| Diabrotica balteata | |
|---|---|
 | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Coleoptera |
| Suborder: | Polyphaga |
| Infraorder: | Cucujiformia |
| Family: | Chrysomelidae |
| Genus: | Diabrotica |
| Species: | D. balteata |
| Binomial name | |
| Diabrotica balteata LeConte, 1865 | |
Diabrotica balteata is a species ofcucumber beetle in the familyChrysomelidae known commonly as thebanded cucumber beetle. It occurs in the Americas, where its distribution extends from theUnited States toColombia andVenezuela in South America.[1] It is also present inCuba.[2] It is apest of a variety of agricultural crops.[3]
This beetle is 5 to 6 millimeters long. It has a red head and blackthorax. Theelytra are yellow, marked with three transverse bands in shades of green or blue-green and a narrower longitudinal green line down the center. The pattern of banding is variable and nearly absent in some individuals.[3] The color of the elytra is influenced by the types of plants the beetle eats.[4] Thelarva is also variable and has threeinstars. The new larva is white and about 2.3 millimeters long. It may turn yellow as it consumes plant material. The later-instar larva may reach nearly 9 millimeters.[3]
The adult mates at about six days of age. The female begins producing eggs about 16 days later. She lays a cluster of eggs every few days for two to eight weeks, producing up to 15 clusters, for a maximum of 850 eggs. A cluster has up to 100 oval yellow eggs each about half a millimeter long. The femaleoviposits the cluster in a crack in the soil, and the eggs hatch in 5 to 9 days. The larva develops for 11 to 17 days,pupation takes 4 to 6 days, and the adult has an average life span of 26 days. There is nodiapause. In the best conditions there can be six or seven generations per year.[3]
InTamaulipas, Mexico, the beetle is most commonly observed in May through July. This may be a time of highdispersal. Abundance is apparently increased by late spring and summer rainfall, and flight activity increases with wind speed.[5]
The beetle likely originated in thetropical Americas and has moved into moretemperate climates. By the early 1900s it was limited toArizona andTexas in the United States.[3] During the 1920s it spread up the coast ofCalifornia at a rate of about 25 miles per year.[6] It has since spread as far asNorth Carolina andFlorida. It probably will not progress farther in the continental United States because it does not tolerate freezing temperatures.[3]
The larva eats theroots andtubers of plants. The adult feeds on most plant parts, such asleaves, seedlingcotyledons,fruits, andflower parts, includingcorn silk.[7]
A polyphagous species, this beetle has a variety ofhost plants from several different families. Among its primary hosts arecucurbits such ascucumber,melon,squash, gourd, and pumpkin,beans such ascommon bean andlima bean,sweet potato,soybean, andwinged bean.[1] Secondary hosts includetomato,potato,cassava,rice,sorghum,wheat,maize, andcrucifers such ascabbages.[1]
Other known wild and cultivated host plants includeamaranth,peanut,crownbeard,[1]watermelon,silverleaf nightshade,[8]bell pepper,[4]mulberry,[6]pea,beet,okra,onion, andlettuce.[3]
The beetle causes the most serious damage to plants when the adult defoliates them and the larva attacks the roots, especially in seedlings.[3] The larva is very damaging to the root tuber of the sweet potato.[3] It riddles the tuber with holes which expand as the root grows, turning into craters.[9] Such root damage reduces plant growth and fruit production, and it makes the crop less marketable.[7]
Another consequence of beetle damage to plants isviral and bacterial infection. Even if the actual damage is minor, the injury can facilitate the entry of pathogens that can be lethal to the plant.[7] This beetle is avector for the pathogens that cause many forms of plant disease, includingcowpea mosaic virus,cowpea severe mosaic virus,cowpea chlorotic mottle virus,bean rugose mosaic virus,bean mild mosaic virus,quail pea mosaic virus,squash mosaic virus,melon necrotic spot virus, andbacterial wilt.[7]
Insecticides are used to control this species, mainly to target the larvae in the roots. ThemermithidnematodeFilipjevimermis leipsandra has been studied as a possible agent ofbiological pest control.[10] Anotherentomopathogenic nematode,Steinernema carpocapsae, will also attack this species.[11]
Some plants are more resistant to the beetle than others. It was noted that inromaine lettuce crops, thecultivar 'Valmaine' is resistant to attack, while 'Tall Guzmaine' is not.[12] Later studies suggest that thelatex produced by 'Valmaine' is repellent to the beetle.[13]
Natural enemies of the beetle includeants, which prey on its eggs, particularly in the tropics.[3] AHeterorhabditis nematode isolated from the larva of this beetle has been demonstrated to be aparasite that causes rapid mortality.[14] It is also a host to thetachinid flyparasitoidCelatoria compressa.[15]
Other common names for the insect includebelted cucumber beetle inEnglish,tortuguilla de franjas verdes del pepino,mayatito con bandas verdes,catarinita doradilla, andgusano alfilerillo inSpanish, andchrysomélide rayée du conconbre inFrench.[16]
Media related toDiabrotica balteata at Wikimedia Commons