Functional response of Telenomus busseolae (Hym.: Scelionidae) an egg parasitoid of the sugarcane stem borer,Sesamia nonagrioides (Lep.: Noctuidae) at different temperatures

Telenomus busseolae Gahan is the most important egg parasitoid of sugarcane stem borers in Iran. Laboratory experiments were conducted to evaluate the functional response of T. busseolae to egg densities of Sesamia nonagrioides (Lefebvre) under four different temperatures (20, 25, 30 and 35°C). Results of logistic regression revealed a type III functional response for all temperatures tested and type of functional response was not affected by temperature. Roger's random parasite equation was fitted to observed data at 35°C. In the other data sets (collected data under 20, 25 and 30 °C) Roger's equation could not provide meaningful parameters, therefore Holling's disk equation was used to fit the data. The attack rate for T. busseolae varying from 0.001784 to 0.10704, 0.0026 to 0.152, 0.0024 to 0.144 and 0.000866 to 0.05196 per h and estimated handling times were 0.59, 0.50, 0.53 and 0.29 h at 20, 25, 30 and 35°C, respectively. Based on asymptotic 95% confidence intervals, functional response parameters did not differ significantly from 20 to 30°C, which indicates that handling time and attack rate are least affected by the temperature changes. The results suggest a similar performance of T. busseolae against S. nonagrioides eggs at temperatures of 20–30°C. These results show that T. busseolae is well adapted to temperature changes during the sugarcane growing season.     

Egg laying and host stage preference at constant temperatures inEncarsia tricolor [Hym.: Aphelinidae]

Encarsia tricolor Foërster is a facultative autoparasitoid that develops on the important pestTrialeurodes vaporariorum (Westwood) in outdoor crop conditions, which makes this aphelinid species promising for biological control programs in regions where field and protected crops coexist. In this paper we report the results obtained in the study of daily and totalE. tricolor egg laying and of adult female preference for different host stages in which to lay eggs at constant temperatures in the range 10 to 32 °C. Only whitefly nymphs were present in the searching arena (tomato leaflets). The mean number of eggs laid per female in one day ranged from 4.0 (10 °C and 32 °C) to 15.2 (24 °C). The mean total number of eggs increased with temperature from 10 to 28 °C, reaching a maximum of 123 eggs per female at 28 °C, and decreased sharply from 28 to 32 °C. The relation between the intrinsic rate of increase (r_m) and temperature in the range 10 to 28 °C followed a straight line whose equation was r_m=?0.076+0.011*T (R²=0.99). The r_m ofE. tricolor was greater than the r_m ofT. vaporariorum when temperature was higher than 9.2 °C. The preference for any particular host instar in which to lay eggs was not always significant. However, N4 was the host instar preferred whenever preference was statistically significant.     

Life history,immature morphology and adult behavior ofTelenomus solitus [Hymenoptera: Scelionidae]

The results of laboratory studies on the life history, morphology of immature stages, effects of food and water on adult longevity, host age preference for oviposition, parthenogenesis, and adult behavior ofTelenomus solitus Johnson are presented.Telenomus solitus completed its development in 10.8 days (egg, 0.3 day; 1^st instar, 2.7 days; 2^nd instar, 3.7 days; and pupa, 4.1 days). The adults lived longest when provided with both honey and water. Without food, they survived less than 24 h. Parasitization of host eggs varied significantly with their age, being highest in 42 h old eggs. Fewer than 10% of eggs older than 60 h were parasitized successfully. The periodicity of oviposition was unimodal; it occurred throughout the 24 h period and peaked in the late photophase. Females ofT. solitus are arrhenotokous. The behavioral sequences during courtship, mating, and oviposition are described.      

