Biologists study swift evolutionary changes in acorn-dwelling insects

August 17, 2018, Case Western Reserve University
The Case Western Reserve biologists ‘explore(d) the potential for parallel (and non-parallel) evolution of thermal tolerance across three cities using acorn ants as a model system’ as these particular ants are ‘highly sensitive to …more

The relatively swift adaptability of tiny, acorn-dwelling ants to warmer environments could help scientists predict how other species might evolve in the crucible of global climate change.

That’s a big-picture conclusion from research into the some of the world’s smallest creatures, according to evolutionary biologists at Case Western Reserve University.

More specifically, the scientists are comparing the adaptability of a certain species of ant raised in the “heat-island” microclimate of three U.S. cities to those in nearby cooler rural areas.

“What we’re finding is the potential for —and other animals, perhaps—to evolve in response to anthropogenic (human-caused) ,” said lead researcher Sarah Diamond, who first began peering into acorns to study the ants in 2015. The research so far has shown that the ants adapt to a hotter world in only about 20 generations, or about 100 years.

This comparatively lightning-fast evolutionary response is adding to scientists’ understanding of evolutionary processes, in general, but also in understanding the effects of urbanization, said Diamond, the George B. Mayer Assistant Professor of Urban and Environmental Studies at the university.

“While we usually think of evolution as happening over thousands of years or more, we’re finding that it is happening more rapidly in these cases,” she said, “and that presents a unique opportunity to test the predictability and parallelism of evolutionary change.”

The most recent study by Diamond and Ryan Martin, an assistant professor of biology at Case Western Reserve, was published in July in the Proceedings of the Royal Society B, a broad-scope biology journal.

The outcome of that earlier study was that ants from the city were more tolerant of heat than rural ants living in colonies about five degrees Fahrenheit cooler—an adaptation that would have arisen only over the last century as the city became urbanized and warmer due to the .

Different cities, mixed results

The new paper describes how the research was extended to two more cities, Cincinnati, Ohio and Knoxville, Tennessee, to test whether the ants would respond in “parallel” to urban heat islands.

The scientists added the two new sites to test whether the outcomes would be consistent, or whether each area is distinctive, and because “cities function as easily replicated warming experiments across the globe” due to the urban heat island effect, Diamond said.

The measurements: Urban ants were again more tolerant to heat but lost some of their tolerance to cold compared to their rural neighbors. The researchers also found that urban ant populations produced more “sexual reproductives”—offspring who could, in turn, reproduce—under warmer laboratory rearing temperatures that mimicked their city habitats; rural populations produced fewer.

This new result suggests that the urban ants are indeed adapting to city life: “Their increased tolerance for warm temperatures is helping them live in cities,” Martin said.

In Cleveland and Knoxville, they did, but “Cincinnati is misbehaving,” Diamond said with a laugh, noting that the city ants there did not show the same degree of adaptability.

“Something is going on with that and we need to figure out what that is,” she said. “But that’s not a bad thing. It’s actually super useful to know just how contingent or deterministic evolution is. We’ll keep looking and try to understand what’s going on.”

Explore further: Species appears to evolve quickly enough to endure city temperatures

More information: Sarah E. Diamond et al, Evolution of thermal tolerance and its fitness consequences: parallel and non-parallel responses to urban heat islands across three cities, Proceedings of the Royal Society B: Biological Sciences (2018). DOI: 10.1098/rspb.2018.0036

Read more at: https://phys.org/news/2018-08-biologists-swift-evolutionary-acorn-dwelling-insects.html#jCp


Plant Parasitic Nematodes – the world’s most important crop pathogen?

By Richard Sikora, Danny Coyne, Johannes Hallman and Patricia Timper


Plant parasitic nematodes – overlooked, neglected, little known and mostly out of sight; surprising then that they cause billions of dollars’ worth of damage to global crop production annually.  In the tropics and subtropics they persistently undermine production, result in massive waste of disfigured and unmarketable produce, and literally plague some crops.

One species alone, the tropical root knot nematode Meloidogyne incognita, has been referred to as the single most important crop pathogen worldwide. And as a group, root knot nematodes are viewed as the most serious biotic threat to tropical crop production. In the tropics, nematodes can occur as a bewildering combination of species that, for example on banana, wheat,  groundnut, cotton, soybean, coffee, sugarcane and most vegetable crops worldwide, can create havoc for small to medium-sized families who often lack means and/or access to modern management tools.

