Corcyra Cephalonica Research Articles

Grain storage and insect pests of stored grain in rural Niger

We surveyed 1293 farmers and traders in southern Niger to learn about their grain storage practices and their views on the storage pest problem. We identified the insect species found in samples obtained from 40 localities in three regions of the country. We stored 371 grain samples collected from respondents in the laboratory for seven months to allow populations of the insects present to develop and emerge and the resultant grain weight loss to be determined. The commodities most commonly stored in Niger were millet and sorghum, kept in storage on average for about 6 months by 53% and 80% of respondents respectively. When millet samples from respondents were kept in the laboratory for seven months, two pests were found, the rice moth Corcyra cephalonica Stainton, and Tribolium spp. This millet experienced a weight loss of 17.1% during seven months storage. Tribolium castaneum Herbst, Sitophilus granarius L., Cryptolestes spp, Sitotroga cerealella Oliver, Trogoderma granarium Everts, Rhyzopertha dominica F. and C. cephalonica were found in stored sorghum, which lost 10.1% weight after seven months. Eleven other grains or foods were stored by 2.9–24.4% of respondents. Recorded weight losses were 15.9% for groundnuts, 12.6% for paddy rice, 7.6% for sesame and 7.4% for maize. Seeds of Hibiscus sabdariffa L. and Bambara groundnut were essentially destroyed by bruchids during storage, mean weight losses being 83.9% and of 61.8% respectively. Most respondents took no measures to control insect pests in their stored grains. Food security and quality in Niger would be greatly improved if Africa-manufactured technology that is safe, low-cost, insecticide free, and widely available could be implemented for postharvest storage of food grains.

Diversity and distribution of stored grain insects among the Soliga Tribal settlements of Biligirirangana Hills, Karnataka, India

Soligas are a tribal community living in the forest areas of Biligirirangana Hills in southern Karnataka, India. Soligas cultivate several crops in small patches located close to their settlements for subsistence. During the present investigation, the diversity, distribution and abundance of insects that infest food grains stored by Soligas were studied and the influence of biotic and abiotic factors was assessed. Grains held in storage by Soligas were found to be infested by 13 species of insects. The distribution and abundance of all the species were mapped. Among these, Sitophilus oryzae was the most widely occurring and abundant species, while, Corcyra cephalonica was the least abundant and less frequently occurring species. Species richness was influenced by the number of food grain types stored by Soligas. It was observed that the biotic and abiotic factors did not influence the diversity and distribution of stored grain insects. Instead, the observed pattern of stored grain insect distribution was found to be influenced by anthropogenic factors like food grain sharing habits among the Soligas and accessibility to the towns and cities from their settlements.

A novel Wolbachia strain from the rice moth Corcyra cephalonica induces reproductive incompatibility in the whitefly Bemisia tabaci: sequence typing combined with phenotypic evidence.

Wolbachia are a group of maternally inherited bacteria frequently found in arthropods and filarial nematodes. They have recently attracted attention for their ecological roles in manipulating host reproduction, their potential use in biological control of pest insects and medical significance. Classification of Wolbachia strains is currently solely based on molecular methods. However, the strains even with identical sequence types may induce different host phenotypes. Here we isolated a Wolbachia strain from the rice moth Corcyra cephalonica (designated as wCcep_B_BJ), which was shown to share multilocus sequence typing and Wolbachia surface protein hypervariable region profiles with a cytoplasmic incompatibility (CI)-inducing strain in supergroup B, but the phenotype wCcep_B_BJ may induce needs to be determined. We thus transinfected it into the whitefly Bemisia tabaci harbouring an A-Wolbachia through nymphal microinjection. Fluorescent in situ hybridization demonstrated that wCcep_B_BJ was successfully transinfected into B. tabaci and transmitted to offspring through host eggs. Reciprocal cross showed that wCcep_B_BJ induced a strong bidirectional CI in the transinfected host without imposing a significant cost on female fecundity. Our results suggest that wCcep_B_BJ may be a promising strain for biocontrol of B. tabaci, an important agricultural pest insect.

Thermal death kinetics of fifth-instar Corcyras cephalonica (Lepidoptera: Galleriidae).

