviposition period, interoviposition period, and the number of days on which eggs were laid. Total fecundity was influenced both by larval and adult diet. The diet that resulted in highly fecund females wasA. pisumalternated daily withO. nubilaliseggs for larvae andO. nubilaliseggs for adults. FemaleC. maculatafedO. nubilaliseggs had the highest intrinsic rate of increase and net reproductive rate.     

Chamaesphecia doryliformis [Lep.: Sesiidae], a second root borer for the control ofRumex spp. [Polygonaceae] in Australia

The host-specificity and biology ofChamaesphecia doryliformis (Ochsenheimer) [Lep.: Sesiidae] are described and the insect is assessed for its potential as a biological control agent for weeds of the genusRumex (Polygonaceae) in Australia. The insect is found in the western Mediterranean region, chiefly in north Africa. Adults emerge from pupation in late spring to summer when they lay eggs. The larvae feed inside the roots of post-reproductive plants belonging to the subgeneraRumex andAcetosa. In host-specificity tests 1^st instar larvae attacked only plants of thePolygonaceae. The insect was judged safe to release in Australia after assessing its level of host-specificity, and attributes of its biology which indicate that native AustralianPolygonaceae will not be endangered.      

Gratiana boliviana, a potential biocontrol agent of Solanum viarum: Quarantine host-specificity testing in Florida and field surveys in South America

Host-specificity tests andfield surveys were conducted to determine thesuitability of the tortoise beetleGratiana boliviana Spaeth (Coleoptera:Chrysomelidae) from Argentina for classicalbiological control of Solanum viarumDunal (Solanaceae) in the USA. Thehost-specificity tests were conducted at theFlorida Department of Agriculture and ConsumerServices-Division of Plant Industry quarantinefacility in Gainesville, Florida (USA). Multiple-choice host-specificity tests wereconducted in small cages using 123 plantspecies in 35 families. Adults fedsignificantly (>41% of the leaf area offeredwas damaged) on the target weed(S. viarum), and fed lightly (<20%) onSolanum torvum Sw. (noxious weed native towest-Africa). Adults did some exploratoryfeeding (<5%) on eggplant, Solanummelongena L. (economic crop), Solanumelaeagnifolium Cav. (major agricultural weedin the western US), and on Solanumtampicense Dunal (weed of Central Americanorigin). No feeding was observed on any of theother 118 plant species that were testedincluding another 21 Solanum species.G. boliviana adults laid an average of 68eggs per female on S. viarum, 5 eggs perfemale on S. torvum, and an average of0.2 eggs on eggplant. No-choicehost-specificity tests were also conducted inwhich G. boliviana adults and neonatelarvae were exposed to 19 and 22 plant speciesrespectively. Tests with the neonatesindicated this insect was able to complete itsdevelopment only on S. viarum (67%reached the pupae stage). The no-choice testswith adults indicated that this insect fed,laid eggs, and completed development only onS. viarum. The unsprayed eggplant fieldsthat were surveyed in its natural range inArgentina, Brazil, Paraguay, and Uruguay fromJune 1997 to March 2000 indicated thatG. boliviana is not a pest of eggplants in SouthAmerica. Therefore, a petition for fieldrelease of G. boliviana for classicalbiological control of S. viarum in theUSA was submitted in April 2000.     

Host specificity of Metriona elatior, a potential biological control agent of tropical soda apple, Solanum viarum, in the USA

The leaf beetle Metriona elatior from Brazil-Argentina was screened in the Florida (USA)State quarantine facility as a potential biological control agent of tropical soda apple, Solanum viarum, a recently arrived weed species. Multiple-choice host-specificity tests were conducted in small cages (60 cm × 60 cm × 60 cm) using 95 plant species in 29 families. Adults fed heavily on the main target weed (S. viarum), and on turkey berry,Solanum torvum (noxious weed of Asiatic origin); fed moderately on red soda apple, Solanum capsicoides (weed of South American origin), and eggplant, Solanum melongena (economic crop); and fed lightly on aquatic soda apple, Solanum tampicense (weed of Mexican-Caribbean-Central American origin), and onsilverleaf nightshade, Solanum elaeagnifolium(native weed widely distributed). M.elatior adults laid 84 to 97% of their egg masses onS. viarum, and 3 to 16% on S. melongena. Non-choice host-specificity tests were also conducted in quarantine in which M. elatior adults and neonate larvae were exposed to 17 and 19 plant species, respectively. Tests with the neonates indicate that this insect was able to complete its development on S. viarum, S. torvum, S. melongena, and S. capsicoides. Although some adult feeding and oviposition occurred on S.melongena in quarantine on potted plants in small cages, no feeding or oviposition by M. elatiorwas observed in field experiments conducted in Brazil. Surveys in unsprayed S. melongena fields in Argentina and Brazil indicated that M. elatioris not a pest of S. melongena in South America. The evidence obtained from the South-American field surveys, Brazil open-field experiments, and Florida quarantine host specificity tests indicate that M. elatior causes significant feeding damage toS. viarum, and does not represent a threat to S. melongena crops in the USA. Therefore an application for permission to releaseM. elatior against S. viarum in the USA was submitted in October 1998. This revised version was published online in July 2006 with corrections to the Cover Date.     

