Differential response of fourTrichogramma species to low temperatures for short term storage

Differential response was noticed when 4 species ofTrichogramma egg parasitoids were stored at 2°, 5° and 10°C for 7 to 49 days. Pupal stage was found to be most appropriate for storage. Emergence ofTrichogramma achaeae Nagaraja and Nagarkatti andTrichogrammatoidea eldanae Viggiani was greater in comparison toTrichogramma chilonis Ishii andTrichogramma japonicum Ashmead at all 3 temperature regimes. Fecundity and longevity declined drastically after storage of 14 days at 2° and 5°C and 21 days at 10°C, when removed to room temperature. 10°C was found to be the best temperature for storage up to 49 days. Contribution No. 51004 of Biological Control Centre (NCIPM), Bangalore.     

Thermal tolerance of potential <Emphasis Type="Italic">Trichogramma</Emphasis> strains for mass-production and paddy field release in the Greater Mekong Subregion

In order to identify suitable Trichogramma strains for mass production and successful control of key lepidopteran pests in paddy fields in the Greater Mekong Subregion, the effects of high temperatures on wasp life history traits were compared among three strains of Trichogramma chilonis Ishii and two strains of Trichogramma ostriniae Pang et Chen, collected from paddy fields in the region. At a rearing temperature of 25 °C, life history traits differed significantly among the five strains tested and the three T. chilonis strains and a T. ostriniae strain were of high performance. When female wasps were exposed to higher temperatures commonly encountered in the region, negative effects were observed on key life history parameters of adult females and their offspring at 34 °C, which became even more serious at 37 °C. In particular, the two T. ostriniae strains were not able to successfully develop to adulthood at all at 37 °C while for the T. chilonis strains adult emergence was significantly reduced. In addition, the emerged offspring females lived only around one day and no parasitism was observed. When the three T. chilonis strains were exposed to 37 °C for 4 to 12 h at prepupal and pupal stages, reflecting heat shocks that the released Trichogramma may experience in the field, adult emergence was significantly reduced after an exposure time of 12 h. In summary, the three T. chilonis strains show a relatively high potential for incorporation in a biological control program in the target region. Our results also highlight that tests at both rearing and field temperatures are necessary in selection of potential Trichogramma strains for an inundative release program where there is significant difference between rearing and field temperatures.     

Effect of fertilized,unfertilized, and UV‐irradiated hosts on parasitism and suitability for Trichogramma parasitoids

Trichogramma spp. (Hymenoptera: Trichogrammatidae) parasitoids have been commonly used as biological control agents in insect pest management. Host quality is believed to influence parasitism, host preference, and suitability for parasitoids. To date, limited studies have compared the parasitism of Trichogramma parasitoids on fertilized, unfertilized, and sterilized host eggs. Hence, we studied the performance of three Trichogramma egg parasitoids, Trichogramma japonicum Ashmead, Trichogramma chilonis Ishii, and Trichogramma leucaniae Pang & Chen, on fertilized, unfertilized, and ultraviolet (UV)‐irradiated fertilized (UVF) eggs of rice moth, Corcyra cephalonica (Stainton) (Lepidoptera: Pyralidae). In a no‐choice test, T. japonicum and T. leucaniae parasitized significantly more fertilized or UVF than unfertilized hosts, and T. chilonis parasitized significantly more UVF than either fertilized or unfertilized hosts. In a choice test, all three Trichogramma parasitoids parasitized UVF hosts the most, and unfertilized hosts the least. There were similar percentages of adult emergence and female progeny among fertilized, unfertilized, and UVF hosts for all three Trichogramma parasitoids, except that T. japonicum had significantly lower adult emergence on fertilized hosts. We also found that all three Trichogramma parasitoids developed slower on unfertilized hosts. Regardless of host treatments, T. leucaniae had the longest developmental time and T. chilonis had the shortest. We conclude that Trichogramma parasitoids prefer parasitizing UVF eggs of C. cephalonica without negative effects on their emergence and sex allocation.     

