Insects | Chemical News | Credits
Volume 7, No. 13 June 15, 1998
COMING EVENTS 43°F 50°F Current DD accumulations (Geneva 1/1-6/15): 1139 767 (Geneva 1997 1/1-6/15): 796 434 (Geneva "Normal" 1/1-6/15): 936 624 Coming Events: Ranges: Cherry fruit fly 1st catch 650-1500 368-961 Lesser appleworm 1st flight subsides 818-1548 444-999 Obliquebanded leafroller 1st flight peak 869-1548 506-987 San Jose scale 1st gen. crawlers present 987-1247 569-784 Apple maggot 1st catch 1045-1671 629-1078 Obliquebanded leafroller summer larvae hatch 1076-1513 630-980 PEST FOCUS Geneva: 1st Obliquebanded Leafroller trap catch in western N.Y. 5/28. DD (base 43°F) since 1st catch = 307. Spotted tentiform leafminer 2nd flight began 6/11. DD (base 43°F) since then = 76. TRAP CATCHES (Number/trap/day) Geneva: 6/1 6/4 6/8 6/11 6/15 Spotted Tentiform Leafminer 1.3 3.2 3.9 132* 561 Redbanded Leafroller 0 0 0 0 0 Oriental Fruit Moth (apple) 1.3 0.2 0 0 0 Lesser Appleworm 5.8 1.3 0.3 0 0.9 Codling Moth 31.8 4.8 0.1 15.2 9.9 San Jose Scale 1.5 0.2 0 0 0 American Plum Borer 0.8 0.2 0 0 0.3 Lesser Peachtree Borer 5.0 0 0 0.5 1.3 Peachtree Borer 0.3 0 - 0.3 0.1 Pandemis Leafroller 2.2 0.2 0.3 1.5 1.5 Obliquebanded Leafroller 2.8 0.3 0 1.3 0.5 Highland (Dick Straub, Peter Jentsch): 5/18 5/26 6/1 6/8 Pear Psylla (eggs/leaf) 15.1 145 40 32 Pear Psylla (nymphs/leaf) 1.8 3.3 3.0 3.5 Spotted Tentiform Leafminer 4.1 1.6 2.9 3.3 Redbanded Leafroller 1.1 0.1 0 0 Oriental Fruit Moth 0.9 0.4 0.2 0 Lesser Appleworm 0.4* 0.1 0.2 0.1 Codling Moth 0.9 2.3 2.9 0.1 Obliquebanded Leafroller 0 0.1* 2.3 0.4 Variegated Leafroller - - 2.2* 0.7 Tufted apple budmoth - - 5.0* 2.0 Fruittree Leafroller - - 0 0 * 1st catch
by Art Agnello
There are many insects present in apple orchards that provide a benefit to growers by feeding on pest species. It is important that growers be able to recognize these natural enemies, so that they are not mistaken for pests. The best way to conserve beneficial insects is to spray only when necessary, and to use materials that are less toxic to them (see Tables 8 & 12, pp. 37 and 44 of the 1998 Recommends). This brief review, taken from IPM Tree-Fruit Fact Sheet No. 18, covers the major beneficial insects that are likely to be seen in N.Y. orchards, concentrating on the most commonly seen life stages. Fact Sheet No. 23, "Predatory Mites", reviews mites that are important predators of leaf-feeding mites.
This fly (Family Cecidomyiidae) is an aphid predator, and overwinters as a larva or pupa in a cocoon. Adults emerge from this cocoon, mate, and females lay eggs among aphid colonies. The adults are delicate, resembling mosquitoes, and are not likely to be seen. The eggs are very small (about 0.3 mm or 1/85 in. long) and orange. They hatch into small, brightly colored, orange larvae that can be found eating aphids on the leaf surface.
Aphidoletes aphidimyza, a cecidomyiid whose larvae prey on aphids
These predacious larvae are present from mid-June throughout the summer. There are 3-6 generations per year. In addition to aphids, they also feed on soft-bodied scales and mealybugs.
The Family Syrphidae contains the "hover flies", so named because of the adults' flying behavior. They are brightly colored with yellow and black stripes, resembling bees. Syrphids overwinter as pupae in the soil. In the spring, the adults emerge, mate, and lay single, long whitish eggs on foliage or bark, from early spring through mid-summer, usually among aphid colonies.