Conditioning as a factor in parasitoid host plant preference

The relative effects of larval and adult conditioning on Diglyphus isaea host plant preference and subsequent parasitism were investigated. Parasitoid larvae were reared on Chromatomyia syngenesiae on lettuce, chrysanthemum or in isolation, and female parasitoids were exposed to hosts on either lettuce or chrysanthemum. Hosts on lettuce and chrysanthemum were then presented to assess parasitoid preference. Larval and adult D. isaea conditioning only slightly affected the females selection of host plant type on which the host larvae were located. The major effect of conditioning was a reduction in the number of eggs laid after larvae and adults were conditioned on chrysanthemum and particularly when both stages were conditioned on this host plant.     

Host-specificity of a root borer,Bembecia chrysidiformis [Lep.: Sesiidae], a potential control agent forRumex spp. [Polygonaceae] in Australia

Bembecia chrysidiformis (Esper) [Lep.: Sesiidae] was examined for its natural history and specificity toRumex spp. (Polygonaceae) which are weeds in Australia. Adults of this southern European insect appear in late spring to summer. Eggs are laid on the dried, seed bearing stems of perennialRumex plants. The larvae tunnel inside the root during summer through to the next spring. In nature, the larvae are round inRumex species of the subgeneraRumex andAcetosa. In host-specificity tests with 1st instar larvae, the roots of a number of genera within thePolygonaceae were attacked. Larvae died on a range of plants from other families except inPersea americana Miller(Lauraceae), Helianthemum nummularium (L.) Miller (Cistaceae) andQuercus ilex L. (Fagaceae) where larvae fed on the stems. The insect was judged safe for release in Australia by assessing aspects of its biology, its known host plants, and the lack of reported attack on other plants.      

The host range and biology of the mesquite psyllid Heteropsylla texana

Prosopis spp. areintroduced rangeland weeds in Australia. In asearch for biological control agents, thepsyllid Heteropsylla texana, which causessevere distortion to growing leaf and floralshoots, was imported from Texas, USA forhost range testing in quarantine facilities.No-choice tests were conducted on 60 plantspecies including P. pallida, P. velutinaand P. juliflora. In these trials, adultssurvived on 45 non-target plants but ovipositedonly on the Prosopis spp., Dichrostachys spicata and Acaciabidwillii. Nymphs developed to ovipositingadults on all Prosopis spp. and both D. spicata and A. bidwillii. Developmentof small numbers of adults on D. spicataand A. bidwillii occurred for only onegeneration. Damage was noticed only on Prosopis spp. In multiple-choice trials usingthree plant species, oviposition and subsequentdevelopment of eggs and nymphs to adults tookplace on P. pallida and D. spicatabut not on A. bidwillii. The low numbersdeveloping, the longer development times toadults when reared on D. spicata and A.bidwillii, and the failure of these plantsto sustain populations beyond one generationindicate that these plants are not hosts ofH. texana. While adult survival on manytest plants may imply that adult feedingoccurred, the risk to populations of theseplants in the field is negligible. It wasconcluded that H. texana is specific toProsopis spp. and could be released inAustralia for control of Prosopis spp.Observations of the biology of this speciesmade during the course of rearing andexperimentation indicated that nymphs developedthrough five instars to adults in 7–8 days sothat total development from egg to adult takes13–17 days. Females produce up to 100 eggs.     