The infestation of rice moth, Corcyras cephalonica (Lepidoptera: Galleriidae), causes severe losses in postharvest walnuts. Heat has been studied as a phytosanitary treatment to replace chemical fumigation for controlling this pest. Information on kinetics for thermal mortality of C. cephalonica is needed for developing effective postharvest phytosanitary thermal treatments of walnuts. Thermal death kinetics of fifth-instar C. cephalonica were investigated at temperatures between 44°C and 50°C at a heating rate of 5°C min−1 using a heating block system. The results showed that thermal-death curves for C. cephalonica larvae followed a 0 order of kinetic reaction. The time to reach 100% mortality decreased with increasing temperature from 150 min at 44°C to 2.5 min at 50°C. The activation energy for controlling C. cephalonica was 466–592 kJ/mol, and the z value obtained from the thermal death time curve was 3.3°C. This kinetic model prediction could be useful in designing the thermal treatment protocol for controlling C. cephalonica in walnuts.

Influence of Seasons and Inoculum Dosages on the Production Efficiency of <i>Corcyra cephalonica</i> Stainton

Corcyra cephalonica is a laboratory host used for multiplication of parasitoids, predators and entomopathogens. The present study is aimed to understand the effect of seasons and inoculum dosages of Corcyra eggs on the production efficiency. Egg production ranged from 3.1 to 5.8 cc per box during the different seasons and minimum production being recorded during dry months. The dosages tested were 0.5, 0.25 and 0.125 cc of Corcyra eggs / rearing box. Maximum per cent moth emergence (83.5%), shorter developmental duration (40.4 days) and higher fecundity (467 no.) of emerged moths were recorded in the boxes with 0.125 cc (2000 eggs) inoculum. Validation of experiments indicated that compared to the boxes with 0.5 cc inoculum, a 2.15, 1.44, 1.35 and 1.49 times increase in average production per box from 0.125cc infested boxes more during monsoon, post monsoon, dry and summer months, respectively. The data generated can be utilized for improving the protocol for mass rearing of Corcyra cephalonica .

Studies on Biology of <i>Amphibolus venator</i> (klug) on <i>Corcyra cephalonica</i> Stainton

The biology of Amphibolus venator was studied on Corcyra cephalonica under laboratory conditions. The egg period was 16.33±1.24 days, with the range of 15-18 days. There were five nymphal instars in Amphibolus venator . The nymphal period for I, II, II, IV and V instar lasted for 23.33±3.14, 30.83±6.06, 38.33±9.70, 40.16±3.67 and 40.00±4.63 days, respectively. The total developmental period was 172.65±15.50 days. The longevity of female was 65.83±2.4 days with range of 63 to 68 days and male was 59.33±2.49 with range of 57 to 62 days; the fecundity per female was 210 with range of 200 to 220 eggs.

Influence of Seasons and Inoculum Dosages on the Production Efficiency of Corcyra cephalonica Stainton

Corcyra cephalonica is a laboratory host used for multiplication of parasitoids, predators and entomopathogens. The present study is aimed to understand the effect of seasons and inoculum dosages of Corcyra eggs on the production efficiency. Egg production ranged from 3.1 to 5.8 cc per box during the different seasons and minimum production being recorded during dry months. The dosages tested were 0.5, 0.25 and 0.125 cc of Corcyra eggs / rearing box. Maximum per cent moth emergence (83.5%), shorter developmental duration (40.4 days) and higher fecundity (467 no.) of emerged moths were recorded in the boxes with 0.125 cc (2000 eggs) inoculum. Validation of experiments indicated that compared to the boxes with 0.5 cc inoculum, a 2.15, 1.44, 1.35 and 1.49 times increase in average production per box from 0.125cc infested boxes more during monsoon, post monsoon, dry and summer months, respectively. The data generated can be utilized for improving the protocol for mass rearing of Corcyra cephalonica .

Effectiveness of the egg parasitoid Trichogramma evanescens preventing rice moth from infesting stored bagged commodities