Syrphid (hover fly) egg
One female lays several eggs. After hatching, the larvae feed on aphids by piercing their bodies and sucking the fluids, leaving shriveled, blackened aphid cadavers.
Syrphid (hover fly) maggot preying on an aphid
These predacious larvae are shaped cylindrically and taper toward the head. There are 5-7 generations per year. Syrphid larvae feed on aphids, and may also feed on scales and caterpillars.
This ladybird beetle is an important predator of European red mite in parts of the northeast, particularly in Pennsylvania, and has been observed intermittently in the Hudson Valley of N.Y., and occasionally in western N.Y. Stethorus overwinters as an adult in the "litter" and ground cover under trees, or in nearby protected places. The adults are rounded, oval, uniformly shiny black, and are about 1.3-1.5 mm (1/16 in.) long.
Stethorus punctum adult, a coccinellid predator of European red mite
Eggs are laid mostly on the undersides of the leaves, near the primary veins, at a density of 1-10 per leaf. They are small and pale white, and about 0.3-0.4 mm (1/85 in.) long. Eggs turn black just prior to hatching. The larva is gray to blackish with numerous hairs, but becomes reddish as it matures, starting on the edges and completing the change just prior to pupation.
Stethorus punctum larva a coccinellid predator of European red mite
There are 3 generations per year in south-central Pennsylvania, with peak periods of larval activity in mid-May, mid-June and mid-August. The pupa is uniformly black, small and flattened, and is attached to the leaf.
Other Ladybird Beetles
Ladybird beetles are very efficient predators of aphids, scales and mites. Adults are generally hemisphere-shaped, and brightly colored or black, ranging in size from 0.8 to over 8 mm (0.03-0.3 in.).
Adult ladybird beetle, a generalist predator of aphids, scales and mites
They overwinter in sheltered places and become active in the spring. Eggs are laid on the undersides of leaves, usually near aphid colonies, and are typically yellow, spindle-shaped, and stand on end.
Ladybird beetle eggs
Females may lay hundreds of eggs. The larvae have well-developed legs and resemble miniature alligators, and are brightly colored, usually black with yellow.
Newly hatched ladybird beetle larvae
The pupal case can often be seen attached to a leaf or branch.
Pupae of ladybird beetles
|There are usually 1-2 generations per year. One notable species that is evident now is Coccinella septempunctata, the sevenspotted lady beetle, often referred to as C-7. This insect, which is large and reddish-orange with seven distinct black spots, was intentionally released into N.Y. state beginning in 1977, and has become established as an efficient predator in most parts of the state.|
Adult lacewings are green or brown insects with net-like, delicate wings, long antennae, and prominent eyes. The larvae are narrowly oval with two sickle-shaped mouthparts, which are used to pierce the prey and extract fluids.
A chrysopid (lacewing) larva, which preys on aphids, leafhoppers, scales, mites and moth eggs
Often the larvae are covered with "trash", which is actually the bodies of their prey and other debris. Lacewings overwinter as larvae in cocoons, inside bark cracks or in leaves on the ground. In the spring, adults become active and lay eggs on the trunks and branches. These whitish eggs are laid singly and can be seen connected to the leaf by a long, threadlike "stem".
Eggs of a chrysopid (lacewing) attached by "stems" to leaf surface
Lacewings feed on aphids, leafhoppers, scales, mites, and eggs of Lepidoptera (butterflies and moths).
There are many species of "true bugs" (Order Hemiptera) such as tarnished plant bug, that feed on plants, but a number of them are also predators of pest species. The ones most likely to be seen are "assassin bugs" or reduviids (Family Reduviidae),
Adult reduviid (assassin bug), a generalist predator
and "damsel bugs" or nabids (Family Nabidae). These types of predators typically have front legs that are efficient at grasping and holding their prey.
Parasitoids are insects that feed on or in the tissue of other insects, consuming all or most of their host and eventually killing it. They are typically small wasps (Order Hymenoptera), or flies (Order Diptera).
Sympiesis marylandensis, a eulophid wasp parasitoid of leafminers
A tachinid fly that parasitizes caterpillars such as larval obliquebanded leafrollers
Although the adult flies or wasps may be seen occasionally in an orchard, it is much more common to observe the eggs, larvae, or pupae in or on the parasitized pest insect. Eggs may be laid directly on a host such as the obliquebanded leafroller,
Tachinid fly eggs deposited on obliquebanded leafroller larva
or near the host, such as in the mine of a spotted tentiform leafminer.
