Are egg parasitoids of the genus Trichogramma (Hymenoptera: Trichogrammatidae) promising biological control agents for regulating the invasive Box tree pyralid,Cydalima perspectalis (Lepidoptera: Crambidae)?

The Box tree pyralid, Cydalima perspectalis Walker (Lepidoptera: Crambidae), is an invasive species in Europe, not yet regulated by natural enemies. It is highly destructive to ornamental and native Buxus due to defoliation by larval feeding. The ability of eight Trichogramma species (T. brassicae Bezdenko, T. bourarachae Pintureau & Babault, T. cacoeciae Marchal, T. cordubensis Vargas & Cabello, T. dendrolimi Matsumura, T. evanescens Westwood, T. nerudai Pintureau & Gerding and T. pintoi Voegele) to parasitise and locate eggs of C. perspectalis was assessed in the laboratory. In direct observation tests, all species started to examine and oviposit into exposed eggs. Resulting egg parasitism was low and ranged between 4% and 20% for most of the parasitoid species after three days of exposure. Only T. dendrolimi parasitised significantly more host eggs with parasitism rates above 40%. On average, two to three progeny emerged from one host egg and the resulting sex ratio was female-biased, indicating suitability of the target host for progeny production. In subsequent cage tests on potted Buxus plants, again T. dendrolimi was the most efficient species in locating host eggs on foliage. We conclude that C. perspectalis eggs are attractive to various Trichogramma species. T. pintoi had the highest number of egg encounters and active females. T. dendrolimi females were most able to locate host eggs and to oviposit and produce successfully on them. Nonetheless, further study is needed to clarify the suspected role of potentially egg defensive mechanisms that may impede higher parasitisation in C. perspectalis.     

Do Trichogramma minutum Riley and Trichogramma bennetti Nagaraja & Nagarkatti (Hymenoptera: Trichogrammatidae) occur in Brazil?

According to some catalogues, Trichogramma minutum and T. bennetti have been recorded in Brazil. However, the information obtained in studies with Trichogramma in recent years indicate that those species do not occur in Brazil.     

Are indigenous strains of Trichogramma sp. (Hym., Trichogrammatidae) better candidates for biological control of lepidopterous pests of the olive tree?

Strains of the egg parasitoid, Trichogramma, indigenous in olive groves in the Mediterranean region (T. bourarachae Pintureau & Babault, T. cacoeciae Marchal, T. cordubensis Vargas & Cabello, T. euproctidis Girault, T. nerudai Pintureau & Gerding, T. oleae Voegelé & Pointel) as well as commercially available strains (T. brassicae Bezdenko, T. cacoeciae, T. evanescens Westwood), were assessed in laboratory and semi-field experiments for their attributes as biological control agents for use against lepidopterous olive pests like the olive moth (Prays oleae Bern.) and the jasmine moth (Palpita unionalis Hübn.). In a choice test, an Egyptian strain of T. cordubensis parasitized significantly more olive and jasmine moth eggs than those of the rearing host Sitotroga cerealella Olivier. This strain was also most efficient in finding eggs of the target pests on olive foliage and on potted olive trees. Survival and fecundity of a Tunisian strain of T. bourarachae was not affected when exposed to hot (35°C) and arid (< 40% relative humidity) conditions in comparison to the mild standard of 25°C and 70% relative humidity. It was concluded that indigenous strains collected from olive groves were more effective against the target pests and more tolerant to arid conditions than commercially available parasitoid species, indicating that biological control agents should preferably be isolated from the relevant pest/crop system.     

The genera of Bethylidae (Hymenoptera: Chrysidoidea) in four areas of Atlantic Rain Forest from Espírito Santo, Brazil

The generic richness and abundance of Bethylidae collected in four different hillside areas of Atlantic rain forest from Espírito Santo, Brazil were studied. The sites are Santa Maria de Jetibá (SMJ), Domingos Martins (DM), Pancas (P) and Atílio Vivacqua (AV). A total of 2,840 specimens of 12 genera were collected. Lepidosternopsis Ogloblin and Bakeriella Kieffer are first recorded from the State. Richness of taxa was calculated using first-order Jackknife richness with EstimateS program. Genera accumulation curves were ran to evaluate the samples. Abundance data were adjusted to the geometric distribution. Parameter k was used to compare areas. The generic profile was not equal for the sites we studied. The areas were considered disturbed. SMJ and DM presented genera richness bigger than in P and AV. The differences in the sites reflect the different preservation of each environment. Pseudisobrachium Kieffer and Dissomphalus Ashmead are most dominant genera in SMJ, DM and P, and Anisepyris Kieffer in AV. This study emphasizes the fact of Dissomphalus as the most abundant genus in rain forests. The generic profile found in AV is similar to that of some areas of Brazilian savannah.     

