Floral Mimicry Induced by Mummy-Berry Fungus Exploits Host's Pollinators as Vectors

Leaves and shoots of blueberries(Vaccinium spp.) and huckleberries (Gaylussacia sp.) when infected by ascospores of Monilinia spp. become ultraviolet-reflective and fragrant and secrete sugars at their lesions. Insects that normally pollinate these hosts are attracted to the discolored leaves, ingest the sugars, and transmit conidia to their flowers, resulting in sclerotia (mummy-berry) formation.

with a Monsanto (type W) tensometer, in a dorsal direction perpendicular to the plane of the aperture by a steel hook of circular cross section (1.16 mm in diameter) inserted under the edge of the shell to mimic the prying action of a rounded crab appendage; the breaking force did not differ significantly In pairwise comparisons among hooks ranging in diameter from 0.67 to 2.64 mm (smallest P > 0.15, n -7 -20; analysis of covariance). 8. Spring scales were used to load (force measured in newtons) the edge of the shell in a manner identical to and on the same sides as the breaking force measurements. Limpets from Lime Kiln Lighthouse (all except N. persona) and False Bay (N. persona) on San Juan Island, Washington, were used both for strength and tenacity measurements. 9. Model I analysis of covariance was used to 24 MAY 1985 calculate TSF and shell strength variance (data were transformed to natural logarithms). For each species and side of the shell, I calculated regression equations for breaking force as a function offoot area (n = 7 -20) and maximum tenacity as a function offoot area (n = 8 -23). All breaking force-maximum tenacity regression pairs were parallel (no statistically significant differences between the regression coefficients of each pair; smallest P > 0.05). Hence, the TSFs were essentially constant over the size ranges tested. Therefore, TSF = exp(ln S -InL,,) where In S was the adjusted mean of the breaking force regression and In L'x was the adjusted mean of the maximum tenacity regression for each species and side of the shell. Shell strength variance equaled the residual variance (MSe) of the breaking force versus foot area regressions. The MSe's are reported as coefficients of variation (CV) where CV = (exp(MSe) -IrjS [P. N. Chalmer, J. Zool. (London) 191, 241 (1980); R. C. Lewontin, Syst. Zool. 15, 141 (1966); S. Wright, Evolution and the Genetics of Populations (Univ. of Chicago Press, Chicago, 1968), vol. 1]. 10. R. B. Lowell, in preparation. 11. D. R. Lindberg, Veliger 20, 399 (1978 14. For each point in Fig. 3, In TSF ± I standard error, and CV ± I standard error: C. digitalis A, 0.67 ± 0.147, 0.45 ± 0.108; C. digitalis P, 0. Abstract. Leaves and shoots of blueberries (Vaccinium spp.) and huckleberries (Gaylussacia sp.) when infected by ascospores ofMonilinia spp. become ultravioletreflective and fragrant and secrete sugars at their lesions. Insects that normally pollinate these hosts are attracted to the discolored leaves, ingest the sugars, and transmit conidia to their flowers, resulting in sclerotia (mummy-berry) formation.
Monilinia vaccinii-corymbosi (Sclero-vector-dependent, host-specific plant tiniaceae), an economically important pathogen appears to be unique. discomycete fungus, blights leaves and We investigated the interrelationships vegetative and floral shoots and mummiamong 22 species of pollinating insects fies fruit of wild and cultivated blueber- (4), Monilinia vaccinii-corymbosi, an unries (Vaccinium spp.; Ericaceae); crop named Monilinia sp. (1), and their reyield losses may reach 85 percent in spective hosts, Vaccinium corymbosum, individual fields (1). This polytrophic, V. vacillans, and Gaylussacia baccata, dimorphic fungus overwinters on moist between 1976 and 1984 in Greenbelt, soil as sclerotia in mummified berries (or Maryland (1). These sympatric wild mummy berries). Unfolding young hosts grow as understory shrubs in moist leaves of the host are infected by wind-soil in a mixed oak-pine forest; most of borne, sexual ascospores released from their flowering is completed within 10 apothecia, which arise from the scierotia days, before the tree canopy fully leafs in early spring; these leaves (blight or out. They have pendant flowers with wilt stage) produce asexual conidia that poricidal anthers that require insect polare transferred by pollinating insects to lination (Fig. IA) for fertilization (5). the host's flowers where the ovaries be-The earliest symptom of infection by come infected, producing seedless, ined-Monilinia is wilting of young leaves and ible mummy berries (1).
shoots, followed within 24 hours by Various polyphagous insects that casbrowning of the upper side of the droopually feed on exudates or spores cf funing shoots, midribs, and lateral veins gal plant pathogens are well known to of leaves (Fig. 1, B and C). Discolordisperse spores randomly (2). Azalea ation, which may spread to engulf the flower spot, caused by Ovulina azaleae entire leaf, ranges (in daylight) from (Sclerotiniaceae), is transmitted by polli-grayish brown to deep brown and dark nators that accidentally contact spores brown, often noticeably to strongly (3). We describe the behavior and role of tinged with moderate violet (6); in Gayinsect pollinators of blueberries and lussacia, the discoloration is dark to huckleberries (Gaylussacia sp.; Erica-moderate olive with a slight violet sheen ceae) in transmitting mummy-berry dis- (6). A grayish mantle of conidia, conidioeases. The exploitative modification of phores, and occasional hyphae appears pollinator behavior through induction of on the surface of infected shoots, pefloral mimicry in infected leaves by a duncles, petioles, and at the base host Plantsor attr e oteewled2~9 Iisprh'~.~li p ndaylgtth wilted le leaves (4) -tei 0.`

