Host specificity and biology ofMegacyllene mellyi [Col.: Cerambycidae] introduced into australia for the biological control ofBaccharis halimifolia [Compositae]

Biology and host plant specificity of the stem boring cerambycidMegacyllene mellyi (Chevrolat) were studied in Brazil to determine its suitability for introduction into Australia for control of the shrubBaccharis halimifolia L. Multiple choice host preference testing of plants related toBaccharis, of desirable plants from a range of plant families, and of the host plants of otherMegacyllene species, showed thatM. mellyi was restricted toBaccharis spp. It was introduced into Australia in 1975 and released in 1978. Recoveries were made 3 years after release and some stems were killed, although damage was slight relative to the number ofB. halimifolia plants in the release area.     

The susceptibility ofTribolium castaneum [Col.: Tenchrionidae] toFarinocystis tribolii [Protozoa: Schizogregarinida]

The LT₅₀ ofFarinocystis tribolii Weiser to larvae ofTribolium castaneum (Herbst) increased with the age of the insect indicating that older larvae were relatively more tolerant to the infection though there was 100 % mortality ultimately. The adults were less susceptible than larvae and between sexes, females were more susceptible than males. The number of spores produced increased with the stage of the larvae, but there was no variation in the size of spores in the different instars. The LC₅₀ on 20th and 40th day of inoculation were 1.4×10⁷ and 2.1×10⁶ respectively. Mortality-time due toF. tribolii was shorter at 35 °C than at 25 °C. Sporulation occurred earlier at 35 °C than at 25 °C.     

Effect on waterhyacinth ofNeochetina eichhorniae [Col.: Curculionidae] combined withOrthogalumna terebrantis [Acari: Galumnidae]

Seven hundred mottled waterhyacinth weevils,Neochetina eichhorniae Warner, were released in a Fort Lauderdale, Florida, canal on a mat of waterhyacinth,Eichhornia crassipes (Mart.) Solms-Laubach. At the time of weevil release, the mat contained ca. 100 adult waterhyacinth mites,Orthogalumna terebrantis Wall-work/plant, and ca. 15 immature waterhyacinth mites/cm². Waterhyacinth weevil populations increased to ca. 4 adults and 5 larvae/plant after 50 weeks, and were unaffected by weather. Waterhyacinth mite populations reached a peak of ca. 840/plant after 16 weeks, at which time they were reduced in number by low temperatures. Decrease in size and density of waterhyacinth closely followed buildup of weevil populations, with petiole length decreasing by 35% and plant density reduced by 45% over a 50 week period. The phytopathogenic fungusAcremonium zonatum (Saw.) Gams., which causes zonate leaf spot disease of waterhyacinth, developed in waterhyacinth mite tunnels after the adult mite created an emergence hole, but was not observed in weevil feeding spots.     

Conservation of two predator species for biological control ofChrysophtharta bimaculata (Col.: Chrysomelidae) in tasmanian forests

Chrysophtharta bimaculata (Olivier) (Coleoptera: Chrysomelidae) is a major defoliator of regeneration eucalypt trees in Tasmania causing a significant reduction in height and diameter increment of trees which reduces wood volume per hectare. A study to conserve and enhance the efficiency of coccinellid species chieflyCleobora mellyi (Mulsant) (Coleoptera: Coccinellidae), and the cantharid,Chauliognathus pulchellus (Macleay) (Coleoptera: Cantharidae), for the biological control ofC. bimaculata was conducted in young regeneration forests in southern Tasmania from 1991–92. Cantharid adults and coccinellid adults and larvae feed onC. bimaculata eggs and, to a lesser extent, young larvae. The study found that coccinellids were more active throughout the egg and early (1^st and 2^nd) stage ofC. bimaculata. The cantharid, however was active only during the egg stage of the prey and then disappeared from the plantation. The coccinellids were therefore the most useful predators, but their population declined when the prey reached the 3^rd and 4^th stages. As shortage of food may account for this decline, supplementary food was provided in the form of sucrose sprays or sugar granules at a feeding station. This resulted in the retention of both predators and particularly the coccinellids and enhanced their efficacy.     

Effects ofBathyplectes curculionis andBathyplectes anurus [Hym.: Ichneumonidae] on the growth and development ofHypera postica [Col.: Curculionidae]

Observations, linear measurements, dissections, and histological preparations were made of parasitized and nonparasitized larvae of the alfalfa weevil,Hypera postica (Gyllenhal), on a daily basis. The observed developmental period lasted from 24 h after oviposition byBathyplectes curculionis (Thomson) orBathyplectes anurus (Thomson) until parasite larvae emerged from their hosts. Adult and larval parasites significantly altered growth and development ofH. postica larvae.B. curculionis andB. anurus caused 24 and 29% greater premature mortality in young host larvae than that observed in the unparasitized controls. Rate of development for parasitized larvae during the 1st 12 days was essentially the same as for nonparasitized larvae. Nonparasitized larvae reached maximum size in 17–18 days, whereas larvae parasitized byB. curculionis andB. anurus required 14–21 and 19–22 days, respectively. Larvae parasitized byB. curculionis are smaller in overall lengths, widths and head capsule widths than nonparasitized larvae and those parasitized byB. anurus.     