In vitro rearing ofTrissolcus basalis [Hym., Scelionidae] an egg parasitoid ofNezara viridula [Hem., Pentatomidae]

In vitro rearing of the egg parasitoidTrissolcus basalis (WOLL.) from eggs collected on the natural hostNezara viridula (L.) was initiated. Several oligidic diets containing insect material (Manduca sexta hemolymph or host egg content) were tested. Our initial medium with 50% hemolymph induced a high egg mortality, but by decreasing the hemolymph concentration, increasing the hen egg yolk concentration and adding 15% of free amino acids mixture, a hatching rate of 85% of the parasitoid eggs was obtained with 39% reaching the second instar and 33% the third instar. In a medium without hemolymph, but with 18% liquid from parasitized host eggs we obtained 90% to 100% hatching, 25 to 27% reaching the second instar and 8% the third instar. We did not obtain pupation from eggsin vitro, but did get pupae and adults from larvae rearedin vivo to second instar and transfered to anin vitro system.      

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.      

Campoletis sonorensis [Hym.: Ichneumonidae] as a parasitoid ofSpodoptera frugiperda [Lep.: Noctuidae]: Host stage preference and functional response

The response of the parasitoidCampoletis sonorensis (Cameron) as a natural control agent of the fall armyworm,Spodoptera frugiperda (J. E. Smith), was evaluated at 6 host densities and 2 temperature regime. A type-II functional response was exhibited by femaleC. sonorensis in response to varying densities of all armyworn larvae at both temperatures. Significantly more larvae were parasitized at 25°C for the host densities of 60 and 75, than for the same densities at 30°C. Third instar fall armyworm larvae were found to be the preferred stage for parasitization byC. sonorensis. This research was supported by funds from HATCH project no. H-368 as allocated to the Georgia Agricultural Experiment Station.     

Laboratory rearing ofAnaphes sordidatus [Hym.: Mymaridae] on carrot weevil eggs [Col.: Curculionidae]

A technique for rearingAnaphes sordidatus (Girault) on eggs of laboratory-reared carrot weevil,Listronotus oregonensis (Le Conte), is described. Individual rearing was possible by using polyethylene embedding capsules that enabled easy manipulation of parasitized carrot weevil eggs for use in subsequent experimental procedures. The technique described resulted in 65% parasitization of carrot weevil eggs and 90 mn per day were sufficient to obtainca. 200 parasites daily.      

Functional response ofChrysopa carnea [Neur: Chrysopidae] larvae feeding onHeliothis virescens [Lep.: Noctuidae] eggs on cotton in field cages

The functional response of 3rd instarChrysopa carnea (Stephens) larvae feeding on 4 densities ofHeliothis virescens (F.) eggs was determined on caged cotton (Gossypium hirsutum L.).C. carnea larvae had a mean search rate of 1.08×10⁻⁵ ha/predator-day or 0.11 row-m/predator-day.      

Effect of parasitoid density on the functional response and sex ratio of a cynipoid hyperparasitoidAlloxysta pleuralis [Hym.: Alloxystidae]

Experiment where variable densities (1, 2, 5, 10, 25, 50, 100 and 150) of the parasitoid (5–7 d postparasitised aphids (Aphis craccivora Koch). — parasitised by aphidiid parasitoidTrioxys indicus Subba Rao & Sharma) were exposed to individual hyperparasitoidAlloxysta pleuralis (Cameron) indicated following: (1) with increase of initial host (primary parasitoid) densities the number of hosts hyperparasitised increases sigmoidally reaching to a plateau at 50 host similar to thetype 3 functional response of Holling; the curve was described by a logistic eqution [N_hyp=44.0/(1+exp (4.0–0.16 N_p))], (2) greater host mortality was recorded at lower initial host densityes (≤50); (3) the area of discovery of the hyperparasitoid is inversely density-dependent at higher host densities (≥25); and (4) the variation in host number has no significant influence on the sex ratio of F₁ offspring of the hyperparasitoid which ranges between 0.56–0.67. The implications of these responses of the hyperparasitoidA. pleuralis are discussed.      

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.     

Host recognition by the gypsy moth [Lymantria dispar] [Lep.: Lymantriidae] hyperparasite,Eurytoma appendigaster [Hym.: Eurytomidae] of cocoons ofCotesia melanoscela [Hym.: Braconidae]

Artificial and modified natural hosts were exposed to females of the gypsy moth [Lymantria dispar (L.)] hyperparasite,Eurytoma appendigaster (Swederus), to investigate its host recognition behavior on the primary host, which are cocooned larvae of the gypsy moth parasite,Cotesia melanoscela (Ratzeburg). Material(s) which caused drilling behavior by the hyperparasite on host cocoons were extracted with both polar and non-polar solvents. However, cocoons washed with large volumes of solvent still caused substantial drilling activities by females, suggesting that additional cues may be important. Results suggest that host recognition in this hyperparasite involves a variety of host characteristics.      

