nikunj suratwala | Pest Control India

Behavioral Resistance: Mosquitoes Learn to Avoid Bed Nets

Malaria is a notoriously tricky infectious disease. Because of a unique genetic flexibility, it is able to change surface proteins, avoiding the immune response and greatly complicating vaccine development. Furthermore, the parasite is transmitted by mosquitoes, which are difficult to control. Insecticides work, but mosquitoes can develop resistance to them.

One method widely used to control malaria is for governments or charities to provide families with insecticide-treated bed nets. Overall, this strategy is very successful, and it has been credited with preventing some 451 million cases of malaria in the past 15 years. But bed nets are not successful everywhere. In some parts of the world, mosquitoes develop “behavioral resistance”; i.e., they learn to avoid bed nets by biting people earlier in the day.

A team led by Lisa Reimer of the Liverpool School of Tropical Medicine monitored mosquito behavior in villages in Papua New Guinea before (2008) and after (2009-2011) the distribution of bed nets. Data from one of the villages, Mauno, depicts a very noticeable shift in mosquito feeding behavior.

Before bed nets were distributed in 2008, the median biting time for mosquitoes was around midnight. After the distribution, the median time shifted back to 10 pm. Also, a greater proportion of mosquitoes took their dinner even earlier, from 7 to 9 pm.

Worryingly, it’s unclear whether the bed nets were effective at preventing malaria transmission. The number of bites per person per night dropped after the introduction of bed nets, but started to climb in subsequent years as mosquitoes began to adapt. Additionally, the prevalence of malaria infection in humans — arguably, the only statistic that actually matters — dropped in one village, remained the same in a second, and ticked up slightly (albeit insignificantly) in a third.

Despite the mixed results in Papua New Guinea, Dr Reimer believes that bed nets should continue to be used worldwide as part of a mosquito control strategy. However, she notes that behavioral resistance may prove just as vexing as insecticide resistance and, in some locations, may limit the efficacy of bed nets.

Thus, mosquitoes must be monitored for both behavioral and insecticide resistance, as the little creeps stubbornly refuse to die and may be cleverer than we thought.

Source: Edward K. Thomsen et al. “Mosquito behaviour change after distribution of bednets results in decreased protection against malaria exposure.”

Source : Acsh.org

Beetle Fossil Nearly Doubles the Age of Known Parasites of Social Insects

When ancient insects first evolved eusocial behavior and began forming colonies, it didn’t take long, paleontologically speaking, for parasites of those resource-rich colonies to evolve, as well. A newly discovered ancient species of beetle found preserved in amber dates this apparent parasitic behavior to at least 98.8 million years ago.

In a paper published in Nature Communications this month, researchers from Kyushu University and Columbia University detail a new species of rove beetle, Mesosymbion compactus, found in a Burmese amber specimen housed at the American Museum of Natural History, that exhibits the hallmark traits of previously known parasitic beetles from the family Staphylinidae, subfamily Aleocharinae. These beetles have specialized to live inside the colonies of social insects such as ants or termites and often feed on eggs, larvae, and pupae in brood galleries.

As revealed through advanced imaging of the fossilized specimen, M. compactus, like modern aleocharines, has a teardrop-shaped body resembling a horseshoe crab, a head hidden below the pronotum when viewed from above, mandibles pointing rearward, and short, compact antennae. “Together, the suite of characters presented by Mesosymbion define an ecomorphology that has arisen numerous times in Aleocharinae, and suggests a non-integrated social parasite that was probably treated aggressively by its hosts, potentially targeting colonies as a brood predator,” the authors write. They also posit that M. compactus was a parasite of termites.

The M. compactus specimen comes from the very same amber deposit in Burma that provided the earliest known fossils of social termites, estimated to be 99 million years old. Previously, however, the earliest known social parasite was a rove beetle dated to approximately 52 million years ago (discovered by the same researchers), meaning M. compactus signifies a significantly earlier beginning to the evolution of parasitism of social insect colonies, placing it much closer to the rise of social insects themselves.