Biology and host range of Mada polluta,a potential biological control agent of Tecoma stans in South Africa

The host range of Mada polluta Mulsant (Coleoptera:Coccinnellidae) was studied to assess its suitability as a biological control agent of Tecoma stans (L.) Juss ex Kunth var stans (Bignoniaceae), an invasive weed in South Africa. Biology of M. polluta and its host range were determined in the laboratory using no-choice and multi-choice feeding, oviposition and larval survival tests. Out of 36 plant species from 12 plant families (Bignoniaceae, Acanthaceae, Asteraceae, Verbenaceae, Lamiaceae, Oleaceae, Cucurbitaceae, Fabaceae, Scrophulariaceae, Solanaceae, Apiaceae, Chenopodiaceae and Poaceae) within the order Lamiales that were tested during the host specificity testing, M. polluta showed a very strong preference for T. stans, depositing its eggs on T. stans and none on non-target plant species. In no-choice tests, an average of 246 eggs was laid on T. stans, and from these, 133 larvae developed to adulthood. The beetle also showed very promising biological attributes that will contribute to its success as a biological control agent of T. stans. These attributes include highly damaging larvae and adults, high fecundity (532 eggs/female) and a short life cycle (four weeks). The short life cycle will enable multiple generations per year and rapid population increase in the field. It is concluded that M. polluta is sufficiently host-specific to be released against T. stans in South Africa. It is, therefore, strongly recommended that permission be granted to release this beetle from quarantine for biological control of T. stans in South Africa.     

Artificial diets for rearing the coconut hispine beetle Brontispa longissima and its parasitoid Asecodes hispinarum

We tested artificial diets for rearing the coconut hispine beetle, Brontispa longissima, a serious invasive pest of coconut (Cocos nucifera) in Southeast Asia. We examined three artificial diets that were identical except for their agar content. The survival rate from hatching to adult emergence was 26.0% when beetles were reared on a ‘soft diet’ (20 g/l agar), 16.0% on a ‘hard diet’ (40 g/l agar), and 41.0% on a ‘mixed diet’, in which the hard diet was used for the first instar and the soft diet for later instars. Females raised as larvae on the mixed diet and then as adults on the soft diet laid few eggs, which did not hatch. However, females reared on the mixed diet as larvae and then on fresh leaves as adults consistently laid eggs that hatched. We then examined the suitability of B. longissima larvae reared on the mixed diet as hosts for the larval parasitoid Asecodes hispinarum, a specialist parasitoid of this beetle. Of the oviposited hosts, 75.0% became mummified and 41.7% produced adult wasps. These results indicate that the mixed diet may be useful for rearing B. longissima larvae as hosts for the rearing of A. hispinarum.     

Biology and life table studies of the oriental tobacco budworm,Helicoverpa assulta (Lepidoptera: Noctuidae), influenced by different larval diets

Development, survivorship, pupal weight, oviposition, and life table parameters of the oriental tobacco budworm, Helicoverpa assulta Guenée, were evaluated in the laboratory on an artificial diet, pepper (Capsicum frutescens L.), and tobacco (Nicotiana tobacum L.). We found that the average developmental time of immature stages was longest on tobacco (36.2 d), intermediate on pepper (34.4 d), and shortest on artificial diet (33.5 d). Immature survival from egg to pupa varied from 31% on tobacco, 43% on pepper, and 74% on artificial diet. Pupal weight ranged from 197.4 mg/pupa on tobacco, 233.1 mg/pupa on pepper and 253.4 mg/pupa on artificial diet. The average numbers of eggs laid by adults reared as larvae on the artificial diet, pepper, or tobacco were 614, 421 and 334 eggs/female, respectively. Numbers of remaining eggs in ovaries of the adult females reared as larvae on the artificial diet, pepper, or tobacco were 16, 26, and 42 eggs/female, respectively. The longevity of adult females developed from larvae reared on the three diets was not significantly different, whereas the longevity of male adults from the larvae reared on artificial diet was longer (16.8 d) than that for males reared on tobacco (13.8 d) and pepper (13.3 d). The intrinsic, finite, gross, and net rates of increase were highest for females reared as larvae on artificial diet, lowest for females emerging from larvae reared on tobacco, and intermediate for females emerging from larvae reared on pepper. Generation times and doubling time of H. assulta were shortest for larvae fed artificial diet, intermediate from larvae reared on pepper, and longest from larvae reared on tobacco. We concluded that the artificial diet was the most suitable larval diet of H. assulta followed by pepper, and tobacco.     

