Saskatoon fruitinfesting

Transcription

1 Saskatoon fruitinfesting insects Northwest Michigan Orchard & Vineyard Show January 18, 2017 Dr. Duke Elsner, Small Fruit Educator Michigan State University Extension

2 Sampling & dissection process Established saskatoons at Northwest Michigan Horticultural Research Center No insecticide treatments in Collected 20 fruit clusters weekly May 31 through July 18 Approximately berries per sample 99% ripe berries in sample by July 11

3 Sampling & dissection process Recorded for each berry- External evidence of injury or infestation Internal evidence of injury or infestation All intact specimens preserved Some parasitoids reared to adults Unfortunately, not repeatable at this site

4 Characteristics of recovered insects All were complete metamorphosis insects Egg larva pupa adult life cycle Members of three insect orders Coleoptera -- beetles Hymenoptera wasps, ants & bees Lepidoptera moths and butterflies

5 Encountered Insects Apple curculio Plum curculio Saskatoon sawflies Saskatoon bud moth Case-bearer moth Gall wasps Parasitoids

6 Apple curculio Adults are hard-bodied beetles Larvae are grub-like Pupates inside fruit One generation per year

7 Apple curculio Adults are beetles in the weevil family Adults feed by drilling into berries with jaws at the end of a long snout Injury is usually near the stem

8 Apple curculio Adult feeding results in a tunnel & scar tissue Same drilling process is used for oviposition Oviposition tunnels often plugged with chewed berry material

9 Apple curculio Larvae are grub-like No legs Tan / brown heads with distinct jaws Feed on internal tissues and developing seeds Larval frass accumulates inside berries

10 Apple curculio woody callus tissue may form in area around feeding

11 Apple curculio Pupation occurs inside berries

12 Apple curculio Adults emerge from pupae but do not exit berries immediately

13 Apple curculio Adults chew exit holes and depart Once outside of the berries the actions / whereabouts of adults is not clear

14 Apple curculio It can be difficult to recognize an infested berry

15 Apple curculio until it s too late!

16 % Apple curculio % berries with AC eggs, unsprayed saskatoons /6 6/13 6/20 6/27 7/4 7/11 7/ DD base 50

17 % Apple curculio 25.0 % berries with AC larva, unsprayed saskatoons /6 6/13 6/20 6/27 7/4 7/11 7/18

18 % Apple curculio % berries with AC pupa, unsprayed saskatoons /6 6/13 6/20 6/27 7/4 7/11 7/18

19 % Apple curculio % berries with AC teneral adult, unsprayed saskatoons /6 6/13 6/20 6/27 7/4 7/11 7/18

20 % Apple curculio % berries with AC exit hole, unsprayed saskatoons /6 6/13 6/20 6/27 7/4 7/11 7/18

21 % Apple curculio % berries occupied by AC, unsprayed saskatoons /6 6/13 6/20 6/27 7/4 7/11 7/18 Series1

22 % Apple curculio % combined AC injury, unsprayed saskatoons Seri /31 6/6 6/13 6/20 6/27 7/4 7/11 7/18

23 Parasitoids of curculios Species not yet determined Wasp larvae and pupae found in association with apple curculios A few specimens were reared to adults Level of parasitism not sufficient for economical control of curculios

24 Parasitoids of curculios Adults are very small wasps

25 Plum curculio Adults are hard-bodied beetles Larvae are grub-like One generation per year

26 Plum curculio Adults are beetles in the weevil family Berry feeding by adults was not observed

27 Plum curculio Oviposition scars are crescent-shaped with the egg tucked under a flap of fruit skin Very superficial compared to apple curculio

28 Plum curculio Some variability in the crescent shape

29 Plum curculio Egg is just under the flap of fruit skin

30 Plum curculio Larvae are grub-like No legs Tan / brown heads with distinct jaws Tunnel into berries to feed on flesh and seeds No full-grown larvae were found in samples

31 % Plum curculio % berries with PC egg scar, unsprayed saskatoons /31 6/6 6/13 6/20 6/27 7/4 7/11 7/18

32 % Plum curculio % berries with PC egg, unsprayed saskatoons /6 6/13 6/20 6/27 7/4 7/11 7/ DD base 50

33 % Plum curculio % combined PC injury, unsprayed saskatoons /31 6/6 6/13 6/20 6/27 7/4 7/11 7/18

34 Saskatoon sawflies Adults are wasp-like Larvae are caterpillarlike grubs inside or outside of fruits Exits fruit before pupation One generation per year TWO spieces?

