Five beneficial insects that control the Squash Bug

Jan 31

Biological control of squash bug

The squash bugs (Anasa tristis) are the economically important pests of many plants in the Cucurbitae family. Adult bugs are grayish in color and about 5/8 inch long. [caption id="attachment_457" align="aligncenter" width="300" caption="The adult squash bug found on zucchini leaf"]"An adult squash bug"[/caption] Female bugs lay yellowish orange or reddish colored eggs on the underside of leaves or on stems. [caption id="attachment_458" align="aligncenter" width="300" caption="Squash bugs generally lay eggs in a group of 20- 25 on the underside of leaves but they can also lay eggs on the uppersurface of leaf"]"Eggs of squash bug"[/caption] Immediately after hatching from eggs, nymphs start feeding on the leaves, leaf stalks and stems, and become mature by going through five nymphal stages. [caption id="attachment_456" align="aligncenter" width="300" caption="Single Squash bug nymph feeding on a zucchini leaf"]"The squash bug nymph"[/caption] [caption id="attachment_551" align="aligncenter" width="300" caption="Squash bug nymphs feeding on Zucchini leaf stalks"]"The squash bug nymphs"[/caption] Both adults and nymphs suck cell sap from leaves and leaf stalks using their sucking piercing types of mouth parts. Heavy infestation causes wilting of leaves and eventually killing the entire plant. There are several species of predatory and parasitic insects that feed on the both mature and immature stages, and eggs of squash bugs. For example, predatory insects including the bigeyed bug (Geocoris punctipes), Pagasa fusca and the damsel bug (Nabis sp) directly munch on the all the stages of squash bugs whereas the feather-legged fly (Trichopoda pennipes) adults parasitizes both the nymphal and adult squash bugs but adults of the scelionid wasp (Gyron pennsylvanicum)parasitizes eggs of squash bugs. Thus these beneficial insects have a potential to keep populations of squash bugs below economic threshold level in your garden. Therefore, if you want to have presence of more of these beneficial insects in your organic garden, you need to plant specific types of attractive plants that will serve as food source for their adults to hang around in your garden. For example, the adult feather-legged flies that parasitize and kill the squash bugs in your organic garden are attracted to plants such as carrot, dill and parsley. [caption id="attachment_552" align="aligncenter" width="300" caption="Dill flowers can attract both predatory and parasitic insects to your organic garden"]"The dill plant"[/caption] The predatory bigeyed bugs are attracted to sunflowers whereas damsel bugs are attracted alfalfa, clover and radish flowers.

Literature:

Decker, K.B. and Yeargan, K.V. 2008. Seasonal phenology and natural enemies of the squash bug (Hemiptera : Coreidae) in Kentucky. Environmental Entomology 37: 670-678. Olson, D.L., Nechols, J.R. and Schurle, B.W. 1996.   Comparative evaluation of population effect and economic potential of biological suppression tactics versus chemical control for squash bug (Heteroptera: Coreidae) management on pumpkins. Journal of Economic Entomology 89: 631-639. Pickett, C.H. Schoenig, S.E. and Hoffmann, M.P.  1996. Establishment of the squash bug parasitoid, Trichopoda pennipes Fabr (Diptera: Tachnidae), in northern California. Pan-pacific Entomologist 72: 220-226. Vogt, E.A. and Nechols, J.R. 1993. Responses of the squash bug (Hemiptera, Coreidae) and its egg parasitoid, Gryon-pennsylvanicum (Hymenoptera, Scelionidae) to 3 cucurbita cultivars. Environmental Entomology 22: 238-245.

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