Preference for medium dense grass tussocks byHippodamia convergens [Col.: Coccinellidae]

The preference in the choice of hibernacula of the convergent lady beetle,Hippodamia convergens Guérin-Meneville, was investigated with regard to morphological aspects of 2 introduced range grasses,Panicum coloratum (L.), andEragrostis curvula (Schrad.) Beetles strongly preferred tussocks with a ratio in the range of 1.0–3.0 stems per cm² for lovegrass. Preference for klein grass tussocks ranging from 110–130 stems/clump was found. No preference was shown for a particular tussock circumference. It was demonstrated that tussocks could successfully be designated as suitable for beetle aggregation.     

Adult diapause ofCybocephalus nigriceps nigriceps [Col.: Cybocephalidae]

During autumn and winter (October–February)Cybocephalus nigriceps nigriceps (J. Sahlberg) adults undergo a facultative diapause. The diapausing adults agregate in hiding places, development of the ovaries is arrested, and prey consumption is lowered. Diapause can be prevented by exposure to a long-day photoperiod (16 hr light) at high temperatures (29° and 32°C). Diapause is induced mainly by short-day conditions, but the termination of diapause is affected by both photoperiod (long-day conditions) and temperature (29°, 32° and 34°C). In mature females, diapause induction causes ovarian degeneration. The induction or inhibition of adult diapause is affected by photoperiods occurring during larval development as well as during adult life.     

The observed sex ratio ofPediobius foveolatus [Hym.: Eulophidae] in field populations ofEpilachna varivestis [Col.: Coccinellidae]

Larvae ofEpilachna varivestis Mulsant, parasitized byPediobius foveolatus (Crawford), were collected in soybean fields in Maryland during 1975. AdultP. foveolatus emerging from the larvae were sexed and counted. The ratio of males to females increased as the availability of food within the host decreased. This information is useful in development of exponential models predicting hostparasite interactions.     

Superparasitism ofEpilachna varivestis [Col.: Coccinellidae] byPediobus foveolatus [Hym.: Eulophidae]: Influence of temperature and parasitoid-host ratio

Superparasitism ofEpilachna varivestis Mulsant larvae by the hymenopterous parasitoid,Pediobius foveolatus (Crawford), occurred under laboratory conditions. However,P. foveolatus avoided previously parasitized larvae in a manner which was directly related to the number of times host larvae were initially parasitized. Increasing the parasitoid-host ratio also increased percent host mortality and highest overall host mortality occurred at 15.6°C when the parasitoid-host ratio was 10∶10. Higher temperatures (22° and 28°C) and higher parasitoid-host ratios yielded higher numbers of parasitized larvae although a significant number of parasitoids failed to emerge at the highest parasitoid-host ratio. Higher temperatures along with increasing parasitoid-host ratios favored production of more male parasitoids.     

Note on breeding the argentine stem weevilHyperodes bonariensis [Col.: Curculionidae] and its egg parasitePatasson atomarius [Hym.: Mymaridae]

Hyperodes bonariensis Kuschel underwent ovarial diapause from March to August in the Bariloche area in Argentina. Feeding on germinating seedlings ofTriticum aestivum L. andPoa annua L. in continuous dark induced the weevil for oviposition in 24 and 32 days, respectively. Breeding techniques are described forH. bonariensis and its parasitePatasson atomarius (Brethes).     

Parasites of bark beetles [Col.: Scolytidae] on pine and cypress in Israel

Ten species of hymenopterous parasites were reared from logs of pine and cypress, naturally infested with 5 species of bark beetles,viz., Orthotomicus erosus Woll.,Pityogenes calcaratus Eichh., andTomicus destruens Woll. — on pine;Phloeosinus armatus Reitt. andP. aubei Perris — on cypress, in Israel. The parasites were:Dendrosoter chaenopachoides Rusch,D. hartigii (Ratz.),D. middendorfi (Ratz.),D. protuberans Nees (Braconidae), Eurytoma morio Boheman (Eurytomidae), Cerocephala eccoptogastri Masi,Heydenia pretiosa F?rster,Metacolus unifasciatus F?rster,Rhaphitelus maculatus Walker andRoptrocerus xylophagorum (Ratz.) (Pteromalidae). The most common wereM. unifasciatus on pine and cypress,D. chaenopachoides andR. xylophagorum on pine, andD. protuberans on cypress, occurring in samples collected during most seasons. Less common wasE. morio, which was reared from both conifers.D. middendorfi was found on pine, and only during winter. The other species were found only occasionally.     