Because plant parasitic nematodes have shorter lifecycles, leading to more rapid multiplication and population buildup, damage occurs more suddenly and devastatingly than in temperate agriculture. Occurrence of multiple genera and species at the same time limits management options, in particular the use of resistance or crop rotation. Some species of nematodes, including M. incognita, also have a bewildering number of crop hosts which they can parasitise, feed and multiply.


Plant parasitic nematodes mostly infect roots but can infect tubers, stems and leaves. They either enter the plant tissue and feed from within, or feed from the outside using a modified tooth to pierce cells and suck out the contents for nourishment. The feeding action results in physical damage to the tissue through necrosis, stunting roots or distorting tissue. They also create entry points for fungal and bacterial pathogens, resulting in increases in overall root rot damage. Some nematodes even transmit plant pathogenic viruses, while others disrupt tissue growth affecting root and tissue functionality and additionally leading to physical disfigurement that affect marketability of root and tuber crops.  All in all, they cause serious damage to many crops and add to the problem of food security worldwide, especially for “approximately 2 billion of the world’s poorest [who] live in households that depend on agriculture in some form for their livelihoods”.


Because of their size and presence in the soil ecosystem, it is surprising that we have not heard more about these pests and are not more aware of the damage they cause. In general, tropical nematodes have been less studied and therefore we know less about them than their cooler cousins in the temperate climatic zones. To some extent, this is due to a lack of expertise in this field and in particular the limited number of tropical nematologists to inform the uninformed.

The future of agriculture is strongly tied to the issues of food security, natural resource conservation and overall sustainability. Only improvements in the way we conduct agriculture will help feed the ever growing world population. Problems are especially dramatic in the tropics and subtropics where production is predominantly linked to small and medium-sized family farms where a large proportion of yield is lost to soil-borne pests, in particular nematodes. As climate change and soil degradation continue to advance, the management of soil-borne nematodes and their effect on crop health and food production will be critical. Improving root health using established and modern technologies for plant parasitic nematodes will become of the utmost importance. The root systems of all crops in these regions are negatively affected by extreme climate, adverse ecologic constraints and poor nematode management, and this problem needs to be addressed.

Plant Parasitic Nematodes in Subtropical and Tropical Agriculture, edited by Richard Sikora, Danny Coyne, Johannes Hallman and Patricia Timper, is available now from the CABI Bookshop.

Richard Sikora headed Nematology and Soil-Ecosystem Phytopathology at the Institut für Pflanzenkrankheiten of the University of Bonn, Germany, from 1971 until retirement in 2008. 

Danny Coyne is a Soil Health Scientist / Project Manager for the East Africa Banana Breeding Project. 

 Johannes Hallman has worked as a nematologist at the Julius Kühn Institute, Federal Research Centre of Cultivated Plants, in Münster, Germany, since 2001.

Patricia Timper is currently employed as a Research Plant Pathologist with the Agricultural Research Service (United States Department of Agriculture) in Georgia, USA.


Inside Science

How Drought Turned an African Savanna Into a Wildlife Paradise

Drought killed off inedible plants in Kruger National Park, making room for other plants that animals like to eat.


Image credits: BlackstoneAustria via Shutterstock

Thursday, August 16, 2018 – 16:15

Nala Rogers, Contributor

(Inside Science) — In 2015, disaster struck South Africa’s Kruger National Park — or so it seemed. It was the worst drought on record, lasting 28 months and reducing the once-verdant grassland in the park’s south-central region to bare dirt.

“It was really shocking to see,” said Sally Koerner, a community ecologist at the University of North Carolina at Greensboro. “There were a lot of bones.”

But when the rains returned, the region made a remarkable recovery, transforming into what may be an even better wildlife habitat than before the drought. Koerner presented her findings on Aug. 7 at the Ecological Society of America meeting in New Orleans.

Koerner and her colleagues had been studying the region for nine years when the drought struck. They were measuring the effects of grazing and fire on plant growth, putting up fences to exclude herbivores from small patches of land in areas that were burned on different schedules. The landscape at Kruger is thought to naturally burn about every three years, but roads and other human activities suppress wildfires, so managers deliberately burn patches of land to keep the habitat healthy.