Galerucella birmanica (Coleoptera: Chrysomelidae), a promising potential biological control agent of water chestnut,Trapa natans

Water chestnut, Trapa natans, has become a major invasive plant in shallow water bodies in the northeastern United States. The failure of chemical and mechanical means to provide long-term and economically sustainable suppression of the species resulted in interest in the development of biological control. Field surveys in Asia and Europe identified a number of potential biological control agents in the native range of T. natans. The most promising species appeared to be the leaf beetle Galerucella birmanica, which is considered a pest of farmed T. natans in China. However, initial attempts to develop biological control faltered when field observations in China suggested that G. birmanica may not be host specific. Of particular concern was attack on water shield, Brasenia schreberi, a species native to China and North America. We conducted a number of laboratory and field investigations in China to assess preference and performance of G. birmanica on T. natans and B. schreberi. Initial no-choice experiments using 19 different plant species in 13 different families demonstrated that G. birmanica oviposited and was able to complete development only on Trapa spp. and B. schreberi. In larval no-choice tests G. birmanica was able to complete development on B. schreberi, however, larvae showed a 20% increase in mortality and longer development time compared to larvae developing on T. natans. In laboratory and field choice tests adults strongly preferred T. natans and in the field only occasionally laid eggs on B. schreberi. In addition, adults emerging from larvae reared on B. schreberi were less fit with reduced feeding and a declining oviposition rate. Their strong preference for T. natans was maintained in the field, even when T. natans was completely defoliated and adults were forced to migrate. We found only occasional “spill-over” of beetles onto B. schreberi and our data indicate that G. birmanica is a more promising biological control agent of T. natans than previously thought, although additional host specificity tests with many more North American plant species need to be completed.     

Development of Asian parasitoids in larvae Of Drosophila Suzukii feeding on blueberry and artificial diet

In just a few years, the Asian fly Drosophila suzukii has invaded several continents and has become a very serious pest of many fruit crops worldwide. Current control methods rely on chemical insecticides or expensive and labour‐intensive cultural practices. Classical biological control through the introduction of Asian parasitoids that have co‐evolved with the pest may provide a sustainable solution on condition that they are sufficiently specific to avoid non‐target effects on local biodiversity. Here, we present the first study on the development of three larval parasitoids from China and Japan, the Braconidae Asobara japonica and the Figitidae Leptopilina japonica and Ganaspis sp., on D. suzukii. The Asian parasitoids were compared with Leptopilina heterotoma, a common parasitoid of several Drosophilidae worldwide. The three Asian species were successfully reared on D. suzukii larvae in both, blueberry and artificial diet, in contrast to L. heterotoma whose eggs and larvae were encapsulated by the host larvae. All parasitoids were able to oviposit one day after emergence. Asobara japonica laid as many eggs in larvae feeding in blueberry as in artificial diet, whereas L. heterotoma oviposited more in larvae on the artificial diet and the Asian Figitidae oviposited more in larvae feeding on blueberry. Ganaspis sp. laid very few eggs in larvae in the artificial diet, suggesting that it may be specialized in Drosophila species living in fresh fruits. These data will be used for the development of a host range testing to assess the suitability of Asian parasitoids as biological control agents in invaded regions.     

Risk to nontarget plants from <Emphasis Type="Italic">Ophraella communa</Emphasis> (Coleoptera: Chrysomelidae), a potential biological control agent of alien invasive weed <Emphasis Type="Italic">Ambrosia artemisiifolia</Emphasis> (Asteraceae) in China

Ophraella communa LeSage is an oligophagous insect that shows promise for controlling the alien invasive weed Ambrosia artemisiifolia L. in China. This study was performed to evaluate the risk of O. communa on the basis of host-specificity testing of larval development under no-choice conditions and of oviposition preferences under choice conditions in greenhouses and in the open field. Under no-choice conditions, O. communa larvae experienced much higher mortality rates on the nontarget plants than on the target weed, but a small proportion of larvae completed development on the nontarget plants examined, including Xanthium sibiricum Patrin ex Widder, Helianthus tuberosus L., and H. annuus L. Multiple-choice tests indicated that O. communa showed a strong oviposition preference for the target weed over the nontarget plants and laid few eggs on the economically important Helianthus crops tested. In paired-choice trials, O. communa adults showed an obvious preference for the target weed over X. sibiricum but preferred X. sibiricum to H. annuus. The results suggest that X. sibiricum might be used as a lower-ranked host plant next to the target weed by O. communa, and that Helianthus crops would not be at risk of being used for oviposition in the field.     

