Information

Can fruit fly larvae eat plastic?


I highly doubt that fruit flies or their larvae can digest any plastic used in everyday products. But are there any documented cases where they attempted to eat plastic? I ask this because last Sunday I was setting up a Wii U at my grandparent's house. It had been in this plastic bag that has been sitting in the same room for about three weeks because I only use it at other people's houses and is never set up in my house. This plastic bag was similar in shape and size to many re-suable grocery bags that supermarkets distribute, example Whole Foods. But this bag was made entirely out of plastic. Of course I don't know what type because it wasn't recyclable. It was also more rounded on the edges. Okay, here comes the biology part. I took the Wii out and there were light-brown, rice-shaped and approximately rice-sized "things" on some of the controllers, the power adapter and on the inside of the bag. There were a couple of fruit flies flying around when I took everything out. This immediately led me to believe that the "things" were fruit fly larvae, or dead larvae. I came to this assumption because in the past few weeks there have been more fruit flies than normal in my house, probably because of compost staying inside for too long (in a container in the kitchen sink) and a few too many rotting bananas that weren't eaten or disposed of for a while. And after seeing two or three live flies flying around the controllers I assumed that's what it must be. When searching for fruit fly larvae on Google Images the best picture that represents what I'm describing is this. There were also smaller brown dots where the larvae were and in some places they were not. I don't know what these are. They are smaller than 1mm in diameter. I understand that the flies probably thought that the bag was a dark and safe place to reproduce, but there are two things that I could not figure out, and they seem to be related. One of the Wii remote controller's strings (handles?) was dark brown and slightly wet. It looked like it had been soaking in muddy water. I was very confused by this. I took the bag outside to try and empty it but the supposed larvae were stuck to the inside of the bag. What did fall out of the bag that I missed before was a black ball about two inches in diameter that was also slightly wet upon touching it and was apparently plastic. There were a couple larva on it as well. The bottom of the bag looked like it had some plastic removed from it. This led me to believe that larvae had eaten some of the bag and detached it from the bottom. And somehow this ended up in the form of a ball. (Not a perfect sphere, but round.) I really wish I had taken more time and examined it more to confirm that it was from the bag. I don't have pictures of any of this because everyone was pressuring me to throw out the bag and clean off the equipment, apparently not caring about what actually happened. I also don't have pictures of the Wii remote string because I cut that off and threw it away as well. I later realized that I should have taken pictures because it is so difficult to describe. I began thinking of explanations for each part of what happened. My hypothesis is: Fruit flies in our house reproduced until there were too many to be sustained by the amount of food that was available. This probably happened when there were no bananas left or compost had just been taken outside. Some found the bag which was dark and safe, so they reproduced there. There wasn't any food for the larvae so they tried to eat the plastic that they were on but couldn't digest it, so they died.

This is way longer than I wanted to it to be… So it comes down to these questions: 1. Would fruit flies lay eggs where there is no food? 2. Would fruit fly larvae attempt to consume something that clearly wasn't food? 3. What are the small dots on the adapter?


As someone commented, it seems likely that this was just caused by a piece of fruit that had been accidentally left in the bag. It attracted fruit flies and for weeks they were reproducing.


Cannibal fruit flies: Lab maggots hunt one another

In "crowded laboratory conditions", the larvae, or maggots, will often pursue, attack and eat one another, footage reveals.

Scientists investigating the effects of malnourishment on the flies found that they were able to rear keener, more capable cannibals.

The team, from the University of Lausanne, Switzerland, says that because the fruit fly Drosophila melanogaster is so well-studied, the observations pave the way to discovering the biological secrets of cannibalism.

This might sound like a macabre endeavour, but cannibalism is an important part of nature.

It can be a crucial source of nutrition - some crickets and locusts that migrate in vast swarms rely on eating each other to survive the journey.

And it occurs in many larger carnivores many big cats for example will kill and eat the offspring of their rivals - eliminating the competition by eating it.

"For a long time, cannibalism has been known as a factor that contributes to evolutionary processes," says lead researcher Dr Roshan Vijendravarma.

