Prey preference and feeding capacity of the larvae ofAblattaria arenaria [Coleoptera: Silphidae], a snail predator

The larval stages ofAblattaria arenaria were provided with 4 different snail species:Monacha syriaca (Ehrenberg),Xeropicta derbentina (Krynicki),Candidula sp., andZebrina eburnea (Pfeiffer) to determine if the prey species affected developmental time and food preference of larvae. Functional response of each larval stage ofA. arenaria was also tested for increasing density ofX. derbentina, the most common prey species found in association withA. arenaria locally. The developmental time of each larval stage did not show any statistical difference when fed with different snail species. The total developmental time from egg hatch to adult emergence was 19.0, 19.1, 18.0 and 21.4 days for prey speciesM. syriaca, X. derbentina, Candidula sp., andZ. eburnea, respectively. When prey was offered to larvae either as a single species or as combination of several species,M. syriaca was the most preferred. The prey least consumed wasCandula sp. when prey was given separately, andZ. eburnea was least preferred when other prey species were present in the arena. The 3^rd larval stage did not eat anyZ. eburnea if other prey species were present. The amount of prey consumed by the 1^st larval stage did not show any statistical differences with increasing density ofX. derbentina. But the response of 2^nd and 3^rd larval stages was very similar to each other although the amount of prey they consumed was very different. They both showed a rapid increase in consumption rate at early densities, then a negatively but slowly accelerated rise to plateaus at higher densities, a type-2 functional response curve. All larval stages were very sensitive to starvation. Mortality started after the 2^nd day, and all individuals of all larval stages were dead by the 5^th day.      

Biotic soil factors affecting the growth and development of Ammophila arenaria

Summary To study the origin of replant disease of Ammophila arenaria (L.) Link the growth and development in sand originating from the rhizosphere of a natural Ammophila vegetation was compared with the growth in sand from the sea-floor. In a greenhouse experiment, the growth of Ammophila seedlings in rhizosphere sand, when compared with that in sea sand, was significantly reduced. As sterilization by means of gamma-irradiation increased the biomass production of Ammophila seedlings significantly, it was concluded that the rhizosphere sand contained biotic factors that were harmful to Ammophila. In rhizosphere sand the roots of Ammophila were brown and poorly developed, and the specific uptake rates of N, P and K were reduced. The shoot weight proportion of the total plant dry matter was hardly influenced. In an outdoor experiment with Ammophila seedlings and cuttings, using both sands, the mortality was high and the plants were feeble in rhizosphere sand whereas plants in sea sand grew vigorously. It seems plausible that the plants in rhizophere sand were dessicated because the root system was shallow and badly developed. In the greenhouse experiments, Ammophila cuttings were less sensitive to the inhibiting factors in the rhizosphere than seedlings. This was confirmed in the outdoor experiment. Calammophila baltica (Fluegge ex Schrader) Brand, however, was hardly affected by the harmful biotic factors in the greenhouse. These results are discussed with reference to the ecology of Ammophila. It is assumed that the catching of fresh windblown sand provides Ammophila with a way to escape from harmful biotic soil factors, and it was concluded that degeneration of Ammophila is caused mainly by self-intolerance due to these biotic soil factors.     

Biological studies ofBrachyserphus abruptus [Hym.: Proctotrupidae], a nitidulid parasite

Data are presented on survival, fecundity, and hosts ofBrachyserphus abruptus (Say), a solitary internal parasite of nitidulid (sap beetle) larvae. In the laboratory these wasps have been successfully reared fromCarpophilus hemipterus (L.),C. freemani Dobson,C. lugubris Murray,Stelidota geminata (Say),S. octomaculata (Say),S. ferruginea Reitter,Glischrochilus quadrisignatus (Say),Lobiopa insularis (Castelnau), andHaptoncus luteolus (Erichson). Field collections ofB. abruptus have been made fromS. geminata, S. octomaculata, C. hemipterus, C. lugubris, L. insularis andH. luteolus. Oviposition continues throughout most of the adult female's lifetime. Under laboratory conditions life expectancy of females wasca. 6 days. Mean number of progeny reaching adulthood per female was 57, with a 1∶1 sex ratio. First and 2^nd instar nitidulids were suitable for successful development ofB. abruptus. Third instars were attacked byB. abruptus but were not successfully parasitized. Parasite development required 29 days in 1^st instar hosts and 27 d. in 2^nd instars. Percent parasitism in 1^st instarC. hemipterus averaged 65% and for 2^nd instar 45%. After parasitism, larvae ofC. hemipterus surviving to become adults averaged 0.6% for 1^st instar, 9.3% for 2^nd instar, and 90% for 3^rd instar. This article reports the results of research only. Mention of a proprietary product does not constitute an endorsement or a recommendation for its use by The Ohio State University.     