The researchers found that under most conditions, the landscape was dominated by a tough, foul-smelling bunch grass known as “stinking grass,” which is resistant to fire and unappealing to herbivores. Stinking grass is hard to kill, but as the drought stretched on, it finally withered and died.

The stinking grass’s death created an opportunity for more palatable plants to grow. In lands that had burned frequently, herbaceous flowering plants tended to move in, while in lands that had rarely burned, the stinking grass was replaced by other types of grasses. While it’s too soon to know how animals will respond to the bounty, it seems likely that they will flourish.

The habitat’s transformation suggests we shouldn’t be too quick to judge the impacts of ecological disasters. Drought is almost never thought of as a good thing, noted Koerner, but in this case, it allowed the ecosystem to reset.

“While it can have really negative effects in the short term, in the long term it can switch [the area] into a trajectory that might be more beneficial.”

western farm press

Santa Ynez vineyard YaskoCreative/iStock/Getty Images

Drought may be increasing camel cricket numbers

University of California researchers started noticing more of the leaf-chewing insects several years ago.

Tim Hearden | Aug 08, 2018

A few years ago, University of California viticulture and pest management advisors noticed unusual leaf symptoms in certain Napa County hillside vineyards that were right next to oak woodlands.

As described by the UC Cooperative Extension’s Monica Cooper and Lucia Varela, the feeding activity they noted in April 2015 resulted in a “lace-like” appearance to damaged leaves. Then last year, in March, they observed feeding damage to expanding buds.

The insect associated with this damage was the arboreal camel cricket (Gammarotettix bilobatus), found in North America and abundant in California. According to non-profit research publishing firm BioOne, it emerges mid- to late February, survives into late May and early June; host plants include coast live oak, Christmas berry, and Monterey pine. Researchers say the cricket appears to switch host plants intra-seasonally, and can even act as an inadvertent pollinator of some of its host plants.

Where vineyards have come into play is when they were situated on hillsides next to oak woodlands and mixed species of white alders, madrone, California bay, and Douglas fir, according to Varela, a north coast integrated pest management advisor, and Rhonda Smith, a UCCE viticulture advisor.


Arboreal camel crickets feeding on leaves cause numerous holes, resulting in leaves that appear “lace-like” because of the thread-like remnants of leaf tissue in many of the holes they leave behind, Varela and Smith note in an online guide to chewing pests posted by UCCE Sonoma County.

Continuous feeding on a single leaf can result in a blade consisting only of tissue surrounding the main veins and numerous holes throughout any remaining tissue.

It’s the adult cricket that feeds and causes the damage, they note. Adults don’t have wings; rather, they have powerful muscles on their rear legs that make them strong jumpers. Their bodies are somewhat humpbacked, and brownish with variable black markings. According to literature, they pests have so far only been reported as occurring in the north coast region.

The crickets have one generation per year, with adults appearing in April and being gone by July. In vineyards, they can be seen during the day feeding on the underside of basal leaves or resting at the base of the shoot or on the spur.

Their coloration blends with that of the spur or cane, making them harder to see, but when disturbed they readily jump to the ground. As with other crickets, they are active at night.


While grapes aren’t recognized as a major host for arboreal camel crickets, vineyards surrounded by suitable cricket habitat can experience some damage every year, the UCCE advises. The pest may have become more widespread in recent years as drought conditions have persisted in their arboreal range, researchers say.

The crickets are among numerous chewing pests that vineyardists have to watch for each year, since they can cause damage to buds and young shoots in grapevines. Others include European earwigs, cutworms, humped green fruitworms, and various piercing and sucking insects, according to the UCCE Sonoma County guide.

Smith and Varela say they’ve been getting numerous calls and photos of insect damage of buds and emerging shoots, with damage often including a hole or a depression in an unopened bud; holes of various sizes inside the margins of a leaf blade; leaves that are misshapen because of marginal feeding; or young shoots that are missing a shoot tip or entire leaf blades.

Companies market various pesticides and traps to deal with the pests. However, arboreal camel crickets are usually not a problem in the vineyard unless they move into adjacent vines early and feed on buds, Smith and Varela note. Vines generally outgrow early-spring leaf injury.