“Mesosymbion reveals that this adaptive versatility extends deep into the Mesozoic, when eusocial colonies presented novel niches for occupation that few other taxa were equivalently predisposed to fill. The notion of Mesozoic social parasitism by aleocharines implies that ant and termite societies were subject to exploitation during most of their evolution, including a long period when both social insect groups are inferred to have been rare and ecologically insignificant,” the authors write.

Source: Entomology Today

Ants communicate by mouth-to-mouth fluid exchange

The study from the University of Lausanne, Switzerland, suggests Florida carpenter ants can collectively influence their communities by shifting the cocktail of proteins, hormones and other small molecules that they pass mouth-to-mouth to one another and their young through a process called trophallaxis.

“Food is passed to every adult and developing ant by trophallaxis. This creates a network of interactions linking every member of the colony,” says senior author Laurent Keller, Professor in the Department of Ecology and Evolution.

“A lot of researchers consider trophallaxis only as a means of food-sharing,” adds Professor Richard Benton of the Center for Integrative Genomics, also a senior author of the study. “But trophallaxis occurs in other contexts, such as when an ant is reunited with a nest-mate after isolation. We therefore wanted to see if the fluid exchanged by trophallaxis contains molecules that allow ants to pass other chemical messages to each other, and not just food.”

To answer this question, the team, led by first author and postdoctoral researcher Dr Adria LeBoeuf, analysed fluid from pairs of ants engaged in trophallaxis. Surprisingly, they identified a large number of proteins that appear to be involved in regulating the growth of ants, along with high levels of juvenile hormone, an important regulator of insect development, reproduction, and behaviour.

To see what effect this hormone has on the growth of larvae fed by trophallaxis, the scientists added it to the food of larvae-rearing ants and discovered that the hormone made it twice as likely that the larvae would survive to reach adulthood.

“This indicates that juvenile hormone and other molecules transferred mouth-to-mouth over this social network could be used by the ants to collectively decide how their colony develops,” says LeBoeuf. “So, when the ants feed their larvae, they aren’t just feeding them food, they are casting quantitative ballots for their colony, administering different amounts of growth-promoting components to influence the next generation.

“The effects of juvenile hormone that we see are consistent with previous studies in other ants and in bees where larvae treated with an analogue of this hormone tend to develop into larger workers and even queens.”

Along with growth proteins and juvenile hormone, the team also identified small molecules and chemical signals in the carpenter ants’ trophallactic liquid that help them recognize their nest-mates. They demonstrated for the first time the presence of chemical cues in the fluid that are known to be important in providing ants with a colony-specific odour that allows them to distinguish family from non-family members.

“Overall, we show that liquid transmitted among ants contains much more than food and digestive enzymes,” adds LeBoeuf. “Our findings suggest that trophallaxis underlies a private communication channel that ants use to direct the development of their young, similar to milk in mammals.”

“More generally, this opens the possibility that the oral exchange of fluids, such as saliva, in other animals might also serve previously unsuspected roles.”

Source : ScienceDaily

Common insecticides are riskier than thought to predatory insects

Neonicotinoids — the most widely used class of insecticides — significantly reduce populations of predatory insects when used as seed coatings, according to researchers at Penn State. The team’s research challenges the previously held belief that neonicotinoid seed coatings have little to no effect on predatory insect populations. In fact, the work suggests that neonicotinoids reduce populations of insect predators as much as broadcast applications of commonly used pyrethroid insecticides.

“Predatory insects contribute billions of dollars a year to agriculture through the elimination of crop pest insects,” said Margaret Douglas, postdoctoral researcher in entomology, Penn State. “We have found that neonicotinoid seed coatings reduce populations of these natural enemies 10 to 20 percent.”

According to John Tooker, associate professor of entomology, Penn State, the use of neonicotinoids has risen dramatically in recent years, especially for large-acreage crop species like corn, soybeans and cotton. The insecticide is most often applied to seeds as a prophylactic coating. When the seeds are planted, the insecticide enters the soil where some of it is taken up by plant roots. The chemical then runs systemically through the plant, protecting young seedlings from insect pests.

“Applying insecticides to seeds rather than broadcasting them across a field was thought to reduce unwanted effects on natural enemies,” said Douglas. “But we found that seeds treated with neonicotinoid insecticides reduced populations of natural enemies by 10 to 20 percent in North American and European farming systems. Surprisingly, this effect was about the same as that associated with broadcast applications of pyrethroids.”

