Angoumois Grain Research Articles

Mass rearing and release of Trichogramma for biological control of insect pests of corn in China

Corn (Zea mays L., Poaceae) is ranked first as food crop in planting area and in total yield production in China. Asian corn borer, Ostrinia furnacalis, is the most destructive pest of corn in China, causing 6–9 million tons of yield loss per year on average. Trichogramma has been released for control of Asian corn borer at large scale since the 1970’s, partly triggered by the fact that Trichogramma dendrolimi can be successfully mass reared on eggs of the Chinese oak silkworm, Antheraea pernyi. Eggs of different hosts, such as Eri-silkworm, Samia cynthia ricini, A. pernyi, the Rice moth, Corcyra cephalonica, the Angoumois grain moth, Sitotroga cerealella and also artificial host eggs were tested and successfully used to mass-rear various Trichogramma species in China since then. The mass production technology and release technique of Trichogramma have been greatly improved in recent years making Trichogramma production and field application more practical and cost efficient. Nowadays, nearly 4 million hectares of corn are treated with T. dendrolimi, Trichogramma chilonis and Trichogramma ostriniae annually, mainly in North-east China. Large ecological and economic benefits have been achieved in areas where Trichogramma have been released continuously for many years. This includes an increase of natural populations of Trichogramma and other natural enemies in cornfields, the avoidance of any insecticide treatments in corn, a reduction in mycotoxin contamination and overall higher yields. The release of Trichogramma for controlling Asian corn borer and other lepidopteran pests became one of the key measures in corn IPM in China. Trichogramma applications combined with other non-chemical control measures for corn insect pests IPM began a new era in China as the new concept of “Public Plant Protection, Green Plant Protection” was put forward in 2006 as the guideline for plant protection in China. The future prospects and challenges of Trichogramma application are also discussed in this review.

Insecticidal activity of four medicinal plant powders and extracts against Angoumois grain moth, <i>Sitotroga cerealella</i> (Olivier) [Lepidoptera: Gelechidae

Powders and extracts prepared from Capsicum frutescens, Cymbopogon citratus, Moringa oleifera, Anacardium occidentale were tested for their insecticidal potential against Angoumois grain moth, Sitotroga cerealella . The powder of C. frutescens had the highest mortality rate of 100% after 2 days of application at all tested concentrations. The extracts killed all the adult moths introduced at all tested concentrations. The survival of the moth from egg to adult when treated with the plant powders showed significantly greater mortality. Extracts of all the tested plants were toxic to adult moths and also prevent hatching of the eggs of S. cerealella . Keywords: mortality, hatchability, adult emergence

English

  During storage, maize grains are severely destroyed by insects and other pests. One of the most important causes of grain loss in stored maize is the damage caused by Angoumois grain moth, Sitotroga cereallela O. A study was conducted to evaluate selected locally available botanical powders and two cooking oils for their effectiveness as grain protectants against S. cereallela at Jimma University College of Agriculture and Veterinary Medicine in 2011. The plant powders and cooking oils were compared with untreated control and Malathion super dust as standard control. The experiment was laid-out in completely randomized design with three replications for each treatment. Different dependent variables such as adult mortality, F1 progeny emergency and grain damage were assessed. The results revealed that there was an increase in adult mortality, decrease in F1 progeny emergency and grain damage as a result of botanical powders and cooking oils application to maize grains. Among the botanicals, very low mortality of 27.80% was recorded from Maesa lanceolata (with LT50 of 219.8 days) and Echinops kebericho (with LT50 of 338.10 days) similar to the untreated control. Cumulative mortality of 39.00% was registered from Azadirachta indica bark powder (with LT50 of 30.40 days) and Cympopogon citratus leaf (with LT50of 171 days) against Sitotroga cerealella 20 days after insect exposure to the botanicals. Maximum moths mortality, 94.4%, was recorded from standard control (Malathion) followed by the two cooking oils (77.8%). No F1 progeny emerged from the grains treated with the two cooking oils similar to the standard chemical over the exposure period of 40 days leading to no seed with hole, minimum weight loss and maximum seed germination percentage (97.30%). Thus, the two cooking oils were found to be most potent bio-insecticides against maize grain moth on par with standard check, Malathion.   Key words: Angomois grain moth, Sitotroga cereallela, cooking oils, exposure time, grain damage, maize grains, mortality and plant powders.

