Larviposition response ofBonnetia comta [Dipt.: Tachinidae] to a kairomone ofAgrotis ipsilon [Lep.: Noctuidae]

A kairomone in the frass and vomitus of larvae ofAgrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae) triggered larviposition activity in its habitual parasitoidBonnetia comta (Fallen) (Diptera: Tachinidae). Laboratory bioassays showed that no measurable differences existed in the larviposition-stimulating activity of frass fromA. ipsilon larvae reared on 3 different food sources. In other tests, corn seedlings damaged by late-instar larvae ofA. ipsilon elicited strong larviposition activity inB. comta; other corn seedlings damaged with a razor blade did not elicit strong activity. Frass aged for 8-days was only slightly less effective at releasing a larviposition response when compared to fresh frass.B. comta was not stimulated to larviposit by oven dried frass or an India ink dot the color and shape of a fresh pellet from a host larva. The host habitat location and host finding process forB. comta and other tachinid species that deposit free-living maggots is discussed.     

Searching and ovipositional behavior ofAmitus hesperidum [Hym.: Platygasteridae] andEncarsia opulenta [Hym.: Aphelinidae] parasitoids of the citrus blackfly [Hom.: Aleyrodidae]

Searching behavior ofAmitus hesperidum Silvestri andEncarsia opulenta (Silvestri) for immatureAleurocanthus woglumi Ashby was similar. Both parasitoids moved unidirectionally until they encountered a host aggregation at which time they changed to a pattern of short walks with numerous turns. Parasitoid ovipositor insertion was generally at midbody between the host sternites and tergites.Amitus hesperidum females showed a significant preference for 1st instar hosts, have an ovipositional marker, do not feed on exudates from ovipositional wounds (host feed), and have significantly shorter ovipositional times and adult life spans thanE. opulenta which showed a significant preference for 2nd instar hosts, lack an ovipositional marker, and host feed.Encarsia opulenta females showed a significant preference for hosts previously parasitized byA. hesperidum but the reverse was not true. The average number of hosts parasitized by females of both parasitoid species was uninfluenced by the previous presence of the other parasitoid species on the same leaf.     

Observations on the oviposition behaviour ofGoniozus sensorius [Hymenoptera: Bethylidae] a parasite ofDiaphania indica [Lepidoptera: Pyralidae]

Goniozus sensorius Gordh (Hymenoptera: Bethylidae) was recorded as a major parasite of the pumpkin caterpillar,Diaphania indica (Saunders) (Lepidoptera: Pyralidae). This paper provides detailed information on the oviposition behaviour ofG. sensorius. Prior to oviposition, the parasite temporarily paralyses the host larva. The paralysed condition lasts for about 2 h. The egg laying process on each larva requires 30 to 60 min. The maximum number of eggs are laid on the 6^th and 7^th segment, and none in the terminal segments. Generally, oviposition is restricted to 1 segment of the host larva and occasionally on 3 segments. The maximum number of eggs are laid on the 2^nd and 3^rd day after emergence and the mean number of eggs laid on each host larva was 7.1.     

Biology ofclausicella suturata [Dipt.: Tachinidae] a parasite ofEctomyelois ceratoniae [Lep.: Phycitidae]

The tachinid flyClausicella suturata Rondani is a solitary parasite ofEctomyelois ceratoniae (Zeller). It was grown under laboratory conditions (26±0.5°C, 55±5% R.H.) and the host-parasite relationships were studied. The different stages of the parasite were briefly described. The eggs are deposited on the carob (Ceratonia siliqua L.,Caesalpiniaceae) pods, near the openings of the host's tunnels and hatch immediately. The Ist instar maggot is directed by the web fibers of the host towards the caterpillar which is hidden in the carob pod. The parasites develop normally only in 4th and 5th instar caterpillars. The parasitized caterpillar spins its cocoon inside the carob pod before being killed by the parasite. The fully grown maggot leaves the host and pupates inside its cocoon. Adult longevity is dependent upon the presence of carbohydrate in the diet. Maximal male and female longevity (50% survival of 21 and 17.5 days respectively) was reached on a carbohydrate diet and water, at 26°C and 55% R.H. Newly emerged females readily mate with one or two-day old males. The average fecundity of a female is 202 eggs, deposited during 13.6 days, after an incubation period of 6.9 days. Superparasitism is common in nature but only one maggot is successful in completing its development.     