The team’s research appeared in the online journal PeerJ.

The team used a statistical method, called meta-analysis, to combine the results of more than 1,000 observations from 20 field studies across North America and Europe that tested the effects of seed-applied neonicotinoids on predatory insects. “Unfortunately, the available literature is difficult to interpret,” said Tooker. “Some studies show little influence of neonicotinoids presented as seed treatments on arthropod predators that are common in crop fields, whereas others show a strong influence of these seed treatments. By using a meta-analysis approach, we were able to combine the results of many studies to quantitatively reveal the overall influence of neonicotinoids on predator populations.”

Not only did the researchers find that neonicotinoid seed coatings significantly reduced natural enemy populations, they also found that the insecticide acted more strongly on insect predators than on spiders. In other words, spiders appeared to be less susceptible to neonicotinoids than insects, which is consistent with previous research.

“This result suggests that neonicotinoids are reducing populations of natural enemies at least partly through their toxic effects rather than simply by reducing the availability of their crop pest foods,” said Douglas. “After all, insects are more susceptible to these toxins than spiders, whereas the two groups should be similarly affected by a lack of food.” The researchers note that their results may help farmers and pest management professionals better weigh the costs and benefits of neonicotinoid seed treatments versus alternatives.

“Several governments have restricted the use of neonicotinoids out of concern for their possible effects on pollinators,” said Douglas. “But this raises the questions, ‘What will farmers do without these products? If they switch to broadcast applications of pyrethroids, will those products be better or worse for predatory insects?’ While our results do not speak to the pollinator issue, they do suggest that predatory insects are affected similarly by seed-applied neonicotinoids and broadcast pyrethroids.”

The answer to the problem, noted Tooker, lies in the application of integrated pest management (IPM), a strategy that uses a combination of techniques — which may or may not include the targeted use of insecticides — to control pests, rather than universally deploying prophylactic tactics like insecticidal seed coatings.

“Substantial research exists supporting the value of IPM for pest control,” he said. “It is the best chance we have of conserving beneficial insect species while maintaining productivity in our agricultural systems.”

Source: Science Daily

Dengue cases in Mumbai highest in 6 years

MUMBAI: The number of dengue cases recorded in the city this year has been the highest in the last six years. However, the good news is that fatalities have declined significantly over the last three years.

According to figures recently released by the state, Mumbai has recorded 1,088 cases so far this year and four confirmed deaths. The last time dengue cases had crossed the 1,000mark was in 2012. Within the state too, the highest number of cases were reported from the city. Dengue infected 6,376 people and claimed 26 lives in Maharashtra between January 1 and November 21this year. Doctors say the increase in incidence is a reason for concern as it can lead to longer hospital stays, lost manhours and bigger hospital expenses. “Dengue causes mortality in merely 1%-3% of cases. It is the morbidity that needs to be looked into closely,” said infectious disease consultant Dr Om Srivastava. He said that patients this ye ar had complained of pro blems in resuming their routine lives long after they had recovered from the mosquitoborne illness.

A senior physician from KEM Hospital in Parel too added that patients came to the hospital three months after recovering from the disease with complaints of lethargy . “In a few cases, the symptoms had persisted from six weeks to three months,” the doctor said. Srivastava added that many patients fail to follow the post-recovery regimen like drinking water and taking adequate rest which prolong their suffering.

Source: Times Of India

Dengue Claimed 179 Lives, no Death Due to Chikungunya: Government

Dengue has claimed 179 lives across the country this year while no death has been reported due to chikungunya, though it affected 21,000 people, the Rajya Sabha was told today.

“During 2016 (till November 13), a total number of 179 deaths due to dengue and no death due to chikungunya has been reported in the country.

“The number of positive cases for dengue and chikungunya in the country during 2016 (till November 13) are 90,277 and 21,094 respectively,” Health Minister J P Nadda said in a written reply.

He said the reason behind the steep increase in the number of cases are– water storage practices, poor solid waste management, construction activities, large migratory population, inadequate vector management and lack of protective immunity in the affected population.