Walking patterns of Trichogramma chilonis and Trichogrammatoidea bactrae upon vegetable leaf surfaces

Trichogramma chilonis Ishii (Hymenoptera: Trichogrammatidae) and Trichogrammatoidea bactrae Nagaraja (Hymenoptera: Trichogrammatidae) are egg parasitoids of the diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae). We observed and recorded the walking patterns of T. chilonis and T. bactrae females on leaves of Raphanus sativus L., Brassica juncea (L.) Czern. et Coss., Brassica campestris L. ssp. chinensis var. utilis Tsen et Lee, and Brassica oleracea L. Our analysis indicated that Trichogramma females spent more time and moved more slowly on R. sativus leaf surface, compared with the other vegetable leaf surfaces. In addition, Trichogramma females were more likely to walk in straight line on B. oleracea leaf surfaces than R. sativus, B. juncea, and B. campestris leaf surface. Compared to T. bactrae females, T. chilonis females spent significantly less time on the leaf surface, and the walking path of T. chilonis was less affected by leaf surface characters (e.g., trichomes, wrinkle, and waxes). During the period of residence on the leaf surface, parasitoid females spent more than 87.8% of their time moving. This study demonstrates that vegetable leaf surface can influence Trichogramma's walking pattern while they are foraging for hosts.     

Effects of host-egg ages on host selection and suitability of four Chinese Trichogramma species,egg parasitoids of the rice striped stem borer,Chilo suppressalis

The striped stem borer, Chilo suppressalis (Walker), is one of the most economically important rice pests worldwide. However, biological control of this pest using natural-enemy insects has been rarely documented to date. With the objective of screening suitable candidate species for controlling the striped stem borer, we investigated the effect of the age of host eggs on the host selection and suitability by four indigenous Trichogramma species on their native host, C. suppressalis. The results indicated that the differently aged eggs of C. suppressalis were all accepted by T. japonicum, T. dendrolimi and T. chilonis, and there was a clear tendency to parasitize older eggs less under no-choice and choice conditions. The number of parasitized host eggs by T. ostriniae also decreased with the increasing host age in the no-choice test, but more 2-day-old host eggs were parasitized in the choice test. When 0-, 2-day-old eggs were offered, T. dendrolimi, T. japonicum and T. chilonis exhibited similar parasitism ability, whereas T. ostriniae appeared to have a stronger ability to attack the older host eggs (4-day-old). Trichogramma japonicum developed and emerged on parasitized C. suppressalis eggs of all ages tested, while showing a better adaptation to younger host eggs with significantly faster developmental time, higher survival and more female progeny on 0-day-old eggs. No adults for each of the other three Trichogramma species emerged from parasitized 4-day-old host eggs, and they had similar developmental time, survival and female progeny on parasitized 0-, 2-day-old host eggs with an exception of female progeny for T. chilonis. On 0-day-old host eggs, T. japonicum developed faster and T. ostriniae had lower progeny survival than the other three Trichogramma species evaluated, respectively. The current study provides useful information to select suitable Trichogramma species for controlling the striped stem borer, C. suppressalis.     

Trichogramma parasitoids for control of Lepidopteran borers in Taiwan: species,life‐history traits and Wolbachia infections

Trichogramma, polyphagous endoparasitoids of lepidopteran eggs, are used against a variety of crop pests throughout the world including those of sugar cane and corn in south‐eastern Asia. Their ability to be easily and economically reared on factitious hosts and their wide host range have contributed to their widespread use in pest control. The overall aim of this study was to select strains for eventual release in crop areas for control of lepidopteran borer pests of sugar cane and corn. To this end, we identified common Trichogramma species emerging from corn borer egg masses throughout south‐western Taiwan, compared their life‐history characteristics, assessed their thermal limits and identified the Wolbachia infection status of collected Trichogramma parasitoids. Trichogramma ostriniae was the most commonly collected species on corn, with occasional detection of T. chilonis and an unidentified species designated as T. sp. y. Although the sex ratio varied widely between sites, Wolbachia infection was detected only at a single site in one species (T. ostriniae). Wolbachia‐infected T. ostriniae were tolerant to high temperature stress. Trichogramma chilonis had lowest fecundity of the three species tested, and a Wolbachia‐infected T. ostriniae strain had lower fecundity than an uninfected strain. Given the limited availability of distribution and historical data for Trichogramma species in Taiwan, the current study provides a baseline for future work and also highlights the importance of accurately identifying species when establishing colonies of natural enemies for biocontrol.     