Longevity ofBracon brevicornis [Hym: Braconidae] adults as influenced by nourishment on artificial and natural foods

Laboratory trials were undertaken to investigate the nutrition ofBracon brevicornis Wesmael adults on: (1) artificial diets (sucrose, treacle, honey bee and tap water); (2)Sesamia larvae (exposed under 3 manipulations); (3) 5 host species (Galleria, Ephestia, Sesamia, Spodoptera andOstrinia); in addition to starvation at 12, 15, 20, 25, 30, 35 and 40°C. Among artificial diets, honey bee solution was the most suitable that prolonged significantly each sex to be more than 1 month at 25°C.A Bracon female supplied daily with a freshSesamia-larva was significantly longer-lived than when kept with the “unchanged”Sesamia-larva. Larvae of borers (Sesamia andOstrinia), gave significantly the highest longevity for females among other host species. Adult-longevity was significantly decreased with an increase in temperature. Females were significantly longer-lived than males when kept only with living host insects. However, such sex difference was generally uncertain when either was supplied with an artificial diet or starved under temperatures ranging from 12–40°C.     

Diversity of commensal bacteria from mid-gut of pink stem borer (Sesamia inferens [Walker])-Lepidoptera insect populations of India

Sesamia inferens (W.) is polyphagous agricultural pests and prevalent in the India, China, South Asia and South East Asia. Insecticides is not recommended because, apart from the hazardous effects of chemicals, its larvae tunnel throughout the stem from first instar. Associated bacteria with insects provide several benefits to their host, revealing the types of bacteria associated with S. infersns will give basic information, which may throw light on management of this noxious pest. The culture dependant, 16S rRNA gene technique revealed thirty two bacterial isolates from gut of S. inferens from different region of India and host, comprising phyla Proteobacteria, Firmicutes and Bacteroidetes. Among which proteobacteria phyla was dominant with families and genus like Enterobacteriaceae (Citrobacter, Enterobacter, Serratia, Klebsiella and Xenorhabdus), Pseudomonadaceae (Pseudomans), Moraxellaceae (Acinetobactor) and Comamonadaceae (Comamonas). The phyla Firmicutes less dominant with four families and one genus each viz., Staphylococcaceae (Staphylococcus), Bacillaceae (Lysinibacillus), Streptococcaceae (Lactococcus) and Enterococcaceae (Enterococcus). Third phyla had only one family viz., Flavobacteriaceae (Chryseobacterium). The bacterial diversity varied greatly among insects that were from different host plants than those from the same host plant of different locations. This result suggested that the type of host plant greatly influences the mid-gut bacterial diversity more than the location of the host plant of S.inferens. These bacterial populations may have a key role in digestion, as well as other benefits to the S. inferens larvae. Determination of the bacterial community and its biological functions within the insect could provide us with basic information for future pest control research.     

Host specificity and aspects of the biology ofCalligrapha pantherina (Col.: Chrysomelidae), a biological control agent ofSida acuta [Malvaceae] andS. rhombifolia in Australia

The host specificity of a chrysomelid beetle,Calligrapha pantherina Stål, from Mexico, was verified in the CSIRO quarantine facilities in Brisbane, Australia on 80 species of plants in 28 families, either closely related to Malvaceae or in families containing economically important species.C. pantherina oviposited and developed successfully on its preferred host,S. acuta, and less successfully onS. rhombifolia andS. spinosa, all of which are weeds in Australia. Aspects of oviposition, larval development, and adult feeding and longevity ofC. pantherina are described.C. pantherina was released in Australia during 1989 and readily established onS. acuta but established at only a few sites onS. rhombifolia.     

