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Early emergence of insects expected due to unseasonable winter and spring conditions

by Adam Russell, Texas A&M AgriLife

Above-average temperatures throughout late winter and early spring have Texas A&M AgriLife Extension Service experts around the state experiencing and expecting earlier-than-usual emergence of insects, said Dr. Charles Allen, AgriLife Extension entomologist and integrated pest management coordinator, San Angelo.

Allen said producers should be prepared not only for earlier-than-normal pest emergence but also possibly higher numbers of multi-generational species.

“There’s a good chance we will see odd stuff this year,” he said. “There are a lot of producers who mark a date on their calendar based on what happened in previous years, but if they do that this year they could be spraying too late.”

Allen said AgriLife Extension and Texas A&M AgriLife Research experts and other state agencies are monitoring ongoing and emerging pest problems across the state, including cattle fever ticks and sugarcane aphids.

Cattle fever ticks continue to be a major concern for producers in South Texas, as the pest has moved north and been found in 41 locations outside the quarantine zone along the Texas-Mexico border, he said. Sugarcane aphids, which have caused annual losses in the millions of dollars to Texas sorghum producers since they emerged in 2014, have been spotted in the Lower Rio Grande Valley several weeks earlier than usual this year.

But entomologists around the state are also receiving earlier-than-usual inquiries about infestations of pests from fleas, flies and mosquitoes to Crape Myrtle bark scale and forest tent caterpillars, Allen said. Experts expect other insect species to follow that trend.

Pecan nut casebearer is a pest Allen said producers need to watch carefully because they are so well adapted to the trees’ schedule, both of which are responding by emerging early with this spring’s weather conditions. Adult pests emerge to lay eggs when the tree produces nutlets.

“Growers can use traps to biofix the adults,” he said. “They can then use the heat unit model on Pecan ipmPIPE (at http://pecanipm.tamu.edu/Index) to determine when eggs will be laid and larvae will hatch and begin feeding on nutlets.”

Allen said pests with multiple generations per year, such as sugarcane aphids and fall armyworms, could become a bigger problem for producers if they emerge sooner than usual and their reproduction window is lengthened.

“You get stair-step population growth curves with those pests,” he said. “With the warm spring weather we can expect to add a generation or two. So you’re looking at an early start and potentially a late finish, which could add one or two generations and contribute to damaging populations in the fall.”

Allen said potential lengthened breeding time could add cost for producers, who might face additional pesticide treatments to address infestations.

One scenario would be horn fly treatments on beef cattle, he said. Standard fly pesticide treatments have an 80-day efficacy. Additional heat units could lengthen the feeding and breeding window to 100-120 days.

One positive Allen noted is that predatory insect species are also adapted to emerge alongside pests, and beneficial insects often do a pretty good job of suppressing pest populations.

Allen said the key for producers will be shifting the timeline for vigilant scouting and to be prepared to treat crops as pest populations approach economic thresholds.

“We’re all creatures of habit and expect things to happen like they did the year before,” he said. “But with this warm winter I think that won’t work this year. There will be factors that play into how good or bad things will be – dry weather and predators can make a huge difference in populations – but we should expect this to be an odd year.”

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