Temperature-Dependent Parasitism,Survival, and Longevity of Five Species of Trichogramma Westwood (Hymenoptera: Trichogrammatidae) Associated with Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae)

Egg parasitoids of the genus Trichogramma Westwood play an important role in the control of the velvetbean caterpillar Anticarisa gemmatalis Hübner in soybean crops in Southern Brazil. The effectiveness of Trichogramma species as biocontrol agents is dependent of several factors, but their adaptation to the climatic conditions of the region where they will be released is one of the most important. In this context, this study evaluated the effects of five constant temperatures ranging from 14 to 30°C on parasitism, age-specific survival, progeny production and longevity of Trichogramma pretiosum Riley, Trichogramma atopovirilia Oatman & Platner, Trichogramma acacioi Brun, Moraes & Soares, Trichogramma lasallei Pinto, and Trichogramma rojasi Nagaraja & Nagarkatti. We demonstrate that temperature differently affected the species of Trichogramma investigated when using eggs of the velvetbean caterpillar. We also demonstrate that T. pretiosum and T. atopovirilia are better adapted to a wide range of temperatures than the other species evaluated, and are therefore better suited as biocontrol agents for applied biological control programs of A. gemmatalis.     

Variations in the “spontaneous” dynamics of the tendency to diapause among generations of Trichogramma telengai Sor. (Hymenoptera, Trichogrammatidae)

Variations in the tendency to diapause were investigated in 5 successive generations of 6 parthenogenetic clones of Trichogramma telengai Sor. reared under constant laboratory conditions (the temperature of 20°C and the day length of 18 h). The tendency to diapause was estimated by the proportion of the progeny which diapaused at temperatures of 13, 14 and 15°C. Although the variations in the tendency to diapause in successive generations of different clones were positively correlated, the dynamics of the proportion of diapausing progeny in one of the studied clones was significantly different from that in the other clones reared under the same conditions. Moreover, the differences among subclones originated from the same female were also revealed. Analysis of the results suggests that the interclonal variations in the proportion of diapausing progeny were at least partly caused by endogenous factors. The differences between clones can arise during the development of one generation but can also damp very fast or, at least, they are not accumulated over generations. These variations are probably based on the same epigenetic mechanisms that form the basis of the maternal effect on the progeny diapause in Trichogramma species.     

Влнянне характера эаселення ноля капустноii совкоii(Barathra brassicae L.) эффективноеть трихограммы (Trichogramma evanescens Westw.) (Lepidoptera,Noctuidae; Hymenoptera,Trichogrammatidae)

TSWV belongs to the genus Tospovirus which was established in the family Bunyaviridae, a family of animal viruses. Besides TSWV, Impatiens necrotic spot virus (INSV) and ground nut bud necrosis virus (GBNV) were established as different Tospovirus species. Tospoviruses have quasispherical particles of 85 nm diametre which are surrounded by a membrane and contain 3 RNA species and 4 structural proteins. In Tospovirus infected plant cells virions were detected in cavaties of the endoplasmatic reticulum and additionally amorphous electron dense material accumulates in infected cells. Defective forms of TSWV lack the ability to form complete virus particles. TSWV is the only plant pathogenic virus that is transmitted by thrips which transmit the virus with different efficiency. The virus has an extensive plant host range of more than 360 different species. The developing symptoms depend on the Tospovirus species, the virulence of the virus strains and the environmental conditions.

Based on the reaction of TSWV isolates with N‐specific polyclonal antisera, 3 serogroups were established. The most frequently used technique for serologically based diagnosis of Tospoviruses is DAS ELISA with N‐specific or preadsorbed antisera against complete virus. For TSWV epidemiology distinct weeds and cultural host plants play an important role for the survival of virus and vector. Breeding for resistance is the most important preventive measure of control.     