Naturally-occurring biological control of the boll weevil [Col.: Curculionidae]

Red imported fire ants,Solenopsis invicta Buren, are effective predators of the boll weevil,Anthonomus grandis Boheman, in east Texas cotton fields. Boll weevils caused no economic loss in 11 years due to mortality attributed primarily to ants. Removal of the ants resulted in an increase in crop damage by the boll weevil. Insecticides used for cotton pests greatly reduce the abundance of the ants. To capitalize on this effective predation of boll weevils by ants, unnecessary applications of insecticides should be eliminated.     

Propagation of the Colorado potato beetle [Col.: Chrysomelidae] egg parasiteEdovum puttleri, [Hym.: Eulophidae]

The parasitic wasp,Edovum puttleri Grissell, was successfully reared onLeptinotarsa decemlineata (Say) in the laboratory and increased in sufficient numbers for inoculative release studies in the spring and summer. The effects of temperature on parasite development, and host-parasite ratios in the laboratory are presented. The sex ratio of parasites reared in the laboratory are compared to those released and recovered in the field.     

Impact of foraging byMonochamus titillator [Col.: Cerambycidae] on within-tree populations ofDendroctonus frontalis [Col.: Scolytidae]

The impact of foraging byMonochamus titillator (Fab.) on within-tree populations ofDendroctonus frontalis Zimm. was described. Total population estimates forD. frontalis and inner bark area foraged byM. titillator were computed for 89 loblolly pine,Pinus taeda L., sampled over a 3 year period. Frequency histograms were prepared for the surface area of habitat infested, area foraged byM. titillator, and within-tree populations ofD. frontalis. These data were used to calculate the proportion of area foraged byM. titillator, the proportionalD. frontalis mortality for the entire tree, and the proportional mortality occurring in the foraged area. Histograms showing the variation of these components were prepared and described using nonlinear mathematical models. Ca. 20% of the infested surface area was foraged byM. titillator. Mortality toD. frontalis on a per tree basis was ca. 14%. Mortality in the area foraged byM. titillator was ca. 70%. These estimates were highly variable between individual trees and a procedure for predicting the probability of a given level of foraging and mortality was described. Sources of variation influencing foraging byM. titillator and mortality toD. frontalis were investigated. Variation between years and season followed similar trends with both foraging and mortality increasing from the base to the top of the infested bole. Variation between tree size-class was highly significant. Larger size-class trees had substantially greater foraging and mortality than did the smaller size-classes. Mortality within the foraged area was also found to be greater at the extremes of the infested bole.

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Résumé L’impact de l’activité deMonochamus titillator (Fab.) sur les populations à l’intérieur de l’arbre deDendroctonus frontalis Zimm. est décrit. Le total des évaluations de population deD. frontalis dans des zones à l’intérieur du tronc attaquées parM. titillator a été soumis à l’ordinateur pour 89 pins,Pinus taeda L., échantillonnés pendant 3 ans. Les histogrammes de fréquence ont été établis pour la surface de l’habitat infesté, la surface explorée parM. titillator et pour les populations deD. frontalis présentes dans l’arbre. A partir de ces données on a calculé la part de surface utilisée parM. titillator, la mortalité deD. frontalis extrapolée pour l’arbre entier et la mortalité se produisant dans la surface exploitée. Les histogrammes traduisant les variations de ces composantes ont été dressés en ayant recours à des modèles mathématiques non linéaires. Environ 20% de la surface infestée a été exploitée parM. titillator; la mortalité du scolyte fut d’environ 14% dans l’arbre et de 70% dans la zone attaquée parM. titillator. Ces évaluations sont très variables d’un arbre à l’autre et on a mis au point un procédé pour prévoir la probabilité d’un taux donné d’activité alimentaire du cerambycide et de mortalité du scolyte. Les causes de cette variabilité ont été étudiées. La variation suivant les années et les saisons suit les mêmes tendances à savoir l’augmentation à la fois de l’activité alimentaire et de la mortalité de la base au sommet du pin attaqué. La variation selon les classes de taille des arbres est hautement significative: les arbres les plus gros présentent une exploitation et une mortalité beaucoup plus importantes que les arbres plus petits. La mortalité du scolyte dans la zone attaquée par le cerambycide est également plus élevée aux extrémités du pin infesté.

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Texas Agricultural Experiment Station No.TA15244.     

