Biology and management of palm weevils
Robin M. Giblin-Davis University of Florida/IFAS Fort Lauderdale Research and Education Center Dryophthoridae:
Palm Weevils: (Rhynchophorini) Rhynchophorus species Dynamis borassi Sugarcane/Palm Weevils: (Sphenophorini) Metamasius hemipterus and other species Rhabdoscelus obscurus 1 1 scutellum
Dynamis borassi 1. Rhynchophorus palmarum R. cruentatus Rhynchophorus R. ferrugineus Distribution ca 1966
R. ferrugineus expansion since 1966
R. bilineatus R. palmarum
R. phoenicis R. quadrangulus R. bilineatus R. cruentatus R. ferrugineus
1 2
R. palmarum R. phoenicis R. quadrangulus 4 3 3
Rhynchophorus quadrangulus Rhynchophorus cruentatus Rhynchophorus ferrugineus Male rostrum without setae 3 3a Nasal plate Male rostrum without 3b setae 3 No nasal plate
Mandible unidentate
Rhynchophorus quadrangulus Mandible unidentate Rhynchophorus cruentatus 3b 3a Submentum Submentum narrow wide
Rhynchophorus quadrangulus Rhynchophorus cruentatus Rhynchophorus cruentatus
female
male Rhynchophorus bilineatus 4 4
4 4 Rhynchophorus ferrugineus 4
4
1 Rhynchophorus palmarum Rhynchophorus phoenicis 5 4a Scutellum Scutellum Tapers broadly tapers acutely
Rhynchophorus phoenicis
Rhynchophorus bilineatus
Rhynchophorus ferrugineus 5a 5b Submentum Submentum straight bowed
Rhynchophorus bilineatus Rhynchophorus ferrugineus R. cruentatus
Stressed Sabal palmetto Intraspecific Semiochemical: Releaser pheromone: Chemical released by sender with immediate reversible effects on receiver (i.e. sex and aggregation pheromones) Primer pheromone: Chemical with long term effects on physiology and development of receiver (i.e. caste determination and reproductive synchrony) Interspecific Semiochemical: Kairomone: Chemical released that benefits the receiver, but not the sender.
Allomone: Chemical that benefits sender or sender and receiver. 10 live R. cruentatus Weekly Weevil Counts from Traps Baited with 10 Live Rhynchophorus cruentatus and/or 1.5 kg of Sabal palmetto Tissue
A 20
15
10
D 5 CD D BC 0 B Empty Females Males Palm Tissue Females + Tissue Males + Tissue Dryophthoridae:
Palm Weevils: (Rhynchophorini) Rhynchophorus species YES Dynamis borassi YES Sugarcane/Palm Weevils: (Sphenophorini) Metamasius hemipterus and other species YES Rhabdoscelus obscurus YES AERATION CHAMBERS
Porapak-Q packed glass columns Gas Chromatograph with Electroantennographic Sample Detector (GC-EAD) insertion Flame ionization detector (FID)
Carrier gas (Helium) Split vent
Electroantennographic detector (EAD) GC Column Oven Electroantennogram
Amplifier 1:100 Ground electrode Chart recorder
Input electrode Ground
Antenna
Fractions from the Saline gas chromatograph solution Rhynchophorus cruentatus FID 5-methyl-octan-4-ol = Cruentol
EAD Weekly Rhynchophorus cruentatus Counts from Traps Baited with 5-methyl-octan-4-ol (0.4 mg/d) and/or 1.5 kg of Sabal palmetto Tissue
A 50 40 30 20 C BC 10 B 0
Empty Palm Tissue Cruentol
Tissue + Cruentol R. cruentatus Rhynchophorus R. ferrugineus Pheromone Distribution
5-methyl-octan-4-ol 4-methyl-nonan-5-ol
(2 E) 6-methyl-hepten -4-ol
4-methyl-nonan-5-ol
3-methyl-octan-4-ol unknown
R. bilineatus R. palmarum
R. phoenicis R. quadrangulus R. cruentatus R. ferrugineus Metamasius “Ferrugineol” hemipterus Distribution
4-methyl-nonan-5-ol
5-methyl-octan-4-ol 4-methyl-nonan-5-ol
(2 E) 6-methyl-hepten -4-ol 4-methyl-nonan-5-ol 4-methyl-nonan-5-ol
R. bilineatus R. palmarum Dynamis borassi Metamasius hemipterus FID
Volatiles from unfed males
EAD Metamasius hemipterus
FID
Sugarcane host volatiles
EAD Metamasius hemipterus Counts from Traps Baited with Ethyl Acetate (600-720 mg/d), 250 g of Sugarcane, and/or Metalure A 250 200 150 B 100 B C B C C 50 0 Metalure Tissue Ethyl Tissue + Acetate EA + Metalure (EA) EA + Metalure EA + Tissue Tissue + Metalure Metamasius hemipterus Counts from Traps Baited with Metalure, 250 g of Sugarcane, and Different Rates of Ethyl Acetate
A A 100
80
60 B 40 B 20
0
1663 mg/d 403 mg/d 29 mg/d
0 mg/d Ethyl Acetate Release Rate Towards Making a Better Weevil Trap: Semiochemicals: (Critical...need aggregation pheromone(s) and host plant volatiles) Design: (Simple is best...a bucket works) Moisture: (Weevils seek high relative humidity to conserve water because of high cuticular permeability...Traps need moisture) Size: (Larger buckets are better) Color of trap: (Not critical) Height: (Not critical for M. hemipterus... Not critical for R. cruentatus if trap connected to tree base)