Grain damage, viability and weight loss in different barley cultivars due to Sitotroga cerealella (Oliv.) infestation

This study was carried out to see the impact of Angoumois grain moth (AGM) on different cultivars of barley so that we must grow resistant variety of barley or improve those which are susceptible to it. Eggs of Sitotroga cerealella (Oliv.) were collected and reared in incubators available in Stored Product Entomology Laboratory, Pir Mehr Ali Shah Arid Agriculture University Rawalpindi, under temperature 27 ± 2°C and 60 ± 2% relative humidity. For the experiment, five different cultivars of barley; Sanober-96, Jau-83, Soorab-96, ICBA and Sterling were selected for AGM feed. After an interval of 30, 60 and 90 days of infestation, percentage damage and weight loss in grains were determined. After carrying out laboratory and field germination tests, viability of different cultivars were checked. Damage was maximum in variety Soorab (99.38%), which becomes susceptible while it was minimum in Sanober-96 (90.62%), which becomes resistant. Weight loss was maximum in variety Soorab (49.71%), which becomes susceptible and was minimum in Sanober-96 (45.32%), which becomes resistant. Damage was positively correlated with weight loss and negatively correlated with seed germination. In germination tests, on filter paper, maximum germination was found in variety Sterling (3%) which becomes resistant and it was minimum in ICBA which becomes susceptible (0%). In sand germination test, maximum seeds germinated in variety Sanober-96 (2%), and minimum seeds germinated in ICBA (0%). By calculating the percentage of losses of different cultivars, it was found that none of cultivars proved itself completely resistant or susceptible.

Effects of .Oils of Eight Different Plants against the Angoumois Grain Moth, Sitotroqa cerealella (Olivier)(Lepidoptera: Ge1echiidae)in Rice.

The efficacy of oils from eight indigenous plants against Angoumois grain moth, Sitotroga cerealella (Olivier) infesting rice (Oryza sativa L.) was investigated in the laboratory at ambient temperature and relative humidity (28±2°C, 75±5%RH). Oils extracted from the seeds of Piper guineense Schum and Thonn, Monodora myristica Dunal, Tectona grandis L, Ricinus communis L, Arachis hypogaea L, Elaeis guineensis, the bulb of Allium sativum L, and the rhizome of Zingiber officinale Roscoe, Jacq. were tested at 1- 3% concentration. Results showed that the oils significantly (P<0.05) prolonged developmental period for eggs, suppressed adult emergence and reduced longevity compared with effects on similar parameters in the control. P. guineense had the highest insecticidal activity by totally preventing adult emergence at 2% oil concentration. P. guineense, A. sativum and A. hypogaea were able to prevent adult emergence at 3% oil concentration. At all concentrations, not more than 10% adult emergence was recorded for M myristica, when compared with P. guineense showing that it also exhibited a high level of insecticidal activity. Adult emergence was also significantly higher (P<0.05) in the controls (46.7 and 48.3%) than in seeds treated with E. guineensis. Developmental period was longest (39.0 days) in seeds treated with M myristica at 3% concentration. The adults in the controls lived longer than those in treated seeds while females generally lived longer than the males. Seed germination was not affected by the oil treatments as the values were virtually at par with those obtained from untreated seeds.