To view the guide, go to https://bit.ly/2KnXIpG

PML Daily


FAO rolls out technology to fight Fall Armyworm

MUKONO – After using a temporary pesticide combination to fight against fall armyworm, Farmers in many parts of the country could start smiling after the Food and Agricultural Organisation developed a new technology that will help farmers to fight against the destructive fall armyworm.

The FAO has been working with the Ministry of Agriculture, Animal Industry and Fisheries [MAAIF] to develop technologies to manage the pest through a community-based approach and has now developed a mobile phone application known as the FAMEWS for monitoring and early detection of the Fall Army Worm.

According to FAO, the new technology provides a lasting solution to the armyworm that has affected more than half of the country posing a significant threat to food security.

Described as FAMEWS mobile app, the technology will monitor and give an early warning system to the farmers regarding the Fall Armyworm which then will build knowledge on how and where the pest spreads, and make it less damaging,

Mr Keith Cressman, the senior agricultural officer who leads who FAO’s digital response to Fall Armyworm and other pests, while handing over the technology to farmers at Mukono Zonal Agricultural Research and Development Institute (MuZARDI) August 13 said the new tool will help farmers recognise the new enemy and take immediate measures to stop it.

“With the new application, farmers can hold the phone next to an infested plant, and they will be able to detect and immediately confirm the Fall Armyworm,” said Mr Cressman.

The equipment handed over to farmers included 126 mobile phones loaded with the FAMEWS app which will be used in 15 districts to pilot a community-based FAW monitoring and early warning system.

These districts include; Mukono, Iganga, Bulamburi, Nakapiripirit, Oyam, Adjumani, Kiryandong, Kibaale, Kasese, Lira, Kayunga, Soroti, Busia, Masindi and Luwero.

The other items handed over to MAAIF included 700 pheromone traps and 6000 lures facilitate detection of the presence and build-up of FAW and to capture adult moths.

Mr Cressman said the use of pheromone traps will be instrumental in detecting the presence and build-up of Fall Army Worm [FAW] in areas where the traps are deployed.

The Pheromones are natural compounds emitted by female FAW moths to attract male moths for mating and that synthetic compounds that mimic natural FAW pheromones, often referred to as lures are placed in traps to attract and trap male moths.

“The moths that are caught are then counted, the number will be recorded on the mobile app and submitted to FAO central platform with countries having rights to access and validate. And from the numbers caught, farmers can know if FAW is present in their fields or in their locality and determine the need for increased scouting,” said Mr Cressman.

The new technology comes at the time farmers are planning and preparing their gardens for the second planting season expected to start by the end of August 2018.

Dr Charles Owach, the Assistant FAO Representative in charge of Programmes underscored the importance of setting up a community-based system for monitoring, early detection and the management of the devastating pest.

He explained that early detection, collecting and analysing information, is essential for tracking and efficiently responding to the large-scale threat posed by FAW.

“The major action required for effective and sustainable management of FAW is at the community level. With the community monitoring system, farmers can make informed decisions for early action, that is, timely scouting of their fields and undertaking appropriate control actions,” Dr Owach said.

He explained that through the community monitoring system, extension workers at local, district and national level will be able to appropriately advise farmers on FAW control and that the system will also monitor the spread of FAW across geographical areas nationally and at a continental level.

The FAMEWS mobile app has been rolled out in a number of countries but more in Sub-Saharan countries in Africa with notable success in Ghana, Tanzania, Kenya, Zambia, Malawi and others. It will be expanded to North Africa, the Near East, India and other parts of Asia where FAW is spreading.

He revealed further that the monitoring system will benefit communities dependent on maize for food and income.

Mr Stephen Byantwale, the Commissioner for Crop Protection at MAAIF, who received the equipment on behalf of Government noted that whereas Uganda realised a bumper maize harvest during the first season of 2018 compared to 2017 where more than half of the maize crop was lost to the FAW), there is a need to continue monitoring because the residual populations of the FAW have the potential to cause more outbreaks.

“We are grateful to FAO for these items that we will be deploying in communities as a pilot project and based on the results, the government will explore opportunities to roll out this approach to other districts given that the data available so far indicates presence of FAW in all districts in Uganda,” said Mr Byantware.

