- Author: Ben Faber
Stink bugs of various species have been an issue on avocado and citrus for many years. Not always an issue, but occasionally they can reach damaging proportions.
http://ucanr.edu/blogs/Topics/index.cfm?start=4&tagname=stink%20bug
For stink bugs to attract a mate or to communicate that they have found food, they use their own chemical language: pheromones.
Virginia Tech researchers have discovered insights into this chemical language, which can be used to develop alternative pest controls.
"We have gained a deeper understanding of how stink bugs synthesize pheromones, and this knowledge may allow us to produce pheromones in expendable food crops - also called 'trap crops' - to lure the bugs away from cash crops," said Dorothea Tholl, a professor of biological sciences in the College of Science and a Fralin Life Science Institute affiliate.
These new environmentally friendly and sustainable alternatives to insecticides could save farmers millions of dollars.
In Virginia, crops such as grapes, sweet corn, and apples, have been under attack by the invasive brown marmorated stink bug since 2004; cabbage has also been affected, but by the harlequin stink bug. A relative, the southern green stinkbug is also a severe pest worldwide and attacks many different crops including beans and soybeans.
Tholl is interested in the chemical communication of organisms and studies how this chemical language has evolved in insects. With support by a grant from the USDA National Institute of Food and Agriculture, her lab investigates the enzymes that produce stinkbug pheromones in an interdisciplinary collaboration with colleagues at Virginia Tech and national and international institutions.
Her team's research has recently been published in the journal Proceedings of the National Academy of Science, or PNAS.
"Our recent paper provides valuable insight into our understanding of how insects synthesize complex sesquiterpene compounds that are typically used as pheromones. The work could pave the way in the future for plants to manufacture insect pheromones, which could be utilized in pest surveillance and pest management strategies, such as attract and kill," said Thomas Kuhar, a professor of entomology in the College of Agriculture and Life Sciences and a Virginia Cooperative Extension specialist.
Very little was known about the biosynthetic evolution of these insect pheromones, and the research of Tholl's team has shown that stink bugs have their own enzymatic machinery to make pheromones without receiving them from symbiotic microbes or the host plant, as was previously thought.
Jason Lancaster of Knoxville, Tennessee, a recent biological sciences Ph.D. graduate from Tholl's lab, used next-generation sequencing to identify and functionally characterize the first enzyme in the biosynthetic pathway of the harlequin bug pheromone compound.
"Pheromones for thousands of insects are known, but very little is known about the synthesis of the pheromones. This paper focuses on terpene derived pheromones from the harlequin stink bug Murgantia histrionica and encompasses many years of research. Besides the development of dead-end trap crops, this research may allow establishing "RNAi interference" type gene silencing mechanisms to disrupt the pheromone production of the insect," said Lancaster.
Lancaster also found that other stink bugs such as the brown marmorated stink bug use enzymes in pheromone biosynthesis similar to that identified in the harlequin bug. Beyond the team's current study on stink bug pheromones, the research may allow for exciting future discoveries in the biosynthesis of pheromones of other insects and their application in pest management.
Two of Tholl's graduate students, Andrew Muchlinski and Bryan Lehner, are co-authors on the paper and contributed substantially to this research.
There is commercial interest in using the genetic tools developed by Tholl's team to produce the pheromones via synthetic biology for application in the field to promote pest mating disruption.
"Overall, we are excited about the prospect that our research has the potential to develop new pest management techniques," says Tholl.
https://www.eurekalert.org/pub_releases/2018-08/vt-dch081718.php
IMAGE: For stink bugs to attract a mate or to communicate that they have found food, they use their own chemical language: pheromones.
- Author: Ben Faber
Akif Eskalen, the Subtropical Crops Plant Pathology Extension Specialist at UC Riverside has accepted a new position at UC Davis. He will be filling the position of his mentor, Doug Gubler. From now on, he will work on grapes, strawberries, caneberries, blueberries and other tree fruits. Although, he will surely keep his interests in the issues he has worked on while at UCR.
Akif has been instrumental in binging new light to the understanding of such basic disease problems as Citrus Twig and Shoot Dieback, Citrus Botryosphaeria Branch Canker, Citrus Dry Root Rot and ‘Fukumoto' Foamy Bark (http://eskalenlab.ucr.edu/citrusdiseases.html). He has cleared up the mysteries surrounding Avocado Black Streak, Dothiorella Branch Canker and Avocado Stem and Leaf Blight. His studies have also covered oak diseases that are exacerbated by invasive pests (http://eskalenlab.ucr.edu/handouts/oakwoodlandsdiseasesmanagement.pdf).
He has worked with other researchers at UC and other organizations to understand and figure out what to do with Invasive Shot Hole Borer and its fungal symbiotic pathogens which damage and kill so many trees in the California landscape, such as CA Live Oak, Sycamore and Willow (http://eskalenlab.ucr.edu/pshb.html).
