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A moth is an insect closely
related to the butterfly (Both are of the order Lepidoptera) they
are typically crepuscular or nocturnal insect having a stout body
and feathery or hairlike antennae |
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Moths
have sucking mouthparts and does not cause feeding damage to
vegetable crops. Normally they are active only at night. Moths
comprise nearly 10 percent of the 1.5 million catalogued living
species, and numerous species of flowering plants are described as
sphingophilous, i.e., loving hawkmoths. The hawkmoths and sphinx
moths (family Sphingidae) constitute an important class of nocturnal
pollinating agents around the world.
The typical sphingid starts life as a solitary egg oviposited on the
lower side of a plant leaf by a female hawkmoth. The round-headed
caterpillar (larva) that emerges are leaf-eating caterpillar, the
adult hawkmoth is a heavy insect with an aerodynamically formed
body. The typical adult is a strong, vigorous flyer that moves
rapidly across long distances that at the face of a flower, it
uncoils a long tubular proboscis to insert into the flower center
and suck the copious nectar. With a few daytime exceptions,
hawkmoths typically perform these foraging acrobatics at night, in
contrast to the daylight-active butterfly and hovering hummingbirds. |
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More than 100.000
plant species utilize hawkmoth pollination and depend on
hawkmoths for successful seed production. The classical feature
of sphingophilous plant include
- White to cream-colored
flowers with long, often narrow floral tubes or spurs;
- Flower opening that lacks a
landing platform for a heavy pollinator;
- Anthesis (flower opening)
close to sunset or during the night, when the flower emits a
pleasant, strong, sweet odour;
- Anther dehiscence delayed
until sunset or after dark, and stamen filaments generally
white;
- Nectar copious (often greater
than four grams per flower), thin, having a relatively low
sugar concentration (about 20 percent), and either
sucrose-dominant or sucrose-rich.
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Hovering
hawkmoths need no landing platform but require a high-energy supply
to maintain active flight. Sweet scents attract the fast-flying
insect to the plant, often in total darkness. The copious nectar
must be easily extractable as a thin liquid, and the form of the
floral tube should accommodate the placement of the slender
proboscis at the nectar source. When the hawkmoth withdraws its
proboscis from the flower, pollen readily sticks to its surface, and
pollen grains are easily entrapped
Hawkmoths tend to use hummingbird flowers more commonly than birds
use hawkmoth flowers.
Although the standard syndrome of hawkmoth flowers is easy to
diagnose, actually only about half of the genera pollinated by
Sphingidae, and only a third of the known species, have narrow
tubes. Two other designs exist: trumpet and brush. The trumpet form
has white flowers with the same sweet fragrance and deeply placed
nectar, but the throat is much wider and spreading. Examples would
be daturas (Datura) and many cacti clearly fall into the trumpet
design (e.g., Echinopsis multiplex, Acanthocereus tetragonus, and
Hylocereus costaricensis) whereas others are more tubular (species
of Selenicereus and Stenocereus eruca). Hawkmoths entering trumpet
flowers are often thickly covered with pollen. For example, in
certain localities of the Sonoran Desert it is possible to find many
hawkmoths species working with cacti such as Stenocereus gummosus,
Lophocereus schottii), and Peniocereus greggii, and species of
several other plant families. It is unlikely that only one species
is pollinating only one flower species, so there will be mixed
pollen grains of many species on the insect. That notwithstanding,
hawkmoths are credited as fairly reliable long-distance
cross-pollinators because they are able to carry even small amounts
of pollen to isolated, self-incompatible plants in tropical forests
to produce fruits with viable seeds.
Sphingophilous flowers are largely unused by other classes of
pollinators. These nocturnal flowers are unavailable to day-active
pollinators until the next morning, and, in fact, bees of various
types sometimes arrive during morning hours to accomplish an even
higher level of pollination success. Most hawkmoth flowers are too
flimsy and have too narrow a tube to permit bat visitation. Probably
because they lack pigmentation, butterflies generally do not
recognize and visit hawkmoth flowers. Hummingbirds may feed on
hawkmoth flowers during daylight hours, but their visits occur
usually after hawkmoths have had a nighttime opportunity for
pollination. Other families of moths, such as Noctuidae and
Geometridae, include many plant pollinators, but these moths utilize
different groups of flowers from those specialized for the
Sphingidae. Hawkmoths, unlike hummingbirds, are nonterritorial and
therefore are potentially able to transport pollen to a much wider
area for greater gene flow. |
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