Host-associated fitness variation in a seed beetle (Coleoptera: Bruchidae): evidence for local adaptation to a poor quality host

The geographic distributions of many generalist herbivores differ from those of their host plants, such that they experience coarse-grained spatial variation in natural selection on characters influencing adaptation to host plants. Thus, populations differing in host use are expected to differ in their ability to survive and grow on these host plants. We examine host-associated variation in larval performance (survivorship, development time, and adult body weight) and oviposition preference, within and between two populations ofStator limbatus (Coleoptera: Bruchidae) that differ in the hosts available to them in nature. In one population,Acacia greggii (Fabaceae: Mimosoideae) andCercidium microphyllum (Fabaceae: Caesalpininoideae) are each abundant, while in the second population onlyC. floridum andC. microphyllum are present. In both populations, egg-to-adult survivorship was less than 50% onC. floridum, while survivorship was greater than 90% onA. greggii. Most of the mortality onC. floridum occurred as larvae were burrowing through the seed coat; very low mortality occurred during penetration of the seed coat ofA. greggii. Significant variation was present between populations, and among families (within populations), in survivorship and egg-to-adult development time onC. floridum; beetles restricted toCercidium in nature, without access toC. floridum, survived better and developed faster onC. floridum than beetles that had access toA. greggii. Large host effects on body size were detected for female offspring: females reared onA. greggii were larger than those reared onC. floridum, whereas male offspring wee approximately the same size regardless of rearing host. Trade-offs between performance onC. floridum andC. floridum were not detected in this experiment. Instead, our data indicate that development time and survivorship onC. floridum may be largely independent of development time and survivorship onA. greggii. Patterns of oviposition preference corresponded to the observed patterns of host suitability: in laboratory preference tests, beetles with access toA. greggii in nature tended to prefer this host more than beetles without access to this host in nature.     

Pre-release assessment ofNanaia sp. [Lepidoptera: Phycitidae] fromOpuntia pascoensis for biological control ofOpuntia aurantiaca [Cactaceae]

Nanaia sp. was collected onOpuntia pascoensis Britton & Rose in Peru and introduced into South Africa for biological control ofOpuntia aurantiaca Lindley. Since this is a new insect-plant association the chances of successful biological control could theoretically be enhanced. However, pre-release insectary studies showed that apart from the adverse affects of insectary rearing, larval development was slower, less larvae survived, smaller adults emerged and reproduction was suppressed onO. aurantiaca compareded toO. pascoensis. The new association ofNanaia sp. onO. aurantiaca will probably not succeed and, although field trials should be conducted to confirm this, an extensive mass-rearing and release programme would be a waste of time, finances and effort.      

Non-target plant use by a weed biocontrol agent in idaho: host expansion or opportunistic behavior?

Larinus curtus Hochhuth (Coleoptera: Curculionidae) was first introduced into the western United States from Greece for the biological control of yellow starthistle (YST), Centaurea solstitialis L., in 1992. The discovery of L. curtus adults in the open flowerheads of safflower (SF), Carthamus tinctorius L., near Lewiston, Idaho in 2007 suggested this weevil might be expanding its host range to include a non-target crop species closely related to YST. In 2008 field plots near the 2007 observation site, 92 L. curtus adults fed in open SF flowerheads (pollen feeding and minor feeding on corolla tubes). No eggs were found in the ovarioles of 19 pollen-feeding females. No eggs, larvae, or evidence of larval feeding were detected in 39 tagged SF capitula, and no adults emerged from approximately 7,135 post-flowering SF capitula. These collective results are not indicative of an expanding developmental host-range of L. curtus. Also, they are consistent with pre-release host-specificity test results.     

Quarantine host range of Bikasha collaris,a potential biological control agent of Chinese tallowtree (Triadica sebifera) in North America