Experiments were carried out in the laboratory with the aim of accessing the effectiveness and parasitism by Trichogramma evanescens to prevent Corcyra cephalonica from infesting rice in paper and jute bags. Eight small jute or paper bags filled with 5 kg of organic rice grains were prepared and the openings sealed. Sentinel egg cards were prepared with thirty fresh eggs of C. cephalonica glued onto small pieces of paper cardboard. Eight sentinel egg cards were introduced into a plastic box measuring 60 × 40 × 21 cm, i.e four cards on top surface of the bag and the box bottom, respectively. Approximately 500 adults of T. evanescens were released 10–30 cm away from the egg cards. The control boxes contained no parasitoids; there were five replicates for all treatments and controls. Two experimental conditions were tested, i) placing a single T. evanescens-release unit with sentinel egg cards placed every 3–4 days without any further replacement of the release unit for three weeks, ii) both new host eggs and T. evanescens release units were replaced every 3–4 days. Mean emergence of C. cephalonica was significantly (p > 0.001) suppressed by the release of T. evanescens. There was statistically no significant difference on the number of emerged moths on paper bag compared to jute bag. All sentinel egg patches were visited by T. evanescens. There was no correlation between the distance (10–30 cm) at which the sentinel egg cards were placed away from the T. evanescens release point and the number of parasitized C. cephalonica eggs. There was no decrease in parasitism over time. The results demonstrate that T. evanescens has the potential for host-location ability and parasitism of C. cephalonica both on paper and jute bags. This parasitoid could be a promising candidate for the biological control of moth pests in bagged stored products.

The Importance of Relative Humidity for Telenomus remus (Hymenoptera: Platygastridae) Parasitism and Development on Corcyra cephalonica (Lepidoptera: Pyralidae) and Spodoptera frugiperda (Lepidoptera: Noctuidae) Eggs

The rearing of Telenomus remus (Nixon 1937) has been limited due to the difficulty of its development in its natural host, the eggs of Spodoptera frugiperda (J.E. Smith). Environmental conditions can strongly affect egg’s parasitoid rearing on factitious hosts; however, until now only the effects of temperature have been studied. The importance of relative humidity in T. remus parasitism is poorly understood; therefore, this study evaluated its parasitism on Corcyra cephalonica (Stainton, 1866) and S. frugiperda eggs under different humidity regimes. Lifetime parasitism and parasitism viability were higher on S. frugiperda eggs and did not differ among humidity regimes. However, these biological parameters were higher at 80% humidity than at both 40 and 60% humidity when T. remus was reared on C. cephalonica eggs. The sex ratio was always higher than 0.6 for all hosts and humidity regimes. Parental female longevity was only influenced by humidity when presented to C. cephalonica eggs: it was higher at 60 and 80% humidity. T. remus egg-to-adult period was longer in C. cephalonica eggs; however, no difference between humidity regimes was noted. In general, relative humidity affected T. remus development only when it was reared on C. cephalonica eggs. For this factitious host, 80% humidity was shown to be appropriate for egg parasitoid rearing due to its better biological performance.

Effect of Different Diets on Biology of Corcyra Cephalonica (Stainton) under Laboratory Condition in Chitwan, Nepal

The experiments were conducted from 10th October, 2013 to 10th January, 2014 in Entomology Laboratory of National Maize Research Program, Rampur, Chitwan, Nepal at 26±2ºC and 70±5% RH in order to assess diet performance on the biological parameters of Corcyra cephalonica (Stainton). Four cereals namely corn, rice, millet and wheat were tested solely and mixed with groundnut. Among the eight treatments, corn + groundnut was superior diet in almost biological parameters of C. cephalonica followed by millet + groundnut. The experiment showed that the corn + groundnut are biologically better option for production of robust eggs of C. cephalonica. DOI: http://dx.doi.org/10.3126/ijasbt.v2i4.11587Int J Appl Sci Biotechnol, Vol. 2(4): 585-588

ESTIMATION OF LOSSES IN STORED MAIZE CAUSED BY CORCYRA CEPHALONICA STAINTON IN SOUTHERN RAJASTHAN AND THEIR ECO- FRIENDLY MANAGEMENT.

