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.     

Experimental studies on parasitization byApanteles Glomeratus V. Relationships between growth rate of parasitoid and host age at the time of oviposition

The growth and development ofApanteles glomeratus L. eggs and larvae in the host larva (Pieris rapae crucivora Boisduval) was investigated by calculating their volume. WhenA. glomeratus eggs increase 90 fold in volume after being laid, larvae hatch from them. The larvae grow exponentially and the growth rate of the parasitoid is dependent on the host stage. Being laid in the 1st instar host, the parasitoids grow more slowly than those laid in 2nd–4th instar host. A pupal host stage prevents the parasitoids’ development. When larvae exceed the threshold size of 5.0×10⁸ μ³, they enter the 2nd instar. A few days after they attain the maximum size of 3.3×10⁹ μ³, they moult and egress from the host body.     

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.     

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.     

Parasitoids of the corn borerOstrinia furnacalis [Lep.: Pyralidae] in the Mariana Islands

A survey of the parasitoids of the Asian corn borer,Ostrinia furnacalis (Guenee), in the Mariana Islands showed that few of the borers were parasitized. Parasitoids were reared from only 30 pupae out of more than 4 500 sampled. Three species of pupal parasitoids were found:Xanthopimpla punctata (F.),Brachymeria albotibialis (Ashmead) andTetrastichus? inferens Yoshimoto. No parasitoids were reared from mature larvae. The only egg parasitoid observed wasTrichogramma chilonis Ishii. During the month prior to the sweet corn harvest, which was the peak period of moth oviposition, about 40% of the egg masses had at least one egg parasitized. An average of about 35% of the eggs within a mass were parasitized.     

Distribution and effectiveness ofAnaphes diana [=Patasson lameerei] [Hym.: Mymaridae], a parasitoid ofSitona spp. Eggs [Col.: Curculionidae] in the Mediterranean region

Surveys conducted from 1973 to 1984 showed thatAnaphes diana Girault was the predominant parasitoid ofSitona spp. eggs throughout the Mediterranean range of Spain, France, Italy, Greece, Bulgaria, Romania, Turkey and Syria. In each of these countries, the mean percentage parasitism of eggs fluctuated between 1.9 and 23.9%. The impact of the mymarid on its host increased considerably from autumn to spring. Two biotypes ofA. diana, one reproducing bisexually, the other being strictly thelytokous, occur sympatrically in the Mediterranean region. The origin of various consignments ofSitona eggs parasitized byA. diana shipped to Australia for field release of the mymarid is recorded. Egg parasitoids were found in the Damascus area (Syria) that may be adapted to and effective under the hot and dry climatic conditions of South Australia.     

Notes onPatasson lameerei [Hym.: Mymaridae], an egg parasitoid ofSitona spp. [Col.: Curculionidae] in the mediterranean region

Patasson lameerei Debauche is the most important of three egg parasitoids found onSitona spp. attacking lucerne and annual medics in the North-Western Mediterranean. The mymarids were lacking in eggs extracted from the soil in Morocco, Algeria and Tunisia. The biology and the behaviour of the egg parasitoid are described. In Central Europe, adults ofP. lameerei are recorded from May to September, but in the Montpellier region (Southern France), this species aestivates in the larval stage within the eggs of its hosts during the same period.     

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.     

The biology ofLophyroplectus luteator [Hym.: Ichneumonidae] onNeodiprion sertifer [Hym.: Diprionidae] in Ontario

Adult femaleLophyroplectus luteator (Thunb.) oviposit in all feeding stages ofNeodiprion sertifer (Geoff.), although they prefer the smallest of any larvae present at a given time. Females tend to distribute eggs contagiously both within and between host feeding colonies. Eclosion of eggs does not occur until after the host has spun its cocoon. Larval development then requires approximately 1 month in the laboratory. There is an obligatory eonymphal diapause which requires a minimum of 60–80 days at 2°C to fulfil, and post-diapause development requires 3–4 weeks.     

Effects of the gregarious parasitoids,Apanteles ruficrus and A. Kariyai,on host growth and development

Two gregarious parasitoids, Apanteles ruficrus and A. kariyai attack larvae of the common armyworm, Pseudaletia separata. Their growth pattern and growth rate of the parasitoids were not affected by host age at the time of oviposition, even though host weight increased exponentially with age. Consequently, the maximal weight of a single parasitoid larva was nearly constant regardless of host instar parasitized. Parasitoid females laid more eggs in later-instar hosts than in earlier-instar hosts. When parasitized at the same age, heavily parasitized hosts attained a larger mass than lightly parasitized larvae. Therefore, the ratio of the maximal weight of the host to the parasitoid mass was nearly constant. These results indicate that host growth is regulated by the parasitoids.     

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.     

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.     