Chinese tallowtree, Triadica sebifera (L.) Small (Euphorbiaceae), is one of the worst invasive weeds of the southeastern USA impacting coastal wetlands, forests, and natural areas. Traditional mechanical and chemical controls have been unable to limit the spread, and this invasive species continues to expand its range. A proposed biological control candidate, the flea beetle Bikasha collaris (Baly) (Coleoptera: Chrysomelidae), shows high specificity for the target weed Chinese tallowtree. Results from a series of no‐choice and choice feeding tests of B. collaris adults and larvae indicated that this flea beetle was highly specific to Chinese tallowtree. The larvae of B. collaris feed by tunneling in the roots, whereas the adults feed on the leaves of Chinese tallowtree. A total of 77 plant taxa, primarily from members of the tallow plant family Euphorbiaceae, were tested in numerous test designs. Larval no‐choice tests indicated that larvae completed development only on two of the non‐target taxa. Of 80 B. collaris larvae fed roots of Hippomane mancinella L. and 50 larvae fed roots of Ricinus communis L., two and three larvae completed development, respectively. The emerging adults of these five larvae died within 3 days without reproducing. Larval choice tests also indicated little use of these non‐target taxa. Adult no‐choice tests indicated little leaf damage by B. collaris on the non‐targets except for Ditrysinia fruticosa (Bartram) Govaerts & Frodin and Gymnanthes lucida Sw. When given a choice, however, B. collaris adults consumed much less of the non‐targets D. fruticosa (7.4%) and G. lucida (6.1%) compared with the control leaves. Finally, no‐choice oviposition tests indicated that no eggs were produced when adults were fed all non‐target taxa, except those fed G. lucida. These B. collaris adults fed G. lucida leaves produced an average of 4.6 eggs compared with 115.0 eggs per female when fed Chinese tallowtree. The eggs produced from adults fed G. lucida were either inviable or the emerging larvae died within 1 day. These results indicate that the flea beetle B. collaris was unable to complete its life cycle on any of the non‐target taxa tested. If approved for field release, B. collaris will be the first biological control agent deployed against Chinese tallowtree in the USA. This flea beetle may play an important role in suppressing Chinese tallowtree and contribute to the integrated control of this invasive weed.     

The effect of a foliar disease (rust) on the development of Gastrophysa viridula (Coleoptera: Chrysomelidae)

Abstract.

• 1 Gastrophysa viridula Degeer (Coleoptera: Chrysomelidae) and the pathogenic rust fungus Uromyces rumicis (Schum.) Wint. both occur on leaves of Rumex crispus L. and R.obtusifolius L. Individual stages of beetle development, and egg laying, were compared on healthy and infected leaves of each plant species in the laboratory. Oviposition choice was investigated in the field and laboratory.
• 2 Beetles reared on infected leaves of each species had greater larval mortality and slower development than those reared on healthy leaves. Although larvae feeding on infected leaves consumed up to 2.5 times more dry weight than those reared on healthy leaves, they had a lower relative growth rate and pupated at a lower weight. These changes were consistent with the reduced nutritive quality of rust-infected Rumex leaves.
• 3 Fecundity of beetles reared on infected leaves of both species was considerably reduced. Eggs laid by beetles feeding on infected R.crispus leaves also had a reduced viability.
• 4 The beetle developed consistently poorer on healthy R.crispus than on healthy R.obtusifolius throughout its life-cycle. Differences in larval performance were greater between host species than between infected and healthy leaves.
• 5 Oviposition was similar on infected and healthy R.crispus in both the laboratory and field. However, adults consumed less, and laid fewer eggs on infected than on healthy R.obtusifolius. The pattern of egg laying on different aged leaves was affected by rust infection: a greater proportion of eggs was laid on the older, infected leaves, than on the equivalent aged leaves on the healthy plants. Few larvae survived from eggs laid on rusted leaves in the field.

     

Biology ofTrichogramma ostriniae (Hym.: trichogrammatidae) reared onOstrinia nubilalis (Lep.: pyralidae) and survey for additional hosts

Trichogramma ostriniae has been identified as a candidate for biological control ofOstrinia nubilalis. As little was known about the biology of this parasitoid when reared onO. nubilalis, we undertook experiments to quantify biological parameters important to mass-rearing and ase ofT. ostriniae. When reared continuously onO. nubilalis, femaleT. ostriniae on average lived 2.7 days and produced 24 progeny. Continuous access to honey resulted in a four-fold increase in longevity and fecundity and a significant increase in the percentage of females parasitizing eggs. Rates of fecundity and parasitism decreased with age of female. Likewise, emergence rates and percentage of female progeny decreased with age of parental female.T. ostriniae successfully parasitizedO. nubilalis eggs until the blackhead stage. Most parasitism of eggs and eclosion of adults occurred during the first half of photophase. Eggs of 13 Lepidopterans were parasitized byT. ostriniae. Eggs of the Noctuidae, Pyralidae, and Plutellidae experienced higher levels of parasitism than others tested.T. ostriniae appears to be similar to other species ofTrichogramma in several respects and does not possess any characteristics that limit its potential for mass rearing and use for augmentative biological control ofO. nubilalis.