Late Season Pests in Cotton and Sesame - Virtual Training (2 IPM CEU's offered) - FREE program!

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Chilli Thrips Outbreak in Cotton in the Lower Rio Grande Valley

I know that recent weather events have changed our focus and this may no longer be a top priority.  However, it is important to note that this thrips species may be established in our area and is one we need to keep a close eye on as it is known to infest a number of different plants.

Recent reports of foliage bronzing and leaf drop in cotton has sparked interest in areas of the Rio Grande Valley.  Upon closer investigation the cause of this damage was identified as a type of thrips, commonly called chilli thrips, Scirtothrips dorsalis.

Chilli thrips are not new to the Rio Grande Valley, but they have the potential to become a pest in multiple crops.  These thrips are thought to originally be from Southeast Asia and were first detected in Florida in 1991 and in Southeast Texas in 2005.  Dr. Mamoudou Sétamou, Professor of Entomology & IPM Specialist Texas A&M University-Kingsville Citrus Center, first discovered and confirmed chilli thrips in the Rio Grande Valley in citrus in 2018 and has detected them every year since in citrus groves located in Hidalgo and Cameron counties. They are known to infest an impressively wide range of host plants, more than 100 species from at least 40 different plant families, and the list may continue to grow as they expand their range.  Among known plant hosts are bean, citrus, corn, cotton, eggplant, melon, peanut, pepper, rose, and tomato.  So, this pest is one we are going to keep a close eye on.

Damage Identification and Life Cycle

In cotton, the first clue that a field is infested with chilli thrips is the bronzing appearance of leaves in the upper canopy. Like other thrips species, they have piercing-sucking mouthparts used extract contents from individual plant cells.  This feeding causes characteristic bronzing and may also lead to cupping or other distortion of leaves.  Severe feeding causes leaves to become brittle and drop from the plant. 

Detection of chilli thrips in the field is difficult, and identification is nearly impossible without magnification.  The tiny (»2mm long) cigar-shaped adults are pale in color with black, feathery wings.  Immatures, called larvae, look similar to adults but are even smaller and lack wings.  Females insert anywhere from 60 – 200 microscopic eggs into plant tissue.  The length of time it takes to complete their life cycle varies depending on temperature and host plant but ranges from 14 – 20 days. 

Unlike similar looking species such as the Western flower thrips, which may be found in flowers feeding on pollen, chilli thrips only feed on foliage and are typically found on the undersides of leaves near the mid-vein or borders of leaves. However, when population densities are high, some individuals may be found feeding on the upper surface of leaves.  When scouting for this pest one must observe the underside of a leaf with a hand lens for several moments.  Initially thrips may not be visible as they are near the mid-vein but will are fast moving and will begin to move around on the leaf surface, making them more visible.

Damage Potential

Chilli thrips have been present in citrus (and possibly other crops) in the Valley since at least 2018.  However, this is the first time we have seen populations outside of citrus large enough to cause noticeable damage on cotton.  It is difficult to determine why populations have “exploded” in cotton this season or to predict what will happen in other crops this year and in seasons to come.  Because we know that this species is capable of feeding and reproducing on many crops grown year-around here in the Valley, we plan to monitor them closely by initiating Valley-wide surveys and management strategies.

Chilli thrips are known to vector at least seven viruses to various crops including chilli leaf curl virus, peanut necrosis virus, tobacco streak virus, melon yellow spot virus, watermelon silver mottle virus, and capsicum chlorosis virus, although there are no reports that they have been vectors of any of these viruses in Texas.

Management

In most cases, there is no longer a need to control chilli thrips in cotton this growing season.  Looking down the road, management may be needed if they move into fall crops.   Although chilli thrips are an invasive species, research in Florida has shown that natural enemies, including minute pirate bugs, lacewings, and lady beetles may aid in reducing chilli thrips populations. Thus, the use of broad-spectrum insecticides may promote thrips outbreaks by removing key beneficial insects.  Studies conducted by Seal et al. (2006, 2008, 2009) have indicated that pyrethroids are not effective in controlling chilli thrips while imidacloprid and spinetoram provide good control and allow for the continued growth of natural enemy populations.  Rotating between different classes of insecticides will be important in reducing the development of resistance.  In addition, controlling weeds, which may serve as alternative hosts is important.

