Sara Prado, an esteemed alumni of our lab, just had her paper selected as Editor’s Choice in Ecological Entomology. When given the choice, parasitoids select the hosts that will increase offspring fitness. Thanks Mom! It turns out this has benefits for biological control in greenhouses because the parasitoids prefer the green peach aphid, an important greenhouse pest, over grain aphids introduced on banker plants.
Nice job Prado!
Read the whole paper here.
On this rainy Tuesday I found boxwood leaf miner adults struggling to emerge from their blister mines. The orange flies were stuck to wet leaves. A few were hovering around. This is the first I have seen this year so it is a good time to check your plants and treat if necessary.
Boxwood leaf miner adult. Photo: SD Frank
The maggots pupate in the leaf blister. As the adult emerges the pupal case get caught on the leaf. This holds the leaf in place so the adult can wriggle out. Boxwoods can be treated with a pyrethroid to prevent flies from landing on the bush to lay eggs but watch out for mite outbreaks. Imidacloprid will kill maggots within the leaves but (based on article above) it is best to apply after flowering.
Boxwood leafminer struggling to emerge from pupal case. The pupal case will be left behind poking out of the leaf. Photo: SD Frank
NCSU Pest News was the original pest blog! This week information on ambrosia beetles, cankerworms, tent caterpillars…..
Other crops are include too if you’re into that.
Eastern tent caterpillars hatched recently
Eastern tent caterpillar nest in a crab apple tree. Photo: SD Frank
and have already established big nests. The easiest way to deal with tent caterpillars is to prune out the nests. Eastern tent caterpillars make nests in the crotch of trees. (Fall webworms make nests at the end of branches). So it you can’t remove the nest you can poke it with a pole pruner. This destroys the nest so many caterpillars fall to the ground and others get eaten by birds. Opening the nest also lets parasitoids in to kill the caterpillars. For severe infestations there are some insecticide options. Products containing Bacillus thuringiensis (Bt) are effective against caterpillars. Other active ingredients labeled for caterpillar control include spinosad, Beauveria bassiana, acetamiprid, acephate, azadirachtin, and bifenthrin. Keep in mind that these caterpillars spend most of their time in a water-proof nest so contacting them is difficult. This limits the efficacy of many insecticide applications.
Boxwood leaf miner larvae are developing fast. I stopped by some boxwood bushes and peeled open some blistered leaves. You can see
Boxwood flowers and leaf blisters. Photo: SD Frank
the larvae wiggling inside. The maggots pupate in the leaf blister and will emerge as adults in a few weeks. The adults hover around boxwood bushes but only for a couple weeks. In addition to the small orange adults you will see pupal casings sticking out of leaves. As the adult emerges the pupal case get caught on the leaf. This holds the leaf in place so the adult can wriggle out. Boxwoods can be treated with a pyrethroid to prevent flies from landing on the bush to lay eggs but again you only have a short window when adults are active. That is why it is good to pick a few leaves each week to see how close they are to emerging. Imidacloprid will kill maggots within the leaves but be careful
Boxwood leafminer larvae inside a leaf mine blister. Photo: SD Frank
because plants are flowering now so it should not be applied. If applying pyrethroids or imidacloprid watch out for mite outbreaks.
After a cool spring I was beginning to think the ambrosia beetles would never come out. Although we have found a few early non-pest species we have not seen the main -granulate ambrosia beetle- until now. We found a couple in traps at cooperating nurseries in Johnston Co, NC. Of course it is freezing this week which could delay them again. The same thing happened last year when we got a few at a time as the weather alternated
Frass tooth-pick from adult ambrosia beetles boring into trees. Photo: SD Frank
between warm and cold.
In experimental trees at lake wheeler and sentinel trees at nurseries we have not had any attacks but it is probably time to start management if you haven’t already.
Management of ambrosia beetle damage requires pyrethroid applications every 3 weeks to the trunks of trees. Ambrosia beetles usually attack below the first scaffold branches so you do not need to spray the canopy. Most folks apply permethrin with an airblast sprayer. We have tested a manual sprayer and fold more complete, even coverage.
You can read about it in a recent paper. The manual sprayer has two opposing nozzles to
Dual nozzle spray wand for permethrin applications. Photo: SD Frank
quickly cover tree trunk with insecticide. It takes a little longer but uses less insecticide and reduces drift and secondary mite outbreaks. Ambrosia beetle attacks also increase when trees are overwatered so resist irrigation until it is warm and trees start leafing out. Summaries of ambrosia beetle biology and management can be found in industry articles, an open source publication in the Journal of IPM, and in a free iBook about nursery pest management