Athula B. Attygalle

SEASONAL ANOINTMENT WITH MILLIPEDES IN A WILD PRIMATE: A CHEMICAL DEFENSE AGAINST INSECTS?

Members of a wild group of wedge-capped capuchin monkeys (Cebus olivaceus) intentionally anoint themselves with millipedes (Orthoporus dorsovittatus). Chemical analysis revealed these millipedes secrete two benzoquinones, compounds known to be potently repellent to insects. We argue that the secretion that rubs off on the monkeys in the course of anointment provides protection against insects, particularly mosquitoes (and the bot flies they transmit) during the rainy season. Millipede secretion is so avidly sought by the monkeys that up to four of them will share a single millipede. The anointment must also entail risks, since benzoquinones are toxic and carcinogenic. We suggest that for capuchins the immediate benefits of anointment outweigh the long-range costs.

DUAL CHEMICAL BARRIERS PROTECT A PLANT AGAINST DIFFERENT LARVAL STAGES OF AN INSECT

The host plants of the native American butterfly, Pieris napi oleracea, include most wild mustards. However, garlic mustard, Alliaria petiolata, a highly invasive weed that was introduced from Europe, appears to be protected from this insect. Although adults will oviposit on the plant, most larvae of P. n. oleracea do not survive on garlic mustard. We used feeding bioassays with different larval stages of the insect to monitor the isolation and identification of two bioactive constituents that could explain the natural resistance of this plant. A novel cyanopropenyl glycoside (1), alliarinoside, strongly inhibits feeding by first instars, while a flavone glycoside (2), isovitexin-6″-D-β-glucopyranoside, deters later instars from feeding. Interestingly, the first instars are insensitive to 2, and the late instars are little affected by 1. Furthermore, differential effects of dietary experience on insect responses suggest that 1 acts through a mechanism of post-ingestive inhibition, whereas 2 involves gustatory deterrence of feeding.

Alkaloids of the Mexican Bean Beetle, Epilachna varivestis (Coccinellidae)☆☆☆

Abstract Two novel alkaloids, 2-(12-aminotridecyl)-pyrrolidine and its 1-(2-hydroxyethyl) derivative, are characterized from extracts of adult Mexican bean beetles. These pyrrolidines, together with a previously identified homotropane alkaloid, euphococcinine, account for 90% of the alkaloids present in this beetle. A number of piperidine derivatives are also identified as minor components. The total mixture represents the most complex bouquet of alkaloids reported hitherto from any coccinellid beetle.

Initial studies of mating disruption of the tomato moth, Tuta absoluta (Lepidoptera: Gelechiidae) using synthetic sex pheromone

The potential of the synthetic major component of T. absoluta (Meyrick) sex pheromone for mating disruption was studied in small plots (0.01 hectares) with fresh-market tomato crop. The effects of the application of the sex pheromone 3E,8Z,11Z-14:Ac (from 0 to 80 g a.i./ha) were assessed on male orientation to pheromone baited traps, mating in cages and plant damage. The highest levels of interruption in male orientation (60-90%) were found in plots treated with 35 to 50 g/ha of sex pheromone. However, no treatment with pheromone was capable of significantly reducing the percentage of mined leaflets or bored fruits or the frequency of mating in cages compared to the control plots. The failure in mating disruption technique may be attributed to the composition of the synthetic pheromone, doses used, high pest population density, and mated female migration to the area treated.

(3E,8Z,11Z)-3,8,11-Tetradecatrienyl acetate, major sex pheromone component of the tomato pest Scrobipalpuloides absoluta (Lepidoptera: Gelechiidae)

The major sex attractant emitted by Scrobipalpuloides absoluta females is shown to be (3E,8Z,11Z)-3,8,11-tetradecatrien-1-yl acetate by a novel strategy involving the random reduction of double bonds, followed by methylthiolation of the reduced products. Each female sex gland contains ca. 1-5 ng of this pheromone. This triene ester, synthesized by a stereospecific procedure, shows spectral and gas chromatographic properties identical to those of the natural substance. In field tests and wind tunnel bioassays, the synthetic ester was found to be highly attractive to conspecific males. The male response to this pheromone, however, is restricted to the same early-morning time window during which females exhibit calling behavior.

Chilocorine : heptacyclic alkaloid from a coccinellid beetle

Abstract A novel heptacyclic alkaloid, for which we coin the name chilocorine , was isolated from a ladybird beetle, Chilocorus cacti . It has a unique structure made up of two tricyclic substructures, 2-methylperhydro- 9b -azaphenalene and 3,4-dimethyloctahydro- 8b -azaacenaphthylene. The proposed structure is based on mass spectrometric, ultraviolet spectroscopic, and NMR evidence.

Microscale, random reduction: Application to the characterization of (3E,8Z,11Z)-3,8,11-tetradecatrienyl acetate, a new lepidopteran sex pheromone

The major sex attractant released by Scrobipalpuloides absoluta, a devastating tomato pest, was identified as (3E,8Z,11Z)-3,8,11-tetradecatrienyl acetate by a novel strategy involving the random reduction of double bonds. The technique is applicable to double bond localization of polyunsaturated compounds available even in nanogram quantities. The triene ester was synthesized by a stereospecific procedure and shown to be highly attractive to conspecific males and identical to the natural substance.

Field Trapping of Tomato Moth, Tuta absoluta with Pheromone Traps

Field evaluations demonstrate that the addition of the minor pheromone component (3E,8Z)-tetradecadien-1-yl acetate to the major component (3E,8Z,11Z)-tetradecatrien-1-yl acetate does not significantly increase the trap catches of Tuta absoluta males in the field. The triene acetate itself is highly attractive, catching about 869 ± 255 males per trap in three consecutive nights. The addition of two isomers of the minor component (3E,8Z)-tetradecadien-1-yl acetate, (3E,11Z)-tetradecadienyl-yl acetate and (8Z,11Z)-tetradecadien-1-yl acetate, to the major component (3E,8Z,11Z)-tetradecatrien-1-yl acetate also did not significantly alter the number of the males caught in the traps.

Evaluation of the synthetic major component of the sex pheromone of Tuta absoluta (Meyrick) (Lepidoptera : Gelechiidae)

In wind-tunnel bioassays, dispensers loaded with 1 μg of the synthetic major component (3E,8Z,11Z)-3,8,11-tetradecatrienyl acetate (TDTA) of the sex pheromone emitted by Tuta absoluta (Meyrick) females were found to be highly attractive to conspecific males. Field experiments were conducted to evaluate the efficacy of five trap designs. The best trap, baited with 100 μg of the synthetic sex pheromone caught on average 1200 males per trap per night, while those baited with virgin females caught only 201 males. The male response to this pheromone is restricted to the same early-morning time window during which females exhibit calling behavior. The high biological activity of the synthetic pheromone suggests that it could be useful for pest monitoring and in mating disruption.

Spirocyclic Defensive Alkaloid from a Coccinellid Beetle

Abstract A new alkaloid, chilocorine B, was characterized from a coccinellid beetle, Chilocorus cacti. This compound represents the first spirocyclic example of the new “dimeric” alkaloid family whose structures are derived from two thirteen-carbon tricyclic subunits, 2-methylperhydro-9b-azaphenalene and 3,4-dimethyloctahydro-8bazaacenaphthylene.