While this is a relatively new potential pest for South Texas, Florida has had a few years to learn about chilli thrips and have produced some very useful information that can be found at the following links:

Good general information:

http://entnemdept.ufl.edu/creatures/orn/thrips/chilli_thrips.htm

Photos of damage on various host plants and more detailed control information:

https://mrec.ifas.ufl.edu/lso/thripslinks.htm

Addition resources cited:

·         Seal DR, Ciomperlik M, Richards ML, Klassen W. 2006. Comparative effectiveness of chemical insecticides against the chilli thrips, Scirtothrips dorsalis Hood (Thysanoptera: Thripidae), on pepper and their compatibility with natural enemies. Crop Protection 25: 949-955.

·         Seal DR, Kumar V, Klassen W, Sabine K. 2008. Response of chilli thrips, Scirtothrips dorsalis, and melon thrips, Thrips palmi, to some selected insecticides. Proceedings of the Caribbean Food Crops Society 44: 578.

·         Seal DR, Kumar V. (2009, in review). Biological response of chilli thrips, Scirtothrips dorsalis Hood (Thysanoptera: Thripidae), to various regimes of chemical and biorational insecticides. Crop Protection.

Is It a Murder Hornet?

There has been a lot of recent concern and media attention around the Asian giant hornet, also called the murder hornet.    We DO NOT have this invasive species in Texas.  However, we have been getting many cicada killers, and a few other wasps and bees, submitted as potential Asian giant hornets.  To help diligent Texans readily differentiate between the Asian giant hornet and some of our common Texas look-alikes, I worked with Dr. Pat Porter, Extension Entomologist and Professor located in Lubbock, TX to create this short video.
Please check it out at the link below:

Asian giant hornet (murder hornet) and it's most common look-alike Texas species

Dear Producer, 

Recent developments in the spread of COVID-19 pandemic have prompted our agency to make adjustments on how we handle in-person programs, it goes without saying that this has ultimately affected our traditional field days that have been held in the past.
In an effort to maintain social distancing we will be hosting a virtual field day via Zoom on July 16, 2020 starting at 9:00 AM. 

The AgriScience Field Day is a pre-recorded field day that took place at Texas AgriScience headquarters in June.
Several topics of discussion include: 

• Industry Professionals will discuss new technologies in grain sorghum and cotton 
• Extension Specialists will describe pests encountered in this year’s crops

A total of 3 CEU’s will be provided to those who are present during the Zoom conference.
There will be a Q&A during the time of the conference. 

To pre-register please click on the following link:

 https://bit.ly/2020AgriScienceFieldDay.  

PLEASE NOTE _ Registration deadline is July 14^th, this Tuesday

A link to Zoom will be sent, the day before the training, to all who pre-registered.  On the day of the event, you will use that link to sign in from 8:30 a.m. to 9:00 a.m. 

Click here for the agenda and additional topics of discussion: 

Texas AgriScience Virtual Field Day 2020

Hope to "see" you there!

Hot Off the Press: Sesame leafroller informational video and efficacy trial results

Sesame growers have had some problems with sesame leafrollers throughout parts of the Valley this past month.  Late-planted sesame still needs to be monitored as small larvae are still being detected.  Below, please find links to a video discussing the biology and management of this pest as well as a link to an efficacy trial we just conducted in Hidalgo Co. on young sesame.


Video: Sesame Leafroller - Biology and Control-



2020 Sesame Leafroller Insecticide Efficacy Trial

Sesame Leafroller / Sesame Webworm

For a few years Sesame grown in the Valley had few insect pests and populations typically stayed well below management thresholds.  Unfortunately, this has been changing over the past few years and we are starting to see several insects cause significant problems here and there. 

One of these is the sesame leafroller, also called the sesame webworm or sesame capsule borer, Antigastra catalaunalis.  It is a type of Crambid or snout moth.  The adults are a cream to brownish moth with a wingspan of a little over ½ inch.  Forewings have  zigzag lines while the hind wings are solid pale yellow.  Adults feed on plant nectar, live around 1 week and spend this time mating and locating host plants where the female will oviposit, or deposit eggs, singly on the underside of sesame leaves. 

Sesame leafroller adult

Eggs hatch in 2-3 days and larvae immediately begin feeding.  These tiny larvae (0.1 cm long) will feed for 10-12 days, going through five instars, or molts, before reaching larval maturity.  As larvae grow, they become yellowish to green with black spots and have a dark brown to black head capsule.  Mature larvae will reach 1 to 1.5 cm in length.