Ethnobotany of caiçaras of the Atlantic Forest coast (Brazil)

Caiçaras are inhabitants of the Atlantic Forest coast in SE Brazil. We studied the uses of plants by five Caiçara communities and compared medicinal plant citations by informants in coastal and island communities. We use diversity indices to evaluate the use of plants and to compare communities. There is a high diversity of plants used in the Atlantic Forest coasts: we found 276 species used for food, medicine and construction. Caiçaras rely on folk medicine, and medicinal plants were especially cited in interviews. Following predictions of island biogeography theory, we found a lower diversity of medicinal plants cited in islands compared to continental communities.     

Diversity of phytoseiid mites (Acari: Mesostigmata: Phytoseiidae) in the Atlantic Forest of São Paulo

The objective of this study was to evaluate the diversity of Phytoseiidae in the Atlantic Forest of São Paulo State, Brazil, and to estimate the possible role of this ecosystem as a reservoir for mites of this family. Samples were taken from 187 plant species belonging to 73 plant families in three vegetation types of the Atlantic Forest, from February 2001 to October 2002. In total, 1102 specimens of 54 species belonging to 20 genera of the three phytoseiid subfamilies were found. Most specimens (93%) and species (91%) belonged to the Amblyseiinae. The majority of species found belong to taxonomic groups largely composed of generalist predators (especially Amblyseius and Euseius). In general, the more abundant mites were found on a diversity of plant species, but a few of the abundant species were found on only a small number of plant species. Only nine of the mites encountered during this study are of known agricultural importance. The results obtained suggest the importance of the wide plant diversity in the region to sustain a wide diversity of phytoseiids. The extensive clearance of the Brazilian Atlantic Forest is a threat to the diversity of these mites, important predators of mite pests.     

Notes on the biology of the ant speciesMyrmecia dispar (Clark) (Hymenoptera: Formicidæ)

Myrmecia dispar (Clark) is found in the drier inland areas of New South Wales and southern Queensland in Australia. Its nests, which are situated adjacent to trees, have a distinctive structure of simple architecture. The composition of the colonies varies seasonally with little or no brood production during the colder months. Colony founding probably takes place in March, April, and/or May. Several myrmecophiles are found in nests ofM. dispar, and some of these are present in relatively large numbers.     

Enhancement of attraction to sex pheromone of Grapholita molesta (Busck) (Lepidoptera: Tortricidae) by structurally unrelated sex pheromone compounds of Conogethes punctiferalis (Guenée) (Lepidoptera: Crambidae)

Grapholita molesta (Busck) (the oriental fruit moth; OFM) and Conogethes punctiferalis (Guenée) are both fruit and stem borers with overlapping habitats, occurrences, and outbreak cycles. These two species are in different families and they have completely different sex pheromone components. Here, the effects of the sex pheromone components of C. punctiferalis, (E)-10-hexadecenal (E10-16:Ald) and (Z)-10-hexadecenal (Z10-16:Ald) and their mixture, were evaluated on the sexual communication of OFM by examining electrophysiological (EAG) and behavioral responses. We found that a considerably large amount of E10-16:Ald or Z10-16:Ald and a tiny amount of OFM pheromone elicited comparable EAG responses in OFM males, indicating the low antennal olfactory sensitivity of OFM males to the heterospecific pheromone compounds. In two different peach orchard parcels, captures of OFM by their pheromone lures baited in delta traps were increased by at least 1.5 times when OFM pheromone lures were combined with lures that contained 1000 μg of either E10-16:Ald, Z10-16:Ald or their mixture. In two other pear orchard parcels, both E10-16:Ald and Z10-16:Ald increased captures of OFM in Unitraps in a dose-dependent manner with more than a four-fold increase. Therefore, the enhanced attractiveness of OFM lures by the two interspecific pheromones suggests their potential application to improve mass trapping, population monitoring and mating disruption of OFM.     

