Adult biology ofTelenomus remus [Hymenoptera: Scelionidae] under laboratory conditions

Males ofTelenomus remus Nixon were attracted to the female by a pheromone present for the last 2 days of pupal life and the first few minutes after emergence, but not thereafter. Females in groups lived 6 times longwer than solitary ones; males did not show such a difference. Unmated males lived 8 days, and mated ones 1 day only. The normal sex ratio of 60–70 % females declined to 22 % as the females aged. Under conditions promoting superparasitism, the sex-ratio was close to 50 %. Duration of oviposition was 37 sec. with young females, but increased to over 50 sec. with age. All 3 layers of the host egg mass were parasitized equally. Several females may oviposit simultaneously on the same host batch without showing any aggression. About 60 progeny were produced during the first day of the female's life, but 20 or fewer thereafter.     

The biology ofHyperaspis jucunda [Col.: Coccinellidae] an exotic predator of the cassava mealybugPhenacoccus manihoti [Hom.: Pseudococcidae] in southern Nigeria

The biology ofHyperaspis jucunda (Muls.) was studied at 27°C and the incubation period averaged 5.1 days. The 1st, 2nd, 3rd and 4th larval instar averaged 2.5; 2.8; 3.4 and 5.0 days respectively. Larval development was completed in about 13.8 days while it took 7.1 days for the pupae. The total developmental time averaged 26.4 days. Mean longevity was 100 and 101 days for males and females respectively. The premating period was 19–24 h while the preoviposition period averaged 6.3 days. The generation cycle (egg to egg) averaged 32.8 days. The oviposition period was about 93 days during which an average female laid 456 eggs.     

Reciprocal host-parasite relations as exemplified byChrysomphalus aonidum [Homoptera: Diaspididae] andPteroptrix smithi [Hymenoptera: Aphelinidae]

The parasitePteroptrix smithi (Compere) prefers to oviposit in hosts (Chrysomphalus aonidum L.) that are at least 5 weeks old. Parasitization of two week old hosts is possible, but only few parasites reach maturity, and the developmental duration is lengthened by about one third. The sex ratio with both large and small hosts was usually 1∶2, whereas the average number of emerging parasites varied from 1.9 for 2 week old hosts to 3–4 for 5 week old ones. Non-ovipositing scales that are attacked by the parasite will fail to reproduce and ovipositing ones will only produce part of their potential progeny. Other externally observable changes in the young parasitized host include the formation of a thinner scale cover that differs in coloration and size from the normal one.     

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.     

Observations onHexamermis albicans [Nematoda: Mermithidae] recovered fromLymantria dispar andStilpnotia salicis [Lep.: Lymantriidae] in west Germany and Austria

The mermithid,Hexamermis albicans (Siebold) was recovered from larvae ofLymantria (Porthetria) dispar (L.) collected from various localities in Burgenland, Austria in 1974 and 1975 and from Würzburg, Germany, in 1974. It was recovered also fromStilpnotia salicis (L.) in Austria in 1974. The mermithid was recovered from all field collected larval instars. The majority of the nematodes emerged fromL. dispar larvae collected as second and third larval instars although some nematodes were recorded from larvae collected as first instar larvae still on the egg mass. Peak emergence occurred in the laboratory during the period June 11–17 of both years, but emergence continued at a much lesser degree through the end of larval development. The nematode was found in both high and low host density populations. In 3 localities studied both years, there was a general increase in the percentage parasitism the second year. However, except for one locality in Austria in 1975 where individual samples produced up to 11% parasitism, the overall parasitism increased from 0.4% in 1974 to only 2.5% in 1975.     

Effect of 3 insect growth regulators on larval development,fecundity and egg viability of the coccinelidChilocorus bipustulatus [Col.: Coccinelidae]

The effect of 3 insect growth regulators — methoprene, diflubenzuron and RO 13-5223, on the coccinelidChilocorus bipustulatus L. was studied in the laboratory. Feeding onChrysomphalus aonidum (L.) orAspidiotus hederae Vallot (Diaspididae) treated with the IGRs at the concentration of 0.025% a.i. revealed the following: diflubenzuron caused a complete mortality of 1 st instar larvae; methoprene and RO 13-5223 did not arrest larval development but inhibited pupation; fecundity of sexually mature females was not affected by the 3 IGRs but egg hatch was completely inhibited; egg viability was regained when IGR-exposed females had been transferred to an uncontaminated environment.     

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.     