ABSTRACT Corcyra cephalonica Stainton is a notorious pest of stored cereals and cereal commodities in India as well as in other tropical and subtropical regions of the world. An experiment was conducted on extent of damage of C. cephalonica in maize under different storage structures during, 2010-2011, revealed that the maximum infested grain samples (61.53%) were recorded from grain stored in loose storage during June-July, 2011. Whereas, infested grain samples were not found from the grain stored in metal bin during November-December, 2010. The maximum weight loss (7.46%) was recorded in grain samples collected from loose storage in Udaipur district during June-July, 2011. No weight loss in grains were recorded in the samples collected from metal bin in Chittorgarh and Udaipur district during November-December 2010. In the quantitative and qualitative studies conducted in the selected districts observed that the maximum germination (78.00%) and protein content (8.60%) were recorded in the samples collected from metal bin in Chittorgarh district during November-December, 2010, while maximum carbohydrate content (72.00%) was recorded in maize samples collected from metal bin in Rajsamand district during November-December 2010. The minimum germination (62.00%) and carbohydrate content (66.50%) were recorded in maize samples collected from loose storage in Udaipur district; whereas, minimum protein content (6.70%) was recorded from loose storage in Chittorgarh district during June-July 2011. The studies conducted on efficacy of different grain protectants against C. cephalonica revealed that the highest larval mortality (82.20%), pupal mortality (10.00%) and minimum adult emergence (6.00%) were recorded in case of application neem leaf powder at 10g/kg seed, after 40 days of release. Application of wood ash at 15g/kg seed was found least effective.

EFFECT OF CALLISTEMON LANCEOLATUS (MYRTACEAE) LEAF OIL VOLATILES ON EGG HATCHABILITY OF CORCYRA CEPHALONICA AND ITS GAS CHROMATOGRAPHY-MASS SPECTROMETRY ANALYSIS

Callistemon lanceolatus (Myrtaceae) plant claimed for the management and control of rice - moth Corcyra cephalonica an insect pest of stored commodities. When freshly laid eggs were exposed to Callistemon lan ceolatus oil volatiles for 12, 24, 48, and 72 h with 20, 40, 80 or 160 µ l of oils, a marked decline in egg hatchability in this pest was seen after exposure period. The oil having insecticidal properties w h ich was extracted by Clevenger apparatus in the laboratory by hydro - distillation process, subjected to Gas chromatography - mass spectrometry technique. The presence of active ingredients of Callistemon lanceolatus oils obtained at 0.001 % yield by hydro - distillation mainly consisted of 1, 8 Cineole*62.25 %; Alpha - terpineol*8.73; D - limonene*8.40 %; Alpha Pinene*7.03 %; Alpha Phellendrene*2.85 %; Linalool*0.67 % etc. The result offers a platform for using Callistemon lanceolatus leaf oils for control and management of rice moth Corcyra cephalonica in godo wns, warehouses around the world.

A laboratory assessment of the potential of Beauveria bassiana (Balsamo) Vuillemin as a biocontrol agent of Corcyra cephalonica Stainton (Lepidoptera: Pyralidae)

Corcyra cephalonica Stainton (Lepidoptera: Pyralidae) is a wide spread pest of stored grains and responsible for considerable damage in godowns and warehouses. Beauveria bassiana (Balsamo) Vuillemin, the most common and ubiquitous fungal entomopathogen is known to have high potential for the control of insects belonging to various orders. To evaluate the pathogenicity of B. bassiana against C. cephalonica, sorghum grains were treated with three conidial concentrations of B. bassiana i.e. 1.49 × 105, 4.05 × 106, 2.02 × 108 spores/ml. The highest concentration was found to be the most effective. It induced significantly higher larval mortality. Adverse effects such as reduced adult emergence and longevity of C. cephalonica were also observed when the grains were treated with B. bassiana. Significantly lesser number of adults emerged from pupae, when shorghum grains were treated with 2.02 × 108 spores/ml. The adverse effects were also exhibited as malformed adults that lived for a short period. Overall study showed that B. bassiana gave effective control of C. cephalonica and thus may play a pivotal role in the integrated pest management program.

Effect of Cannibalism on the Growth and Development ofMallada basalis(Neuroptera: Chrysopidae)

