Evidence of controlled corpus allatum activity in the adult Colorado potato beetle

The in vivo control of corpus allatum (CA) activity in females of Leptinotarsa decemlineata was investigated. Evidence was obtained that CA activity is adjusted by negative feedback when juvenile hormone (JH) titres are changed experimentally. Conclusions are based on determination of the rate of in vitro JH synthesis by the CA, on changes in CA volume, and on JH titres in the haemolymph. These assay methods are used alternatively in some of the experiments.After unilateral allatectomy, the remaining CA had doubled its activity 7 days later. On the other hand, the activity of CA in young adults was suppressed after the JH titre was elevated by the implantations of 2 CA taken from active females. Similarly, in beetles treated topically with exogenous JH the CA atrophied and showed a much reduced activity after 5 days. Denervation of CA in 0-day-old long-day and 7-day-old short-day females did not change CA activity when measured 1 day later.     

The alpha–beta–regional relationship: providing new insights into local–regional patterns of species richness and scale dependence of diversity components

Ecologists frequently regress local species richness on regional species richness to draw inferences about the processes that structure local communities. A more promising approach is to quantify the contributions of alpha and beta diversity to regional diversity (the ABR approach) using additive partitioning. We applied this approach to four local–regional relationships based on data from 583 arboreal beetle species collected in a hierarchically nested sampling design. All four local–regional relationships exhibited proportional sampling, yet the ABR approach indicated that each was produced by a different combination of alpha and beta richness. Using the results of the ABR analysis, we also analysed the scale dependence of alpha and beta using a hierarchical linear model. Alpha diversity contributed less than expected to regional diversity at the finest spatial scale and more than expected at the broadest spatial scale. A switch in relative dominance from beta to alpha diversity with increasing spatial scale suggested scale transitions in ecological processes. Analysing the scale dependence of diversity components using the ABR approach furthers our understanding about the additivity of species diversity in biological communities.     

厦门地区桔小实蝇疫情监测

1994年10月至1996年10月我们在厦门地区设置18个监测点,利用桔小实蝇性诱剂观测,结合室内外调查试验,基本查明本地区桔小实蝇的分布,为害情况及其消长规律。该虫在厦门普遍发生,为害15种果树植物,发生高峰期为8-10月份,影响发生的主要因子有温度和寄主等。     

梨小食心虫性诱剂附加农药诱杀器的设计

通过田间对梨小食心虫雄蛾着陆行为观察,设计出4种诱杀器,其中双翼式和台式最适于雄蛾降落。诱杀器的材料以PVC塑板为好。涂在诱杀器上的缓释型菊酯农药,开始对雄蛾有较强的忌避作用,但在田间暴露10天后,雄蛾着陆率可在80％以上,让雄蛾接触在田间暴露的药膜5秒左右,开始雄蛾可在10分钟内被击倒,当药膜在田间暴露80天后,仍可击倒雄蛾,所以这种性诱剂加农药的诱杀器有可能用来防治梨小食心虫或其它小型害虫。     

Patterns of fluctuating asymmetry in beetle horns: no evidence for reliable signaling

Negative relations between trait size and levels of fluctuatingasymmetry in secondary sexual traits have been claimed to beindicative of honest signaling of male quality. Comparativestudies of beetle horns have been used to illustrate the requirednegative relation between trait size and asymmeiry However,such studies may be confounded by measurement error or samplingbias due to population differences or differences within speciesin the phenotypic expression of hornedness. We examined thepatterns of fluctuating asymmetry within two species of hornedbeetle. We found that, in agreement with theory, horns exhibitgreater asymmetry than naturally selected traits. However, wefound a strong positive relation between horn size and asymmetryin Onthophagus taurs, a species with male dimorphisms, and aflat relation in Bubas bison, a species with continuous variationin horn size. We suggest that these differences may reflectfunctional differences in horns. We conclude that patterns ofasymmetry in horned beetles do not support the notion of honestsignaling.     