Dengue claimed 33 lives in Uttar Pradesh, 28 in West Bengal and 22 in Maharashtra, he said. Replying to another question on the same issue, Minister State for Health Faggan Singh Kulaste said the government has taken measures for prevention and control of dengue and chikungunya in the country, including in Delhi.

He said technical guidelines for prevention and control, clinical management and vector control have been issued to states and UTs while periodic reviews have taken place.

Since January, 2016, 22 review meetings at the levels of Minister, secretary and others were held.

He said since January 12 advisories have been issued at the levels of Secretary (H&FW) and Additional Secretary while states were requested to declare dengue as notifiable disease.

“States were requested to curtail out of pocket expenditure by fixing the rate for testing at Rs 600,” he said.

He said dengue and chikungunya diagnosis is provided through 542 Sentinel Surveillance Hospitals (SSHs) and 15 Apex Referral laboratories (ARLs) identified across the country.

“First version draft of ‘Strategy and Plan of action for Effective Community Participation for Prevention and Control of Dengue’ has been uploaded. A user-friendly App ‘India Fights Dengue’ has been launched while National Dengue Day has been observed on May 16, 2016 throughout the country,” he said.

Source : Smartcooky

School children work on project to fight dengue

BERHAMPUR: At a time when the state is grappling with dengue, students of MM High School, Girishola here have prepared a project to fight the disease.

The project has suggested plantation of marigold, lemon grass and podina (meant) sapling on open spaces of the villages and houses to drive away the mosquito species like aedes and anopheles responsible for diseases like dengue, malaria and chikungunya.

The project ‘Killer dengue in Girishola – a case study, remedy and solution’ has been prepared by five students of Class VIII with active guidance of the science teacher Raghunath Ghadei. It has been selected for National Children’s Science Congress (NCSC) to be held at Vidya Pratishthan’s Institute of Information Technology (VIIT), Baramati, in Maharashtra from December 27 to 31.

The project also suggested development of culture centres of dragonfly and Gambusia fish to prevent increase of mosquito population. “While we have experimented by planting the marigold herbs on the premises of our school, we came to know from the elder persons about the role of dragonfly to kill the small mosquitoes during the preparation of the project,” said P Veketesh, a student involved in the project.

The fragrance of the herbs of marigold, lemon grass and meant can prevent entry of mosquitoes to a particular area, said the guide of the project. Other students, who participated in the preparation of the project, are Rahul Moharana, Balaram Sahu, Asish Moharana and Shankar Pradhan while science supervisor Gopal Krushna Panda was actively involved in the experiments.

While a single dragonfly can eat over 30 mosquitoes a day, its larva also gulps the larva of mosquito, said Ghadei. Similarly the Gambusia fish also eats the larva of mosquito. The students of the high school mooted the project after 200 people were affected by dengue killing six persons in Girishola in July and August.

The team members toured the village and interacted with several victims to know their garbage disposal method. The village along Odisha-Andhra Pradesh border has no space for garbage disposal as the NH-16 passes in one side while railway track is on the other side. In other two sides, there are state highways. The school students along with villagers took 15 days to clean the garbage.

Times of India

New parasitic plant doesn’t use photosynthesis; its flowers never bloom

On the Japanese island of Kuroshima, a scientist has discovered a new species of plant that does not use photosynthesis to derive its nutrition. It steals nutrients from fungi instead.

The plant has another peculiar character: its flowers never bloom.

Researcher Kenji Suetsugu of Kobe University chanced upon some 100 individuals of the new plant in April 2016, during a research trip in the lowland forests in Kuroshima. Detailed examination of the plant revealed that it is a new member of the genus Gastrodia, a rare group of mycoheterotrophic orchids that are distributed in the temperate and tropical forests of Asia, Oceania, Madagascar and Africa. Suetsugu has named the new species Gastrodia kuroshimensis after the island on which it was discovered.

The newly discovered orchid — like most other mycoheterotrophic plants — occurs in the dark understory of forests where little light penetrates, according to the new study published in Phytotaxa. So instead of using sunlight or photosynthesis to generate nutrients, the plant parasitizes fungi in the forest soil for its daily dose of nutrition.
New orchid – Gastrodia kuroshimensis – discovered on Kuroshima island in Japan. Photo by Kenji Suetsugu.New orchid – Gastrodia kuroshimensis – discovered on Kuroshima island in Japan. Photo by Kenji Suetsugu.