A new species ofTrichogramma [T. Cordubensis n. sp.] [Hym.: Trichogrammatidae], parasitoid ofHeliothis eggs in cotton crops in the sw of spain

Trichogramma cordubensis n. sp. is a parasite ofHeliothis armigera Hb. eggs in cotton crops in western Andalusia. Reproduced onEphestia kuehniella Zeller eggs, it is described morphologically and compared withT. chilonis Ishii andT. evanescens Westwood as both present similarities with this species.T. cordubensis can be distinguished in the male genitalia by the shape of the dorsal expansion of the gonobase and the size, shape and relative position of the median ventral projection. Male antennal setae are longer inT. cordubensis than in the other 2 species. In addition, unlikeT. chilonis andT. evanescens, T. cordubensis is thelytokous at 20°C. in our laboratory, though males and gynandromorphs can be obtained by altering the rearing temperature, this being another difference of this species.     

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

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

Maternal thermal effect on diapause in Trichogramma species (Hymenoptera: Trichogrammatidae)

Both direct thermal and maternal photoperiodic effects on diapause induction have been thoroughly investigated in many insect species, while maternal thermal effects have been infrequently studied. We studied the effect of temperature during development of maternal generation on the proportion of diapausing progeny in four species of the genus Trichogramma Westw., minute egg parasitoids, widely used for biological control of lepidopteran pests. The maternal generations were reared at day lengths of 12 and 18 h and temperatures of 17, 20, 25 and 30°C, and their progeny developed under day length of 12 h and temperatures of 13 and 14°C. In T. evanescens and T. piceum, the proportion of diapausing progeny decreased with increasing temperature under all tested photoperiods and thermal regimes of progeny development; the high temperature of 30°C totally averted diapause of progeny. In T. buesi and T. principium, low temperatures of 17 and 20°C resulted in relatively high proportion of diapausing progeny only when the maternal generation developed under short‐day conditions. The threshold of the maternal thermal response varied from 17–18 to 22–23°C. Under field conditions, Trichogramma females are exposed to such high temperatures only during summer, when diapause in their progeny is in any case prevented by the maternal photoperiodic response and by the thermal response of the larvae. We conclude that the maternal thermal effect on diapause induction, although to a different extent, is inherent to Trichogramma species but, at least as suggested by laboratory experiments, it does not play any role in the regulation of seasonal development under natural conditions. However, during mass rearing of Trichogramma wasps, it should be taken into account that high temperature, even when combined with short photoperiod, can avert diapause in the next generation.     

Life histories ofPsyllaephagus yaseeni (Hym., Encyrtidae) andTamarixia leucaenae (Hym., Eulophidae), parasitoids of the leucaena psyllidHeteropsylla cubana

Age specific fecundity of two parasitoids,P. yaseeni andT. leucaenae, of the leucaena psyllidH. cubana, were studied under laboratory conditions. At 25 °C,P. yaseeni had a greater fecundity (R₀=192.9)_thanT. leucaenae (R₀=71.2);T. leucaenae however had a lower sex ratio (about 99 % females) thanP. yaseeni (about 50 % females). Innate capacity for increase (r_m=0.236) ofT. leucaenae was higher thanP. yaseeni (r_m=0.188). Developmental rates of the parasitoids were examined at constant and fluctuating temperatures and equations of the rate of development against temperature were calculated. At 25 °C, mean generation times were 28.0 and 18.1 days forP. yaeseeni andT. leucaenae respectively. At temperatures of 21.5, 25, and 30 °C total development times (egg to adult) were 28.5, 21.9, and 14.7 days inP. yaseeni and 19.2, 12.6, and 9.5 days inT. leucaenae respectively. The level of parasitism was low and pupal mortality was high at the lower temperature of 21.5 °C for both parasitoids. Both parasitoids showed poor survivorship at 100 % RH,P. yaseeni survived particularly well (32 days) at a temperature of 21.5 °C and 44 or 76 % RH. P. yaseeni allocated about 58 % females to first instar psyllid nymphs but only 12 % females to second instars. About 99 % of allT. leucaenae births were females. Significantly largerT. leucaenae females emerged from fifth instar parasitized nymphs than third or fourth instars.     

