Demographic Parameters of Nezara viridula (Heteroptera: Pentatomidae) Reared on Two Diets Developed for Lygus spp.

Two artificial diets developed for rearing Lygus spp., a fresh yolk chicken egg based-diet (FYD) and a dry yolk chicken egg based-diet (DYD), were evaluated as an alternative food source for rearing the southern green stink bug, Nezara viridula (L.) (Heteroptera: Pentatomidae). Survival to adult was 97.3 and 74.67%, respectively, on the fresh and dry yolk diets. Insects fed FYD had 100% survival of nymphs from first through fourth instars. Adult development was significantly shorter on FYD (30.37 ± SE 0.30 d) as compared with DYD (32.77 ± SE 0.16 d). Increased male and female longevity, higher fecundity, and larger egg mass sizes were also observed with N. viridula-fed FYD. However, fertility and hatchability was higher on DYD. A complete cohort life table was constructed to describe the development of N. viridula on both diets.

Fire ant alate wing motion data and numerical reconstruction.

The wing motions of a male and a female fire ant alate, which beat their wings at 108 and 96 Hz, respectively, were captured with a stereo imaging system at a high frame rate of 8,000 frames per second. By processing the high-speed image frames, the three-dimensional wingtip positions and the wing surface orientation angles were determined with a high phase resolution, i.e. 74 and 83 phases per period for the male and the female, respectively. A numerical reconstruction of the stereo wingbeat images demonstrated that the data collected described almost all the details of the wing surface motion, so that further computational fluid dynamic simulations are possible for fire ant alate flight.

Modulation of water activity on fungicide effect on Aspergillus niger growth in Sabouraud dextrose agar medium*.

AIMS: To examine whether water activity (aw) in combination with low concentration of fungicides can be used to effectively control Aspergillus niger van Tieghem growth in cultural medium, the Sabouraud dextrose agar (SDA). The data would be used as baseline information for reducing A. niger contamination in insect artificial diets. METHODS AND RESULTS: Aspergillus niger was isolated from an insect artificial diet. Four concentration levels (i.e. 0, 1, 10 and 20 micromol) of two fungicides (i.e. amphotericin B and itraconazole) were tested against A. niger under four aw levels (i.e. 0.994, 0.961, 0.921 and 0.859) adjusted by including 0, 12.5, 25 and 38% of glycerol in the medium mixture. Aspergillus niger growth was significantly reduced at low fungicide concentration (1 micromol), and at reduced aw. The spore germination was prevented with either higher fungicide concentration (>10 micromol), or low aw in the medium (aw < 0.921). The two ecological determinants (fungicides and aw) showed a significant impact on A. niger survival in the medium (P < 0.0001). Itraconazole is more effective than amphotericin B in controlling A. niger contamination in the agar medium. CONCLUSION: Adjustment of aw (with 12.5% of glycerol) in combination with 1 mumol of itraconazole can effectively prevent A. niger growth in the SDA cultural medium. SIGNIFICANCE AND IMPACT OF THE STUDY: Aspergillus niger contaminations have frequently affected the quality of insects produced from mass rearing facilities. Low aw in combination with low fungicide concentration has the potential to become one of the most cost-effective management strategies to prevent A. niger contamination in insect artificial diets. The effect of fungicides and low aw in artificial diets on insect biology needs to be further examined.

Comparative field stability of selected entomopathogenic virus formulations.

Nucleopolyhedroviruses originally isolated from Anagrapha falcifera (Kirby) and Autographa californica (Speyer) were formulated with various ingredients using a spray dry method and tested for residual field activity in Illinois and Mississippi. In Mississippi, field tests were conducted on cotton in 1997, whereas in Illinois tests were conducted on cabbage in 1997 and 1998. Within 24 h, significant differences were observed among formulations in all tests. Unformulated virus had significantly less insecticidal activity than formulated virus and formulations containing lignin retained activity significantly longer than other formulations. Relatively small amounts of Blankophor BBH, when encapsulated within the formulation, did not greatly enhance (>10x) insecticidal activity based on LC50 determinations nor prolong insecticidal activity based on field evaluations. In most tests, >50% activity remained in formulations containing lignin, whereas unformulated virus retained <50% activity within 24 h after application.

Ultrastructural investigation of the microsporidium Nosema cuneatum (Microspora: Nosematidae) in the grasshopper Melanoplus sanguinipes (Orthoptera: Acrididae) with emphasis on mitosis.

Ultrastructural investigation of the microsporidium, Nosema cuneatum, (Microspora: Nosematidae), a parasite infecting Melanoplus sanguinipes (Orthoptera: Acrididae). Stages in merogony and sporogony are apansporoblastic, occur in a diplocaryon arrangement and undergo binary fission. Nuclei are connected during karyokinesis in a dumbbell-like arrangement. Microtubules within the nucleus are either associated with the kinetochore or extend from spindle plaque to spindle plaque. Merogony stages in the host cytoplasm are surrounded by an intermittent layer. During sporogony, an electron-dense layer is deposited along the parasite plasmalemma. The spore is binucleate and the polar tube is isofilar, with between 10 to 12 polar tube coils in cross-section.