Crambidae

Abstract: Biological control requires specific tools for the accurate detection and identification of natural enemies, and to detect unusual variations in their density, which may follow changes in agricultural practices. Here we have developed specific molecular markers to detect Lydella thompsoni (Herting) and Pseudoperichaeta nigrolineata (Walker) (Diptera: Tachinidae) within the European corn borer, Ostrinia nubilalis (Hubner) (Lepidoptera: Crambidae). Primers amplifying fragments of the mitochondrial COI gene were designed following alignment of comparable sequences for a range of parasitoid and host species. Each of the primer pairs proved to be species specific to a tachinid species, amplifying DNA fragments of 191 and 91 bp in length for L. thompsoni and P. nigrolineata, respectively. This DNA-based technique allowed molecular evaluation of parasitism in O. nubilalis natural populations. In order to study the geographical distribution of both species in France, O. nubilalis diapausing larvae in maize stalks were collected from 12 locations over the whole country. The molecular evaluation of parasitism was compared with the traditional method of maintaining O. nubilalis populations in controlled conditions before breaking off the diapause. The percentage parasitism found in both species of tachinids was higher--approximately three times--using the molecular method, suggesting an underestimation by the traditional rearing protocol. Tachinid parasitism on O. nubilalis was not significantly different between geographical areas (south, central and north France) for both species. This study shows that molecular methods are very promising for the correct detection and identification of tachinid parasitoids in natural field populations.

Abstract: The Asiatic rice borer, Chilo suppressalis (Walker) (Lepidoptera: Crambidae), is an important rice, Oryza sativa L., pest in China and difficult to control with conventional pest management. To develop and optimize integrated pest management strategies, efficient and economic artificial diet and rearing protocols are desirable. A new artificial diet based on soybean, Glycine max (L.) Merr., powder and fresh water bamboo, Zizania caduciflora (Turcz.) Hand.-Mazz, was formulated and rearing technique was developed. Fitness parameters including larval development, immature survival, pupal weight, pupation, adult emergence, egg hatchability, and oviposition were measured to evaluate the performance of C. suppressalis fed on the diet over 15 successive generations. C. suppressalis reared on the artificial diet showed better performance with shorter developmental stage, similar larval survival rate and fecundity, and heavier pupae compared with that fed on rice plants and fresh water bamboo. A positive correlation was observed between number of eggs laid per female and number of generations reared on the diet. Larval development time tended to be shortened with successive rearing on the artificial diet. These results indicated that C. suppressalis adapted well to the artificial diet and successive rearing conditions. The diet could serve as a viable alternative to natural host plants for consecutive rearing of the insect. In addition, the diet is inexpensive (US$1.5/1,000 g) and easy to make. The better preserve ability of the diet required only one diet replacement during the rearing process. The successful development of the diet and rearing technique provides a very useful tool for refining stem borer pest management techniques.

Abstract: AsturodesAmsel, 1956, a Neotropical genus of distinctive pyraloid moths (Lepidoptera: Crambidae) with dark brown lines and silver scales on a yellow ground color on the wings and abdomen, is revised. As defined herein, the genus includes four species: A. fimbriauralis Guenee, the type species, A. bioalfae Solis, new species, A. encisoensis Solis, new species, and A. junkoshimurae Solis, new species. During this study, a petaloid scale formed by a group of coalesced setae in the abdominal androconial organs of the male genitalia was discovered and illustrated for the first time. Androconial organs in the Pyraloidea are briefly discussed. The type species and two new species, A. junkoshimurae, new species and A. bioalfae, new species, were reared from larvae feeding on the leaves of Rhamnaceae in the Area de Conservacion Guanacaste (ACG) in northwestern Costa Rica representing 913 rearing events. This contribution is part of a long-term inventory of ACG caterpillars, their food plants, and their parasitoids, that includes COI DNA barcoding of specimens for discovery and identification.

Abstract: The refuge plus high-dose strategy for resistance management assumes that the frequency of resistance alleles is low. We used an F2 screen to estimate the frequency of resistance to transgenic corn that produces Bacillus thuringiensis Berliner Cry1Ab toxin (Bt corn) in an Iowa population of European corn borer, Ostrinia nubilalis (Hubner). We also proposed a modification to the statistical analysis of the F2 screen that extends its application for nonuniform prior distributions and for repeated sampling of a single population. Based on a sample of 188 isofemale lines derived from females caught at light traps during the 2nd flight of 1997, we show with 95% confidence that the frequency of resistance to Bt corn was <3.9 × 10−3 in this Iowa population. These results provide weak evidence that the refuge plus high-dose strategy may be effective for managing resistance in O. nubilalis to Bt corn. Partial resistance to Cry1Ab toxin was found commonly. The 95% CI for the frequency of partial resistance...