Successful horizontal transfer of Wolbachia symbionts between Trichogramma wasps

Rickettsial symbionts of the genus Wolbachia, harboured by many arthropod species, are implicated in feminization, cytoplasmic incompatibility and parthenogenesis phenomena. These symbionts induce thelytokous parthenogenesis in some egg parasitoids of the Trichogramma genus. In our study of these minute wasps, purified Wolbachia from an infected species, T. pretiosum, were transferred by microinjection into in vitro developed pupae of an uninfected species, T. dendrolimi. We believe this to be the first successful transfer of Wolbachia in parasitoids. The presence or absence of Wolbachia was determined using DAPI staining, PCR and ftsZ gene sequencing. An ftsZ gene fragment from microinjected T. dendrolimi was shown to be identical to that of T. pretiosum, confirming that transfer was successful. Wolbachia were still present in the recipient species 26 generations after the transfer, although only partial induction of thelytoky was observed. Therefore, in Trichogramma, density of symbionts or symbiont–host interactions may be involved in the expression of parthenogenesis. The successful transfer of the symbiont within the Trichogrammatidae, a group of insects used in biological control strategies, could increase their agronomic importance by manipulating their reproductive system.     

Stimulation of A2B adenosine receptors protects against trauma–hemorrhagic shock-induced lung injury

Inflammation is responsible for secondary organ failure after trauma and hemorrhagic shock (T/HS). Adenosine, acting through four G protein-coupled cell surface receptors, A₁, A_2A, A_2B, and A₃, exerts a number of tissue protective and anti-inflammatory effects. The goal of the present study was to test the effect of A_2B adenosine receptor stimulation on T/HS-induced organ injury and inflammation in rats. Rats after T/HS were resuscitated with Ringer’s lactate containing the A_2B receptor agonist BAY 60–6583 or its vehicle. We found that BAY 60–6583 decreased T/HS-induced lung permeability and plasma creatine kinase levels but failed to affect T/HS-induced lung neutrophil infiltration and IκBα expression and plasma alanine aminotransferase levels. Thus, we conclude that stimulation of A_2B receptors protects against T/HS-induced lung and muscle injury.     

Kinetics and thermodynamics of the P870+Q−A → P870+Q−B reaction in isolated reaction centers from the photosynthetic bacterium Rhodopseudomonas sphaeroides

The temperature dependences of the P870⁺Q^?_A → P870Q_A and P870⁺Q^?_B → P870Q_B recombination reactions were measured in reaction centers from Rhodopseudomonas sphaeroides. The data indicate that the P870⁺Q^?_B state decays by thermal repopulation of the P870⁺Q^?_A state, followed by recombination. ΔG° for the P870⁺Q^?_A → P870⁺Q^?_B reaction is ?6.89 kJ · mol^?1, while ΔH° = ?14.45 kJ · mol^?1 and ?TΔS° = + 7.53 kJ · mol^?1. The activation ethalpy, $\text{H}{}^3$, for the P870⁺Q^?_A Δ P870⁺Q^?_B reaction is +56.9 kJ · mol^?1, while the activation entropy is near zero. The results permit an estimate of the shape of the potential energy curve for the P870⁺Q^?_A → P870⁺Q^?_B electron transfer reaction.     

Photoperiodic responses of pupa and adult determining maternal influence on progeny diapause in two species of the genus Trichogramma (Hymenoptera, Trichogrammatidae)

The adult photoperiodic responses of two Trichogramma species were investigated by exposing adults during 3 days to one of the seven light: dark regimes: L: D = 4: 20, 8: 16, 12: 12, 14: 10, 16: 8, 18: 6, and 20: 4. The preimaginal stages of these individuals developed under short (L: D = 12: 12), long (L: D = 20: 4) or intermediate photoperiods (L: D = 14: 10 and L: D = 16: 8 for Trichogramma principium and T. embryophagum, respectively). The progeny of these females developed under short day L: D = 12: 12 and at two moderately diapause-inducing temperatures (13 and 14°C for T. principium, 14 and 15°C for T. embryophagum). In both Trichogramma species which developed at both temperatures, the percentage of diapausing prepupae was significantly dependent both on the photoperiodic conditions of the preimaginal development of the maternal generation and on the photoperiod which influenced the adult females. The adults showed a typical long-day photoperiodic response with a threshold day length of ca 13 h in T. principium and ca 16 h in T. embryophagum, which practically coincided with the thresholds of the pupal photoperiodic responses of these species revealed in our previous studies. However, the ultra-short photoperiods (L: D = 4: 20 and 8:16) caused a relatively stronger diapause-inducing effect on the progeny when applied to the adult females than when it was applied to the pupae. Thus, in both the Trichogramma species studied, the patterns of photoperiodic responses of pupa and adult were somewhat different although they almost coincided in the “ecologically significant” part of the photoperiodic scale.     

