“ History does not necessarily predict the future , ” and “ retiring functioning does not necessarily forebode succeeding performance ” are two clichés that I would like to have a nickel note for every metre I have heard them . Now in vegetable horticulture , those words of wiseness could not be further from the truth when it comes to the never - ending battle with this gadfly in the vegetable garden . I know that every July , the Mexican bean beetle will show up and begin to pig my noggin plot of ground . So before the rush garden season gets revved up , I ’ll take a little time to do a little planning and inquiry on the one-year chance the Mexican attic mallet give me each class with its annual visit to my garden .
History
TheMexican bean plant beetle , Epilachna varivestisMulsant , a relative of the ladybug , is an above - land chew pest which feeds on legumes ( common green beans , carapace dome , lima bean and soybeans ) and is one of only two destructive North American coinage in the otherwise good and economically importantladybird beetle family , which contains over 400 species . The other destructive North American congener is the squash dame mallet , Epilachna borealisFabricius , which feeds chiefly on cucurbits ( cucumber , melon , gourds , squashes and pumpkin ) .
Nativeto the eminent elevations of westerly Mexico , the Mexican noggin mallet was first identified in the United States in the mid 1860 ’s but was not pick out as a serious pests until 1883 , when severe damage to wax bean was reported in Colorado .
In 1918the Mexican noodle mallet was first discovered in Alabama and by the late 1920 ’s , the beetle had spread as far north as Canada and west to Michigan . In the early 1930’sresearch was lead in Connecticut to produce method for “ checking the depredation of the Mexican bean beetle in Connecticut . ”
The determination of the Connecticut researchers evidence to be interesting : that various sprays — both poisonous and non - venomous to humans — were more efficacious when plants were given more space — at least 4 - 6 inches aside . Highly important was the discovery that certain non - toxicant spray and dusts had demonstrate themselves to be just as acceptable as the poisonous type . The use of non - poisonous spray let the grower to spray the plants before and after the fuel pod constitute with no fear of finding poisonous balance on the beans at harvest . The poisonous insect powder used in the enquiry included barium fluosilicate , Ca arsenate , and magnesium arsenate . The grower was instructednot to use materialscontaining arsenic or any fluosilicate compound once bean pods had form . Non - vicious insecticidesutilized in the research were debris and sprays containing pyrethrum and derris root , a tropical industrial plant which check the raw insecticide Rotenone.www.ct.gov/Circular 109(“Control of the Mexican bean beetle in Connecticut , ” 1935 ) .
unluckily for those of us here in fundamental Virginia , damaging populations of Mexican bean beetles are most coarse in the Mid - Atlantic and southern Appalachian Mountain neighborhood of the United States and remain a withering pest to vulgar snap beans and lima noggin .
recognition
Adult Mexican bean beetles are alike in sizing and appearance to their beneficial full cousin , the ladybug . They are either xanthous or bull with sixteen calamitous point coiffe in three rows . Their soundbox are oval and about ¼ column inch long , a fiddling larger than the ladybug . Adults can walk or fly but are mostly sluggish once they situate a suitable works — such as my green bean plot of ground . Most of their adult life is spent feeding and mating in the legion canopy , but grownup beetles will wing long distances if food becomes scarce .
Adult bean beetle generally overwinter in grouping , under foliage bedding or pine needle and emerge in the late natural spring or early summer .
Eggs
Eggs of the Mexican bean beetle are lightly yellow when first fix but darken when they are close to hatching . They are generally lodge in clusters of 40 - 60 nut per cluster on the undersurface of the bean plant leaves . Each female will pose an norm of 460 eggs . In 5 - 14 Clarence Shepard Day Jr. , reckon on the temperature , the nut will hatch .
The larva are cylindrical and soft - bodied . They are yellow and covered in back that are either black or yellow with grim crown . They by and large continue on the underside of the leaves where they continuously flow on folio tissue . The larva will go through four developmental stages or instar stages over an average of 20 days . The first instar stage develop in 4 - 6 24-hour interval , the second instar last about 2 - 4 day , the third instar microscope stage develops over 3 - 5 days , and the fourth and final instar stage develop over a 6 - 10 daytime period of time .
Pupa
pupa are alike in general visual aspect to larvae , however at this stage , the beetle attach to a plant by its posterior ending and becomes fast . Pupae are often found aggregated on a single leaf in the lower half of the industrial plant canopy . Pupation usually last for about nine days , and the life Hz begins again . Multiple multiplication take place annually in Virginia .
flow
Both adult and larva provender on plant tissue with chewing mouthparts . The majority of the alimentation occurs during the third and quaternary instar leg — about 12 to 20 days from when the eggs hatch .
Beetles generally feed on the crushed or underside of the folio , while avoiding veins , create a lacy , skeletonized appearance of the stay leaf . Beetles generally feed primarily on the foliation , but they will also feed on the bean pod and heyday once they become present .
Control
There are several management practices available to the nurseryman to aid in curb the Mexican edible bean overhang .
Plastic mulches
Mexican noodle mallet grownup and larvae are deterred by direct Christ Within . theater experiment at Virginia Tech have shown that Mexican bean beetle are less probable to colonise and deposit eggs on bean mulched with metalized and white charge card , compared to bare ground and black charge plate . There was also less foliar and pod harm and significantly greater yield when the beans were mulched with metalized and white plastics than beans develop on the bare ground or mulch with black plastic .
Timed planting
Planting beans in the early spring or late summer can dilute crop damage from the Mexican bean beetle . In Virginia this pestis generally hits its period of peak activity in July . By embed dome as early as possible or as late as potential , you’re able to avoid the beetles ’ peak period . However , this strategy does pack some hazard : planting beans when the soil and zephyr temperatures are still coolheaded often results in slow sprouting and smaller plants ; in improver , found early or previous increases the risk of infection that the attic plants will be reveal to frost , result in damaged or killed plants .
forcible or Mechanical
Polyester or floating course covers have been shown to successfully shorten the abundance of grownup , larvae and pupae population .