Larval descriptions and biology ofTephritis dilacerata [Dip.: Tephritidae], a candidate for the biocontrol ofSonchus arvensis in Canada

The immature stages ofTephritis dilacerata Loew are described. Newly emerged males become sexually mature in about 1 week; females in 2–5 weeks. Courtship is described. Mated females lay eggs in groups of 6–7 into unopenedSonchus arvensis L. flower buds. The fly weaves the ovipositor between the bracts into the bud so that the release of latex is avoided. The length of the ovipositor corresponds to the length of the oviposition route. At 24 °C the eggs hatch in 4–5 days and the larvae mature in an additional 9–10 days. The larvae transform the bud into a simple gall and consume developing ovaries and receptacle. Attacked buds rarely flower and therefore do not produce seed. Pupation lasts about 2 weeks. The flies overwinter as adults in Europe, but no diapause occurred in the laboratory. The growth of the gall affects larval survival and when food is scarce some larvae develop at the expense of others. The European distribution of the fly is illustrated.T. dilacerata is considered a promising biocontrol agent forS. arvensis in Canada.     

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.     

Laboratory studies on the biology ofSpalangia nigra [Hym.: Pteromalidae]

At 21 °C,Spalangia nigra Latreille (Hymenoptera: Pteromalidae) averaged 29.3 days between exposure and emergence of 1^st progeny from host house flies,Musca domestica L. (Diptera: Muscidae). At 27 °C, the average developmental time to 1^st emergence was reduced to 26.6 days, and a majority of adult wasps emerged from host house fly puparia between 29 and 40 days postoviposition. The sex ratio of progeny ranged from 1.4 to 1.8 female-to-male, but all progeny of virgin females were male. Male wasps lived from 6.8–15 and females 11–17.8 days at 27 °C; honey as a food source increased longevity. No significant differences in parasitism byS. nigra were associated with host house fly pupal densities ranging from 1 to 200 pupae per female-male pair of wasps, but average percent parasitism decreased at host densities greater than 50. House fly pupae exposed to parasitism at ages ranging from 4 to 96 h did not differ in subsequent production of adult flies.S. nigra did not demonstrate preference for house flies or stable flies,Stomoxys calcitrans (L.) (Diptera: Muscidae) as hosts. The results of these studies indicate thatS. nigra may contribute significantly to previously unexplained mortality of house flies and stable flies.      

Bioecology ofLydella thompsoni Herting, [Dip. Tachinidae] within the Rhone Delta in Southern France

Lydella thompsoni Hertin,Tachinidae, is an endoparasitoid frequently associated in southern France with larvae ofOstrinia nubilalis, Pyralidae, Sesamia nonagrioides, Noctuidae, Archanara geminipuncta andA. dissoluta, Noctuidae. The tachinid was reared successfully at 21°C in the laboratory by providing the adult flies with a high humidity, a light intensity of 8,000–10,000 lux for mating and a mixture of casein proteolysate and honey as food. Under such conditions, the flies lived for about 30 days and about half of them mated successfully. Hosts were infested by dissecting mature tachinid females and placing 1–2 of the extracted planidia onto each moth larva. Half of the planidia successfully entered their larval hosts. The biology of the tachinid larvae was studied on the 2 main hosts,O. nubilalis andS. nonagrioides. At 21°C, 25°C and 28°C, larval development took less time onO. nubilalis than onS. nonagrioides. At 25°C, female larvae onO. nubilalis required 9.0±0.5 days and onS. nonagrioides 10.5±0.3 days, male larvae onO. nubilalis required 8.3±0.5 days and onS. nonagrioides 10.6±0.3 days. Pupal duration was also influenced by the larval host. In winter, 2nd instar larvae ofL. thompsoni enter a resting or quiescent condition. This condition is terminated sooner (December–January) in larvae developing onS. nonagrioides than in those developing onO. nubilalis (February–March). The life cycle of the tachinid in the field was studied by trapping flies in water dishes and by collecting parasitized host larvae from various plants. Flies were caught from April to October, mainly in September. Larvae of the spring generation of the parasitoid developed on larvae of species ofArchanara that fed on the reed,Phragmites communis. From 1976 to 1982, parasitism averaged about 16%. Parasitism by summer generation onS. nonagrioides was highest (4–5%) in June. Parasitism ofO. nubilalis did not change by more than 2 fold in either of the 2 summers studied (10–17 % in 1981, 6–10 % in 1982). By September the numbers of host larvae had increased to 10–20 times the number available earlier in the season. Larval populations ofL. thompsoni similarly increased from 3–400 larvae per ha in June to 4–5,000 per ha in September. The stability of the relationship between this parasitoid and its hosts in southeastern France is discussed and compared to relationship described elsewhere.     