Biology ofCryptolaemus montrouzieri Mulsant [Coccinellidae: Coleoptera] in relation with temperature

The effect of temperature on the developmental duration ofCryptolaemus montrouzieri Mulsant was quantified by deriving a regression equation for each developmental stage as well as the total life cycle. While the duration of life stages was shorter during summer and longer during winter, the optimum constant temperature for maximal development was found to be 30°C. The adult longevity was extended when reared at 20°C than at 30°C and ambient temperature. The longevity of adults was longer when maintained on grape mealybugMaconellicoccus hirsutus (Green) than on honey and when maintained at 20°C. The fecundity of the predator was higher at 30°C than at 20°C. Eventhough the adults could survive at 10°C, the productive capacity was impaired.      

Biology ofPhanerotoma hendecasisella [Hym: Braconidae] a parasitoid ofDiaphania indica [Lep.: Pyralidae]

Studies were conducted on the solitary egg-larval endoparasitoidPhanerotoma hendecasisella Cam. [Hymenoptera: Braconidae] to determine its biology onDiaphania indica (Saunders) [Lepidoptera: Pyralidae]. Larvae pass through 3 stages as determined by the shape and size of the mandibles. Mean developmental period from egg to adult was 26.51 days at 26.06 °C and 73.88% RH. There is no preoviposition period. The sex ratio was 1∶1.12 (male/female). Mean adult longevity was not different for ♂♂ and ♀♀.      

Biology ofMicroplitis mediator [Hym.: Braconidae] a gregarious endoparasite ofAgrotis segetum [Lep.: Noctuidae]

Microplitis mediator (Haliday) a gregarious endoparasite was recorded for the first time fromAgrotis segetum (Schiff) in Ankara, Turkey. The female parasites found their hosts by responding to the faeces of the caterpillars. An average, females laid 15.5±1.6 eggs in the bodies of their hosts. The newly laid eggs were elongated, oval in shape and 0.23±0.004 mm long and 0.07 mm wide. They hatched in 5, 4 and 3 days at 20±2°C, 25±2°C and 30±2°C respectively when maintained at 60–70% R.H. and 14∶10 light∶dark regime. At the same temperatures, the larval stage lasted for 24.9±0.6, 18.2±0.4 and 17.1±0.5 days respectively. The prepupal stage was completed in 2 days at 25±2°C, whereas the prepupal and pupal (cocoon) stage lasted 10.9±0.2, 7.0±0.1 and 6.2±0.1 days respectively at the temperatures mentioned above. The adults started mating and feeding shortly after emergence. Female parasites started laying after one day, 7–11 hours and 5–7 hours at the temperatures stated above. At these temperatures females lived for 10.8±0.2, 5.4±0.1, 4.6±0.1 days and laid on average 556, 484 and 363 eggs respectively, whereas the males survived 10.5±0.3, 4.7±0.1 and 4.4±0.1 days respectively.      

Resistance of maize to Meloidogyne arenaria and Meloidogyne javanica

Summary A diallel cross of eight maize, Zea mays L., inbred lines was analyzed for reaction to two species of root-knot nematodes, Meloidogyne arenaria (Neal) Chitwood and M. javanica (Treub) Chitwood. Egg production following inoculation of F₁ hybrid seedlings with nematode eggs was determined in a greenhouse experiment. Data were analyzed using Griffing's Method 4, Model I. General combining ability was a significant source of variation in egg production of both M. arenaria and M. javanica; specific combining ability was not a significant source of variation for either. The correlation between egg production of the two nematode species on the 28 F₁ hybrids was highly significant. Hybrids with Mp313 or SC213 as one parent were the most resistant to both species. This indicates that germ plasm is available for developing inbred lines and hybrids with resistance to both M. arenaria race 2 and M. javanica.This article is a contribution of the Crop Science Research Laboratory, U.S. Department of Agriculture, Agricultural Research Service, in cooperation with the Mississippi Agricultural and Forestry Experiment Station, Journal No. J-7481.     