Moreover, the plant produces dark greenish-brown flowers that remain closed throughout the entire flowering period between April and May. The plants rely completely on self-pollination within closed buds instead.

Such obligate self-pollination, or “complete cleistogamy”, is extremely rare, Suetsugu writes in the paper, but is relatively common in the genus Gastrodia and has been observed in at least three other species: G. clausa, G. takeshimensis Suetsugu and G. flexistyloides.

This unique reproductive strategy may be a product of the environment the plant inhabits, he adds. Since the low-light environment of Mycoheterotrophic plants is usually unsuitable for common insect pollinators, obligate self-pollination may be an evolutionary response that ensures reproductive success when pollinators are absent or limited, the study posits.

So far, the new plant G. kuroshimensis has been found on three Japanese islands — Kuroshima, Akusekijima and Yakushima.

Mongabay

Cities account for 60% of state’s dengue casualties this year

MUMBAI: Around 60% of dengue deaths in the state this year have been reported from urban areas. An analysis of the confirmed cases by the state’s health department also revealed that nearly two-thirds of the positive cases were from the urban areas.

The Mumbai Metropolitan Region, Pune, Nashik and Aurangabad have reported nearly 70% of the 5,391 dengue cases this year. The state’s figures also show a 63% jump in dengue cases between January and October this year when compared with the corresponding period last year. Out of the 22 deaths this year, 13 have been reported from the urban areas.

Mumbai alone has reported nearly 1,000 cases and four confirmed cases. However, more than 10,000 people have been hospitalised during monsoon for suspected dengue or similar illnesses. Speaking to TOI, head of the directorate of health services Dr Satish Pawar said, “It is particularly worrying because only 40% of our population resides in the urban areas. But, we have found out that construction activities are not the sole reason for the growing incidence of dengue. In certain cases where dengue had become complicated, doctors have used aggressive treatment where it was not required. Some of these hospitals were in big cities”.

Pawar added that the state has drawn up uniform treatment protocols and even trained doctors but the indiscriminate use of platelets continues to be an issue. The BMC had, in an analysis last year, found out that the use of platelets rose by 14-15% during months when dengue peaked in the city. This year, however, the situation was much better. A civic official said the use of platelets during dengue was closely monitored. “This year, there was no unusual demand for platelets,” the official said.

Times of India

UT researchers discover bacterial genes that could lead to effective malaria treatment.

Researchers at the University of Tennessee, Knoxville, have identified a set of bacterial genes that may help them find ways to lessen the severity of the disease malaria.

Their findings could also aid the research of fellow scientists working in malaria-stricken regions around the world.

The study was published in the journal Frontiers in Microbiology.

Collaborators in this work include Steven Wilhelm, the Kenneth and Blaire Mossman Professor in the UT Department of Microbiology; Shawn Campagna, UT associate professor of chemistry; Gary LeCleir, UT research assistant professor of microbiology; Joshua Stough, UT doctoral student in microbiology; and Nathan Schmidt, assistant professor of microbiology and immunology at the University of Louisville.

The research team earlier this year released a study that found the severity of malaria depends not only on the parasite or the host but also on the microbes in the infected organism. They examined the gut microbiomes of mice.

This new study is helping researchers better understand how gut bacteria work.

Stough analyzed hundreds of genes and eventually found that 32 bacterial genes and 38 mice genes have the characteristics–or phenotypes–that can affect malaria.

“We’re pretty excited because it means there is a limited number of genes to work with,” Wilhelm said. That discovery will make it easier to find a more effective malaria treatment for people.

Much of the study was carried out in Wilhelm’s UT lab.

When the research team released the first study in February, scientists around the world doing similar microbiome work expressed interest.

“The findings in this second study could allow scientists to look at data they’re collecting and try to draw comparisons to see if what we’re seeing is also happening in their samples from malaria-stricken regions,” Wilhelm said. “We’re collecting data in a way that can be used to answer other questions after the fact.”

Hundreds of children die every year from malaria. “If we can find a way to mitigate this disease, we can positively influence a large number of people,” Wilhelm said.

Source: http://www.news-medical.net/