Seasonal parasitism and biological characteristics of Habrobracon hebetor (Hymenoptera: Braconidae) – a potential larval ectoparasitoid of Helicoverpa armigera (Lepidoptera: Noctuidae) in a chickpea ecosystem

Seasonal parasitism of Habrobracon hebetor (Say) on Helicoverpa armigera (Hübner) in chickpea was studied for three consecutive years. Parasitism by H. hebetor on larvae of H. armigera reached 12.3%. The parasitoid maintained reproductive activity on H. armigera from February to April coinciding with pod formation and maturation stages of the crop. In laboratory assays, we investigated the suitability of larval instars of H. armigera to the parasitoid H. hebetor. This parasitoid attacked third to sixth instars, though fourth and fifth instar larvae were found most suitable with 100% parasitism and development to adults. Parasitoid developmental time was longest in fifth instar (9.1 days) compared to other instars (8.1–8.9 days). Fifth instar larvae resulted in highest numbers of cocoons and adult emergence. In addition, suitability of seven lepidopteran species to H. hebetor was investigated. Corcyra cephalonica, Galleria mellonella and H. armigera were the most suitable hosts with 100% parasitism and development to adults. It was followed by Maruca vitrata and Autographa nigrisigna with 60–76.7% and 40–70% parasitism and parasitoid developmental success, respectively. Though there was 23.3% parasitism, there was no parasitoid development in Spodoptera litura. No parasitism was recorded in Spilarctia obliqua. Development of H. hebetor was most rapid in C. cephalonica (8.7 days), and longest in G. mellonella (9.3 days). Parasitoids that developed on these hosts resulted in highest numbers of cocoons and adult emergence. The parasitoid could be exploited for the biological control of H. armigera in a chickpea ecosystem.     

Oviposition model of Cnaphalocrocis medinalis Guenée (Lepidoptera: Pyralidae)

The longevity and fecundity of Cnaphalocrocis medinalis were investigated at temperatures of 15.0, 17.5, 20.0, 22.5, 25.0, 27.5, 30.0, 32.5, and 35.0 °C. Adult longevity and fecundity were significantly influenced by temperature. Longevity decreased with increasing temperature: it was highest at 15.0 °C (23.6 ± 3.51 days) and lowest at 35.0 °C (6.4 ± 0.48 days). Fecundity was highest at 25.0 °C (170.5 ± 45.54 eggs) and lowest at 17.5 °C (11.0 ± 3.68 eggs). The oviposition period was longest at 20.0 °C (8.0 ± 1.09 days) and shortest at 35.0 °C (2.3 ± 0.48 days). The oviposition model presented in this study consisted of two reproductive components (total fecundity and age-specific cumulative oviposition rate) and a survival component (age-specific survival rate). The relationship between adult developmental rate and temperature was described by the Lactin 2 model (r² = 0.98, p < 0.0001). The age-specific survival rate was well explained by a sigmoid function (r² = 0.97, p < 0.00001). The age-specific cumulative oviposition rate was best described by the three-parameter Weibull function (r² = 0.99, p < 0.00001). Temperature-dependent fecundity was estimated using the Briere-2 model (r² = 0.94, p < 0.007). Daily egg production of C. medinalis in relation to adult age and temperature was estimated.     

Comparative assessments of Gonatocerus ashmeadi and the ‘new association’ parasitoid G. deleoni (Hymenoptera: Mymaridae) as biological control agents of Homalodisca vitripennis (Hemiptera: Cicadellidae)

Egg age preference, competitive ability, and behavior of Gonatocerus deleoni (‘new association’ parasitoid) and G. ashmeadi (the co-evolved dominant parasitoid in California) were investigated in the laboratory to determine whether one species exhibited competitive superiority. When searching concurrently for Homalodisca vitripennis egg masses, G. ashmeadi consistently outperformed G. deleoni by parasitizing 59–89% more eggs under three different experimental systems in the laboratory with varying host densities, egg ages, and exposure times. G. ashmeadi parasitism in control vials containing one parasitoid ranged from 58 to 86% and was up to 28% higher at egg ages 1 and 3 days compared with 5 days. G. deleoni in control vials parasitized on average 7% of H. vitripennis egg masses in 1 h regardless of egg age. G. deleoni failed to parasitize H. vitripennis egg masses in 15 min when caged alone or in competition with G. ashmeadi. In a combined species treatment, parasitism by G. ashmeadi was 11% higher when H. vitripennis eggs were exposed for 5 days compared with 24 h. Conversely parasitism by G. deleoni was 5% lower for this comparison. G. ashmeadi had a significantly female biased sex ratio for all three experimental designs, whereas, G. deleoni offspring sex ratio was not significantly greater than 50%. In comparison to G. ashmeadi, behavioral observations indicated that G. deleoni was absent from host egg infested leaves 53% more frequently and it oviposited 66% less frequently. No incidences of females aggressively chasing competitors off H. vitripennis egg masses were recorded during this study.     

