Influence of rearing hosts on host size acceptance by Trichogramma australicum

We investigated the acceptance of different sized host models by Trichogramma australicum in the laboratory. We used isoline cultures of T. australicum reared in hosts of different sizes. Helicoverpa armigera represent relatively large hosts, and those of Sitotroga cerealella are small, termed the Ha and Sc biotypes, respectively. Five sizes of glass beads were tested for acceptance: diameter 0.5, 0.75, 1.0, 1.5 and 2.0 mm. The acceptance of a host model was determined by persistent attempted drilling of a glass bead by a female. The relationship between host egg size and number of eggs laid by a female was also investigated. We used three sizes of artificial egg (diameter 0.75, 1.00, and 1.50 mm of hemispherical cupules) each containing artificial diet. Ha biotype wasps accepted host models in the range 0.75--1.50 mm dia. (vol. 0.166--1.325 l), whereas those of the Sc biotype accepted host models in the range 0.50--1.00 mm dia. (vol. 0.05--0.393 l). This evidence suggests a lineal (possibly genetic) influence to host size acceptance for T. australicum, dependent on the size of the host in which the wasp has been reared. Also T. australicum lay fewer eggs in smaller artificial eggs than in larger ones. The role of host size in host acceptance and number of eggs delivered, and its implications, is discussed.     

Development of an artificial host egg for in vitro egg laying of Trichogramma galloi and T. pretiosum using plastic membranes

An artificial host egg was developed as a first attempt to improve the techniques for in vitro rearing of Trichogramma galloi Zucchi and T. pretiosum Riley (Hymenoptera, Trichogrammatidae). Plastic membranes (polyethylene, polypropylene and polystyrene) of different thickness were tested for their usefulness in manufacturing artificial eggs, using a thermal system to produce semi-spherical cupules on the plastic surface. These artificial eggs were filled with larval hemolymph of Helicoverpa zea (Boddie) (Lepidoptera, Noctuidae), and the optimal size of the artificial egg and density of females/artificial egg for the highest host acceptance (percentage of artificial eggs with at least one parasitoid egg) as well as the ideal level of parasitism (eggs/artificial egg) were determined. High-density polyethylene 7–8 and 9–10 m thick resulted in the best acceptance and level of parasitization for both parasitoid species. Six females per artificial egg resulted in the best rate of parasitization for these parasitoids, although these data were not different when using 4 or 5 females of T. galloi. The size, shape and surface texture of the artificial eggs were found to provide enough cues to elicit parasitization behavior in Trichogramma females, since no chemical stimulus was provided.     

Survival, growth, health, and reproduction following nursery rearing compared with mother rearing in pigtailed monkeys (Macaca nemestrina)

Nursery-reared primates do not experience psychological "maternal bonding" or immunological benefits of breast milk, so they are expected to be inferior to mother-raised monkeys in growth, health, survival, reproduction, and maternal abilities. Studies of nursery-reared monkeys support aspects of this prediction for infants deprived of social contact or raised in pairs. We present colony record data on 1,187 mother and 506 nursery-raised monkeys, 2-10 yr of age, living in mixed groups. We found no group differences in survival, growth, clinical treatments for disease or bite wounds, or pregnancy outcome and neonatal deaths. Nursery males given breeding opportunities produced an average of 24 offspring. In addition to 24-hr personnel present on every day of the year, we believe that three of our procedures account for differences between our results and other reports. Our infants received 1) intensive human handling, 2) daily social interaction in a playroom, and 3) success and failure experience during learning and cognitive testing. We do not advocate rearing primates without mothers, but we conclude that these procedures are sufficient for producing physical health and adaptive juvenile and adult social skills in nursery-raised monkeys.     