DEVELOPMENT OF NON-CHEMICAL DISINFESTATION METHOD FOR STORAGE RICE USING INFRARED RADIATION HEATING

The objective of this study was to develop rapid, non-chemical, and safe alternative disinfestation method for storage rice while retaining high rice quality. A sample of stored rice, variety M202, with moisture content (MC) of 11.0 ± 0.3% (wb) was used for conducting this study. The main sample was divided into two groups of samples using a sample divider. One was infested with the adults and eggs of lesser grain borers (Rhizopertha dominica) and angoumois grain moths (Sitotroga cerealella) and used for disinfestation tests. The other one was used for milling quality evaluation. All the samples were heated using a catalytic infrared (IR) emitter under radiation intensity of 5300 W/cm2 for different heating times (10, 15, 20, 25, and 30 s). After IR heating, the effect of tempering treatment for various durations on effectiveness of disinfestation and rice quality was evaluated. The evaluated milling quality indicators were total rice yield (TRY), head rice yield (HRY) and whiteness index (WI). The results showed that, a high heating rate for rice was achieved using IR heating. As rice samples were heated for heating times ranged from 10 to 30 s, rice temperatures ranged from 46 to 67 oC. Because of a short heating time and lower moisture content of rice, the moisture loss under different tested conditions was very low and was less than 0.7%, which was relevant to preserve the rice quality. The IR heating for rice storage to temperature of 60 oC followed by tempering treatment for at least 20 min. was sufficient to completely kill the tested insects. However, heating to 60 oC followed by 180 min tempering was optimum to achieve a good milling quality for the storage rice. Therefore, it has been concluded that the complete disinfestation and enhanced milling quality can be achieved by heating storage rice using IR to temperature of 60 oC followed by tempering treatment for 180 min with natural cooling

A NOVEL TECHNIQUE FOR COMMERCIAL MASS PRODUCTION OF NATURAL ENEMIES

Biological control agents is considered as an important factor of IPM strategy, efforts have been and are still being made to evaluate the effects of residual insecticides on natural enemy population. The commercial of predators and parasitoids, using factitious hosts, such as, the Angoumois Grain Moth (AGM), Sitotroga cerealella (Olivier), the Mediterranean Flour Moth (MFM), Ephestia kuehniella Zeller and the Rice moth (RM), Corcyra cephalonica (Stainton) proved successful approach. This study involved, technical improvement for egg laying, collecting the eggs and testing of different collection techniques, manual and automatic rotation cylinders were studied. The main finding indicated that, the total eggs laying during 55 days from 21 trays containing Sitotroga adults reached 478.072 g in case of the mechanical cardboard, while it introduced 289.46 g in case of the manual rotation. Moreover, the patent no. of 2005020071 under the title Egg laying collecting machine for the hosts of mass production was obtained during this work modified machine for egg laying and collection for the mass of insect host.

The effect of modified atmospheres, an alternative to methyl bromide, on the susceptibility of immature stages of angoumois grain moth Sitotroga cerealella (Olivier) (Lepidoptera: Gelechiidae)

The angoumois grain moth, Sitotroga cerealella is recognized as a common pest of grains world-wide. This investigation aimed at determining the most effective CO2 concentration in air against the immature stages of the pest in laboratory tests. The sensitivity of newly-laid eggs (<24 h old), 4th instar larvae and 3-day-old pupae to 4 modified atmospheres (MAs) containing 30%, 45%, 65% and 75% CO2 in air was investigated at 27 °C and exposure periods between 2 h and 264 h. The percentage mortality of the newly-laid eggs, as well as the reduction of adult emergence from 4th instar larvae and 3-day-old pupae tended to increase with the increase of CO2 concentrations in air and exposure period. According to LT95 values, the order of sensitivity of the three developmental stages of S. cerealella to the four MAs tested was as follows: eggs > pupae > larvae.

Insecticidal efficacy of some plant powders and extracts against the Angoumois grain moth, Sitotroga cerealella (Olivier) (Lepidoptera: Gelechiidae)