"But it's risky: Pathogens [disease-causing organisms] are more likely to be transmitted from eating one of your own species or a closely related species."

What made this observation even more interesting for the scientists is that fruit flies are vegetarian.

"Presumably they're poorly equipped to hunt other animals, including their own species, so it's an evolutionary question as to why cannibalism still exists among non-carnivorous animals," he said.

Dr Vijendravarma's primary research was focused on the effects of malnourishment on the flies.

And although all fruit flies he studied would cannibalise one another to some degree, the flies he and his team reared - even generations after their relatives were food deprived - had a "greater propensity to cannibalise".


Biologists show that fruit fly larvae can make decisions about feeding that balance risk against benefit

Fruit fly larvae can make decisions about feeding that balance risk against benefit. Credit: Daeyeon Kim

We humans aren't the only creatures drawn by the smell of a good meal. Fruit fly larvae, it turns out, are equally susceptible to food scents, although the odors that attract them may not appeal to us.

Drosophila melanogaster larvae must gain an enormous amount of weight very quickly to become fully developed fruit flies, so finding food is a high priority—one that motivates their behavior despite any potential risks.

Knowing these larvae respond to odors but not fully understanding the process by which they make decisions via olfactory cues, scientists at UC Santa Barbara are using this model organism to study brain function as it relates to behavior control.

Seeking to improve that mechanistic understanding, the UCSB researchers and colleagues from the Centre for Genomic Regulation (CRG) in Barcelona turned to the Catalan Institute of Nanoscience and Nanotechnology. Asking Catalan engineers to build a vivarium based on microfluidics in which to observe fruit fly larvae feeding behavior, the scientists demonstrated in subsequent experiments that D. melanogaster larvae are capable of making decisions that balance risk against benefit in the context of their food search. The team's findings appear in the journal eLife.

"Larvae have relatively simple brains compared to vertebrates, which make them good candidates for study," said corresponding author Matthieu Louis, an assistant professor in UCSB's Department of Molecular, Cellular, and Developmental Biology. "We wanted to explore the capabilities of these larvae in naturalistic conditions. We know they have a tendency to move toward food when there's an attractive odor, so we designed the vivarium to mimic the conditions of decaying fruit, larvae's favorite meal."

The transparent chamber contains agarose, a hydrogel with a texture that can be adjusted to various degrees of "hardness." The larvae are introduced at the surface of the gel, and when it's not too hard, they dig, an instinctual behavior that helps them avoid predator wasps and sunlight, which can dehydrate them.

The cylindrical bodies of the larvae are oriented head down, and they use two breathing tubes to stay oxygenated below the surface. If yeast or sugar has been mixed with the agarose, they stay close to the surface of the hydrogel. In the absence of food, they modify their behavior.

A food cue added to the bottom of the chamber causes larvae dive deeper and more frequently. Credit: University of California - Santa Barbara

"If the hydrogel contains no food but we add a food cue at the bottom of the chamber, the larvae dive deeper and more frequently," said lead author Daeyeon Kim, who conducted this research at the CRG and is now a postdoctoral fellow at UCSB. "In fact, they can go deeper for quite a long time before returning to the surface to breathe. However, this diving behavior is suppressed when the agarose contains food. Then they just stay at the surface and keep eating the substrate."

Diving is the larvae's food search behavior. If they're desperately hungry at the surface, they start exploring the rest of the vivarium, even though descending into the hydrogel means a lack of oxygen. The researchers wanted to know if they could motivate the larvae to dive more frequently despite this risk. And they discovered they could.

"This is interesting because the larvae are exhibiting risky behavior," Louis said. "In fact, we showed that larvae die if they fail to return to the surface when the substrate is too liquid and low friction hampers their locomotion. Thus, diving entails the risk of drowning. Having observed this behavior and shown that odors make larvae overcome their natural tendency to moderate the risk associated with searching for food, we want to understand the brain areas involved in this process of balancing cost and benefit. That will be work for the future now that we've characterized their digging and diving behavior in detail."