Effect of semolina-jaggery diet on survival and development of Drosophila melanogaster

Drosophila melanogaster is an ideal model organism for developmental studies. This study tests the potential of semolina-jaggery (SJ) diet as a new formulation for bulk rearing of flies. Semolina and jaggery are organic products obtained from wheat endosperm and cane sugar, respectively. Semolina is a rich source of carbohydrates and protein. Jaggery has a high content of dietary sugars. Moreover, preparation of semolina jaggery diet is cost-effective and easy. Thus, the current study aimed to compare survival and developmental parameters of flies fed the SJ diet to flies fed the standard cornmeal-sugar-yeast (CSY) diet. SJ diet enhanced survival of flies without affecting fecundity; male flies showed increased resistance to starvation. A higher number of flies emerged at F₂ and F₃ generation when fed the SJ diet than when fed the control CSY diet. SJ diet did not increase fly body weight and lipid percentage. Therefore, SJ diet can be used for bulk rearing of healthy flies at par with the standard cornmeal-sugar-yeast diet.     

害虫遗传防治的研究历史与现状

作为防治或根除重大害虫最为有效的手段之一,害虫遗传防治在世界范围内被广泛采用并取得了巨大成功。本文综述了不育昆虫技术、雌性致死系统和昆虫显性致死技术等经典害虫遗传防治策略的发展历史、技术特点和应用情况。近年来,许多新的分子生物手段被不断提出并整合到害虫遗传防治策略中,包括归巢核酸内切酶基因、锌指核酸酶、转录激活因子样效应因子核酸酶、CRISPR/Cas9系统、Medea元件、Killer-Rescue系统、Wolbachia-细胞质不亲和性系统等。基于这些新的工具手段,许多国家已经在不同程度上启动了下一代害虫遗传防治项目。而我国在该领域的研究相对薄弱,需要在借鉴国外成功经验的同时,进一步加强害虫遗传防治的基础和应用研究,从而实现本地有害生物的可持续治理和外来入侵生物的有效狙击,确保我国未来的粮食和生态安全。     

Host discrimination and superparasitism in wild and mass-reared Diachasmimorpha longicaudata (Hym.: Braconidae) females

We compared the oviposition behavior and host discrimination ability of wild and mass-reared Diachasmimorpha longicaudata (Hymenoptera: Braconidae) females parasitizing Anastrepha ludens (Diptera: Tephritidae) larvae. Both kinds of parasitoid females were presented simultaneously with parasitized and non-parasitized larvae in choice tests, and their superparasitism performance was evaluated under a mass-rearing situation. At the time of the test, D. longicaudata had 156 generations under mass-rearing conditions. Our goal was to determine the effect of the mass-rearing process on the foraging decisions of this species. One of the primary findings was the apparent ubiquity of superparasitism by D. longicaudata females. Both types of females showed similar patterns in each of the phases of oviposition behavior evaluated. The only notable differences were among the percentages of transition between behaviors, mainly related to the intensity with which each activity was performed. Under a mass-rearing situation, both strains of females had a similar tendency to increase superparasitism (i.e., number of oviposition scars per puparium and the proportion of superparasitized larvae) over time. The mass-rearing process appears to have induced the selection of more aggressive, fertile and precocious females. Despite these observations, we concluded that the process of adaptation to mass-rearing conditions has not substantially influenced the foraging and ovipositional behaviors in this species.     

Landscape-Level Assessment of Brood Rearing Habitat for Greater Sage-Grouse in Nevada

Abstract: Loss of quality brood rearing habitat, resulting in reduced chick growth and poor recruitment, is one mechanism associated with decline of greater sage-grouse (Centrocercus urophasianus) populations. Low chick survival rates are typically attributed to poor-quality brood rearing habitat. Models that delineate suitability of sage-grouse nesting or brood rearing habitat at the landscape scale can provide key insights into the relationship between sage-grouse and the environment, allowing managers to identify and prioritize habitats for protection or restoration. We used Southwest Regional Gap landcover types to identify early and late greater sage-grouse brood rearing in east-central Nevada. We conducted an Ecological Niche Factor Analysis to 1) examine the effect these landcover types and other ecogeographical variables have on sage-grouse selection of brood rearing habitat, and 2) generate landscape-scale suitability maps. We also evaluated if incorporating a fitness component (brood survival) in landscape spatial analyses of habitat quality influenced our assessment of habitat suitability. Because 36% of our 6,500-km² study area was identified as early brood rearing habitat, we believe this habitat may not be limiting greater sage-grouse populations in east-central Nevada, USA, at least in wet years. We found strong selection for particular landcover types (e.g., higher elevation, moist sites with riparian shrubs or montane sagebrush) during late brood rearing. Late brood rearing habitat on which broods were successfully reared represented only 2.8% of the study area and had a restricted distribution, suggesting the potential that such habitat could limit sage-grouse populations in east-central Nevada.     