The green lacewing, Mallada basalis (Walker) (Neuroptera: Chrysopidae), is one of the most important natural enemies used in biological control programs for forestry and agricultural pests. However, it is difficult to mass rear M. basalis instars because they are voracious cannibals. This study was conducted to determine the effect of cannibalism on the development and fecundity of M. basalis. We analyzed the developmental parameters of 3rd instars that cannibalized M. basalis eggs and 1st instars, and the relationship between the proportion of each of the 3rd instars cannibalized and the number of folded paper barriers provided in an arena to minimize the frequencies of encounters. In all treatments the green lacewing instars were provided eggs of the pyralid, Corcyra cephalonica (Stainton). In Treatment I the pyralid eggs were supplemented with M. basalis eggs and in Treatment II, the pyralid eggs were supplemented with M. basalis 1st instars. The developmental times of the 3rd instars and pupae of Treatment I and Treatment II were significantly shorter than in the control. The pupal weights, fecundities and egg hatch rates of Treatments I and II were significantly larger than in the control. When 3rd instars cannibalized M. basalis eggs or 1st instars, the pupal weights significantly increased from 10.3 (control) to 11.0 and 10.9 mg, respectively, fecundities significantly increased from 91 (control) to 141 and 121 eggs, respectively, and the egg hatch rates significantly increased from 62% (control) to 70% and 68%, respectively. Moreover, as the number of folded paper barriers per arena increased, the proportions of 3rd instars cannibalized at first tended to decrease but then increased. When the different instars were studied separately, the proportion of 3rd instars cannibalized was larger than the corresponding proportions of 1st and 2nd instars. The research indicated that cannibalism enhances both development and fecundity of M. basalis. The use of paper barriers to frequent encounters reduced cannibalism somewhat, but this method was not adequately effective for the 3rd instars. Our findings may contribute to the mass production of this economically important predatory green lacewing.

Augmentative on-farm delivery methods for the parasitoid Habrobracon hebetor Say (Hymenoptera: Braconidae) to control the millet head miner Heliocheilus albipunctella (de Joannis) (Lepidoptera: Noctuidae) in Burkina Faso and Niger

Augmentative on-farm delivery methods for the parasitoid Habrobracon hebetor (Say) (Hymenoptera: Braconidae) to control the millet head miner (MHM) Heliocheilus albipunctella (de Joannis) (Lepidoptera: Noctuidae) were investigated in Burkina Faso from 2011 to 2012 and in Niger in 2012. Our findings indicate that 7 cm × 10 cm jute bags containing 50 g of millet grains, 30 g of millet flour, 25 Corcyra cephalonica larvae and two mated H. hebetor females are the most effective option for on-farm delivery of the parasitoid. The parasitoid progeny started emerging from the bags eight days after confinement and 57–71 parasitoid adults emerged from each bag. Using the methods we developed, over 90 % parasitism of MHM larvae was achieved in millet farms. The implications of these findings for a large extension of MHM biocontrol program are discussed.

Analysis of the Vitellogenin gene of rice moth, Corcyra cephalonica Stainton.

Vitellogenin (Vg) is a precursor of the major yolk protein, an essential nutrient for the embryonic development of oviparous animals including insects. Here, the gene(CceVg [Corcyra cephalonica Vg] ) encoding the Vg (CceVg of moth, C. cephalonica, was cloned and sequenced. The gene sequence was 6,721-bp long and contained 5five introns and six exons that together formed a 5,382-bp open reading frame. The deduced protein (CceVg) consisted of 1,793 amino acid residues, including a 16-amino-acid signal peptide. The putative molecular weight of the primary Vg protein was 202.46 kDa. The CceVg contained all conserved domains and motifs that were commonly found in most insect Vgs except the presence of a polyserine tract at the C-terminal region, which had not been reported in other lepidopteran Vgs. The expression pattern showed that CceVg was first transcribed at a very low level in the early larval stage but disappeared in later stage larva. In female, the CceVg mRNA was detected in early pupal stage and throughout adult stage. Interestingly, the CceVg mRNA was detected only in mated males at low levels, not in the virgin ones. Injection of CceVg double-stranded RNA into early-emergent females caused severely abnormal ovaries.

Comparison of concomitant and sequential inoculation of Steinernema sp. in the management of root-knot (Meloidogyne incognita) nematode infecting eggplant (Solanum melongena)

Culture of Steinernema sp. was maintained on Corcyra cephalonica larvae. Steinernema sp. (at 50, 500, 1000, 2500, 5000, 10,000 and 20,000 ij’s /500 g soil) was concomitantly inoculated with 500 J2 of Meloidogyne incognita/500 g soil to the eggplant seedlings in the pots filled with 4 kg sterilised soil. The simultaneous inoculation of M. incognita with either of the inoculum levels (1000, 2500, 5000 and 10,000 J3/500 g soil) of Steinernema sp. significantly reduced the damage caused by M. incognita in terms of plant growth parameters, viz. plant length, dry weight, number of flowers and weight of fruits. Moreover, the highest improvement in plant growth parameters, viz. plant length, dry weight, number of flowers and weight of fruits, was recorded in plants inoculated with 5000 J3 of Steinernema sp./500 g soil followed by 2500, 1000 and 10,000 J3/500 g soil. The highest reduction in the reproduction factor and number of galls/root system was recorded in the plants treated with 5000 J3 Steinernema sp./500 g soil followed by 2500, 1000 and 10,000 J3/500 g soil. Comparison of concomitant and sequential inoculations showed that the sequential inoculation (both prior and after) of Steinernema sp. at different inoculum levels (1000, 2500, 5000, 10,000 and 20,000 ij’s/500 g soil) was more effective in the management of root-knot nematode than the concomitant inoculation. Therefore, the application of Steinernema sp. might be useful for suppression of nematode pest on eggplant and may be used as an alternative for chemicals.