The basis for host plant specificity inTephritis dilacerata andT. Formosa [Dipt: Tephritidae]

Strains ofTephritis dilacerata Loew andT. formosa Loew from galls onSonchus arvensis L. andS. asper (L.)Hill, respectively, could be raised reliably in the laboratory only on their host plants. Ovipositing females of both tephritids select a narrow, but different, range of bud sizes. The hatching of the eggs of both flies is synchronized with the onset of rapid but elongation in their respective host plants. Because the growth characteristics of these 2Sonchus species are different, buds of equivalent developmental stages are different average sizes, and ovipositional behavior that brings about synchronization onS. arvensis is not adapted toS. asper and vice versa. Both flies occasionally laid into the flower buds of each others host plant as well asS. oleraceus L. In these cases the buds aborted or the larvae failed to complete normal development. However, both flies appear to be preadapted to the non-host plantSonchus species in this group and host records forT. dilacerata andT. formosa suggest the existence of “host races” attacking theseSonchus species, or alternatively, the frequent occurrence of ovipositional “mistakes” involving these plants.     

Hexamermis glossinae [Nematoda: Mermithidae] parasitizing tsetse [Diptera: Glossinidae] in Kenya

Glossina pallidipes Austen,G. brevipalpis Newstead andG. austeni Newstead were collected from 5 sites along the south Kenyan coast over a 2 year period. They were dissected and examined for nematodes. Three of the sites yielded tsetse parasitized by juvenile mermithids identified asHexamermis glossinae Poinar et al. Glossina pallidipes andG. brevipalpis are new host records for this parasite, whileG. austeni was captured infrequently and only at a site that failed to yield other parasitized tsetse. Parasite prevalence was low (0.16–0.61 %) and did not differ between male and female hosts. More tsetse than expected by chance harboured nematodes during the long rains season (April–August) than during the short rains (September–November) or dry season (December–March). Early juvenile stages (0.5–2.5 mm long) were recovered mainly from tsetse less than 50 days old, while late juvenile stages (35–85 mm long) were only found in flies older than 30 days. Late stages occurred singly while early ones usually occurred as two or more per host.     

A biological review of the genusEuplectrus [Hym.: Eulophidae] with special emphasis onE. Laphygmae as a parasite ofSpodoptera littoralis [Lep.: Noctuidae]

The life history and behavior ofEuplectrus laphygmae Ferrière were studied. The parasites paralyse the host larvae temporarily before ovipositing 1–2 eggs on their dorsum. Egg and larval development takes place externally in the location of egg deposition and pupation is in a silken cocoon under the dead host. Development lasts 11.7 days for both sexes. The eggs are attached to the host with a pedicel that is inserted under the cuticle but above the hypodermis, and which may have physiological and mechanical functions. The adult parasites host-feed, but do not lay on the same host. All hosts stung by parasites die, regardless whether oviposition has occurred, or whether host larvae develop upon them. Multiparasitism with internal parasites ofSpodoptera littoralis (Boisd.) was observed. A comparison with otherEuplectrus species was made. They have a wide range of lepidopterous hosts but very similar biological characteristics. Only very few utilizations for biological control have been reported with this genus.     

Natural enemies ofAcraea terpsicore [Lep.: Nymphalidae] in ghana,with particular reference to the parasiteCharops diversipes [Hym.: Ichneumonidae]

The arthropod parasites and predators ofAcraea terpsicore (L.) were determined in the forest zone of Ghana. An unidentified mite was predatory on the very young larvae. The pentatomidsPlatynopus rostratus Dru. andMacrorhaphis acuta (Dall.) were also predatory on the larvae.Telenomus sp. parasitized the eggs. The tachinidCarcelia normula (Curran) and the ichneumonidCharops diversipes Roman were parasitic on the larvae.C. diversipes was hyperparasitized by the chalcididBrachymeria feae Masi and the eulophidPediobius taylori Kerrich. Laboratory tests showed that parasitism ofA. terpsicore byC. diversipes was significantly highest in the 1st instar, followed by the 2nd, 3rd and 4th. The 5th instar was not parasitized. These results seemed to reflect both host susceptibility and parasite preference. Only a singleC. diversipes larva developed in a host. The developmental period of the parasite egg and larva varied inversely with the age of the host at which it was parasitized. A femaleC. diversipes could oviposit immediately after emergence.     