Gardeners commonly use mechanically skillful or by - helping hand remotion to tighten harm from Mexican bean beetle . Because beetles complete their full aliveness cycle within the bean canopy , this simple-minded strategy can help control gadfly harm .
Biological Control
The Mexican bean plant beetle is an invading pest , and like other invasive criters , has no natural predators in its new mother country . In accession , they are well protect from predatory organisms . They not only have protective spines that beautify the larvae , but also bring forth toxic , alkaloid secretion that are do it to deter many predators on contact .
There have been observance that predatory stink bugs , lady beetle , damsel bugs and assassin hemipteron have attack the Mexican bean plant beetles during their various life stages . However , these insects have proven ineffective at moderate this pest .
In 1966a tiny , exotic parasitoid white Anglo-Saxon Protestant , Pediobiusfoveolatus , primitively let out in India , was imported into the United States to be tested for potential control of the Mexican bean overhang . Initial testing determined that this bantam wasp would pronto parasitize the larva of the Mexican attic beetle , while leaving the native , predatory insects unharmed . In 1972 , several mid - Atlantic states began releasing these wasps to command the Mexican bean overhang . The USDA branches in New Jersey , Maryland , Delaware , and Virginia liberate wasps throughout these states , focusing on areas with large soybean land area and high Mexican beetle population .
In the region where these wasps were released , the results were pretty prominent — reducing the bean plant yield loss80 - 100 % . ThePediobiusfoveolatuscannot overwinter in the United States due to the cold weather condition and the want of an overwinter host . In the wasps ’ native dominion , the winter is either contributing to yr - round exposure , or the wasps overwinter in their host ( winter as larvae ) . Because the Mexican bean beetle overwinters as an adult , these beneficial wasps are without adequate winter recourse in the United States , and they die off during the wintertime ; thus , they must be discharge each year . ThePediobius faveolatuswasps are mass produced by the New Jersey Department of Agriculture and other commercial insectaries . They can be purchased from various on - line vender that supply biocontrol agents . A list of commercial suppliers can be found atwiki.bugwood.org/Pediobius .
The female WASP lay about 20 eggs in a individual noodle beetle larvae . The wasp larvae crosshatch from these ballock pour down the mallet larvae . The infect larvae eventually turn dark-brown and die . fully grown wasps emerge from the larvae after about 15 day , mate , and then look for more beetle to taint . These wasps will also parasitize the larva of the squash beetle , a closely related relative of the Mexican attic mallet that feeds on cucurbit plants . These black wasps are very small — about 1 - 2 millimeter long – and will not harm humans or beneficial worm .
A trivial provision is take to be successful with this biocontrol factor ; it is crucial to clock the release . Ideally , the WASP should be released at both one and two week after the first instar mallet are discover on the bean industrial plant . precise scouting and timing of passing is essential because the WASP reproduce within the third or quaternary instar stagecoach of the Mexican edible bean mallet larvae : so it is very important that the Mexican bean mallet instar larvae are present when the wasps are exhaust . The cosmopolitan principle of thumb is to release the wasps as shortly as the beetle egg set out to hatch .
Chemical Control
There are a number of insecticides approve to control the Mexican bean beetle . The common names for theseapproved insecticidesinclude : acephate , carbaryl , malathion . A number of organic insecticides have been evaluated , let in azadirachtin , pyrethrins , and spinosad , and all provide significant mastery of the Mexican bean beetle . You ’ll find more information on these insecticides and their use at your local extension position .
The Mexican bean beetle has quite the history , and like other invasive pests , it arrive in our area without a natural enemy and has outlive in generous phone number . as luck would have it , the home nurseryman has a number of ways to control this pestilence in the edible bean patch . They include : plastic mulch , removing them by hand , row covers , biological ascendency , and chemical , both organic and synthetic .
Thanks for stopping by The Garden Shed ; we look forwards to your visit next calendar month .
Sources :
“ Featured Creatures , The Mexican Bean Beetle,”University of Florida , Department of Entomology and Nematology.http://entnemdept.ufl.edu/creatures/veg/bean/mexican_bean_beetle.htm
“ Mexican Bean Beetle , ” Virginia Cooperative Extension , Publication ENTO-51,http://pubs.ext.vt.edu / content / dam / pubs_ext_vt_edu / ENTO / ENTO-51 / ENTO-51 - pdf.pdf
“ Control Of The Mexican Bean Beetle in Connecticut , ” Connecticut Agricultural Experiment Station New Haven , November 1935,www.ct.gov / caes / lib / caes / document / publications / circulars / c109.pdf
“ Natural chronicle , Ecology , and Management of the Mexican Bean Beetle ( Coleoptera : Coccinellidae ) in the United States , ” Journal of Integrated Pest Management(Nottingham , Dively , Dively , Schultz , Herbert , and Kuhar , 2016 ) 7(1 ): 2 ; 1–12,https://vtechworks.lib.vt.edu / bitstream / handle/10919/73788 , /Reprint_Nottinghmam et al Mexican bean overhang JIPM.pdf?sequence=1
“ Mexican Bean Beetle , ” Indiana Cooperative Extension , Purdue University , https://extension.entm.purdue.edu / fieldcropsipm / insects / mexican - bonce - beetle.php
“ Home Grounds & Animals 2017 , ” Virginia Cooperative Extension Publication , https://pubs.ext.vt.edu / content / dam / pubs_ext_vt_edu/456/456 - 018 / section2 - home - veg.pdf
