National Distribution. Canada. Origin: Native. Regularity: Regularly occurring. Currently: Present. Confidence: Confident. Type of Residency: Year-round. Scientific Names: Pickleworm (Diaphania nitidalis); Melonworm (Diaphania hyalinata); Crambidae (formerly Pyralidae); LEPIDOPTERA. Diaphania nitidalis, the pickleworm, is a serious agricultural pest insect in the Crambidae family. It damages squash primarily, but it is also a common pest of.
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Row covers prevent moths from laying eggs on the plants, and should be applied immediately after planting; however they must be removed to allow diaphania nitidalis pollination by bees and other pollinating insects.
There are two approaches to this depending on the size of the planting and effort one wishes to devote to manipulating row covers: Remove diaphania nitidalis covers permanently after plants begin to flower.
This would prevent early-season infestation probably most important for melonworm but would of course allow any adult moths diaphania nitidalis to lay eggs on plants and could result in subsequent damage by larvae. After plants begin diaphania nitidalis flower, remove row covers during the day to allow for pollination, and replace covers in the late afternoon to prevent egg-laying by the nocturnal moths.
Trap Cropping Several researchers including Smith have shown that, because squash is a preferred diaphania nitidalis for pickleworm, it can be used as a trap crop to deter pickleworm from attacking other cucurbit crops like cantaloupe and cucumber.
Smith recommended that squash blossoms be destroyed periodically to keep pickleworms from moving to adjacent cantaloupes. Research in Alabama demonstrated that 6-row cucumber plots Vlas-Pic variety bordered on both sides by two rows of squash Dixie variety sustained significantly lower pickleworm damage compared with cucumber grown without border rows of squash Zehnder, unpublished data.
However, in these experiments a synthetic insecticide was applied to the trap crop as soon as larvae were detected on plants, which would not be allowed in certified organic production. Organic growers may use approved materials such as spinosad see below.
Squash may diaphania nitidalis be used as a sentinel crop to detect diaphania nitidalis first appearance of pickleworms in flowers.
Biology and Management of Pickleworm and Melonworm in Organic Curcurbit Production Systems
This information can be used to help time applications of Bacillus thuringiensis and nematodes, as described below. Two row perimeter trap crop of Buttercup squash diaphania nitidalis a main crop diaphania nitidalis Butternut squash for cucumber beetle control.
Natural control by parasites and predators Capinera reported that, although pickleworm has many natural enemies including predatory beetles, fire ants, and several species of parasitic wasps, none can reliably suppress damage. Other authors suggest diaphania nitidalis natural enemies have a significant impact on pickleworm and melonworm and that hard insecticides should be avoided to preserve the effectiveness of beneficial organisms McCleod, Brewer and Story developed sampling plans for pickleworm larvae in squash.
They suggested that the most reliable sampling unit is the large green staminate flower bud. However, the small eggs, night- diaphania nitidalis behavior, and inability to trap the insect reliably lead most growers to depend on diaphania nitidalis applications of insecticides.
Diaphania nitidalis - Wikipedia
Cucurbit producers in areas where pickleworm damage is likely to occur usually apply diaphania nitidalis insecticides from the onset of fruiting through harvest.
The internal feeding behavior of larvae, which is so difficult to detect at harvest, causes particular emphasis on prevention of damage.
In areas that are on the fringe of the normal range there are many seasons when damage will not occur, but producers diaphania nitidalis insecticides as a preventative measure because prediction of occurrence is so difficult.
Pollinators, particularly bees, are very important diaphania nitidalis cucurbit production, and insecticide application can interfere with pollination by killing bees.
If insecticides are to be applied when blossoms are present, it diaphania nitidalis advisable to use insecticides with little residual activity, and to apply insecticides late in the day, when honeybee activity is minimal.
The entomopathogenic nematode Steinernema carpocapsae diaphania nitidalis been shown to effectively suppress pickleworm injury in squash Shannag et al. Nematode survival is quite good in large-blossomed squash, where diaphania nitidalis nematodes can kill the young pickleworm before it burrows into the fruit.
This approach is probably ineffective for species with small, open blossoms such as cucumber, however, because the nematodes die diaphania nitidalis when exposed to sunlight.
Bacillus thuringiensis will kill pickleworm, but is usually not recommended because the internal diaphania nitidalis behavior puts the feeding larvae beyond the reach of a stomach-active toxin.
Moth Photographers Group – Diaphania nitidalis –
It is possible to cover plants with screen or row covers to prevent moths from depositing eggs on the foliage Webb and Linda However, because the plants must be pollinated, usually by honey bees, some allowance must be made to leave the plants uncovered.
Given the night-flying behavior of the moths and the daytime activities diaphania nitidalis honeybees, this is not a difficult task on a small planting but is prohibitive diaphania nitidalis large acreage.
Some growers are able to prevent plant injury through careful timing of their cropping diaphania nitidalis.