He urged farmers to start scouting as they prepare to plant maize for the onset second season adding that the move is aimed at minimising the use of pesticides in the management of FAW.

“Now that we know what the pest is, there is need for sustainable control and management mechanisms which are safer for both humans and the environment such as the use of natural biological control agents, mechanical destruction of egg masses and larvae among others and let the Pesticides should come as a very last resort” Mr Byantware added.

He revealed that the use of biological mechanisms such wasps, nematodes, and some fungus that attack and destroy the caterpillars is being studied by the National Agricultural Research Organization (NARO)..

He stated that Uganda has a national strategy and action plan for control of FAW which has short, medium and long-term measures and commended FAO for supporting the Government of Uganda to implement national its FAW control and management strategy through the technical cooperation project and sub-regional project on FAW.

About Fall Army Worm [FAW]

Fall Armyworm (FAW) is an insect pest native to tropical and subtropical regions of the Americas. Since it was first reported in 2016, FAW has spread across sub-Saharan Africa, causing extensive and widespread damage, particularly to maize crops. By mid-2017, FAW was present in all of Uganda’s districts, causing between 15 and 75 percent yield loss. An estimated 450 000 metric tonnes of maize, equivalent to US$ 192 million was lost during the first cropping season of 2017, directly affecting 3.6 million people or 9% of the population.

science d-logo

An alternative to nicotine-based pesticides could be just as bad for bumble bees.

Phil Savoie/Minden Pictures

A new pesticide may be as harmful to bees as the old one

Bees around the globe are in trouble, and many scientists worry that a common pesticide bears some blame. Now, scientists have shown that a chemical hailed as a potential replacement has similar harmful effects, reducing the number of new queens and males in bumble bee colonies. The finding could force farmers to seek alternative solutions to reduce crop damage from insect pests.

So-called neonicotinoid pesticides protect crops against pests such as aphids by blocking receptors in the insects’ brains—paralyzing and killing them. In small doses, the pesticides aren’t lethal to larger creatures, including mammals, birds, and even bees. But they can wreak havoc on bees’ abilities to navigate, find food, reproduce, and form new colonies. That kind of data convinced the European Union to ban the outdoor use of five neonicotinoid pesticides in April; Canada is phasing them out starting today, but they’re still used widely in the United States.

Some insects have developed resistance to neonicotinoids in recent years. In the search for an alternative, scientists hit on sulfoximine, a group of neonicotinoid-related chemicals that act on the same class of receptors in the insect brain but can dodge the enzymes that offer insects some resistance. But sulfoximine is starting to court the same controversy as its predecessor: Despite being approved for use in China, Canada, and Australia, a French court last year suspended licensing for two sulfoximine-containing products, citing environmental concerns including potential toxic effects on bees.

To investigate sulfoximine’s effects on bumble bee colonies, Harry Siviter, a graduate student in behavioral ecology at Royal Holloway University of London, and colleagues fed bumble bees sugar laced with sulfoxaflor, the first sulfoximine-based pesticide on the market. Dosing—one of the most controversial aspects of pesticide studies—was determined from U.S. Environmental Protection Agency data that measured the concentration of the pesticide in nectar collected by bees from cotton flowers sprayed with the chemical.

After 2 weeks, the researchers released their colonies of bees into the field. Between 2 and 3 weeks after exposure—the time it takes for bumble bee larvae to reach adulthood—colonies fed the pesticide produced fewer worker bees than control colonies that received only sugar. And after 9 weeks, exposed colonies produced 54% fewer new queens and males (the only bees that reproduce), they report today in Nature. That suggests, they write, that sulfoximine could have a significant impact on the reproductive success of bumble bee colonies.

“The body of evidence demonstrating [neonicotinoids’ negative effects] on pollinators … is now overwhelming,” says Edward Mitchell, an ecologist at the University of Neuchâtel in Switzerland, who was not involved in the research. “This study shows that we can expect the same for sulfoxaflor.”

But questions remain, such as how the exact timing of bee exposure and the kind of application—spraying crops versus coating their seeds—could alter the impact of the pesticide. Mitchell says he thinks the new results are a “conservative estimate” of the actual harm from the pesticide.