As part of the same study, the investigators also examined a fruit pest from the same family, D. suzukii. Capable of attacking fresh fruit, this species uses an ovipositor to pierce berries and cherries and deposit eggs that eventually turn crops into an unappealing puree. To date, no effective insecticides or management techniques are available to control these crop pests.

In this second experiment, the team modified the hydrogel to mimic the harder surface of fresh fruit and found that D. suzukii could dig more and dive longer than D. melanogaster. Their findings indicate that this pest species is better adapted to hypoxic conditions.

The investigators also found an organic compound that acted as a deterrent to D. suzukii: geosmin, which is produced by microorganisms. Geosmin was so repellent to this species that the larvae not only suppressed their diving behavior but escaped the vivarium by squeezing through shallow air channels only 200 micrometers in diameter.

"Geosmin is probably not the odor people will want to use in the future to try to create some kind of repellent for D. suzukii," Louis said. "It smells like wet soil, an odor you probably don't want on your strawberry. But we have provided a proof of concept that the vivarium could be used to test other substances that one day may lead to an effective solution to manage these crop pests."


Yes, fruit flies are essentially sponges for bacteria and disease. … This is where humans can find themselves in danger with fruit flies. While the risk is low, some fruit flies have been proven to be carriers of pathogenic bacteria, which has the ability to spread to humans via contact.

Most flies lay eggs, but some give birth to live maggots. What happens if I accidentally eat a fly’s egg? Nothing will happen to you if you eat a fly egg. The fly egg will die.


ɼow eating rabbit'

The gruesome larval attacks also appeared to be chemically co-ordinated once a larva had injured its victim, others were attracted by the injury and joined the feeding frenzy.

The larvae used their mouth hooks - hooks with serrations, or teeth, on their surface.

"The cannibal uses the mouth hooks to rasp across the victims' flesh and then rips it open," explained Dr Vijendravarma.

And a diet of fellow fruit fly actually made the larvae develop more effective flesh-eating mouthparts larvae raised on a cannibalistic diet developed more of these tiny teeth of their mouth hooks.

Prof Matthew Cobb, a biologist from the University of Manchester, also studies fruit flies.

He explained that the flies had been a valuable tool, used for over a century - first to understand the basic laws of genetics, and more recently to reveal how animals develop from a single cell into a complex, functioning organism.

"They are simple vegetarian insects that eat yeast and can be reared on porridge," he said.

"This study shows that we still have to learn about them.

"Although the authors don't think this occurs very often in the wild, you only have to search on the internet for ɼow eating rabbit' to come up with a well-known image of a malnourished cow eating a dead rabbit in order to get vital nutrients.

"Even the hardiest of vegetarians may have to turn to meat-eating in harsh conditions, giving us an insight into how different feeding habits may have evolved in the past."


DISCUSSION

In this study we showed, first, that female fruit flies strongly prefer to lay eggs on a food substrate already occupied and consumed by larvae (Fig. 1B). Second, both female and male adult fruit flies are attracted to cues emanating from food that is occupied by larvae (Fig. 1C). Third, females learn to prefer novel cues associated with food consumed by larvae over novel cues associated with unused food of similar quality (Fig. 2A). Fourth, if females experience a flavour associated with food used by larvae for the same duration as another flavour associated with food without larvae, they do not subsequently prefer the flavour associated with larvae (Fig. 2A). Finally, females that experience only a single flavoured food used by larvae do not subsequently show a stronger preference for that flavour compared with females that experience a single flavoured food without larvae (Fig. 2B). Altogether, this suggests that female experience with a flavour regardless of the presence of larvae can explain the later preference for that flavour, but that larval presence is attractive and can bias female experience. We should note that our previous work on social attraction in larval fruit flies critically established that such social attraction is mediated by odours because we conducted all our experiments either in total darkness or under far-red light not perceived by fruit flies (Durisko and Dukas, 2013). Furthermore, work in our laboratory (Venu et al., 2014) has recently identified larval gut bacteria as the source of the odour cues that are attractive to larval and adult fruit flies. Because we have critical evidence for odours being the social cues, we preferred to conduct the experiments described in this study under the regular photoperiod to help flies orient in the cages. While the experiments reported in this study do not rule out a possible role for visual cues, experiments to be reported elsewhere show no social attraction by larval and adult fruit flies when only visual cues are available (Venu et al., 2014).

