Posts Tagged: beetles
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.
click on Download this PDF file
Rhapsa scotosialis – a potential avocado pollinator?
Rhapsa scotosialis female
You've heard the phase, "wear your heart on your sleeve"--which means to show your emotions...
EGSA's 2018 t-shirt winners: Brendon Boudinot wearing his t-shirt, "REPRESANT"; Jill Oberski with her onesie, "My Sister Loves Me" and Corwin Parker wearing his "BarBeeCue" t-shirt. All are available online at https://mkt.com/UCDavisEntGrad/. (Photo by Kathy Keatley Garvey)
"The Beetles" t-shirt is the EGSA's all-time best seller. Instead of the English rock band John Lennon, Paul McCartney, George Harrison and Ringo Star crossing Abbey Road in single file (that's the iconic image on the cover of their album, Abbey Road), think of The Beetles (four insects) crossing Abbey Road in single file. Beneath the images of the beetles are their family names: Phengogidae, Curculionidae, Cerambycidae and Scarabaeidae. Think glowworm, snout, long-horned, and scarab beetles.
They came. They saw. They bugged out. Who wouldn't, when you get an opportunity to pet a...
Entomologist and Bohart associate Jeff Smith introduces a crowd to Snuggles, a rose-haired tarantula. (Photo by Kathy Keatley Garvey)
Two-year-old Teddy Owens of Davis, held by his mother, Dina Owens, high-fives Snuggles, the rose-haired tarantula, held by entomologist and Bohart associate Jeff Smith. (Photo by Kathy Keatley Garvey)
Bohart associate Jeff Smith shows Snuggles, a rose-haired tarantula, to inquiring youngsters. (Photo by Kathy Keatley Garvey)
Quite a handful! Visitors at the Bohart Museum of Entomology's open house on Picnic Day watch Snuggles, a rose-haired tarantula. (Photo by Kathy Keatley Garvey)
Visitors check out the beaver/beetle display at the Bohart Museum of Entomology. In the foreground is Lynn Kimsey, museum director and UC Davis professor. At far left is undergraduate student Ivana Satre. (Photo by Kathy Keatley Garvey)
Bohart Museum director Lynn Kimsey smiles at the reaction of visitors to the beaver/beetle display. (Photo by Kathy Keatley Garvey)
UC Davis entomology doctoral candidate Charlotte Herbert shows youngsters how scorpions fluoresce under ultraviolet light. (Photo by Kathy Keatley Garvey)
The bee display encompassed honey bees, bumble bees, sweat bees, sunflower bees and more. (Photo by Kathy Keatley Garvey)
Wow, woolly whitefly covered with waxy, curly filaments , Aleurothrixus floccosus.
One of the consequences of fire and the resulting ash is that the biocontrol agents that keep whiteflies, scale, mealybug and other pests in balance is that they will spend so much of their time preening that they don't have time to go after their prey. Lacewing larvae, minute pirate bug, ladybird larvae, parasitic wasps and others rely on moving around to get at their food sources. When they cant move fast, they stop and clean their joints to stay limber. Whitefly and scale insects just hunker down and don't need to do a lot of moving. They just breed, and without actively moving biocontrol agents, their populations can explode. Or that's my human analogy. In dusty areas or areas affected by ash, the particles get in their joints and they need to spend time cleaning in order to move fast.
Whiteflies suck phloem sap, which in some cases can cause leaves to wilt and drop when there are high numbers of whiteflies. However, the primary concern with whiteflies is the honeydew they produce. Honeydew excreted by nymphs and adults collects dust and supports the growth of sooty mold; large infestations blacken entire trees, including fruit, as well as attract ants, which interfere with the biological control of whiteflies and other pests. The sooty mold can also affect tree yields by reducing photosynthesis and requiring extra handling time for cleaning.
So pests under good control prior to a fire can get out of hand. This is a good example of a tree in the town of Ventura where ash was a problem. A seemingly clean tree, free of whitefly, started to defoliate with blotchy leaf spots. On the undersides of the leaves corresponding to the blotches are colonies of whitefly. And looking closely you can see that some of the nymphs have exit holes, indicating that they have been parasitized by a wasp. So nature is kicking in and taking it's course. The whitefly should get cleaned up soon too by some forager, such as lacewing larvae or pirate bug. No need to spray because it would just be a further disruption.
See more about whiteflies at:
Photos: Defoliating 'Meyer' lemon tree, blotches on upper side of leaf, whitefly colonies with exit holes in some of the nymphs
lemon leaf drop
lemon leaf blotch
You always wanted to know what pollinated rambutan, litchi, blueberries and all those other plants dependent on insect pollen movement? O yes, and also what is pollinating avocado?
Insect Pollination Of Cultivated Crop Plants
by S.E. McGregor, USDA
Originally published 1976
The First and Only Virtual Beekeeping Book Updated Continuously.
Additions listed by crop and date.
This book is out-of-print, but can be found on-line at ABE Books and then you can get the images that are missing from the online version of the book
This is an old book with a lot of old information, but a lot of it is still good. There is definitely more up-to-date information, but this is a good starting point. For avocado, another good source, or course is AvocadoSource which also has quite a number of articles on pollination of other tree species
Recently a group of UC Riverside researchers met to align themselves around the topic of pollination - The biology, effects, interactions of the various pollinator and pollinizers and how they are affected by our environment and how we might be able to manage them better. The participants in this pollination group have all manner of expertise and hopefully their interaction will bring a synergy of understanding to this very complicated subject.
Photos: Syrphid (hover) fly, bumblebee, honeybee, thrips carrying pollen
bumblebee on clover
bee avocado flower
thrips carrying pollen