Policymakers will need more data before they can come to the same conclusion. But the new results could be included as part of licensing risk assessments in the European Union, which must take into account the risk to wild pollinators. “In terms of policy, we can’t know what the implications will be yet,” says social insect biologist Elli Leadbeater, a co-author at the Royal Holloway University of London. Mitchell says the new pesticide “should be treated like just another neonicotinoid, unless a strong case can be made that it does not pose the same environmental problems.”

But invertebrate ecologist Richard Gill of Imperial College London questions whether outright bans are the best solution. He suggests that improved scientific understanding of the risks could help develop strategies to minimize negative effects on pollinators, rather than forcing farmers to move to understudied replacement compounds.

The Plantwise Blog

New study shows that bacteria can be engineered to create their own fertilizer using air


Researchers have successfully engineered bacteria to use nitrogen at night to create chlorophyll for photosynthesis. This new development could reduce the need for human-made fertilizers on agricultural crops, thus reducing the cost and manpower required for fertilizer application.

Research undertaken at Washington University, led by Professor Himadri Pakrasi of the Department of Biology and director of the International Center for Energy, Environment and Sustainability (InCEES), has shown that this may be possible. So far this technology has only been developed using bacteria, but in the future it is hoped that this will be developed using plants and eventually crops to revolutionize the agriculture industry.

Public Domain CC0

With the world’s population increasing exponentially, there are higher demands for food. Coupling this, due to increasing agricultural threats from pests, diseases and climate change, we are facing greater food security risks such as reduced crop yields and loss of soil fertility. Soil conditions are a big problem for agriculture, particularly throughout Sub-Saharan Africa where areas of land can experience prolonged periods of drought and uneven rainfall. This is why there is a global need for improved fertilizer use, to improve the ability of crops to withstand these fluctuating environmental conditions and produce the required yields. Fertilizers provide plants with the necessary nutrients for improved growth, such as potassium for improved stem vigor, nitrogen for increased growth and phosphorous for improved seed germination and root development. By applying fertilizers we are improving soil and plant health as well as the ability for plants to resist pest and diseases.

Aside from the use of fertilizers to provide nitrogen, there is also another major source that could be made available. The Earth’s atmosphere is roughly 78% nitrogen and was the target source for this study. Researchers working with Professor Pakrasi engineered bacteria that could use the atmospheric nitrogen in a process known as nitrogen fixing to produce the energy required for photosynthesis.

“Cyanobacteria are the only bacteria that have circadian rhythm,” said Pakrasi, “interestingly, Cyanothece photosynthesize during the day, converting sunlight to the chemical energy they need as fuel, and fix nitrogen at night after removing most of the oxygen created during photosynthesis through respiration.”


The team identified 35 genes which were accountable for this process, 24 of which were transferred into another bacteria, Synechocystis, to determine the ability to transfer this nitrogen fixing process into another living organism. This was shown to be successful, with Synechocystis fixing nitrogen at a rate of 30% of Cyanothece.

The next steps for the team will be to study the finer details of this process, and identify the specific genes required for this nitrogenous process. With further development of this work with bacteria, it is hoped that with collaboration this study will be taken to the next level to develop nitrogen-fixing plants. If crops were able to use nitrogen in the atmosphere to increase their growth, this would benefit  not only global soil health, but also reduce the struggle for improving fertilizer application throughout the agriculture industry.

With the publication of this study, the issues have been raised behind global soil health and the management practices that need to be better implemented to improve soil fertility. Whilst innovations such as this are taking place in the lab, here is what CABI has been doing to reach smallholder farmers in terms of Integrated Soil Fertility Management (ISFM):

“To improve the livelihoods of smallholder farmers and farm productivity, we need to tackle the issue of poor soil fertility. The OFRA project was designed to help improve efficiency and profitability in fertilizer use in 13 sub-Saharan countries within the framework of ISFM practices. This has been a successful project, with over 70 fertilizer optimization tools (FOT) developed and over 3500 extension workers and agrodealers trained on how to use FOT to advise farmers,” stated George Odour, Project Manager of OFRA, CABI. “I am hopeful for the future of soil health with the development of exciting novel studies such as this and that ISFM practices are applied further to help combat this pressing challenge to global food security.”

If you would like to read further information on the subjects covered in this article, please see the links below:

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