Mortality fecundity and longevity of parasitoids of the spotted tentiform leafminer,Phyllonorycter blancardella [Lep.: Gracillariidae] at constant temperatures in the laboratory

The results of laboratory tests showed that mortality of adult eulophids, primarily,Sympiesis sericeicornis (Nees),S. marylandensis Girault andPnigalio flavipes (Ashmead), was significantly (P<0.05) lower than that of adultPholetesor ornigis (Weed) when exposed to temperatures between 20° and 36°C for 48 h. However, adultP. ornigis lived longer than those of the eulophids at 15°C, but were shorter liver at 33°C. The fecundity ofP. ornigis was little affected at temperatures of 15°, 20°, 24° and 33°C. Exposure of adultP. ornigis to 30°C for 16 h resulted in reduced longevity of both sexes but did not affect fecundity or the proportion of females ovipositing. Mortality of pupae of the eulophids was significantly lower than that of pupae ofP. ornigis at temperatures of 20°, 30° and 33°C. The sex ratio of surviving adults was not affected by temperature.      

Lysiphlebus testaceipes,an introduced aphid parasitoid in portugal [Hym.: Aphidiidae]

Lysiphlebus testaceipes (Cresson), an exotic parasitoid species introduced in 1973–74 into southern France and subsequently widespread over the whole mediterranean France, Italy and Spain has become established even in Portugal since 1985. It was found on the southern coast of Portugal parasitizingAphis nerii Boyer de Fonscolombe. In 1986 it spread towards the North, its host range expanded and now includesAphis chloris Koch,Aphis citricola van der Goot,Aphis fabae Scopoli,Aphis frangulae Kaltenbach,Aphis gossypii Glover,A. nerii, Aphis parietariae Theobald,Aphis sedi Kaltenbach,Toxoptera aurantii (Boyer de Fonscolombe). The proved complete development and a high parasitization ofL. testaceipes onA. citricola is the 1st case in the whole Mediterranean, from where only incomplete development and a negligible percentage of parasitization (Italy) have been reported. Both the host range composition and development ofL. testaceipes indicate an increase of genetic polymorphism in the established populations. Interspecific relations ofL. testaceipes and the indigenous parasitoid species indicate an increasing dominance of the exotic biocontrol agent.      

Importation,colonization and establishment ofAnagyrus indicus [Hym.: Encyrtidae] onNipaecoccus viridis [Hom.: Pseudococcidae] in Jordan

Anagyrus indicus Shafeeet al. was collected on the island of Guam and released in the Jordan River Valley of Jordan in order to regulateNipaecoccus viridis (Newstead) on citrus.A. indicus was originally released in February 1984 and became colonized by April of the same year. It also dispersed by natural means up to 61 km following the original release and colonized that same year on infestedZizyphus sp. By spring of 1985 it became the dominant parasitoid attackingN. viridis. Another parasitoid,Anagyrus kamali Moursi, was collected in Jordan in June of 1985 for the first time. This latter parasitoid apparently moved into the Jordan River Valley by means of natural dispersal from a neighboring country. Infestations ofN. viridis have been greatly reduced in areas whereA. indicus became established. This paper reports the results of research only. Mention of a proprietary product does not constitute an endorsement for its use by USDA.     

Cold tolerance of coccons ofAllorhogas pyralophagus [Hym.: Braconidae]

Cold tolerance studies were conducted under laboratory conditions for coccons ofAllorhogas pyralophagus Marsh, a Mexican parasitoid of graminaceous borers. By storage, developmental time (from cocoon to adult emergence) could be extended by 2 to 6 times. However, cocoons stored for more than 14 days at 2°C failed to survive, while at 5 and 10°C, about 50% emergence was recorded for upto 21 days of storage. With respect to survival and adult longevity, 10°C seemed to be the most suitable storage temperature. Pre-emergence period was also significantly increased by storing cocoons for 21 to 35 days at this temperature. Sex-ratio of emerging adults was not significantly affected by storage. Fecundity was adversely affected in all the treatments except in the case of females emerging from cocoons stored at 5°C for 7 days. The progeny of parasitoids which emerged from cocoons stored at 5 and 10°C for 35 days consisted of only males. It is clear from the present study thatA. pyralophagus cocoons are more amenable to short-term storage. Contribution No. 285/87 of the Indian Institute of Horticultural Research, Bangalore-560 089.     