Potential of an Insect Growth Regulator in the Management of the Rice Moth Corcyra Cephalonica Stainton, 1866 (Lepidoptera: Pyralidae)

Abstract The present investigation reveals the influence of methoprene, an IGR, on the ontogeny, growth duration and adult longevity of the rice moth Corcyra cephalonica. Twenty-five larvae of different instars (1st, 2nd, 3rd and 4th) of C. cephalonica were exposed to the juvenile hormone analogue methoprene in order to evaluate its potential effect on larval mortality, pupation, pupal mortality, adult emergence, growth duration and adult longevity. These different instars larvae were treated with 2, 4, 8 and 12 ppm of methoprene in an artificial diet (coarsely ground jowar mixed with 5% yeast powder) where the control received acetone alone. The results reveal significant differences in all the parameters mentioned above as compared to the control.

EFFECTS OF CITRUS OIL VOLATILES ON THE REPRODUCTIVE BIOLOGY OF THE RICE MOTH, CORCYRA CEPHALONICA (STAINTON) (LEPIDOPTERA: PYRALIDAE)

Rice moth, Corcyra cephalonica (Stainton) (Lepidoptera: Pyrali dae) is an important pest of stored food su ch as cer e als, cereal products, oil seeds puls es dried fruits nuts and spices . A sharp reduction in percent egg hatchability was n oticed at 72 hours exposure of the volatile s in comparison to 6, 12, 24 or 48 hours e xposure period to th e vapo r action of 20, 40, 80, or 160 µl volume of Citrus oil. There was a marked decline in egg output and egg hatchability in reproductive pairs, whose larval development for the first 15 days/from 16 th day till 30 days/continuous till 30 days took place in an environment ema nating from 20, 40, 80 or 160 µl volume of this oil. A ppreciable reduction in egg laying capacity and egg viability was noticed at 6 hour exposure of the volatile s in comparison to 3 hour exposure period to the action of different volume s of this oil. Ther e was significant reduction in Glycogen level , Total lipids , Total protein and Total free amino acids level in testes and ovaries of adults following the ir expo sure to the action of selected volatile s for 6 hours , emanating from 20 , 40, 80 or 160 µ l volume of Citrus oil.

The suitability of Ostrinia furnacalis (Lepidoptera: Crambidae) eggs for Trichogramma dendrolimi (Hymenoptera: Trichogrammatidae) can be changed by T. ostriniae

This study compared the host specificity of two Trichogramma species on Corcyra cephalonica (Stainton) and Ostrinia furnacalis (Guenee) eggs. Trichogramma ostriniae Pang et Chen (TO) took more time for oviposition during probing and laying eggs, compared with Trichogramma dendrolimi Matsumura (TD). Furthermore, the proportion of host eggs oviposited actually by TD was lower than that by TO on O. furnacalis eggs, whereas there was no significant difference on C. cephalonica eggs. TO produced more females and total offspring than TD on O. furnacalis eggs. This indicated that O. furnacalis was less suitable for the development of TD, compared with the combination of C. cephalonica and TD or O. furnacalis and TO. Microinjection with 4.0 eq μl−1 extract of TO female abdomens induced lower hatchability and longer developmental duration of O. furnacalis egg, whereas the extract from TD prolonged developmental duration only slightly, indicating weak toxicity of TD extract. TD emerged from 72.0 % of O. furnacalis eggs helped by oviposition of TO females irradiated with 800 Gy/h 60Co for 6 min, of which the intensity produced no TO offspring, whereas only 6.5 % of the eggs were parasitized solely by TD. This indicates that the suitability of O. furnacalis to TD can be increased by the addition of TO parasitization factors.