Forest and laboratory evaluations of hybridizedApanteles melanoscelus [Hym.: Braconidae], a parasitoid ofPorthetria dispar [Lep.: Lymantriidae]

Hybrids ofApanteles melanoscelus (Ratzeburg) were produced from colonies originating from France, Yugoslavia, and Connecticut. All strains, as well as freshly collected “wild” Connecticut parasitoids of the same species were evaluated in the laboratory for developmental rate, host attack rate, and sex ratios. Development was significantly slower in all the laboratory strains compared to the progeny of forest collected Connecticut females. Progeny production was greater (almost 2X) for the “wild” females and the French-Yugoslavian-Connecticut hybrid than for the laboratory Connecticut strain. The proportion of females collected from the “wild” (Connecticut) strain was higher than that observed in any laboratory strain. A field test was conducted using the triple hybrid in 3 release plots with ca. 6000A. melanoscelus cocoons released per plot in central Connecticut, U.S.A. Weekly collections of gypsy moth larvae showed that the % parasitism was significantly higher in release plots than in the 3 check plots. These results suggest the value of inundative releases ofA. melanoscelus for reduction of sparse gypsy moth populations, but they did not show that hybridization of these strains produced a more effective parasitoid under forest conditions.     

Effect of the number of parasitoid (Apanteles kariyai) eggs [Hym.: Braconidae] on the growth of host (Leucania separata) larvae [Lep.: Noctuidae]

The developmental interactions between a gregarious endoparasitoid,Apanteles kariyai Watanabe and its host,Leucania separata Walker, were investigated. The parasitoid laid more eggs in older hosts. Host size increased gradiently as the instar advanced, but the number of eggs laid per host did not increase accordingly. The net weight of the host was correlated positively with the number of eggs laid and with the total weight of parasitoids, especially in cases of parasitization at 3rd (5th-instar type), 4th and early 6th instar where the correlation was significant at 1% level. It follows therefore that the more parasitoids there are relative to their host size, the more they contribute to make the host size larger.     

Fecundity,nymphal development and longevity of field‐collected tropical bedbugs,Cimex hemipterus

This study examined the fecundity, oviposition, nymphal development and longevity of field‐collected samples of the tropical bedbug, Cimex hemipterus (Fabricius) (Hemiptera: Cimicidae). Under environmental conditions of 26±2°C, 70 ± 5% relative humidity and a 12‐h photoperiod, with bloodmeals provided by a human host, six strains of tropical bedbug had a fecundity of up to 50 eggs per lifetime, over 11–14 oviposition cycles. Increased feeding frequency improved fecundity. After feeding and mating, adult females normally took 2–3 days to produce a first batch of eggs. The oviposition period lasted 2–7 days before cessation of the oviposition cycle. The egg incubation period usually lasted 5–7 days before the emergence of first instars. The nymphs underwent five stadia (the first four of which each took 3–4 days, whereas the last took 4–5 days) before becoming adults at a sex ratio of 1 : 1. More than five bloodmeals were required by the nymphs to ensure a successful moult. Unmated adults lived significantly longer than mated adults (P < 0.05). Unmated females lived up to almost 7 months, but the longevity of mated males and females did not differ significantly (P > 0.05).     

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.     

Effects of parasite density and host availability on progeny production byBiosteres (Opius) longicaudatus, [Hym.: Braconidae], a parasite ofAnastrepha suspensa [Dip.: Tephritidae]

Progeny production ofBiosteres (Opius) longicaudatus Ashmead, a larvalpupal parasite of the Caribbean fruit fly,Anastrepha suspensa (Loew) was affected by host availability, previous ovipositional experience, and parasite density and age. Parasitization rates were evaluated in 24.5 cm³ ovipositional cages at parasite densities of 25, 125, and 250 male-female pairs by exposingB. longicaudatus adults to (a) 500A. suspensa larvae for a 24 h period or (b)ad libitum host larvae for each of the 14 days following eclosion. The mean numbers of parasite progeny produced at the 25, 125, and 250 densities were 1076, 1896, and 2038, respectively. The number of progeny produced per surviving female parasite was inversely proportional to the adult parasite density and relatively more female progeny were produced as the adult parasites aged. Host mortality was significantly higher among parasitized larvae. Maximum rearing efficiency was achieved at the 125 density.     