Parasitoid egg laid near the mine of a Spotted tentiform leafminer
After the parasitoid consumes the pest, it is not unusual to find the parasitized larvae or eggs of a moth host, or aphids that have been parastized ("mummies"). Exit holes can be seen where the parasitoid adult has emerged from the aphid mummy.
Parasitized leafroller larva
Parasitized leafroller egg mass
Mummies of parasitized aphids showing emergence holes of wasp parasites
There is a diversity of other beneficial species to be found in apple orchards, most of which are rarely seen, but whose feeding habits make them valuable additions to any crop system. The use of more selective pesticides helps to maintain their numbers and contributes to the level of natural control attainable in commercial fruit plantings. Among these beneficials are:
Spiders (Order Araneae): All spiders are predaceous and feed mainly on insects. The prey is usually killed by the poison injected into it by the spider's bite. Different spiders capture their prey in different ways; wolf spiders and jumping spiders forage for and pounce on their prey, the crab spiders lie in wait for their prey on flowers, and the majority of spiders capture their prey in nets or webs.
Ants (Family Formicidae): The feeding habits of ants are rather varied. Some are carnivorous, feeding on other animals or insects (living or dead), some feed on plants, some on fungi, and many feed on sap, nectar, honeydew, and similar substances. Recent research done in Washington has shown certain species (Formica spp.) of ants to be effective predators of pear psylla.
Earwigs (Family Forficulidae): Although these insects may sometimes attack fruit and vegetable crops, those found in apple orchards are probably more likely to be scavengers that feed on a variety of small insects.
Codling moth development in the state has progressed beyond the appropriate point for control of the 1st generation larvae; we will begin advising of the second brood management window when it approaches later in the season.
Although we haven't yet seen any, obliquebanded leafroller egg masses are being laid and we've therefore been keeping track of their presumed development in various locations, as cued by the first moth catches at those sites. We have already accumulated enough heat units to reach the first hatch in the Hudson Valley, which is predicted at approximately 360 DD (base 43°F), and many of the western N.Y. inland sites will reach this stage this week. Growers waiting for this event to either make an application or else determine the need for treatment should note their local temperature readings this week and add appropriate DD's to the OBLR developmental totals we've calculated as of this morning, 6/15:
SITE FIRST CATCH DD (43°F) TOTAL Highland May 26 - Geneva May 29 288-307 (range from different sites) Lyndonville May 29 267 Wolcott June 1 227 (Sodus) Albion June 2 214
Last Friday, June 12, the N.Y. DEC approved the federal label for SpinTor 2SC for use in New York State without any modifications. This product, which contains the active ingredient spinosad, is intended for the control of leafrollers, leafminers and thrips in apples, citrus and a number of vegetable crops. However, Dow AgroSciences informs us that there will be only a limited supply of SpinTor available for purchase during the 1998 season, primarily in the vegetable sector. In apples, a number of grower demonstration trials will instead be conducted around the state to first verify its efficacy against lepidopterous pests, with widescale fruit market distribution set for the 1999 season.
Pyramite Compatibility Revisited
The May 26 (No. 10) issue of Scaffolds reported on an incompatibility of Pyramite acaricide with the spreader-sticker NuFilm. Further information from BASF technical representative Viv Harris clarifies that the trouble derived, as it often does, from incomplete breakdown of the water-soluble bag in which the product is packaged. If care is taken to assure that the Pyramite bag is completely dissolved first before adding the NuFilm, the incompatibility problems described will also dissolve, and these two products can be tank-mixed without complication.
Scaffolds is published weekly from March to September by Cornell University - NYS Agricultural Experiment Station (Geneva), and Ithaca - with the assistance of Cornell Cooperative Extension. New York field reports welcomed. Send submissions by 3 p.m. Monday to:
Scaffolds Fruit Journal
Editors: A. Agnello, D. Kain
Department of Entomology, NYSAES
Geneva, NY 14456-0462
NOTE: Every effort has been made to provide correct, complete and up-to-date pesticide recommendations. Nevertheless, changes in pesticide regulations occur constantly, and human errors are possible. These recommendations are not a substitute for pesticide labelling. Please read the label before applying any pesticide.
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Photographs courtesy of New York State Integrated Pest Management Program