Developmental interactions between the army wormLeucania separata [Lep.: Noctuidae] and its parasiteApanteles ruficrus [Hym.: Braconidae]

The developmental interactions between the gregarious endoparasitoidApanteles ruficrus Hal. and the army worm,Leucania separata Walker were investigated. The parasitoid preferred young host larvae and developed in 9.5 days irrespective of host age at the time of parasitization. The growth of parasitized host larvae were depressed. The net maximum weight of the host larva was positively correlated with the number of parasitoid eggs laid when the 2nd instar was parasitized. And when parasitizing in 2nd instar, the weight of parasitoid was negatively correlated with the number of eggs laid. The parasitoid has an ability to regulate the size of the host and the parasitoid itself according to the number of eggs laid when the host larva is very small.     

Regulation of host larval development by the egg-larval endoparasitoidChelonus insularis [Hym.: Braconidae]

In laboratory studies the effect of parasitism by the egg-larval endoparasitoidChelonus insularis Cresson on the resulting larvae of 2 host species,Heliothis virescens (F.) andSpodoptera ornithogalli Guénée) were determined by comparing daily measurements of larval weights. Growth of parasitized larvae of both host species was slower than growth of unparasitized larvae. Injections of fluids from the female parasitoid's calyx or poison gland intoH. virescens eggs retarded subsequent larval growth. However, a combination of fluids from these 2 organs produced the most significant reduction in the host larval growth rate. The growth reducing factor(s) was also effective when injected into 5-day-old host larvae.     

Assessment ofPaulinia acuminata [Orthoptera: Acrididae] for the biological control ofSalvinia molesta in Australia

The biology and host specificity of the aquatic grasshopper,Paulinia acuminata (De Geer) were studied in quarantine in Australia. Adults and nymphs fed on the leaves of salvinia (Salvinia molesta), water lettuce (Pistia stratiotes) and azolla (Azolla pinnata). Fifty-three plant species representing 38 families were exposed to adults and nymphs ofP. acuminata. Adult feeding occurred on 17 plants but nymphs failed to feed on 9 of these species in the presence ofS. molesta. In starvation trials, 14 plants (excludingS. molesta, P. stratiotes andA. pinnata) were attacked by adults, of which only 5 were attacked by nymphs. Heavy feeding occurred on strawberry (Fragaria xananassa) but no oviposition occurred even when the leaves were held in contact with the water surface. The life cycle ofP. acuminata was completed only onS. molesta, P. stratiotes andA. pinnata. Eggs deposited on water hyacinth (Eichhornia crassipes) failed to hatch. Laboratory evaluation was supplemented with observations on the distribution and abundance ofP. acuminata on the Zambezi River system, Zimbabwe, during October 1984.     

Sharing a Host Plant (Wheat [Triticum aestivum]) Increases the Fitness of Fusarium graminearum and the Severity of Fusarium Head Blight but Reduces the Fitness of Grain Aphids (Sitobion avenae)

We hypothesized that interactions between fusarium head blight-causing pathogens and herbivores are likely to occur because they share wheat as a host plant. Our aim was to investigate the interactions between the grain aphid, Sitobion avenae, and Fusarium graminearum on wheat ears and the role that host volatile chemicals play in mediating interactions. Wheat ears were treated with aphids and F. graminearum inoculum, together or separately, and disease progress was monitored by visual assessment and by quantification of pathogen DNA and mycotoxins. Plants exposed to both aphids and F. graminearum inoculum showed accelerated disease progression, with a 2-fold increase in disease severity and 5-fold increase in mycotoxin accumulation over those of plants treated only with F. graminearum. Furthermore, the longer the period of aphid colonization of the host prior to inoculation with F. graminearum, the greater the amount of pathogen DNA that accumulated. Headspace samples of plant volatiles were collected for use in aphid olfactometer assays and were analyzed by gas chromatography-mass spectrometry (GC-MS) and GC-coupled electroantennography. Disease-induced plant volatiles were repellent to aphids, and 2-pentadecanone was the key semiochemical underpinning the repellent effect. We measured aphid survival and fecundity on infected wheat ears and found that both were markedly reduced on infected ears. Thus, interactions between F. graminearum and grain aphids on wheat ears benefit the pathogen at the expense of the pest. Our findings have important consequences for disease epidemiology, because we show increased spread and development of host disease, together with greater disease severity and greater accumulation of pathogen DNA and mycotoxin, when aphids are present.     