Comparative vitellin pattern and cladogenesis in Bacillus (insecta: Phasmatodea)

• 1.1. Under denaturing conditions (SDS-PAGE) the two natural vitellins of Bacillus taxa released five different polypeptides (A₁, A₂, A₃, B₁, B₂).
• 2.2. A₂ and B₂ bands from the two bisexual species (B. rossius and B. grandii) were found to differ; furthermore a non-vitellin yolk protein characterizes the subsepecies B.g. benazzii.
• 3.3. From gels and their densitometric scanning profiles it is clear that parental polypeptides are expressed in the thelytokous parthenogenetic hybrids (B. whitei, B. lynceorum) and in the hybridogenetic B. rossius-grandii benazzii.
• 4.4. A comparative approach of vitellin patterns appears fully adequate for tracing phylogenetic relationships and recognizing cladogenetic events.

     

Thermal tolerance of dried shoots of the moss Bryum argenteum

We conducted laboratory experiments to determine the lethal temperatures of the shoots of dried Bryum argenteum and to determine how this restoration species responds to extreme environments. We specifically assessed changes in gene expression levels in the shoots of dried B. argenteum plants that were subjected to sudden heat shock (control (20 ± 2°C), 80°C, 100°C, 110°C or 120°C) followed by exposure to heat for an additional 10, 20, 30 or 60 min. After they were exposed to heat, the samples were placed in wet sand medium, and their survival and regeneration abilities were evaluated daily for 56 days. The results showed that lethal temperatures significantly reduced the shoot regeneration potential, delayed both shoot and protonemal emergence times and reduced the protonemal emergence area. In addition, the expression of nine genes (HSF3, HSP70, ERF, LEA, ELIP, LHCA, LHCB, Tr288 and DHN) was induced by temperature stress, as assessed after 30 min of exposure. Additionally, a new thermal tolerance level for dried B. argenteum – 120°C for 20 min – was determined, which was the highest temperature recorded for this moss; this tolerance exceeded the previous record of 110°C for 10 min. These findings help elucidate the survival mechanism of this species under heat shock stress and facilitate the recovery and restoration of destroyed ecosystems.     

The Oak-silkworm Egg Antheraea pernyi (Lepidoptera: Anthelidae) as a Mass Rearing Host for Parasitoids of the Genus Trichogramma (Hymenoptera: Trichogrammatidae)

The acceptance of 40 different strains of 24 Trichogramma (Hymenoptera: Trichogrammatidae) species for oak-silkworm host eggs, Antheraea pernyi Guerin-Meneville (Lepidoptera: Anthelidae) was tested in laboratory experiments. The oak-silkworm, which is commercially used in China to mass produce Trichogramma dendrolimi Matsumura on a large scale, was accepted for egg laying by 10 out of the 24 species tested but only 3 species (four strains of T. dendrolimi, three strains of T. chilonis Ishii and one strain of T. cacoeciae Marchal) successfully completed development to adult emergence. The number of adults emerged per host egg averaged 83.2, 37.0, 42.3, 53.0 for four different strains of T. dendrolimi; 42.5, 10.0 for two strains of T. chilonis; 24.5 and 0 for two strains of T. cacoeciae.

Seven other Trichogramma species develoedp in A. pernyi eggs, but no adult emergence occurred and no emergence holes on the chorion were found. The number of Trichogramma larvae, pupae, and adults together per host egg averaged 81.7 and 67.4 for two strains of T. embryophagum Hartig; 39.0 for T. japonicum Ashmead; 35.0, 16.7, 19.0, 0 for four strains of T. evanescens Westwood; 18.7, 0, 0, 0 for four strains of T. brassicae Bezdenko; 11.5 for T. piceum Dyurich; 76.4 and 23.0 for two unidentified strains collected in apple and vine orchards in Germany, respectively.

The following 14 Trichogramma species did not parasitize any A. pernyi eggs: T. atopovirilia Oatman & Platner, T. bourarachae Pintureau & Babault, T. buesi Voegél, T. funiculatum Carver, T. ivelae Pang & Chen, T. meyeri Sorokina, T. minutum Riley, T. nerudai Pintureau, T. nubilale Ertle & Davis, T. ostriniae Pang & Chen, T. principium Sugonjaev & Sorokina, T. pretiosum Riley and two further unidentified strains that originated from France and Switzerland.

The results confirmed that A. pernyi is a suitable host for rearing T. dendrolimi and T. chilonis and that the two species T. cacoeciae and T. embryophagum, under optimal conditions, might be possible candidates for rearing.