Development of an improved attractive lure for the pine shoot beetle, Tomicus piniperda (Coleoptera: Scolytidae)

Abstract 1 The pine shoot beetle, Tomicus piniperda (L.) (Coleoptera: Scolytidae), is an exotic pest of pine, Pinus spp., and was first discovered in North America in 1992. 2 Although primary attraction to host volatiles has been clearly demonstrated for T. piniperda, the existence and role of secondary attraction to insect‐produced pheromones have been widely debated. 3 Currently, commercial lures for T. piniperda include only the host volatiles α‐pinene in North America and α‐pinene, terpinolene and (+)‐3‐carene in Europe. Several potential pheromone candidates have been identified for T. piniperda. 4 We tested various combinations of host volatiles and pheromone candidates in Michigan, U.S.A., and Ontario, Canada, to determine an optimal blend. 5 Attraction of T. piniperda was significantly increased when trans‐verbenol (95% pure, 3.2%cis‐verbenol content) was added with or without myrtenol to α‐pinene or to blends of α‐pinene and other kairomones and pheromone candidates. 6 Our results, together with other research demonstrating that trans‐verbenol is produced by T. piniperda, support the designation of trans‐verbenol as a pheromone for T. piniperda. A simple operational lure consisting of α‐pinene and trans‐verbenol is recommended for optimal attraction of T. piniperda.     

Development of Copris tripartitus (Coleoptera: Scarabaeidae) in Two Different Rearing Media

ABSTRACT Like many other sub-social insects, Copris tripartitus Waterhouse requires parental care during the development period in the brood balls. Mass-rearing is achieved by using indoor rearing systems and adding more dung after taking away the brood balls containing eggs. Without parental care, larvae are often affected by desiccation, as well as by fungal or sciarid fly intrusion of the brood balls. This study developed a good substitute for brood ball rearing medium. A significantly greater number of progeny survived to adulthood from broods produced by beetles reared on vermiculite medium (90.69±10.98%) than on peat moss medium (44.82±13.92%). Results of the study suggest that to protect the brood balls from desiccation and to produce healthy adults, 15-20% moisture content vermiculite must be used as brood ball rearing medium for most species reared in the laboratory.     

Activity of conventional and reduced-risk insecticides for protection of grapevines against the rose chafer, Macrodactylus subspinosus (Coleoptera: Scarabaeidae)

Abstract:  Bioassays were conducted to compare the residual toxicity and leaf protection activity of conventional broad-spectrum and reduced-risk insecticides against the rose chafer, Macrodactylus subspinosus . Insecticides were applied to a Vitis labrusca (F.) vineyard and residues were aged for 1, 3 or 7 days before leaves were collected and exposed to beetles in no-choice tests. Azinphosmethyl caused rapid knockdown and mortality for up to 1 week after application, with 1-day-old residues providing 95.6% protection against feeding, dropping to 51.6% when residues were a week old. Fenpropathrin caused mortality and knockdown after beetles had been exposed to fresh residues for 72 h. Although these effects diminished as residues aged, this compound provided the best protection of leaves against beetle feeding, with 77.9% reduction in feeding compared with the control after 7 days of aging in the vineyard. Of the reduced-risk insecticides, imidacloprid caused the greatest initial mortality and knockdown of beetles, providing protection against feeding that was equivalent to azinphosmethyl. Exposure to azadirachtin caused a low level of knockdown and mortality when residues were 1- and 3-days old. Protection against feeding was also low, lasting for only 3 days. Beetles were minimally affected by capsaicin and kaolin, with mortality and knockdown seen only when beetles were exposed to 1-day-old residues for 72 h. Foliage protection from these compounds was minimal, with between 10 and 15% reduction in feeding injury. Results are discussed in relation to development of semi-field bioassay methods for evaluating reduced-risk insecticides, and the management of M. subspinosus within grape pest management programs.     

Quality of two aphid species (Rhopalosiphum padi and Sitobion avenae) as food for the generalist predator Tachyporus hypnorum (Col., Staphylinidae)

Abstract:  The quality of two aphid species ( Rhopalosiphum padi and Sitobion avenae ) as food for the staphylinid generalist predator Tachyporus hypnorum was investigated. Fruit flies ( Drosophila melanogaster ) were used as prey for comparison. T. hypnorum has been reported to prey on aphids, to consume large quantities and to show a high preference for aphids. This study showed that compared with fruit flies aphids are not high-quality prey for neither adult females nor larvae of T. hypnorum . Larvae were less able to utilize aphids than adult females. Reproduction was affected by both aphid species; a diet of S. avenae reduced fecundity, and a diet of R. padi reduced egg hatching success and prolonged the time spent in the egg stage compared with a fruit fly diet. For the T. hypnorum larvae pure diets of both S. avenae and R. padi resulted in high larval mortality. Overall ranking of the three prey types based on several fitness parameters differed between larvae and adults. The adult fitness parameters gave rather conflicting rankings of all three prey types though the two aphid species were of approximately the same overall value, whereas the larval fitness parameters gave identical rankings: D. melanogaster  >  S. avenae  >  R. padi . In the larval stage survival was greatly reduced by both aphid diets, while this was not the case for the adult females.