Artificial diet and rearing methods for Thanasimus dubius (Coleoptera: Cleridae), a predator of bark beetles (Coleoptera: Scolytidae)

Clerid beetles are common natural enemies of bark beetles, and could potentially be used as biological control agents if they could be reared in sufficient numbers. We developed an artificial diet devoid of insect components for rearing Thanasimus dubius (Fabricius), a clerid that attacks several economically important bark beetles in eastern North America. We reared larvae of this predator using the artificial diet, and then used either natural or factitious prey to feed the adults so produced. Two different methods of presenting the diet were also examined. We then compared the performance of T. dubius reared on the artificial diet with newly-emerged wild individuals collected from the field. Our results suggest that adult predators reared on the diet are near in quality to wild ones, and high R₀ values can be obtained. No difference in prey preference was found between wild and diet-reared individuals after five generations in the laboratory. Sufficient numbers of predators could be generated using these techniques to permit limited field trials of augmentative biological control.     

Interactions betweenAulonium ruficorne [Coleoptera: Colydiidae] and other natural enemies of bark beetles [Coleoptera: Scolytidae]

The within tree distribution of some common natural enemies of bark beetles in pine plantations in Israel and some aspects of their feeding habits were studied with special emphasis on the potential impact on the predatorAulonium ruficorne Olivier. A total of 12 predators and 2 parasite species were found associated withA. ruficorne in the natural enemy complex of bark beetles on pines. No secondary parasites were detected. The anthocoridScoloposcelis pulchella (Zetterstedt) and the dipteranMedetera striata Parent were observed feeding on immature stages ofA. ruficorne in the absence of scolytids. The associated Coleoptea:Nemosema elongatum F.,Rhizophagus bipustulatus L.,Corticeus spp.,Plastysoma spp. andPlegaderus discisus Erickson are thought to compete withA. ruficorne on larvae and pupae of bark beetles when the latter are in limited quantities (especially in the lower section of the tree). The parasites, mainlyMetacolus unifasciatuss Forster andDendrosoter caenopachoides Ruschka are assumed to compete withA. ruficorne during the larval period in the smooth bark section of the stem. Competition might occur mainly during spring and fall. Deutonymphs of the miteIpiduropoda sellnicki were detected on the abdomen ofA. ruficorne adults. Larvae of the predator were rarely infected in the field by the bacteriaSerratia sp. while laboratory cultures suffered high rate of mortality caused by this pathogen.      

Bionomics ofTetrastichus sesamiae [Hymenoptera: Eulophidae], a pupal endo-parasitoid ofMaruca testulalis [Lepidoptera: Pyralidae]

The biology and behaviour ofTetrastichus sesamiae Risbec, a pupal endoparasitoid ofMaruca testulalis Geyer, were studied under laboratory conditions. Most adults emerged from the host pupae between 08.00 h and 09.00 h and mating and oviposition started almost immediately. Both ♂♂ and ♀♀ mated repeatedly, and each ♀ could lay eggs for up to 6 days and in up to 5 host pupae. Progeny production ranged from 0–263 offspring per ♀ and adult longevity was from 4.3–13.9 days. The quality of food available to the adults was a major factor influencing progeny production, and longevity. The species was capable of parasitizing and completing development on pupae of such other major Lepidopteran crop pests asChilo partellus Swinhoe,Busseola fusca Fuller,Eldana saccharina Wlk andSpodoptera exempta Wlk, an important finding for biological control of these pests under intercropped agro ecosystems. Apart from parasitism, ♀♀ ofT. sesamiae also caused considerable mortality by stinging, and presumably paralyzing, host pupae without ovipositing.      

Preliminary studies on the efficacy and establishment ofRoptrocerus xylophagorum [Hym.: Torymidae], a parasitoid ofIps grandicollis [Col.: Scolytidae], in Australia

Parasitization ofIps grandicollis Eichhoff byRoptrocerus xylophagorum (Ratzeburg), and intra-specific competition withinIps broods, were studied under laboratory conditions. Largest numbers of immatureR. xylophagorum were found in logs sampled when about half theIps brood were callow adults. Rates of parasitization rarely exceeded 20 %, and were usually much lower. Numbers of parasitoids were not affected by bark thickness. In the absence of parasitism,Ips broods suffered a density-dependent mortality which increased greatly in intensity and continued to act later in development of the broods when initial densities of larvae exceeded a threshold of about 400 per 1 000 cm² of bark. The possible significance of this mortality is discussed in relation to the ability of parasitoids to reduceIps numbers. A field experiment was done to investigate the ability ofR. xylophagorum to establish in a new habitat. Populations were established for 1 or more generations by releasing 50 females at sites prepared by supplying small numbers of logs containing immatureIps.     