Stable expression of human growth hormone over 50 generations in transgenic insect larvae

Developments in insect transgenesis using transposons combined with available mass rearing technology for insects such as the Medfly, Ceratitis capitata, provide opportunity for the production of protein for industrial, agricultural and healthcare purposes on a very large scale. In this study, we report the germ-line transformation and expression of a cDNA encoding human growth hormone (hGH) in transgenic Drosophila using the Minos transposon. Production and secretion of a bioactive hGH into the haemolymph of transgenic larvae was demonstrated by immunoblot analysis, ELISA and a proliferation bioassay. Stable expression of hGH was observed over 50 generations. The results indicate that mass reared transgenic diptera with a rapid period of larval growth could provide cost effective production systems for the manufacture of therapeutic and other high value proteins.     

Olfactory responses of western flower thrips (Frankliniella occidentalis) populations to a non‐pheromone lure

Western flower thrips (WFT), Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), is a major pest of horticultural crops worldwide. The search for alternative pest management techniques has resulted in increasing interest in the use of kairomones and other behaviour‐modifying chemicals to mitigate the impact of this pest. In this study, we determined whether the origin of populations, feeding history, and/or genotype influence the response of WFT to the thrips kairomone lure methyl isonicotinate (MI) in a Y‐tube olfactometer study. Four New Zealand thrips populations were tested: (1) from a commercial glasshouse capsicum crop, (2) from a long‐established laboratory colony (>222 generations) kept on chrysanthemums, (3) from a laboratory colony (6–9 generations) kept on French dwarf beans, and (4) thought to be a separate cryptic non‐pest species from outdoor yellow tree lupins, Lupinus arboreus Sims (Fabaceae). In the laboratory tests, significantly more WFT from all four populations chose the MI‐laden arm of a Y‐tube olfactometer when it contained 1 μl methyl isonicotinate (61.3–73.2%) compared with the blank no‐odour arm. No differences in response to MI were found between the two laboratory and the one glasshouse WFT populations. Both laboratory populations and the greenhouse population belonged to the ‘glasshouse pest’ genotype of WFT. However, the cryptic non‐pest WFT genotype responded more strongly to MI than any of the other populations, although the response was only significantly stronger than that of the long‐established laboratory population. Significant differences were also found among populations in the average time taken for thrips to make a choice to enter either arm of the Y‐tube olfactometer, with the cryptic non‐pest lupin genotype taking the shortest time, followed by thrips from the capsicum glasshouse. The results are discussed with respect to the variability in olfactory perception and olfactory behaviour within a species and the relevance to the use of such a kairomone lure in pest management programmes.     

Do experimental units of different scale affect the biological performance of European sea bass Dicentrarchus labrax larvae?

The effects of different tank volumes (2000, 500 and 40 l) on European sea bass Dicentrarchus labrax larval rearing, relating to growth, survival, quality and stress variables, were investigated. A dynamic energy budget (DEB) model was used to analyse the results. The hydrodynamics of the tanks exhibited differences, with the water currents in the 2000 l tanks to be almost one order of magnitude stronger than those in the 40 l ones. Important differences in fish growth were observed between small and large tank‐rearing volumes, with the smallest tank resulting in the slowest growth. Based on the DEB model analysis, growth differences were related to feeding rates, with growth in the smaller tank limited by food availability. Differences in survival rates were not statistically significant among the tank‐rearing volumes. The quality evaluation of the fry (in terms of swimbladder, jaw and skeletal abnormalities) showed differences, with the smallest tank having the highest percentage of deformed individuals. This could be attributed to both the feeding variances and the hydrodynamics in the tanks. No differences were observed in terms of whole‐body cortisol at the two developmental stages; flexion, and when the larvae body was fully covered by melanophores; when analysis was performed. This indicates that the allostatic load exerted on fish of different groups was similar and inside the fish‐coping abilities range, in terms of the cortisol response axis. The selection of the experimental scale is of importance, especially when the results are to be transferred and applied on an industrial scale.