Powder and extract from four plants were evaluated for their insecticidal efficacy against the Angoumois grain moth, Sitotroga cerealella (Olivier) in the laboratory at a temperature of 28 ± 2°C and a relative humidity of 75 ± 5%. The plants included Aristolochia ringens L., Khaya ivorensis (K.), Strophanthus hispidus (D.C.) and Zanthoxylum zanthoxyloides Lam. The powder was applied at the rate of 0.2, 0.4 and 0.6 g/20 g of paddy rice, while the extract was applied at the rate of 1%, 2% and 3%/20 g of paddy rice. Parameters evaluated were adult moth mortality, adult emergence and weight loss in treated paddy after infestation. Results shows that adult moth mortality increased as concentration of powder increased. Significant differences (p < 0.05) existed among the plant powders andthe concentration. A 100% mortality rate was obtained within 7 days when A. ringens was applied at 0.4 and 0.6 g/20 g of paddy. S. hispidus was able to effect 100% mortality only at 0.6 g. This shows that A. ringens had the greatest insecticidal activity while the least effective was K. ivorensis. Adult emergence shows that more adult S. cerealella emerged from the control (40.3) which was significantly higher (p < 0.05) than others. Fewer adults emerged from paddy treated with plant powder with the least in A. ringens. Generally, adult emergence reduced with an increase in the concentration of powder. The extract from all the four plants tested against S. cerealella was able to effect 100% mortality of the adult moths within 24 h of application at all concentrations. Significant differences (p < 0.05) existed among all the different plant powders in terms of weight loss. The weight loss in paddy was significantly higher (p < 0.05) in the control (57.7%) than others. Weight loss was least in paddy treated with A. ringens at 0.4g/20 g of paddy with 2.2%. Generally, weight loss decreased with increase in powder concentration. The treatment with the highest adult emergence (control) also had the highest weight loss, while the treatment with the lowest adult emergence (A. ringens) had the lowest weight loss.

Insecticidal activities of garlic substances against adults of grain moth, Sitotroga cerealella (Lepidoptera: Gelechiidae)

Abstract The angoumois grain moth, Sitotroga cerealella (Olivier), is one of the most serious stored grain pests around the world. In attempts to reduce the losses caused by the moth and to suppress its populations, the fumigant activities, behavioral influence and ovipositional inhibition of garlic (Allium sativum) essential oil and its two major components, diallyl disulfide and diallyl trisulfide, were investigated against the adult grain moth. Their effects on reduction in survival of first instar larvae to adult emergence were also evaluated. Results showed that these three materials (garlic essential oil, diallyl disulfide and diallyl trisulfide) had significant fumigant activity with 50% lethal concentration values at 1.33, 0.99, and 1.02 μL/L air space, respectively; meanwhile, the three materials possessed high behavioral deterrent activities against adults in the Y‐tube olfactometer. When applied to rice grains, these materials reduced adult longevity and inhibited oviposition, with ovipositional inhibition above 70% at a concentration of 1.5 μL/25 g in either no‐choice or two‐choice tests. In short, the study showed that both diallyl disulfide and diallyl trisulfide, like garlic essential oil, acted as fumigants, produced behavioral deterrence and inhibited oviposition against angoumois grain moth. Our work here indicates that diallyl disulfide and diallyl trisulfide may serve as potential alternatives for grain protectants since both of them can be prepared easily from readily available chemicals.

The occurrence and phenology of moth pests in different granary of Borsod-Abaúj-Zemplén County

The aims of my studies were the followings: primarily to find correlation between the conditions of granary and the occurrence of moth pests. Secondly I studied the effect of disinfection on individual numbers in the population of moths. My studies were started in May 2009 in six different places of Borsod-Abaúj-Zemplén County. Indianmeal moth (Plodia interpunctella) and Mediterranean Flour Moth (Ephestia kuehniella) traps with pheromone were installed in four repetitions as well as Angoumois Grain Moth (Sitotroga cerealella) traps in also four repetitions. Control traps without attractant were also placed at every place.From my researches, it became clear that the disinfection alone is not enough to protect cereals from moths. As in the case of crop protection, we need to apply integrated pest management.We have to make differences between preventive protections from moth pests and the elimination of them by chemicals.Up to my opinion, the regular checking and cleaning of the granary are important as well as the prognosis of the possible occurrence of moths. The prognosis is considered important because the studied moths do not feed at the adult stage or only at a low level. However, the caterpillars coming from the eggs placed by females can cause a significant damage in the stored cereals.The studied sex pheromone traps are proved to be useful for the reduction of number of moths since the traps caught lots of them. These traps are relatively cheap because only the temporarily changes of pheromones increase the cost.