35 Saskatoon sawflies Adults are wasp-like Active during bloom Lay eggs at petal-fall to early green fruit stage

36 Saskatoon sawflies Egg scars are small punctures near calyx end of fruits No egg scars were detected in my samples

37 Saskatoon sawflies Larvae are caterpillar-like Distinct, dark head head 6 true legs on thorax Prolegs on abdomen anal shield Dark anal shield on many older larvae found in samples

38 Saskatoon sawflies Larvae feed inside of fruits May tunnel to surface and Reenter the same fruit Tunnel into a different fruit All sizes of larvae may be found on inside or outside of fruits

39 Saskatoon sawflies Entry borings of several sizes may be seen Most tunnels enter at an angle and may show discoloration on one side Tunnels may be found anywhere on fruits

40 Saskatoon sawflies Larva blocks the tunnel entrance with their anal shield Older larvae can emit a defensive scent that smells like stinkbugs

41 Saskatoon sawflies Injured fruits are more extensively hollowed out compared to curculio injured fruits

42 Saskatoon sawflies Larvae exit fruits to pupate in the soil Empty berries typically hard, dry and dark colored Most larvae have exited well before first ripe berries

43 % Sawflies 25.0 % berries with sawfly larva, unsprayed saskatoons /6 6/13 6/20 6/27 7/4 7/11 7/ DD base 50

44 % Sawflies 30.0 % berries with sawfly injury, unsprayed saskatoons /31 6/6 6/13 6/20 6/27 7/4 7/11 7/18

45 Saskatoon budmoth Adults are tiny, delicate moths Larvae are typical caterpillars Tan to brown Less than ½ inch long Very few found in this sampling

46 Saskatoon budmoth Larvae infest tender foliage early in growing season Tie leaves together with silk Injury from this stage is insignificant

47 Saskatoon budmoth Larvae move to floral clusters Flowers, fruits are tied together with silk Feeding is mostly external Silk is main distinguishing characteristic

48 % Saskatoon bud moth 3.0 % berries injured by SBM, unsprayed saskatoons /31 6/6 6/13 6/20 6/27 7/4 7/11 7/ DD base 50

49 Casebearer moth Adults are small, delicate moths Larvae construct cases to protect their bodies Head and front legs come out of cases for feeding Fruit injuries typically circular and superficial No mention of this pest in references

50 Casebearer moth On foliage, injury is a leafmining Larva chews through one layer of the leaf and then chews inside the leaf near the point of entry This injury is insignificant to production

51 Casebearer moth Fruit injury is a circular, superficial scar Looks like a tiny lamprey wound Injured fruits appear to ripen normally

52 % Casebearer moth % berries injured by CBM, unsprayed saskatoons /31 6/6 6/13 6/20 6/27 7/4 7/11 7/ DD base 50

53 Gall wasps (??) Really a guess, as I was unable to recover any adults Very small grubs with distinct heads Found inside developing seeds Very low incidence

54 What about spotted wing drosophila? Late in season, some berries showed symptoms like SWD on blueberries No larvae found in dissections I was not convinced from by my data

55 Are Saskatoons Susceptible to Spotted Wing Drosophila Infestation? I asked the research technicians of the Northwest Michigan Horticultural Research Center to find out for sure! Karen Powers conducted the study

56 Spotted Wing Drosophila SWD females can lay eggs in intact fruit using serrated ovipositor Prefer thin skinned fruit, both cultivated and wild Can infest fruit that is just beginning to turn color and ripen Adult flies live for 3-9 weeks, and females can lay over 300 eggs Highest risk Cherries Strawberries Raspberries Nectarines Blueberries Blackberries Saskatoons? Lower risk Pears Apples Peaches Grapes Serrated ovipositor of a female SWD fly

57 Bioassay test Unsprayed fruit of two levels of ripeness used for the study A no choice bioassay was used Fruits were exposed to 5 male and 5 female SWD adults Processed to reveal larvae after 8 day incubation period

58 We forgot to take pictures! This is what it looks like with cherries as the test fruit Processing the sample is a very messy business Bioassay test

59 YES, saskatoons are an acceptable host for SWD This does not verify that SWD will infest fruit under field conditions Saskatoon harvest occurs before SWD numbers build up We better be looking for SWD each year, just in case Results

60 Injuries of unknown origin Coarse, irregular injuries I suspect most were from assorted species of leafroller moth caterpillars

61 % Injuries that could not be attributed to a particular species % berries with injury of undetermined origin, unsprayed saskatoons /31 6/6 6/13 6/20 6/27 7/4 7/11 7/18

62 Multiple infestations Some berries injured by two or more species Very common for case bearer injury to be found together with injuries from other species Occasionally two or more internal feeders at work in one fruit

63 % Risk of finding an egg, larva, pupa or adult in a berry % berries occupied by AC, PC or sawflies, unsprayed saskatoons /31 6/6 6/13 6/20 6/27 7/4 7/11 7/18

64 % Clean fruit % "clean" berries, unsprayed saskatoons /31 6/6 6/13 6/20 6/27 7/4 7/11 7/18

65 Points to Ponder It is very difficult to recognize infested berries without a close examination It is very likely that employees or U-pick customers will pick infested berries at some point in time How can we provide assurance to buyers that berries are relatively free of insects and pesticide residues?

66 % No insecticides needed after 1080 DD base 45?? % of berries with AC eggs and sawfly larvae AC eggs sawfly larvae Treatment window? /6 6/13 6/20 6/27 7/4 7/11 7/ DD base 50

67 Conclusions Apple curculio can be an important pest Potential for significant yield loss Potential for contaminated fruit at harvest Sawflies can be important pests Potential for significant yield loss Further work is needed to refine best treatment application window Don t rule out SWD as a pest

68 Dr. Duke Elsner Small Fruit Educator Michigan State University Extension