Trichilogaster sp. [Hymenoptera: Pteromalidae], a potential biocontrol agent for the weedAcacia pycnantha [Fabaceae]

The gall wasp,Trichilogaster sp., was imported from Australia to assess its potential as an agent for the control of the invasive shrub/treeAcacia pycnantha Benth. in South Africa. Host specificity tests indicate safety for release; of 19 tree/shrub species tested, including 16 species closely related toA. pycnantha, galls developed only onA. pycnantha. However, galling intensity remained consistently low on the host plant; only 21–29% of the branches exposed to the wasp were galled during 3 years of rearing. Neither the prolonged presence of males in test cages (someTrichilogaster species are thelytokous) nor the stage of maturity of reproductive buds exposed to oviposition affected the percentage of branches galled. It is not recommended thatTrichilogaster sp. be released before the possibility of insect-plant homeostasis or mis-matching of wasp and host plant populations/strains/subspecies is investigated, especially since galling intensities of 30% were ineffective in reducing seed production of a relatedTrichilogaster species/Acacia association.      

Phenotypic expressions of polygenes inMuscidifurax raptorellus [Hym.: Pteromalidae], a synanthropic fly parasitoid

The precise phenotypic measurements, percent multiple oviposition and the number of parasitoids developed per host, can be used to assess quantitative genetic variation governing multiple oviposition and development in the muscoid Diptera parasitoid,Muscidifurax raptorellus Kogan & Legner. Evidence for polygenic control was based on the significance of correlations between expected genomic content and behavioral expression. Data accumulated from 8 oviposition days seem sufficient to measure accurately polygenic expression in this species.      

Limited genetic variation and structure in softshell clams (Mya arenaria) across their native and introduced range

To offset declines in commercial landings of the softshell clam, Mya arenaria, resource managers are engaged in extensive stocking of seed clams throughout its range in the northwest Atlantic. Because a mixture of native and introduced stocks can disrupt locally adapted genotypes, we investigated genetic structure in M. arenaria populations across its current distribution to test for patterns of regional differentiation. We sequenced mitochondrial cytochrome oxidase I for a total of 212 individuals from 12 sites in the northwest Atlantic (NW Atlantic), as well as two introduced sites, the northeast Pacific (NE Pacific), and the North Sea Europe (NS Europe). Populations exhibited extremely low genetic variation, with one haplotype dominating (65–100%) at all sites sampled. Despite being introduced in the last 150–400 years, both NE Pacific and NS Europe populations had higher diversity measures than those in the NW Atlantic and both contained private haplotypes at frequencies of 10–27% consistent with their geographic isolation. While significant genetic structure (F _ST = 0.159, P < 0.001) was observed between NW Atlantic and NS Europe, there was no evidence for genetic structure across the pronounced environmental clines of the NW Atlantic. Reduced genetic diversity in mtDNA combined with previous studies reporting reduced genetic diversity in nuclear markers strongly suggests a recent population expansion in the NW Atlantic, a pattern that may result from the retreat of ice sheets during Pleistocene glacial periods. Lack of genetic diversity and regional genetic differentiation suggests that present management strategies for the commercially important softshell clam are unlikely to have a significant impact on the regional distribution of genetic variation, although the possibility of disrupting locally adapted stocks cannot be excluded.     

Survivorship,potential, and realized fecundity ofBiosteres tryoni [Hymenoptera: Braconidae], a larval parasitoid ofCeratitis capitata [Diptera: Tephritidae]

Laboratory-rearedBiosteres tryoni (Cameron) reached peak ovarian maturation on the 5^th and 7^th days after emergence in unmated and mated ♀♀, respectively. When ♀♀ were not allowed to oviposit, contents of the oocytes were hydrolyzed and reabsorbed. However, when hosts were available for oviposition a significant increase of egg maturation rate was noticed. Mean realized fecundity during the life span was 71.7±8.1 and 69.0±6.7, and mean longevity was 13.5±0.9 and 15.1±0.6 days for mated and unmated ♀♀ respectively.      

Some observations onStrongwellsea castrans [Zygomycetes: Entomophthorales], a parasite of root flies [Delia spp.], in the south of Scotland

Root flies,Delia radicum (L.) andD. floralis (Fallén) (Diptera: Anthomyiidae), trapped in swede crops in the south of Scotland, were infected withStrongwellsea castrans Batko and Weiser (Zygomycetes: Entomophthorales). The pathogen was associated mainly with females of the 1st and 2nd generations ofD. radicum and of the single generation ofD. floralis. Disease incidence showed time-lagged density dependence. Greatest sustained infection levels were recorded in the coolest wettest season. Higher proportions ofD. radicum were infected in the headland than in the crop. Unbaited yellow water traps caught greater proportions of infected flies than traps baited with mustard oil (allyl isothiocyanate). The reasons for high levels of infection in Scotland are discussed.