Ecological requirements for hibernatingPropylea quatuordecimpunctata (L.) andCoccinella septempunctata [Col.: Coccinellidae]

During 3 successive winters, we studied the dormancy sites ofPropylea quatuordecimpunctata (L.) andCoccinella septempunctata L., 2 species of ladybirds which hibernate in leaf litter. Samples of litter were taken from several kinds of forest to study the influence of 3 variables (exposure; altitude; sampling place: edge or inner wood) on the abundance of ladybirds. We found the ecological requirements of the 2 species of coccinellids to be quite different:C. septempunctata prefers forest edges orientated towards the South and the West.P. quatuordecimpunctata prefers the inner wood and does not show a preference for station exposure. For each species, the number of ladybirds collected in the samples is positively correlated with station altitude. In addition, some observations were carried out to examine the main mortality factors just before and during dormancy. In maize fields near dormancy sites, the harvest is very harmful forC. septempunctata. During the winter,P. quatuordecimpunctata andC. septempunctata suffer fromBeauveria ssp. and some ladybirds have parasitoïds.     

Longevity and reproductive rate ofPatasson lameerei [Hym.: Mymaridae], a parasitoid ofSitona spp. [Col.: Curculionidae] eggs

Patasson lameerei DeBauche produced an average of 28.5 offspring under 2 temperature regimes usingSitona hispidulus (Fabricius) eggs as hosts. Although its fecundity was not affected by the temperature regimes,P. lameerei lived significantly longer at 6.7/18.3°C than at 21.1°C. When ample hosts were available,P. lameerei produced more offspring during the 1st few hours of its adult life than during any other comparable period. When the parasitoids were denied access to host eggs for 1,2, or 3 days after emergence, they still produced similar numbers of offspring during their 1st 24 h exposure to hosts.     

Edovum puttleri [Hym.: Eulophidae]: Biological activity and responses to normal and frozen eggs ofLeptinotarsa decemlineata [Col.: Chrysomelidae]

Biological control of eggplant pests in general, and (CPB)Leptinotarsa decemlineata (Say) in particular, is highly problematic.Edovum puttleri Grissell, an exotic egg parasitoid which has been found potentially effective, is being reared to this end. Frozen CPB eggs (?18°C) proved to be accepted and suitable for parasitization byE. puttleri. However, when given a choice between 20 frozen and 20 normal eggs every 2 days, the females exhibited a significant preference for the latter. Parasitization and host predation patterns related to female age are described by 2 opposing fourth-order polynomial functions. Parasitization increased up to day 10, followed by progressive decline. Average life span per female was 31.10±.58, with a recorded maximum of 56 days. High predatory behaviour of older females, which showed a decrease in parasitization, was observed in these experimental conditions.     

Affects of two cotton varieties on levels of boll weevil parasitism [Col.: Curculionidae]

The cotton plant has a profound affect on the behavior and ability of parasites to successfully attack the boll weevil,Anthonomus grandis Boheman. The most important native parasite of the boll weevil,Bracon mellitor Say, prefers to oviposit on Frego bract cotton rather than normal bract cotton. An imported parasite,Heterolaccus grandis Burks prefers ovipositions on normal bract cotton rather than Frego.     

Zoophthora phytonomi andConidiobolus osmodes [Zygomycetes:Entomophthoraceae], two pathogens ofHypera species [Col.: Curculionidae] coincidental in time and place

Two entomophthoraceous species, found at different localities in Israel, caused epizootics onHypera variabilis Herbst. larvae during spring of 1976 and 1977.Zoophthora phytonomi (Arthur) Batko, emend.Ben-Ze’ev & Kenneth (syn.Entomophthora phytonomi Arthur) produced in the field only conidia, whereasConidiobolus osmodes Drechsler formed only dark, rough-walled resting spores that had been erroneously thought in the past to belong toZ. phytonomi. In culture,Z. phytonomi, isolated from conidia, produced subhyaline, smooth resting spores, whereasC. osmodes from resting spores produced rotund conidia, which proved pathogenic toH. variabilis larvae and adult houseflies. All species connected by different authors withZ. phytonomi are discussed, includingE. elateridiphaga, transferred here toZoophthora.     

Lixus cribricollis [Col.: Curculionidae] for biological control of the weedsEmex spp. andRumex crispus in Australia

The biology and host specificity of a colony ofLixus cribricollis Boheman originating in Morocco were studied in quarantine in Australia.L. cribricollis adults are long lived, have an aestivation and are univoltine.Rumex crispus L.,Emex australis Steinheil andE. spinosa (L.)Campdera were shown to be the only satisfactory hosts of 40 species of plants from 17 families that were exposed to sexually mature adults ofL. cribricollis. Normal feeding and occasional oviposition were observed on some other plants within the same family,Polygonaceae, including the minor crops rhubarb and buckwheat, but almost invariably larvae died in the 1st instar. It was concluded thatL. cribricollis may be a useful biological control agent for the weedsR. crispus, E. australis andE. spinosa and that establishment of this weevil in Australia would be without risk to non-target plants.