Potential ofGeocoris punctipes [Hemiptera: Lygaeidae] andNabis spp. [Hemiptera: Nabidae] as predators ofEpilachna varivestis [Coleoptera: Coccinellidae]

Predation byGeocoris punctipes (Say) andNabis spp. onEpilachna varivestis Mulsant was studied in the laboratory at 26.7°C and in field cages containing soybeans. Both predator groups fed uponE. varivestis eggs, 1st, 2nd and 3rd stage larvae, but not upon 4th stage larvae, pupae, or adults. G. punctipes females produced significantly fewer eggs when fedE. varivestis eggs or 1st stage larvae than those fedGalleria mellonella (L.). Longevity of maleG. punctipes was significantly reduced when fedE. varivestis eggs; however, female longevity was not affected. Results from field cage tests indicated bothG. punctipes andNabis spp. could significantly reduce the density ofE. varivestis.     

Influence of parasitism byEucelatoria bryani [Dip.: Tachinidae] on the consumption and utilisation of chickpea flour diet byHeliothis armigera [Lep.: Noctuidae]

Fourth and 5th instar larvae ofHeliothis armigera (Hübner) parasitised byEucelatoria bryani Sabrosky consumed significantly less chickpea flour diet than unparasitised larvae of the same age in the laboratory. Significant reduction in diet consumption, larval weight gain and frass produced at 24 and 48 h following parasitisation was observed in 5th instar host larvae. Parasitised larvae retained a greater percentage of food ingested (AD) than did the unparasitised ones. Unparasitised 5th instar larvae ofH. armigera were more efficient in converting the ingested food (ECI) and digested food (ECD) into body substance than larvae of similar age parasitised byE. bryani.     

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.     

Biology ofEpidinocarsis [=Apoanagyrus] lopezi [Hymenoptera: Encyrtidae] an exotic parasite of cassava mealybug,Phenacoccus manihoti [Homoptera: Pseudococcidae] in Nigeria

The biology ofEpidinocarsis (=Apoanagyrus) lopezi (DeSantis) was studied under fluctuating laboratory conditions of 24–31°C and 79–90% R.H. It is a solitary internal parasite. There are 4 tailed larval instars. The total developmental time from egg to adult ranged from 11–25 days, average 18 days. The duration of each developmental stage was: egg 2 days, 1 st instar 1 day, 2nd instar 1 day, 3rd instar 2 days, 4th instar 2 days, prepupa 4 days and pupa 6 days. Males mated several times, females mated once. Mated females produced both males and females, unmated females produced only males. Mated ovipositing females lived for 13 days while non-ovipositing mated females lived for 25 days. Parasitization decreased with increasing host density from 30% at a density of 10 hosts/plant/female to 11% at a density of 50. There was virtually no pre-oviposition period. Based on 10 females, the highest mean daily progeny production was 10. Females have an average oviposition period of 11 days and an average of 67 adult progeny. The sex-ratio was 1∶2.3 in favour of females.     

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.     

Aerial dispersal ofScelio fulgidus [Hym.: Scelionidae], parasite of eggs of locusts and grasshoppers [Ort.: Acrididae]

Scelio fulgidus Crawford, a hymenopterous parasite of eggs ofAcrididae, was discovered in samples of the aerial fauna, collected at 100–300 m altitude over grassland at a site in central western New South Wales at 2 sampling periods in October/November 1979. The parasite was recorded throughout the day in conditions of convective uplift suggesting that extensive diurnal dispersal occurred on the prevailing wind at distances varying from 100 to 300 km per day. Take-off at dusk of its major host, the Australian plague locust (Chortoicetes terminifera Walker), was observed in one period and direct aerial sampling at 100–300 m altitude subsequently confirmed the presence of this locust in the upper airflow at night. The mean wind vector did not differ greatly between day or night during this sampling period, suggesting that parasite and host were dispersed independently over the same general area by prevailing winds. Aerial dispersal provides a new explanation of the parasitism byScelio of egg beds of immigrant swarms of the plague locust in areas where hosts were previously absent.     

Synchrony and impact ofAmitus hesperidum [Hym.: Platygasteridae] on its host,Aleurocanthus woglumi [Hym.: Aleyrodidae] in southern Florida

The synchrony of the citrus blackfly (CBF)Aleurocanthus woglumi Ashby and its parasitoidAmitus hesperidum Silvestri was studied in southern Florida.A. hesperidum adults emerge from 4th instar nymphs 160–300 thermal units after CBF adults. This insured excellent temporal synchronization between the parasitoids and the early CBF instars they prefer since egg to 3rd instar nymph in CBF takes 380 thermal units. AlthoughA. hesperidum parasitized only 29% of the surviving 4th instar CBF, it was the factor responsible for the observed decline in the CBF population level in southern Florida.     

Host discrimination byChelonus insularis [Hym.: Braconidae], telenomus heliothidis [Hym.: Scelionidae], andTrichogramma pretiosum [Hym.: Trichogrammatidae]

The ability of female parasitoids (Chelonus insularis Cresson,Telenomus heliothidis Ashmead, andTrichogramma pretiosum Riley) to distinguish between parasitized and unparasitized tobacco budworm,Heliothis virescens (F.), eggs was determined in laboratory studies. All 3 species were relatively efficient at detecting eggs that were previously parasitized by conspecific females.T. heliothidis andT. pretiosum were able to discriminate on the basis of external examination of host eggs, whereasC. insularis appeared to examine hosts internally as well as externally. In interspecific tests, no species readily rejected eggs parasitized by the other 2 species.