Can cruciferous agroecosystems grown under variable conditions influence biological control of Plutella xylostella (Lepidoptera: Plutellidae)?

Determining the most efficacious method for the release of parasitoids is challenging, depending on the crop area to be covered and the environmental conditions created by the agroecosystem. Release of the parasitoid Oomyzus sokolowskii (Kurdjumov) and the effect of crucifers cropping systems were investigated in relation to diamondback moth (DBM), Plutella xylostella (L.) control. First, we investigated the dispersal ability of O. sokolowskii. Kale plants were infested with 20, 25, 30 and 35 DBM larvae each, at distances of 0, 8, 16, and 24 m, from a central release point in the field. Second, the effect of a multiple host plant system composed of cabbage, broccoli and Napa cabbage on the parasitism capacity of O. sokolowskii was investigated. Lastly, the parasitism capacity of O. sokolowskii and the colonization rate of DBM were investigated comparing cropping systems composed of either a monoculture of cabbage, or three different intercropping systems: cabbage and green onion, cabbage and cilantro, and cabbage, green onion and cilantro. For all experiments, selected plants were infested with sentinel DBM larvae and caged with mesh that allowed parasitoids to search inside the cages while reducing the impact of opportunists on DBM larvae. Results showed that parasitoids were able to disperse and parasitize P. xylostella at similar rates throughout a field of kale up to 24 m from the release point. Intercropping of cabbages with other crop plants did not negatively affect parasitism rates of O. sokolowskii, which makes it promising for DBM biological control; however it did not interfere with cabbage colonization by DBM.     

Passive evasion of encapsulation in Macrocentrus cingulum Brischke (Hymenoptera: Braconidae), a polyembryonic parasitoid of Ostrinia furnacalis Guenée (Lepidoptera: Pyralidae)

The hymenopteran Macrocentrus cingulum usually deposits one egg into the larval body cavity of lepidopteran Ostrinia furnacalis, and the egg subsequently splits into several dozens of embryos during its development. How the parasitoid eggs and embryos avoid encapsulation by the host's immune response remains unknown. We compared hemocyte counts, morphologies and behaviors between unparasitized O. furnacalis larvae, and larvae parasitized by M. cingulum. No distinct differences were observed. Sephadex A-25 beads elicited a strong encapsulation response when injected into the parasitized host larvae, which indicates that parasitism by M. cingulum does not affect host's cellular immunity. However, there were significant differences in the host's encapsulation reactions towards injected eggs from different sources. Injected M. cingulum mature eggs excised from the lateral oviducts of the female wasps were not encapsulated, while immature eggs or driselase treated mature ones provoked an encapsulation response within 2 h after injection. Inspection of eggs by transmission electron microscopy revealed that the driselase collapsed the surface fibrous layer of the eggs, indicating that surface fibrous layer may play a role in protecting eggs from host's immune attack.     

Factors affecting the parasitism rate and the number and sex ratio of offspring of Asecodes hispinarum Bouček (Hymenoptera: Eulophidae), a biological control agent of Brontispa longissima (Gestro) (Coleoptera: Chrysomelidae)

To optimise the production of Asecodes hispinarum Bou?ek (Hymenoptera: Eulophidae), a parasitoid of coconut leaf beetle, Brontispa longissima (Gestro) (Coleoptera: Chrysomelidae), some of the factors affecting rates of parasitism, number of offspring produced per host and sex ratio of A. hispinarum were investigated. The numbers and sex ratio of A. hispinarum offspring per host reduced significantly at extreme low humidity (30% relative humidity [RH]), but there was no significant effect on parasitism. Photoperiod had no significant effects on any of the life traits tested. A. hispinarum was able to reproduce via arrhenotoky, and while increasing the proportion of female parents increased the number of parasitoids produced, the proportion of female offspring decreased. Older females showed a lower rate of parasitism than young females, however, maternal age did not affect the number or the sex ratio of offspring. Increasing the number of hosts offered to a pair of parasitoids significantly increased the number of parasitised hosts but decreased the parasitism rate while the sex ratio of progeny was not affected. Present work showed that to maximise the production of female parasitoids, a parasitoid/host ratio of 1:1, using one-day old A. hispinarum at a female/male ratio of 3:1 and RH of at least 55% is recommended.     