Egg-laying patch flavour preference after experience. (A) We trained females with a dish of each of two flavours, only one of which contained larvae, either simultaneously (N=254) or successively (N=114), with the latter controlling for duration of exposure to each flavour. During a subsequent test, females significantly preferred to lay eggs on the flavour paired with larvae only if they had been trained with the two flavours simultaneously. When we controlled for exposure duration, females no longer preferred the social flavour. (B) We trained females with a single flavoured dish, which either did or did not contain larvae. Females trained with a flavour containing larvae did not prefer that flavour more than females experiencing the flavour without larvae (N=67). NS, not significant. Error bars indicate ±1 s.e.m.

Egg-laying patch flavour preference after experience. (A) We trained females with a dish of each of two flavours, only one of which contained larvae, either simultaneously (N=254) or successively (N=114), with the latter controlling for duration of exposure to each flavour. During a subsequent test, females significantly preferred to lay eggs on the flavour paired with larvae only if they had been trained with the two flavours simultaneously. When we controlled for exposure duration, females no longer preferred the social flavour. (B) We trained females with a single flavoured dish, which either did or did not contain larvae. Females trained with a flavour containing larvae did not prefer that flavour more than females experiencing the flavour without larvae (N=67). NS, not significant. Error bars indicate ±1 s.e.m.

Our easiest result to explain is that males are attracted to food that has been used by larvae. The odour emanating from such food is probably a cue that can lead them to a food source and to sexually receptive females. Females' attraction to such food patches with larvae is more complex, as choosing an oviposition site that already contains larvae will have both costs and benefits. Like with males, the cues associated with foraging larvae will guide a female to a good site that has already been chosen by both other females and the larvae themselves. Given a choice between food patches of varying quality, larvae will settle on the better alternative (Durisko and Dukas, 2013), suggesting that the presence of larvae may be a particularly informative cue. Additionally, larvae may actually improve the quality of the substrate for subsequent larvae owing to changes in texture, suppression of mould and facilitation of favourable microbes, including beneficial yeast species (Rohlfs and Hoffmeister, 2003 Stamps et al., 2012 Wertheim et al., 2002).

While the informational value of odours emanating from feeding larvae is probably substantial, there are obvious costs as well. Because it takes about a day for eggs to hatch, a female laying eggs on substrates already occupied by larvae guarantees that her larvae will encounter a substrate containing harmful waste products (Borash et al., 1998) and likely competition for food. Increased larval density can slow development rate, increase mortality and, even with one versus three larvae on abundant lab food, decrease adult body mass (Durisko and Dukas, 2013). Similar effects of density on larval success under different experimental settings have been previously reported (Sang, 1949 Wertheim et al., 2002).

Given the cost–benefit tradeoffs associated with laying eggs on substrates containing other larvae, we expect that females would be attracted to low larval densities and repelled by very high densities. Indeed, some reports have indicated that oviposition is inhibited by extremely used food (Chess and Ringo, 1985 Chiang and Hodson, 1950), but this effect has yet to be investigated directly. Interestingly, interactions between different larval species (Budnik and Brncic, 1974 Budnik and Brncic, 1975 Hodge et al., 1999 Miller, 1964) and genotypes (Dawood and Strickberger, 1969 Lewontin, 1955 Saltz et al., 2012) can affect larval development and survival differently, and it would be interesting to see whether females can attend to and modulate their attraction to cues associated with different species and genotypes accordingly. We expect females to be more strongly attracted to cues associated with beneficial larval species, genotypes and densities.