Parasitism byEphedrus cerasicola [Hym.: Aphidiidae] developing in different stages ofMyzus persicae [Hom.: Aphididae]

The parasitoidEphedrus cerasicola Stary oviposited in the 4 nymphal instars and in newly moulted apterous adults ofMyzus persicae (Sulzer). Development and reproduction of unparasitized and parasitized aphids at 21°C were compared. Unparasitized aphids developed to adults in 6.5 days and started to reproduce after 7 days. Longevity varied between 7 and 42 days. Net reproductive rate (R₀) was 40.7. In contrast to older nymphs, aphids parasitized in the 1 st instar almost never reached the adult stage before mummification. Aphids parasitized in 2nd, 3rd and 4th instar and as newly moulted adults produced respectively 0.07 %, 2 %, 23 % and 32 % of offspring produced by unparasitized aphids. Corresponding reproductive periods were 1, 1.4, 3 and 4 days. Host age at parasitization had a slight effect on the parasitoid's developmental rate and had no effect on egg or pupal survival, or on the sex ratio of the emerging parasitoids.     

Laboratory studies ofDiadegma cerophagus [Hym.: Ichneumonidae], a parasite introduced to controlPlutella xylostella [Lep.: Hyponomeutidae] in Malaysia

Laboratory studies were conducted to determine some of the attributes ofDiadegma cerophagus Gravenhorst, a parasite introduced to controlPlutella xylostella (L.). Longevity studies have shown that ♂ and ♀ could live for 40 and 73 days respectively when fed on diluted honey. The parasite is capable of attacking an average of 117±10 caterpillars per ♀. The number of caterpillars attacked per ♀ is dependent on the life span of the ♀. The average area of discovery ofD. cerophagus, based on studies of single searching parasites, was found to be 1.20±0.21. The area of discovery was found to decrease with increase in parasite or host density. However, the k-value would increase with increasing parasite density and decrease with increasing host density. The life-cycle ofD. cerophagus is as follows: egg stage, 1.5 to 2 days; larval stage, 5 to 8 days and pupal stage, 6 to 9 days. There are 4 larval instars and the duration of each instar is dependent on the age of the host attacked. The duration of the larval stage averaged 6.5 days when 1- and 2-day old caterpillars were exposed toD. cerophagus and took 5 days when 3- and 4-day old caterpillars were exposed.     

Oviposition of potato tuber moth,Phthorimaea operculella zell. (Lepidoptera: Gelechiidae); fecundity in relation to mated state,age, and pupal weight

The fecundity of individually held potato tuber moths ranged from 0 to 236 eggs deposited over the total life span. The number of eggs laid was not correlated with pupal weight, but pupal weight and the number of mature eggs in the ovaries shortly after emergence from the pupa were positively correlated. This initial egg complement accounted for slightly more than half of the total number of eggs laid. Among moths held in groups at 25°c in the absence of host‐plant material, multiple‐mated females did not lay significantly more eggs (mean 98.4) than those mated only once (mean 91.0), but their life span was shorter (8.5 days cf. 14.4). Virgin females laid a small number of non‐viable eggs (mean 7.7), and lived about as long as single‐mated females. Males were significantly longer‐lived (23.6 days) than all groups of females. Peak oviposition of mated females occurred 2–5 days after emergence, and declined to low levels by age 7 days.     

Aspects of the reproductive biology of Pseudaphycus maculipennis (Hym: Encyrtidae), a parasitoid of obscure mealybug,Pseudococcus viburni (Hem: Pseudococcidae)

Laboratory experiments to determine aspects of the reproductive biology of Pseudaphycus maculipennis are described. All experiments were carried out at a constant temperature of 21 ± 2 °C, a 16-h photoperiod and ambient RH. Pseudaphycus maculipennis was shown to be an arrhenotokous, synovigenic, gregarious endoparasitoid of Pseudococcus viburni. Females and males lived for 16 and 11 days, respectively, when fed either honey-agar or mealybug honeydew. Relatively, large instars (third instar or adult females) were preferred for oviposition; mated females parasitized more mealybugs than unmated females, and the progeny sex ratio favored females by 3:1. Egg load increased with age from emergence to day 8, averaging 23 mature eggs/female. Mean realised daily fecundity never exceeded 5, with a mean lifetime fecundity of 46 eggs/female. Parasitised mealybugs remained alive for about 5 days and then mummified. Total development period was 20–21 days (larva 4–5 days, prepupa 3 days, pupa 8–9 days). Development periods of eggs and individual larval instars were not measured. A mean of 3.01 ± 0.1 parasitoids/mealybug were reared after individual parasitism events, increasing through super-parasitism (either self or conspecific) to 9 parasitoids/mealybug when hosts were exposed to competing females. Pseudaphycus maculipennis progeny emerged from the mummies in discrete cohorts over periods ranging from 3 min to 18 h (depending on the number of cohorts).