Showing two instars of leafroller larvae

Sesame leafroller larvae (Photo by Danielle Sekula)

Larvae are the damaging stage and feed on tender foliage, pods, and shoots.  As their name suggests, they web the top leaves and terminal portion of the plant to provide a protected location where they will feed, often destroying the apical meristem of the plant. 

The damage is easy to detect and is often full of little black balls of frass, or excrement.  If you pull this webbing apart, you will find one or more larvae feeding.  In many cases they can be seen between the stem and pods where they bore holes into the developing pods and destroy the seeds inside. 

Showing webbing and feeding damage by sesame leafroller

Feeding damage to seed pod/capsule

Once larval feeding is complete, they will pupate inside webbed leaves, or may drop to the ground and pupate in the soil.  Pupation lasts 5-6 days when adults will emerge and begin the cycle again.  It is likely there will be at least several generations in the Valley so sesame developing at different times can be infested.

Sesame leafroller pupa between stem and capsule

We do not have a lot of information on control of this pest in Texas.  Studies done worldwide have suggested that earlier planted sesame may not experience as high of levels of infestation as later planted sesame.  This may be because several generations have built up resulting in larger populations later in the season.  However, we have no data to show that this is the case in South Texas.  This insect does have other reported hosts including Amarathus species meaning it will have alternative hosts when sesame is not available, and thus weed control may aid in keeping webworm populations down.

We do not have established thresholds for this pest.  However, because they are feeding directly on flowers and pods, relatively low populations can likely cause significant yield loss. 

Insecticide applications are currently the best recommendation for control.  There are relatively few insecticides labelled for use in sesame at this time. When spraying for this pest, keep in mind that while they are often on the tip of the plant, they are also protected in webbing.  For this reason, contact insecticides will require plenty of carrier and good pressure to penetrate webbing and get the insecticides to where larvae are feeding. Growers and consultants have reported that an application of Chlorantaniliprole has provided good control of this pest.    

It's Swarming Season!

With all the rain we have had throughout the Valley these past few weeks, many ant and termite colonies are producing winged “swarmers” or “reproductives”.  Shortly after one of these rains you may see hundreds to thousands of insects suddenly fluttering around.  These sudden swarms consist of males and females that all emerge at one time. They mate and males die shortly after while the females will fly to a new location to start a new colony. 

While most of these females do not survive and are unable to successfully establish a new colony, it is worth taking the time to determine if you have ants or termites, especially if you are finding them fluttering around inside a home or other structure.  There are several species of termites in South Texas and many different species of ants.  While termites, if infesting wood in a structure, will require treatment, most ant species do not feed or nest in wood and thus are more of a passing nuisance.  

There are 3 characteristics that will readily distinguish an ant (any species) from termites. 

1.   The Antennae

2.  The Waist

3.  The Wings

After mating both ants and termites may drop their wings so it is not uncommon to find wingless individuals near the swarm. 

For more information on termite identification, biology and control please visit:

o    What is a termite? (ENT-6002)

o    Subterranean termites – general information (E-368)
General information about termite biology and control.

o    Frequently asked questions about subterranean termite control (ENT-2002)
Still confused about termite control?  Chances are that your questions have been asked before.  Check out this information before you call a termite control professional.

o    How to select a termite control company (E-369)
Termite control can be a big investment in maintaining your home.  Be an informed consumer.

o    Drywood termites (E-366)
If you live along the Gulf coast, or in more southerly parts of Texas, drywood termites are a common pest. The biology and treatment methods for drywood termites are distinctively different from subterranean termites.

For more information on ant identification, biology, and control please visit:

o    The Texas two-step method for fire ant control (L-5070)
One of the most popular factsheets in the Extension library.  Fire ant control made simple.

o    Managing household ant pests (B-6183)
This publication will help you understand and manage the different pest ant species common to Texas homes.

o    Identifying household ants (ENT-2013)
NEW!  The first step in knowing how to get rid of an ant problem is knowing what kind of ant you have. You won’t need a microscope or specialized skills to identify the most common household ants with this F@ctsheet.

o    Swarming insects indoors
Something’s flying around indoors, but you’re not sure what it is?  It could be an ant.

o    Carpenter ants around homes (ENT-2001)
This updated F@ctsheet clears up some of the misunderstanding about carpenter ants in Texas, and suggests practical steps to deal with a carpenter ant problem.

o    Carpenter ants (E-412)
This publication explains how to identify carpenter ants, recognize their nest site preferences, and take proper preventive and control measures. (4 pp., 1 photo, 1 figure)