A Comparative Study on the Functional Response ofWolbachia-Infected and Uninfected Forms of the Parasitoid WaspTrichogramma brassicae

Trichogramma species (Hymenoptera: Trichogrammatidae) are haplo-diploid egg parasitoids that are frequently used as biological control agents against lepidopteran pests. These wasps display two reproductive modes, including arrhenotoky (bisexuality) and thelytoky (unisexuality). Thelytokous forms are often associated with the presence of endosymbiotic Wolbachia bacteria. The use of thelytokous wasps has long been considered as a way to enhance the efficacy of biological control. The present study investigates the potential of a thelytokous Wolbachia-infected and an arrhenotokous uninfected Trichogramma brassicae Bezdenko strain as inundative biocontrol agents by evaluating their functional response towards different egg densities of the factitious host, the Angoumois grain moth, Sitotroga cerealella (Olivier) (Lepidoptera: Gelechiidae). The results revealed a type II functional response for both strains in which parasitism efficiency decreases with host egg density because of an increasing host handling time. A model with an indicator variable was used to compare the parameters of Holling's disc equation in different data sets. It was demonstrated that the two strains did not differ in host attack rate. However, the Wolbachia-infected strain did have an increased host handling time when compared to the bisexual strain. Some applied aspects of the findings are discussed.

Seasonal dynamics of three lepidopteran stored grain pests in Slovenia

In the period 2004-2006 seasonal dynamics of Mediterranean flour moth ( Ephestia kuehniella ), Indianmeal moth ( Plodia interpunctella ) and Angoumois grain moth ( Sitotroga cerealella ) was studied in the mills and grain warehouses in central Slovenia. For this purpose pheromone traps were used from April until December, and the males of all three lepidopteran pests were counted in two week intervals. The three insect pests under investigation developed two peaks in capture per year that might represent two distinct generations per year. In the maize open air storage Ephestia kuehniella was the most numerous, while Plodia interpunctella was more frequent in the closed storage in mills and warehouses, Sitotroga cerealella was slightly less common in these latter closed warehouses. Keywords : Monitoring, Lepidoptera, Stored grain pest, Pheromones, Slovenia

On the effects of diet and photoperiod on Harmonia axyridis (Pallas) (Coleoptera, Coccinellidae) larval development

It is known that the light day length and diet could act as cue factors inducing adult (reproductive) diapause in aphidophagous coccinellids. However, the rate of coccinellid larval development could also depend on photoperiod and diet. The present study examines the effects of photoperiod (L: D = 12: 12 or 16: 8) and diet (the green peach aphid Myzus persicae or eggs of the Angoumois grain moth Sitotroga cerealella) on preimaginal development of the multicolored Asian lady beetle Harmonia axyridis. At 20°C, a short light day and feeding on aphids shortened larval development by 1.4 and 4.6 days, respectively. In combination, both factors caused a simple sum of separate impacts indicating the absence of their interaction. The duration of the pupal stage was independent of photoperiod, but decreased by 0.3 days in individuals fed on aphids. The proportion of the larvae that successfully completed preimaginal development was also independent of the light day length, but significantly depended on diet (84 and 60% in individuals fed on green peach aphids and on grain moth eggs, respectively). In sum, these results suggest that in the case studied, diet does not play the role of cue factor, but directly influences the larval growth and development of H. axyridis.

Effects of Cry1F and Cry34Ab1/35Ab1 on storage pests

Two crystalline protoxins from Bacillus thuringiensis (Bt), Cry1Fa1 and Cry34Ab1/Cry35Ab1 (Cry1F, Cry34/35Ab1), were evaluated for efficacy against lepidopteran and coleopteran storage pests. Cry1F was tested against the lepidopterans Sitotroga cerealella (Angoumois grain moth) and colonies of Plodia interpunctella (Indian mealmoth) that are susceptible or resistant to Bt Cry1Ab and Cry1Ac toxins, Bt subspecies entomocidus, and the commercial formulation Dipel ®. Cry1F was also tested against the coleopterans Cryptolestes pusillus (flat grain beetle) and Tribolium castaneum (red flour beetle). Cry34/35Ab1 was tested against S. cerealella, C. pusillus, and T. castaneum, and against additional coleopteran storage pests, including Tenebrio molitor (yellow mealworm), Trogoderma variabile (warehouse beetle), Oryzaephilus surinamensis (sawtoothed grain beetle), Rhyzopertha dominica (lesser grain borer), and Sitophilus oryzae (rice weevil). Strains of Bt-susceptible or -resistant P. interpunctella generally were more sensitive to Cry1A protoxin or toxin than either Cry1F protoxin or Dipel. Despite difficulties with the bioassay of S. cerealella larvae, the data suggest that Cry1F and Cry34/35Ab1 caused increased larval mortality, and a developmental delay was observed and no pupae emerged with 0.9% Cry1F. Neither Cry1F nor the corn rootworm-active toxin Cry34/35Ab1 significantly affected the biological parameters of the coleopteran species evaluated.

