What are peanut burrower bugs?
The peanut burrower bugs are true bugs because they belong to an insect family Cydnidae in the order, Hemiptera. The peanut burrower bugs are scientifically known as Pangaeus bilineatus and considered as one of the major insects pests of peanuts in the peanut, Arachis hypogaea producing States in the U.S. (Lis et al. 2000) . Adults of this bug are small oval shaped with brownish to blackish colored wings and needle-like piercing and sucking type of mouthparts. These bugs generally overwinter as adults under previous crop residues, rocks or dead rotting wood and during spring, they come out of their overwintering sites and start mating. Females generally lay eggs near peanut roots and pods. The immature stages of these bugs are called nymphs that are brown in color and look-like their parents.
How peanut burrower bug causes damage to peanuts?
Both adults and nymphs use their needle-like piercing and sucking mouthparts to cause damage to peanut kernels. During feeding both adults and nymphs insert their needle-like mouthparts through hull into kernel and suck cell sap. The injured kernels develop yellowish to brownish lesions or pits beneath their seed coat. These damaged kernels are unmarketable or degraded due to their decreased quality and weight.
Biological control of the peanut burrower bugs with entomopathogenic nematodes
Presence of several natural enemies including parasitic (Triozocera mexicana) and predatory (Solenopsis xyloni, and ground and rove beetles) insects have been recorded in the peanut fields that infested with peanut burrower bugs but their effects on the natural suppression of populations of the peanut burrower bug is unknown. The only published research study I came across is by Mbata and Shapiro-Ilan (2013) who demonstrated that a beneficial nematode called Heterorhabditis bacteriophora strain Oswego when applied in combination with an insecticide, chlorpyriphos caused highest mortality of peanut burrower bugs as compared to the treatments that applied as Heterorhabditis bacteriophora nematodes alone or insecticide alone. In this study, these researchers also used entomopathogenic fungi called Beauveria bassiana Strain GHA in combination with beneficial nematodes or with chlorpyrifos or alone and reported that this fungus had no detrimental effect on the peanut burrower bugs. Thus results of this study shows that beneficial entomopathogenic nematode, Heterorhabditis bacteriophora in combination with chlorpyrifos has a potential to use as biological control agent to reduce damage caused by the peanut burrower bugs.
What are Heterorhabditis bacteriophora nematodes?
Heterorhabditis bacteriophora nematodes natural enemies of many insect pests. These nematodes use “cruise foraging” strategy meaning their infective juveniles move actively throughout the soil profile to look for their insect hosts. Therefore, they are naturally distributed throughout the soil profile and can attack and infect even less mobile insect hosts like white grubs and black vine weevils. Heterorhabditis bacteriophora nematodes never nictate but they respond to carbon dioxide released by insect hosts as cues. Infective juveniles of Heterorhabditis bacteriophora nematode carry symbiotic bacteria scientifically called as Photorhabdus luminescens in their guts. After locating host insects, they enter into body cavity of insects via natural openings such as mouth, anus or spiracles (breathing pores). After entering into host’s body cavity, Heterorhabditis bacteriophora nematodes release their symbiotic bacteria in the insect blood where bacteria multiply, cause septicemia and then kill their host usually within 48 hours after infection. Nematodes also use these bacteria as food for development and reproduction inside the host cadaver. Heterorhabditis bacteriophora nematodes are known to cause over 60% mortality of many insect pests under field or laboratory conditions. This nematode is considered as warm temperature adapted nematode because it is more effective in killing insect pests in the field when temperature is above 20oC. Heterorhabditis bacteriophora nematodes are commercially available and generally applied at the rate of 1 billion nematodes per acre using traditional sprayers or water cans to control many soil-dwelling insect pests (Grewal et al., 2005).
- Grewal P.S., Ehlers, R-U, Shapiro-Ilan D.I. 2005. Nematodes as Biocontrol Agents. CABI, New York, NY. PP 505.
- Lis, J. A., Becker, M. and Schaefer, C.W. 2000. Burrower bugs (Cydnidae), In Heteroptera of economic importance. Schaefer, C.W. and Panizzi, A.R. (eds.), Pp. 405-419. CRC Press, Boca Raton, FL.
- Mbata, G.N., and Shapiro-Ilan, D. 2013. The Potential for Controlling Pangaeus bilineatus (Heteroptera: Cydnidae) Using a Combination of Entomopathogens and an Insecticide. Journal of Economic Entomology 106: 2072-2076.