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Résumé Les mouches des racines,Delia radicum (L.) etD. floralis (Fallén) [Diptera: Anthomyiidae] attrapées dans la culture du rutabaga dans le sud de l'écosse, étaient contaminées parStrongwellsea castrans Batko & Weiser [Zygomycetes: entomophthorales]. Le pathogène était surtout associé aux fe nelles de la lère et de la 2ème générations deD. radicum et de la seule génération deD. floralis. Les cas de maladie montraient avec retard leur dépendance avec la densité des mouches. Les niveaux d'infection les plus grands étaient enregistrés pendant la saison la plus froide et la plus humide. Les bordures en friche des parcelles hébergeaient de plus grandes proportions deD. radicum infectés que les cultures. Des pièges jaunes sans appat ont attrapé de plus grandes proportions de mouches que lorsqu'ils étaient appatés avec de l'huile de moutarde (allyl-isothiocyanate). Les raisons qui expliquent pourquoi les niveaux d'infection en écosse sont plus élevés qu'ailleurs sont discutées.

     

Biology of Lilioceris spp. (Coleoptera: Chrysomelidae) and their parasitoids in Europe

The biology and parasitoid complex of the lily leaf beetle (LLB), Lilioceris lilii Scopoli, and two congeneric species were investigated in Europe, as part of a biological control program against the LLB in North America. Eggs, larvae, and adults of L. lilii were collected in several countries in Europe, on both cultivated and wild Lilium spp., and reared in the laboratory and under natural conditions. Parasitoids were obtained and their biologies were studied. Similar investigations were made in Switzerland on two closely related species Lilioceris tibialis (Villa) found on wild Lilium spp., and Lilioceris merdigera (L.) on several other Liliaceae. The three species are strictly univoltine. Adults overwinter and lay eggs on leaves in early spring. The three beetle species have four instars, which were characterized by their head capsule width. Pupation occurs in a cocoon in the soil. Adults emerge in late summer and start feeding before reaching overwintering sites. Egg and larval parasitoids were obtained. Eggs of L. lilii and L. merdigera were parasitized by the mymarid Anaphes sp., a multivoltine species that needs alternate hosts for overwintering. Larvae were heavily attacked by several parasitoids, among which the most abundant were three ichneumonids, Lemophagus pulcher (Szepligeti), L. errabundus (Gravenhorst), and Diaparsis jucunda (Holmgren), and the eulophid Tetrastichus setifer Thomson. All four parasitoid species were found in the three beetles and in most European regions, but strong variations were observed in their relative abundance among hosts and geographic regions. Three of the four main larval parasitoids are strictly univoltine, whereas L. pulcher has a partial second generation. Lemophagus spp. are frequently parasitized by the ichneumonid hyperparasitoid Mesochorus lilioceriphilus Schwenke. Further details of the biology of the parasitoids are described, and their potential as biological control agents is discussed.     

Introduction,colonization and establishment ofLysiphlebus testaceipes [Hymenoptera: Aphidiidae], in Argentina

The introduction, colonization, and establishment ofLysiphlebus testaceipes (Cresson) for the biological control ofSchizaphis graminum (Rondani). in Argentina is briefly discussed.     

Interactions between an eucoilid [Hymenoptera] and a staphylinid [Coleoptera] parasitoid of the cabbage root fly

The interaction betweenTrybliographa rapae andAleochara bilineata, 2 parasitoids of the cabbage root fly, is discussed. Larvae ofA. bilineata could not differentiate between cabbage root fly pupae containingT. rapae in its endoparasitic state and unparasitized pupae but could recognize pupae containingT. rapae once the latter had reached its ectoparasitic state. Attack byA. bilineata whileT. rapae was still in its endoparasitic state usually resulted in the staphylinid killing the eucoilid. IfT. rapae had reached the ectoparasitic state before the host pupa was attacked byA. bilineata larvae the eucoilid survived attack by the beetle larva. Multiparasitism, however, resulted in increased levels of mortality of both parasitoid populations.      

Observations on the biology and host specificity ofEpiblema strenuana [Lepidoptera,Tortricidae], a potential biocontrol agent forParthenium hysterophorus [Compositae]

The tortricid mothEpiblema strenuana (Walker), which attacksAmbrosia spp. over most of North America, is shown to have the annual weedParthenium hysterophorus L. [Compositae] as its main host in northern Mexico. The larvae produce galls in the stems and growing-points which can considerably stunt growth when young plants are attacked. In tests it was shown to have a restricted host-range and not to damage any composite of economic importance. Its release in Australia for trial as a biological control agent againstP. hysterophorus has been approved.