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.     

Effects of winter temperatures on the sex ratios ofAphytis melinus [Hym.: Aphelinidae] in the San Joaquin Valley of California

Laboratory bioassays of overwintering field populations of the California red scale parasitoidAphytis melinus DeBach showed a shift in sex ratio of F₁ progeny after prolonged exposure to winter temperatures in Tulare County, California. In 7 of 8 tests, short-term winter field exposure (<75 days) did not result in a significant male bias in sex ratios of F₁ progeny when compared to sex ratios observed in laboratory cultures maintained at 27°C. Long term exposure (109–139 days), however, resulted in significantly (P<0.05) higher male bias in F₁ sex ratios in 5 of 6 tests. These results from field populations ofA. melinus agree with conclusions of low temperature laboratory tests onAphytis species (lingnanensis, melinus) by other workers. Mention of a proprietary or commercial product in this paper does not constitute an endorsement of this product by the University of California.     

Competition betweenBracon mellitor [Hym.: Braconidae] andCatolaccus grandis [Hym.: Pteromalidae] for their hostAnthonomus grandis [Col.: Curculionidae]

BioControl - Laboratory studies of competition between populations of 2 parasitoids of the cotton boll weevil,Anthonomus grandis Boheman, showed that populations ofCatolaccus grandis (Burks)...     

Biological studies withChrysocharis parksi [Hym.: Eulophidae] a parasite ofLiriomyza spp. [Dipt.: Agromyzidae]

Biological studies withChrysocharis parksi Crawford, a parasite of agromyzid leafminers, were conducted.C. parksi successfully parasitized the following species in the genusLiriomyza Mik.,L. huidobrensis (Blanchard),L. sativae Blanchard,L. trifolii (Burgess), andL. trifoliearum Spencer. Successful parasite development was recorded from 8 plant families and 16 genera. Host plants which were suitable for leafminer development to the adult stage were also suitable for parasite development. Mean immature developmental period (egg to adult, usingL. trifolii as the host) at 21.1°, 26.7°, and 32.2° C was (for both sexes) 23, 14, and 14 days, respectively. Longevity of females provided only water was inversely related to temperature; significantly longer survival occurred at 21.1° C (5.0 days) compared to 26.7° C and 32.2° C (3.2 and 2.1 days, respectively). The addition of honey to the diet significantly improved longevity of both sexes at all temperatures. Adult female parasites which were provided an average of 33.0L. trifolii larvae per day produced an average of 135 offspring at a constant 26.7° C.C. parksi host-fed on ca. 3.7 leafminer larvae per day over an 11-day adult lifespan.      

Bionomics ofTrioxys indicus [Hym.: Aphidiidae], a parasitoid ofAphis craccivora [Hem.: Aphididae]: 31. Effect of host haemolymph on the numerical response of the parasitoid

The influence of kairomones on the numerical response of the parasitoidTrioxys indicus against its hostAphis craccivora at its varying density was studied. The kairomones (applied as aqueous extract of the host) significantly enhanced the rate of parasitisation and multiplication and the area of discovery of the parasitoid and also the K-values of mortality of the host at all parasitoid densities introduced (1, 2, 4, 8, 12 and 16 parasitoids) into troughs having about 200 hosts. The sex-ratio of F₁ offspring decreased at lower parasitoid densities and remained more or less unchanged at higher parasitoid densities after the application of kairomones. The present findings indicate that if kairomones are applied properly, the number of hosts destroyed by a stimulated parasitoid will be about 200, twice the number reported earlier, thus fewer parasitoids will be needed to regulate an estimated population of the hosts.