Observations on the Behavior of Rain Forest Peccaries in Perú: Why do White-lipped Peccaries Form Herds?

The ecology and behavior of Tayassu tajacu and T. pecari were studied for a total period of 16 months in the years 1975–1978 in the Manú National Park in southeastern Perú. It appears from 132 sightings of T. tajacu at the study site, and from reports from other regions, that groups of this species in rain forest usually contain fewer than 12 individuals. The more observers were at the study site, the more frequently this species was encountered. T. tajacu also repeatedly used wallows in the forest. These observations suggested that individuals of this species were relatively sedentary. Herds of T. pecari were encountered on 60 occasions. Five counts indicated that there were over 100 individuals in the herds. This species was encountered at practically random intervals, independent of number of observers at the site, but more frequently in the dry season than in the rainy season. Adults of both species are prey primarily of large cats and humans. Both species feed on green plant parts, fruits, nuts and seeds, but T. pecari feeds on more resistant seeds and nuts than T. tajacu. The hardest palm nuts that only T. pecari can consume are distributed in a patchy manner. Cracking these nuts between the teeth causes the animals to be heard more than 50 m away. The patchy distribution of the hard nuts and seeds prevents T. pecari from being sedentary, and group formation likely has several individual benefits for foraging efficiency and defense against predators. These may include (1) avoidance of searching for food in places recently visited by others, (2) benefitting from the knowledge of experienced foragers, (3) reducing the per capita probability of detection by predators, (4) reducing the probability of being captured after group detection by predators, (5) increasing the ability to counterattack as a group, (6) increasing the probability of detecting the predator before it can attack, and (7) “confusing” the predator through escape behavior. T. tajacu seems to live in small groups because its typical foods are distributed more evenly and because consumption of these foods does not cause individuals to be so noticeable to predators.     

Biological aspects of Autoplusia egena (Guenée) (Lepidoptera: Noctuidae, Plusiinae)

Autoplusia egena (Guenée) is a moth distributed throughout the Western hemisphere. The larvae have already been found feeding on several different plant families, including important crops such soybeans and beans. To contribute to the knowledge of its biology in laboratory conditions, and considering the duration and the morphometry of each development stage, a laboratorial rearing was accomplished at 25 +/- 1 degrees C, 70 +/- 10% RH and 14h photophase. The larvae were fed with black bean leaves and the adults were fed with a honey solution at 10%. The results, expressed by the mean (+/- SE), for the periods of each stage were: egg 3.0 +/- 0.00 d; larva 15.7 +/- 1.25 d; pre-pupa 1.9 +/- 0.05 d; pupa 8.8 +/- 0.09 d and adult: longevity 12.1 +/- 0.95 d, pre-oviposition 5.4 +/- 0.50 d, oviposition 6.3 +/- 1.10 d and post-oviposition 1.4 +/- 0.87 d. The larvae went through five instars, for which the mean width of the cephalic capsules were 0.302 +/- 0.001 mm; 0.500 +/- 0.003 mm; 0.854 +/- 0.008 mm; 1.424 +/- 0.011 mm and 2.744 +/- 0.053 mm. The average length, width, and weight of the pupae were 16.965 +/- 0.003 mm, 4.674 +/- 0.040 mm and 0.217 +/- 0.003 g, respectively.     

The invasive gall wasp Quadrastichus erythrinae (Hymenoptera: Eulophidae) in South America: is classical biological control needed?

The invasive gall wasp Quadrastichus erythrinae, a pest of Erythrina plants, is recorded for the first time in South America in Espírito Santo, Brazil. Research on Q. erythrinae and its potential natural enemies in this region is required to determine the need for classical biological control of this invasive pest.