Given that larval presence at a food patch is perhaps the best indication that it is highly suitable for larval development, it is clear why females that were attracted to substrates occupied by larvae learned and subsequently sought out similar substrates (Fig. 2A). However, females did not show direct social learning under strictly controlled conditions that equalized the duration of fly exposure to social and non-social flavoured food patches (Fig. 2B). Further analyses indeed agree with our interpretation that this difference is due to females spending relatively more time on the social food during training when they experienced the flavours simultaneously than when they experienced the flavours in succession. Females laid 95.0±1.5% versus 72.2±4.1% of their eggs on the social food during training in the simultaneous and succession experiments, respectively (Mann–Whitney U=5050.5, Z=4.8, P<0.001). Thus it appears that social learning in this context is due to strong social attraction coupled with individual experience. While we must be careful not to over-interpret null results, adult females have been shown across labs with similar protocols to engage in robust direct social learning from other adults (Battesti et al., 2012 Sarin and Dukas, 2009), and so we may speculate on why females do not learn directly from interactions with larvae. Given that females possess the necessary learning abilities and can perceive both the cues of larvae and the food flavours, presumably they would have evolved to learn directly from larvae if it were beneficial. One possible explanation for the absence of more direct social learning is that, in this context, strong social attraction combined with individual learning may be mechanistically simpler yet will result in a similar outcome: attraction to similar patches in subsequent decisions. Another possible explanation is that a female's individual experience is the most relevant indicator of site quality. Thus, while larval cues may be attractive at a distance, experiencing a high quality food regardless of larvae overrules social information and results in a learned preference for this flavour. Fruit flies, which are a growing model for the study of social information use and social learning, can help shed light on the mechanisms and evolution of social attraction and social information use.


Fruit Fly Puparium – The Metamorphosis Begins

The Third Step In The Fruit Fly Life Cycle Time

Fruit Fly Puparium

At this point the larvae has consumed enough food and grown enough to grow a hard outer skin that will house it for about 4-6 days. While in this protect layering, a process known as metamorphosis takes place. It is a natural phenomenon that allows a living creature to change from one form to another and is an important part of a fruit fly lifespan. In this case, it will be transforming from a fat maggot to a winged insect which is nothing short of amazing. Its important to note that during the fruit fly puparium phase, the larvae does not feed on anything at all and depends completely on the food that it has stored in the previous stage of its lifespan. The fruit fly is almost ready to be born and reproduce and its been under a week since it was conceived. This extremely fast reproduction rate is one of the reasons why its hard to free yourself from a fruit fly infestation.


Can fruit flies survive in heat?

Below 60 degrees Fahrenheit, common fruit flies experience a sharp decrease in lifespan temperatures below 53 degrees Fahrenheit inhibit their development entirely. However, it may not kill eggs and larvae already on the fruit they may continue their arrested development when they warm up again.

Similarly, can flies die from heat? Even a little heat can keep bugs from making babies. Exposure to mild heat as juveniles negatively affects fruit flies' chances of producing offspring as adults, report researchers. &ldquoWhile these insects don't die because of the mild heat&mdashthey produce fewer offspring.&rdquo

Beside this, can fruit flies survive in cold weather?

Winter weather doesn't kill off fruit fly populations &ndash after all, winter in many areas can be quite warm. Cold temperatures, however, will stunt the development of new generations of fruit flies. When the temperatures fall below 53°F, these flies stop developing entirely.

What temperature do flies die heat?

Adult house flies are affected by temperature as much as their young, becoming inactive when temperatures fall below 45 degrees and dying when they fall below 32.


Pick ripe fruit promptly and keep the ground around the tree clear of debris. Destroy all infested fruit by cooking or by sealing in plastic bags in the sun for several days, since larvae can develop successfully in fallen fruit. Never bury affected fruit and remove debris completely from your yard. Use sticky traps or lures, available in hardware stores and nurseries. Always report the evidence of Mexican fruit fly maggots to your local county extension office.

Bonnie Singleton has been writing professionally since 1996. She has written for various newspapers and magazines including "The Washington Times" and "Woman's World." She also wrote for the BBC-TV news magazine "From Washington" and worked for Discovery Channel online for more than a decade. Singleton holds a master's degree in musicology from Florida State University and is a member of the American Independent Writers.