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.     

Competitive displacement ofAnagyrus antoninae [Hym.: Encyrtidae]. by its ecological homologueNeodusmetia sangwani [Hym.: Encyrtidae]

The displacement ofAnagyrus antoniaae Timberlake byNeodusmetia sangwani (Rao) was demonstrated by reduced parasitism by the former in two localities after the latter was introduced into these sites. The competitive factors were: (1) the host-regulative action ofN. sangwani maintained a low host reciprocal balance, and (2) the inability of the female ofA. antoninae at the prevailing host density to find hosts sufficient for reproduction. The lack of competitiveness ofA. antoninae was a result of its inability to develop at high vapor deficits.     

Egg parasitism of the yellow rice borer,Scirpophaga incertulas [Lep.: Pyralidae] in Bangladesh deepwater rice

Studies on deepwater rice in Bangladesh from 1977 to 1980 showed that 61–89% of the egg masses of the yellow rice borer,Scirpophaga incertulas (Walker), were attacked by hymenopterous parasites. Egg parasitism increased from 43–48% in broods 2–4 (May–August) to 64–88% in broods 5–6 (September–November). Parasitism was reduced in broods 4 and 5 in 1979 (because of lower host densities) and in 1980 (possibly due to extreme late flooding). Telenomus rowani (Gahan), active throughout the year, parasitized 64% of the eggs in the masses it attacked, 32 larvae/mass surviving.Tetrastichus schoenobii Ferrière first appearing at medium host densities, increased rapidly to attack half of the brood 5 and 6 masses. More than 98% of the eggs in the attacked masses were parasitized, leaving only 1.6 surviving larvae/mass. In 1979 its appearance was delayed by 10 weeks and fewer masses were parasitized due to lower host densities.Trichogramma japonicum Ashmead andTelenomus sp. (a new record) were less important. Multiple parasitism of masses rose from 7% in brood 2 to 28% in brood 5. Egg parasites clearly reduce the numbers ofS. incertulas, a major pest, and thus probably improve the yields of deepwater rice.     

Sound and vibration are not obligatory host finding stimuli for the bark beetle parasite,Coeloides brunneri [Hymenoptera: Braconidae]

Previous researchers, have speculated or concluded thatCoeloides brunneri Viereck females detect their bark beetle hosts by perception of the vibrations or sound made by boring larvae. However, when placed on logs containing various actively mining stages ofDendroctonus pseudotsugae Hopkins,C. brunneri females actively searched for the host only on logs infested with young or maturing brood larvae, and oviposited only in logs with maturing brood larvae. Moreover, when offered larvae in logs that had been frozen at approximately ? 50°C, and then allowed to thaw at room temperature for 2 days, they found the motionless, dead larvae, and oviposited through the bark on to them. Therefore,C. brunneri is able to find ist host by perception of some stimulus (or stimuli) other than sound or vibration.     

Host specificity and biology ofcystiphora sonchi [Dip.: Cecidomyiidae], a candidate for the biological control ofSonchus species

The host specificity ofCystiphora sonchi (Bremi), a promising biocontrol agent of the sow-thistles,Sonchus arvensis L.,S. oleraceus L., andS. asper (L.)Hill, was investigated. These are widespread, serious weeds in Canada and the United States. In the laboratory, 6 females produced up to 721 galls on 1 plant ofS. arvensis, and up to 245 galls on 1 leaf. A total of 59 plant species in 49 genera of the familyCompositae were tested.C. sonchi produced viable galls onSonchus species only, thus confirming European field records.C. sonchi was approved for release in Canada.