Suitability of Different Lepidopteran Host Species for Development ofBracon hebetor(Hymenoptera: Braconidae)

Bracon hebetor Say (Hymenoptera: Braconidae) is a gregarious larval ectoparasitoid of several species of Lepidoptera that are associated with stored products. The suitability of 12 potential lepidopteran host species representing four families was studied in this study for the development and reproduction of B. hebetor. The Lepidoptera species used were the Indianmeal moth, Plodia interpunctella (Hübner), Mediterranean flour moth, Ephestia kuehniella (Zeller), almond moth, E. cautella (Walker), rice moth, Corcyra cephalonica (Walker), navel orangeworm, Amyelois transitella (Stainton), greater wax moth (laboratory reared and commercial), Galleria mellonella (Linnaeus) (all Pyralidae); tobacco budworm, Heliothis virescens (Fabricus), corn earworm, Helicoverpa zea (Boddie), beet armyworm, Spodoptera exigua (Hübner) (all Noctuidae); webbing clothes moth, Tineola bisselliella (Hummel) (Tineidae); and Angoumois grain moth, Sitotroga cerealella (Olivier) (Gelichiidae). Experiments were conducted using petri dishes (100 by 15 mm) as experimental arenas at 29 +/- 1 degrees C, 65 +/- 5% RH, and a photoperiod of 14:10 (L: D) h. B. hebetor females were introduced singly into arenas and given a full-grown host larva every day for 5 consecutive d. Paralysis of the host larvae and oviposition by B. hebetor females were significantly affected by host species. The cumulative fecundity in the 5-d period was highest on A. transitella (106.42 +/- 5.19) and lowest on T. bisselliella (9.64 +/- 1.28). The egg-to-adult survivorship and progeny sex ratio were also significantly affected by the host species. The highest percentage of parasitoid survival to the adult stage was on A. transitella (84.07 +/- 2.26) and zero on T. bisselliella. Egg to adult development time was shortest on E. cautella (9.75 +/- 0.25 d) and longest on G. mellonella (12.63 +/- 0.28 d). Results from these studies suggest that B. hebetor females can use a wide range of lepidopteran hosts for paralysis and oviposition. However, B. hebetor cannot necessarily develop and reproduce on all host species that it can paralyze and oviposit on, and optimum reproduction is with the stored-product pyralid hosts.

On the effect of temperature on the induction of host parasitization by Trichogramma buesi Voegele (Hymenoptera: Trichogrammatidae) females

Laboratory experiments demonstrated that females of the egg parasitoid Trichogramma buesi started parasitization of the Angoumois grain moth, Sitotroga cerealella, eggs at 25 °C faster than at 15 °C. Obviously, high temperature increases host search, inspection, and parasitization activity. Moreover, most of females that started to parasitize at 25 °C, continued parasitization at 15 °C. However, in the absence of host eggs or in the dark (when Trichogramma did not start to parasitize) high temperature did not influence further parasitization. Special experiments show that parasitization of at least one host is necessary to promote further parasitization at low temperature. Thus, the minimal effective time of exposure to high temperature in an individual female is equal to several minutes which are required to parasitize one host egg. However, the period of time from offering hosts to the beginning of parasitization vary considerably even among females of laboratory line kept under standard conditions, and, that is why, at the population level the effect on the further parasitization gradually increases with the duration of the exposure to high temperature.

