Warmer temperatures limit impact of parasites, boost pest populations

Climate change is expected to disrupt ecosystems by changing the life cycles of insects and other organisms in unpredictable ways - and scientists are getting a preview of these changes in cities. Research from North Carolina State University shows that some insect pests are thriving in warm, urban environments and developing earlier, limiting the impact of parasitoid wasps that normally help keep those pest populations in check.

At issue is something called a "phenological mismatch," which occurs when the timing of life stages for one organism change in relation to the timing of life stages for other, associated species. In other words, species that once had synchronized are no longer synchronized.

"We wanted to know whether higher temperatures caused phenological mismatch in a tree pest - a scale insect called Parthenolecanium quercifex - and the three that lay their in the scale insects," says Emily Meineke, a Ph.D. student at NC State and lead author of a paper on the work. "And the answer was yes and no."

Specifically, the researchers found that P. quercifex does develop earlier in the year in a city, due to the warmer urban temperatures. But the parasitic wasps that attack scale insects are not developing earlier, which allows the scale insects to lay more eggs. This, in turn, contributes to larger pest populations.

The wasps rely on scale insects to help raise their young. Female wasps punch a hole in the shell of female scale insects and lay their eggs in the scale insect's body cavity. The wasp eggs spend the winter lying dormant inside their hosts before hatching inside the scale's body. The larval wasps then feed on the hemolymph, or blood, of the scale. Meanwhile, the scales are busy producing their own eggs.

Normally, the wasp larvae hatch early in the scale's egg development cycle, and the feeding larvae weakens the scale insect, causing it to produce fewer eggs.

But the researchers found that warmer temperatures can change that outcome significantly.

For the study, the researchers collected more than 1,500 scale insects in Raleigh, North Carolina. Half of the scale insects were collected in "cold" sites with lots of foliage and less pavement, with the other half coming from "hot" sites with fewer trees and more paved surfaces. Scale insects that hosted parasitic wasp larvae in the hot sites produced twice as many eggs as parasitized scales in the cold sites.

"We think the scales at hot sites begin producing eggs earlier in the year, before the wasp larvae hatch," Meineke says. "This effectively gives them a head start, allowing them to produce more eggs than scales in cooler environments.

"To be clear, the wasp larvae aren't affected either way - but the warmer temperatures clearly limit the impact that the wasps have on scales," Meineke says. "Basically, with global temperature increases, one way that nature used to limit scale populations may not work anymore."

"Increasingly, the warming that is happening in cities seems to be offering us a lens through which we can understand the effects of future global warming," says Dr. Rob Dunn, a professor of biological sciences at NC State and co-author of the paper. "And the future is often dependent on complex interactions among species we know little about."

Explore further

Museum specimens, modern cities show how an insect pest will respond to climate change

More information: The paper, "Early pest development and loss of biological control are associated with urban warming," will be published online Nov. 19 in the journal Biology Letters. rsbl.royalsocietypublishing.or … .1098/rsbl.2014.0586
Journal information: Biology Letters

Citation: Warmer temperatures limit impact of parasites, boost pest populations (2014, November 18) retrieved 17 October 2019 from https://phys.org/news/2014-11-warmer-temperatures-limit-impact-parasites.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.

Feedback to editors

User comments

Nov 18, 2014
Watching the Biosphere respond to what we have done to it will be interesting, . . as in "May you live in interesting times".

Nov 18, 2014
" Meanwhile we are enjoying the one of the coldest Novembers on record."

Yes. More heat into the oceans does not mean more balmy weather. That heat is the engine of weather, and the more heat, the more extreme the weather.

Nov 18, 2014

More heat into the oceans does not mean more balmy weather. That heat is the engine of weather, and the more heat, the more extreme the weather.

Ummm...you're contradicting the premise of the article. Is this really what you wanted to do?

He was responding to your ignorant statement, not the article.

Nov 19, 2014
verkle claimed & showed even more ignorance
Notice that somehow all of these bad effects are supposed to arise in the near future. If only we could see these effects now. Meanwhile we are enjoying the one of the coldest Novembers on record.
Only in your isolated, tiny corner of your residence.

Climate change impacts weather, greater diversity, greater extremes & all in different places than the static we have become comfortable with, here is a tiny example where I live:-


Our rainfall has declined & humidity up

If you traveled outside your local region you will notice more, been to Tuvalu, see this link
http://en.wikiped.../Tuvalu, esp section 12.6

Other examples. IIRC the London Thames barrier planning some time ago needed to take into account rise in sea levels re the channel also the proposed sea barrier for Venice etc.

Given your belief in the claim of moses, you might ask your god to tell u more - directly ?

Nov 19, 2014
verkle apologies, I will put this another way since you didnt have the chance of lab time in science environment
Meanwhile we are enjoying the one of the coldest Novembers on record.
You can do this at home in your own bath, no problem.

Obtain a non contact IR thermometer, the one with the laser pointer is helpful and get access to a bath and some ice.

- Half fill the bath
- Place sizable amount of ice at one end of the bath fixed rigidly part in/out of water
- Take temp. measurements

Heat up bathroom, keep recording, U will notice more ice melts & as it does so more cold water comes off it which COOLS the water close to the ice.

Now increase scale, imagine land, wind & U can see WHY many regions within "weather distance" of iced regions will cool as the planet warms.

Straightforward experiment, imagination & "thermal logic".

Interesting to do some calculations on the mass of ice & melted water but factor in specific heat - conclusion is concerning !

Nov 19, 2014

Re noticeable effects of climate change

Please take a look at this page:-

Especially down the page re specific climate issues

Good thing here re data, is there are sizable number of references, no arbitrary claims as primitive sporadic dehydrated & doubtfully nutritious humans once accepted without question because (partly) it suited their notion they might become immortal ;-)

Isnt it grand verkle, that humans dropped a book which only claimed; Status, Authority & Punishment, now we have a method not racially bound, not arbitrary that requires data, which time would you prefer to live in I wonder ?

btw: Question of your christian logic.

God enacted suffering on everyone as punishment for Eve's decision (despite being set up), so therefore, if anyone alleviates suffering then are they going against god, true ?

So if you were that god wouldn't U then punish doctors & nurses to be consistent then ?

Nov 19, 2014
enjoying the one of the coldest Novembers on record
climate and weather are two different things, for starters

and for 2- there is ample evidence supporting why you can have colder or more extreme weather events while during global warming
see: http://marine.rut..._pub.pdf

if you can't figure that out by now, perhaps you should start posting elsewhere?

Nov 19, 2014
stumpy: If your link is reel, Peet's on MD Blvd off 1st in the AM.

Nov 20, 2014
stumpy: If your link is reel, Peet's on MD Blvd off 1st in the AM.

nowhere near a Peet's ... and i don't know where you are referencing, which link are you referring to ?

the closest Pete's to me is a 3.5 hour drive

also, traveling this morning headed to NE corner of state... business
PM me on one of the sites i mentioned or use my profile on SAPO's joint, add periods after every word and mail me at google mail

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more