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Feeding tests with loggerhead shrikes (Lanius ludovicianus) showed this bird to acceptUtetheisa ornatrix, a moth (Arctiidae) protected by pyrrolizidine alkaloids, but to avoidLytta polita, a beetle (Meloidae) containing cantharidin.

Evidence is presented from predation tests with ants (Formica exsectoides) that the slimy coating ofCaliroa cerasi and the waxy investiture ofEriocampa ovata serve in defense.

The cervical gland secretion of larvae ofSchizura unicornis andS. badia (Lepidoptera: Notodontidae) contains formic acid, acetic acid, and a mixture of lipophilic compounds, including 2-alkanones, 2-alkanols, and formates of the alkanols. InS. unicornis, the secretion also contains severalω-monounsaturated analogs of the alcohols, ketones, and formates. The absolute configuration of two of the alcohols (2-tridecanol and 2-pentadecanol) was established asS in both species. The larvae spray their secretion when physically disturbed, aiming it accurately in the direction of the offending agent.

Larvae of the mothUtetheisa ornatrix are shown to cannibalize eggs in the laboratory. They proved most cannibalistic if they were systemically deficient in pyrrolizidine alkaloid (PA), the defensive agent that protectsUtetheisa at all stages of development against predation, and whichUtetheisa acquire as larvae from their food plant. In exercising cannibalistic choice,Utetheisa larvae feed preferentially on eggs that are PA-Iaden rather than PA-free. Egg cannibalism can therefore provideUtetheisa with a supplemental means of PA procurement. Moreover, presence of PA in the egg, while providing the egg with defense against predation, can increase its vulnerability to cannibalism. Although evidence is presented thatUtetheisa larvae cannibalize eggs in nature, it is argued that such feeding may occur only opportunistically in the wild, rather than as a matter of course.

Eggs ofUtetheisa ornatrix proved equally vulnerable to fungal infection (Beauveria bassiana, Paecilomyces lilacinus) whether they contained parentally provided pyrrolizidine alkaloid (monocrotaline) or were free of such alkaloid. In in vitro tests, monocrotaline, either as free base or N-oxide, had no inhibiting effect on fungal cultures.

Diploptera punctata, a Pacific islands cockroach, discharges a fine aerosol ofp-benzoquinones from a pair of tracheal glands in response to disturbance or CO2 anesthesia. In addition, the glands and their contents are shed at each molt. We measured the amount ofp-benzoquinones discharged in response to pinching and anesthesia and the filling of glands after discharge and molting. Roaches discharge highly variable amounts of quinones but appear to retain approximately 11% of their lifetime total benzoquinone content after repeated discharges. Roaches rapidly fill their glands after molting (18Μg quinone/day) but after discharging appear to refill at a much slower rate or not at all. This lack of refilling could result from an inability to produce quinones after a finite time period or in excess of a fixed quantity. The delayed accumulation ofp-benzoquinone with respect to the alkylated derivatives in newly molted adults suggests competition for aromatic amino acids between cuticular and defensive quinone synthesis.

The distribution of microscopic glandular structures (hairs, capsules, nodules) on a leaf or other plant part can be recorded visually by pressing the plant part against an indicator surface (filter paper, thin-layer chromatography plate) soaked in Tollens' reagent. The glandular sites are revealed instantly on the test surface as dark spots.

A new bioassay employing a natural fungivore, the opossumDidelphis virginiana, is described. Using this bioasssay, eighteen species of fungi were tested for palatability. Five species of mushrooms, all of which taste pungent to humans, were found to be unpalatable to the opossum. From the least palatable of these,Lentinellus ursinus, the pungent principle was isolated and identified as isovelleral, a previously described fungal metabolite. The compound was shown to be a potent antifeedant to opossums. By means of difference NOE and relaxation time NMR studies, the relative configuration and solution conformation of isovelleral were deduced.

The defensive secretion of the carabid beetlePasimachus subsulcatus is a concentrated solution (up to 90%) of carboxylic acids, amounting to about 1% of body mass. It contains three major components (methacrylic, tiglic, and angelic acids) and four minor components (isobutyric, 2-methyl-butyric, isovaleric, and senecioic acids). In the single population of this large flightless beetle that was examined, the relative ratio of acidic components was remarkably constant from individual to individual.

Two compounds recently isolated from the defensive gland ofNecrodes surinamensis, α-and β-necrodol, first representatives of a new category of monoterpenes (the necrodanes), are shown to be repellent to ants and other insects and irritating to cockroaches and flies. The compounds doubtless play a defensive role inNecrodes. The possible long-range applied significance of research on insect repellents is discussed.

The acetylenic acid,Z-dihydromatricaria acid (DHMA), previously isolated from the defensive secretion ofChauliognathus lecontei, and now shown to occur also inC. pennsylvanicus, is a potent feeding deterrent to jumping spiders (Phidippus spp.). A simple bioassay withPhidippus is described, which is generally applicable to studies dealing with the isolation and evaluation of feeding deterrency of natural products from insects. By use of this assay,Phidippus were shown to be sensitive to as little as 1 μg DHMA, an amount equivalent to less than 2% of the DHMA content ofC. pennsylvanicus.

The abdominal defensive glands ofC. maxillosus secrete a mixture (70μg/beetle) of isoamyl alcohol (I), isoamyl acetate (II), iridodial (III), actinidine (IV), dihydronepetalactone (VE), and (E)-8-oxocitronellyl acetate (X). When disturbed, the beetle everts the glands and revolves the abdomen so as to wipe the glands against the offending agent. Fecal fluid is commonly emitted at the same time and may become added to the glandular material. Ants (Formica exsectoides) are effectively fended off by the beetle and were shown in bioassays (Monomorium destructor) to be repelled by the four major components of the secretion (II, III, X, VE); the principal component (VE) was the most active. Some anatomical features of the glands are described.