Susceptibility of some Indian sorghum varieties to angoumois grain moth, &lt;i&gt;Sitotroga cerealella&lt;/i&gt; (Olivier) (Lepidoptera: Gelechiidae)

The susceptibility of some Indian sorghum varieties to the Angoumois grain moth, Sitotroga cerealella (Olivier) was investigated in the laboratory at a temperature of 28.0±2.0°C and relative humidity of 65.0±1.5%. The sorghum varieties tested included CSV 15, AVHT 303, AVHT 310, AVHT 313, AVHT 328, AVHT 644, AVHT 646, IHT 405, IHT 419 and IHT 424. In the first experiment, 100 (0-24h old) eggs of S. cerealella were used to infest twenty grammes of each sorghum variety while in the second experiment 0-24h old adults were paired in glass vials. Results showed that IHT 405, an initial variety (experimental), with longest developmental time (29.7days) and least percent survival of egg to adult of 20.6% was the least susceptible variety to S. cerealella infestation while CSV 15, with shortest developmental time (26.7days) and highest percent survival of egg to adult of 47.4%, had highest susceptibility. The weight of newly emerged adults ranged from 1.55g (AVHT 313) to 2.09g (AVHT 310) in males and 2.79g (IHT 405, 419) to 3.93g (IHT 424) in females. Virgin females lived longer than their mated counterparts while females generally lived longer than males. Significant differences were found in the number of eggs laid. Fecundity was highest (130eggs/female) in AVHT 303 and lowest (96eggs/female) in IHT 405. Hatchability ranged from 88.0% in AVHT 644 and 97.2% in AVHT 646. Key words: fecundity, hatchability, Sitotroga cerealella , sorghum, susceptibility

Relative resistance of paddy varieties to Sitotroga cerealella (Lepidoptera: Gelechiidae)

Relative resistance of paddy varieties to the Angoumois grain moth, Sitotroga cerealella was investigated in the laboratory at a temperature of 28 ± 1.0°C and relative humidity of 65 ± 1.5%. The study was carried out on Indian Agricultural Research Institute (IARI), New Delhi, India varieties and a Taiwan variety. The larvae of S. cerealella were allowed to feed and developed inside the grain while adults did not feed. Results showed that the performance of S. cerealella was least in T (N)-1 (Taichung Native-1), with the longest developmental time (26.3 days) and egg to adult survival of 38% making the variety the most resistant. The performance was best in Pusa 44 with the shortest developmental time (23.0 days) and egg to adult survival of 68.7% making the variety the least resistant. The heaviest females and males with 4.04 g and 2.38 g, respectively, were reared on Pusa sugandh 3, which are large seeds. Moths reared on T (N)-1 had the lowest weights for males and females. Unmated females lived longer than their mated counterparts while females generally lived longer than males. Fecundity was highest (164.2 eggs/female) in Pusa 44 and lowest (108.1 eggs/female) in T (N)-1. Hatchability ranged from 81.2% in T (N)-1 to 96.2% in Pusa 834. Generally, grain characters tested in this study influenced moth herbivore performance but the influence was not significant except for grain width which appeared to be the most important trait. With advances in biotechnology, it is possible to transfer desirable characters to other varieties to improve their resistance to S. cerealella and other stored products insects. However, care must be taken since this could change the grains susceptibility to some pests affecting pest-host relationships.

Detection and identification of Wolbachia endosymbionts from laboratory stocks of stored-product insect pests and their parasitoids

Endosymbiotic bacteria belonging to the genus Wolbachia are maternally inherited and can cause various effects on the reproductive system of their invertebrate hosts. Owing to their critical effects on insect reproduction, Wolbachia are potential tools for future insect pest control strategies. Here, we explored Wolbachia infections among stock collections at the National Food Research Institute of Japan, where stored-product insect pests and their parasitoids are maintained. Diagnostic polymerase chain reactions (PCRs) and sequencing of a fragment of the Wolbachia surface protein ( wsp) gene revealed that, among 59 strains (38 species) belonging to the Coleoptera, Psocoptera, Lepidoptera and Hymenoptera, 18 strains (13 species) were infected with Wolbachia. Among them, 14 strains of Wolbachia were identified based on wsp gene sequences. Database searches showed that at least 6 Wolbachia strains were shared by multiple host species. Co-infections with two distinct Wolbachia strains were found in the drugstore beetle Stegobium paniceum and Angoumois grain moth Sitotroga cerealella. Detection and characterization of Wolbachia strains from these pests and their parasitoids provide us with basic information for future pest control strategies using these endosymbiotic bacteria.