Moth Larvae Manipulate Host Plant Physiology

a white moth with dark brown spots rests on a leaf with a blurry green background

Biological Strategy

Spotted tentiform leafminer

AskNature Team

Image: Patrick Clement / Wikimedia Commons / CC BY - Creative Commons Attribution alone

Regulate Reproduction or Growth

Reproduction and growth are two physiological processes that occur in all living systems. There are situations when conditions are right for both, and other situations when continuing either harms the living system because both have a very high energy cost. Reproduction and growth are unique in that both can stop until conditions improve, although stopping either for an extended time can cause problems. An example of regulating reproduction is a process called delayed implantation or embryonic diapause found in some mammals, such as otters. An otter’s embryos sometimes temporarily cease developing and won’t develop further until the female senses that conditions are suitable.

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Cooperate/Compete Between Different Species

From parasitism to mutualisms, there are endless interactions between organisms in nature. Interactions between species that lead to a negative outcome for one species are known as competition. Cooperation occurs when organisms work together for the benefit of each organism or species. While competition often occurs over resources or mates, the more biologists have begun to look for examples of cooperation in nature, the more they have found. For example, around 90% of plants have a beneficial partnership with fungi. Fungi provide the plant with nutrients such as nitrogen and phosphorus, in exchange for sugars from the plant.

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Insects

Class Insecta (“an insect”): Flies, ants, beetles, cockroaches, fleas, dragonflies

Insects are the most abundant arthropods—they make up 90% of the animals in the phylum. They’re found everywhere on earth except the deep ocean, and scientists estimate there are millions of insects not yet described. Most live on land, but many live in freshwater or saltwater marshes for part of their life cycles. Insects have three distinct body sections: a head, which has specialized mouthparts, a thorax, which has jointed legs, and an abdomen. They have well-developed nervous and sensory systems, and are the only invertebrate that can fly, thanks to their lightweight exoskeletons and small size.

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Larvae of leaf-miner moths keep patches of wilting host leaves alive to ensure successful development with the help of bacterial endosymbionts.

“The life cycles of many organisms are constrained by the seasonality of
resources. This is particularly true for leaf-mining
herbivorous insects that use deciduous leaves to
fuel growth and reproduction even beyond leaf fall. Our results suggest
that
an intimate association with bacterial
endosymbionts might be their way of coping with nutritional constraints
to ensure successful
development in an otherwise senescent environment.
We show that the phytophagous leaf-mining moth Phyllonorycter blancardella (Lepidoptera) relies on bacterial endosymbionts, most likely Wolbachia,
to manipulate the physiology of its host plant resulting in the ‘green-island’ phenotype—photosynthetically active green
patches in otherwise senescent leaves—and to
increase its fitness. Curing leaf-miners of their symbiotic partner
resulted
in the absence of green-island formation on leaves,
increased compensatory larval feeding and higher insect mortality. Our
results suggest that bacteria impact green-island
induction through manipulation of cytokinin levels. This is the first
time,
to our knowledge, that insect bacterial
endosymbionts have been associated with plant physiology.” (Kaiser et al. 2010:2311)