Intracellular Stimulation of an Identified Neuron Evokes Cardioacceleratory Peptide Release
Abstract. The central nervous system ofthe tobacco hawkmoth, Manduca sexta, is known to contain two cardioacceleratory peptides (CAP's), both ofwhichfunction in vivo as cardioregulatory neurohormones. Intracellular electrical stimulation of a single abdominal ganglion neuron evokes the release of CAP-like bioactivity. This stimulation-evoked bioactivity is destroyed by prior treatment with protease. The possibility that intracellular stimulation of a CAP-containing neuron synaptically activated additional spiking neurons is eliminated.
Neuropeptides in the central nervous system (CNS) are capable of acting as neurotransmitters (1)(2)(3) and as neurohormones (4)(5)(6). It is often easier to define a role for a neuropeptide if that neuropeptide can be unequivocally associated with an identifiable neuron or neurons.
There are several physiological, anatomical, and pharmacological criteria that must be met before a neuropeptide can be established as a neurochemical mediator at the cellular level (7). Most of these criteria are similar to those for the rigorous identification of conventional neurotransmitters (8). One crucial criterion frequently overlooked is the demonstration that the neuropeptide is released when the putative peptidergic neuron is individually depolarized above threshold. Although peptide release from the CNS has been shown in several preparations by treatment with K+-rich saline (9)(10)(11) or by electrical stimulation of peripheral nerve roots (12)(13)(14), it has been difficult to demonstrate peptide release resulting from the activity of single cells regardless of whether the neuropeptide is acting as a neurotransmitter or as a neurohormone. We show here that intracellular electrical stimulation of a single, identified neuron is sufficient to elicit the release of neuropeptide activity from its terminal endings.
We have studied the cardioacceleratory peptide (CAP) system in the tobacco hawkmoth, Manduca sexta.  have shown that two cardioactive neuropeptides, known as cardioacceleratory peptide 1 (CAP1) and cardioacceleratory peptide 2 (CAP2), are present in the pharate adult ventral nerve cord (VNC). The two CAP's are coreleased into the hemolymph from the segmentally repeated transverse nerves (Fig. 1B) immediately after adult emergence, and they act to increase heart rate significantly and to facilitate inflation of T-_1 so electrical properties of its soma. As is typical 20 sec of insect neurosecretory cells (24, 25), the somata of the new MB neurons were electrically excitable, capable of supporting overshooting action potentials with durations of approximately 50 msec. Thus, as a group these neurons were uniquely recognizable during recording sessions. As it proved impossible to maintain somatic activity with dye-filled microelectrodes, we were unable to distinguish between the two anteriormost pairs of new MB cells. We collected CAP activity by erecting a Vaseline well (volume -0.1 ml) around the transverse nerve at a point distal to the transverse nerve-ventral nerve anastomosis. The contents of the well were collected at various times, frozen on Dry Ice, and stored at -20°C, usually for less than 24 hours, until bioassayed for CAP activity. Abbreviations: TN, transverse nerve; DN, dorsal nerve; VN, ventral nerve; MN, median nerve. (C) Cardioacceleratory activity of samples collected during intracellular stimulation of a new MB cell. Each sample was sequentially bioassayed on the same in vitro Manduca heart as described (16,17,21). For these experiments, the variability in the basal heart rate was < I percent. Arrows denote application of samples. The heart rate increased after application of the Stim sample. A standard lepidopteran saline (16) was used in all experiments.