Stem Pests: (some Homoptera)

1. Stem Pests: (some Homoptera)

2. Before we move on to stem pests, there are still some basic entomological topics to discuss. In particular, the digestive system. Why? In order to better understand your favorite aphid and other homopterans

3. Remember Aphid Feeding

4. Hindgut Midgut Foregut Rectal area Mouth Malpighian tubules Generalized insect digestive system

5. Foregut Midgut Midgut Malpighian tubule Filter chamber of aphids and other homopterans Hindgut Honey dew

6. Honeydew from aphids

7. 0.5mm Now we can move on to the stem pests, starting with the balsam woolly adelgid1 1 Really belong to the family Phylloxeridae

8. The Balsam Woolly Adelgid1, Adelges piceae. Galls Galls 1 Phylloxerid

9. 1905 in a small coastal town in Maine, a Quarantine Inspector. These European fir trees have only female Adelges piceae -- I’ll let them pass.

10. “Males? We don’t need males; we’re parthenogenic.”

11. BWA Dead Fraser-fir Unfettered population growth by the BWA began and in a few decades; they killed fir trees in the Canadian Maritime Provinces and today are into the Appalachian Mtns. destroying Fraser fir across thousands of acres.

12. The Balsam Woolly Adelgid Comes West in 1950 Adelgid

13. The BWA infest and kill: No. 1 subalpine fir, No. 2 grand fir, No.3 silver fir & noble fir, and No. 4 Shasta-red fir is barely attacked.

14. Life Cycle of the BWA (1) The BWA overwinter as a diapausing 1st instar, the winter form. (2) In early spring, the 1st instar swells and begins to produce honey dew as the tree sap starts flowing. (3) The immature female molts several times and becomes an adult in ± 3 weeks. (4) Each female then lays ± 100 eggs. BWA laying eggs

15. BWA crawlers (5) Eggs hatch in about a week and each motile nymph crawl rapidly around the new foliage, twigs and branches.

16. (6) These motile nymphs then thread their stylets through the bark and tap a vascular bundle -- they are stuck for life, a life of sucking sap, the summer form. (7) This summer generation, then aestivates for 1 - 2 months. (8) In July they “wake up” and quickly molt to adults. These summer-generation adults lay ± 50 eggs apiece. (9) Depending on the climate, elevation, site, aspect etc., there maybe 2 - 3 generations/yr.

17. The BWA in action! One mm Motile nymph Egg Adult Bark surface Nymph stuck in the phloem

18. As BWA feed they inject a toxin into the actively growing tissues, which causes hyperactive growth & galls

19. A few BWA Millions BWA The BWA Disaster

20. Subalpine fir near the town of Concrete More BWA Damage

21. In order to understand why its so difficult to control the BWA, let’s discuss the Mortality Quotient. The Mq asks: “how many individuals of an insect population must be killed to prevent the population from increasing.” Mq depends on: (1) fecundity number of eggs a female will lay, & (2) sex ratio.

22. Mq = (F)(SR) - 1 (F)(SR) Mq = Mortality Quotient F = Average No. Eggs SR = No. Females No. Females + Males

23. (75) - 1 (75) = 0.986 The iris bulb fly: Fecundity = 150 Out of 1000 puparia you collected, 500 are males. There is one generation/yr of the gladiola bulb fly. Mq = (150)(0.5) - 1 ( 150)(0.5) 150 X 0.986 = 148 So: 150 - 148 = 2 (a male and a female) 150 eggs

24. BWA (100)(1) - 1 Mq = = 0.99/generation (100)(1) i.e., 100 eggs - 99 killed = 1 female!

25. Management of BWA in the urban environment: • Avoid planting subalpine fir • Maintain a high vigor in plantings • of other Abies spp. • Consider applied control of BWA-infested firs if they have special intrinsic value, e.g. a historical fir planting within the Japanese Garden. • Consider applied control when the aesthetic value of a commercial Abies spp. planting is threatened, • e.g. the Christmas tree industry.

26. With valuable trees, you may have to treat -- about bud-break time.

27. Apply insecticide at time of budburst, you should see tiny crawlers. 7

28. The balsam twig aphid, Mindarus abietinus Twisting new growth Stem mothers Eggs BTA on the stem

29. The balsam twig aphid can severely damage true firs: • In nurseries, the terminal needles twist and become deformed. • In urban plantings, BTA suck on twigs and foliage producing great amounts of honey dew and sooty mold -- firs become unsightly.

30. April - May: stem mothers sucking on stem next to new buds or on new foliage – needles twist. Mom? May - Mid June: vivipary in action: 2 or more generations of wingless females. Mom? Mom? Mom? Mom? Mom? Mom? Mom? Mom? Mom?

31. June: a winged generation flies off to an alternate host.

32. Unknown host? July - August: both males and females are produced and they fly back to true firs Late summer: males & females occur Male Female True fir: primary host

33. Mating Aphids August - September: egg laying and the winter is spent in the egg stage. Early next spring eggs hatch and stem mothers start inserting their stylets at the bases of buds.

34. The bowlegged aphid, Cinara curvipes; occurs in California Oregon, Washington, Colorado and Utah -- on firs, Engelmann spruce, and deodar cedar. The Cinara spp. aphids have a typical conifer-aphid life cycle and they feed on trunks, stems, and roots. These aphids often are herded by ants, typically Formica spp. (e.g. western thatching ants) and Camponotus spp., the carpenter ants. Ants tending Cinara aphids and Cinara curvipes on bark of white pine.

35. What to do?

36. Aphids: • Pest description and crop damage: Soft-bodied insects that suck sap on stems, branches, leaves etc. • Biological control: Aphids have many natural enemies. • Cultural control: A strong spray of water often effectively removes these suckers. • Chemical control: It’s important to cover foliage thoroughly • as well as stem and branches with: • azadirachtin • insecticidal soap • acephate • horticultural oils as dormant sprays • imidacloprid