Yeah, so now he will have fun working out all the various disease issues of some major fruit crops grown throughout California. Go man go.
A recognition party was recently held at the Huntington Library in San Marino to celebrate his work and his new challenges. The Garden and he have worked closely to build a program to manage Invasive Shot Hole Borer and Fusarium Dieback.
Shot Hole Borer Bye-Bye Cake. The Coup de Grâce along with co-worker Sylvia.
- Author: Ben Faber
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https://www.nass.usda.gov/Statistics_by_State/California/Publications/Specialty_and_Other_Releases/Citrus/Acreage/201808citac.pdf
/table>- Author: Brad Hanson
As troublesome herbicide resistant weeds continue to develop and spread across the United States, effective weed management strategies require the use of multiple effective techniques to be used rather than relying on a singular method of weed control. Integrated weed management (IWM) is the practice of utilizing multiple weed management tactics to achieve weed suppression superior to what a single tactic could provide.
This brief, 20-question quiz is anonymous and will provide insight to the understanding and adoption of IWM practices across the United States.
Click here to take the survey: https://www.surveymonkey.com/r/SD9RT6R.
This IWM quiz was written by weed scientists from 14 universities and the USDA with funding from the USDA Agricultural Research Service. Find more information on integrated weed management at www.integratedweedmanagement.org.
- Author: Ben Faber
And doing it in the dark?
In a recent paper, David Pattemore and associates reveal some fairly different observations about avocado flowering. One, that the female stage can be open and potentially receptive to pollination at night. And Two, that moths and crane flies amongst other nocturnal insects are visiting the flowers and carrying pollen!!! These are two very new observations, made possible by the digital world we live in.
Of course, insect visitation doesn't mean fruit set. Is there pollination, transfer of pollen to the female stage? Is there enough pollen? Is it the right pollen? Is it the right temperature for fertilization to occur? Whatever else needs to happen for fruit set, is it happening?
But these observations are opening up new discussion topics for the avocado world.
LOW OVERNIGHT TEMPERATURES ASSOCIATED WITH A DELAY IN ‘HASS' AVOCADO (PERSEA AMERICANA) FEMALE FLOWER OPENING, LEADING TO NOCTURNAL FLOWERING
David Pattemore1,2*, Max N. Buxton1, Brian T. Cutting1, Heather McBrydie1, Mark Goodwin1, Arnon Dag3
1The New Zealand Institute for Plant & Food Research Limited, Ruakura Research Centre, Hamilton 3210, New Zealand
2School of Biological Sciences, University of Auckland, Auckland, New Zealand
3Gilat Research Center, Agricultural Research Organization, 85280, Israel
Abstract—Avocado (Persea americana) has synchronously protogynous flowers: flowers open first in female phase before closing and opening the next day in male phase. Cultivars are grouped based on whether the flowers typically first open in female phase in the morning (type A), or in the afternoon (type B). However, it is known that environmental factors can alter the timing of flower opening, with cold temperatures being shown to affect the timing of flowering. The aim of this study was to investigate how low spring temperatures in New Zealand affect the flowering cycle of commercial avocado cultivars, focusing primarily on the receptive female phase of ‘Hass', a type A cultivar. Time-lapse photography was used to assess flower opening times of ‘Hass' over three years. Decreasing minimum overnight temperatures were associated with a delay in the timing of ‘Hass' female flower phases and resulted in nocturnal flowering of both male and female phase flowers. We recorded insects visiting female flowers at night, and some nocturnal flower visitors collected were carrying avocado pollen. Our study suggests that nocturnal pollination needs to be considered for avocados grown in temperate regions. Furthermore, as the timing of the female phase of ‘Hass' varied significantly with overnight temperature, the activity patterns of potential pollinators need to be considered to ensure adequate pollinator activity across the range of times in which ‘Hass' flowers are receptive.
Eight different invertebrate orders were captured from avocado flowers at night. Coleoptera, Diptera and Lepidoptera were the most frequently caught floral visitors, but it was coleopteran, dipteran and neuropteran individuals that carried the greatest number of pollen grains on average. This is an important distinction to make, as not all floral visitors behave as pollinators: visitation does not necessarily infer pollination. Species such as Costelytra zealandica (Coleoptera), Micromus tasmaniae (Neuroptera), along with Tipulidae and Sylvicola species (Diptera) may be especially important, as these were both frequently caught and often carried a high number of pollen grains. Compared with diurnal pollination, nocturnal pollination is poorly understood and relatively little research in New Zealand has tested assumptions that nocturnal floral visitors can act as pollinators.
This is an interesting read and introduces further areas of pursuit to understanding what brings on fruiting in the wild avocado.
Read On:
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Rhapsa scotosialis – a potential avocado pollinator?