Effects of the Juvenile Hormone Mimic Pyriproxyfen on Egg Development, Embryogenesis, Larval Development, and Metamorphosis in the Desert Locust Schistocerca gregaria (Orthoptera: Acrididae)

Pest Management Science

2003

Effects of a juvenile hormone analog, pyriproxyfen, on various developmental stadia of the onion thrips, Thrips tabaci Lindeman, were determined on cabbage leaves in the laboratory. Pyriproxyfen was applied at 0.064 or 0.128 g AI liter(-1) on leaves (residual contact-ingestion), thrips (direct contact) and leaf-thrips (residue contact-ingestion-direct contact). Pyriproxyfen did not have any significant lethal effects on thrips pupae in any treatment. Lethal effects on thrips larvae varied depending on application method and dosage. In the leaf and the leaf-thrips treatments, few larvae and pre-pupae molted to the next stage, and none developed to adults. In contrast, in the thrips-only treatment, pyriproxyfen did not show any significant lethal effects. The developmental times of larvae and pre-pupae were prolonged when larvae were treated with pyriproxyfen, and those of pre-pupae and pupae were shortened when pre-pupae and pupae were treated. The longevity and survival rates of thrips adults were generally shorter when they contacted and ingested pyriproxyfen-treated leaves than those in water control. Significantly fewer progeny (0.22-1.15 larvae per female) were produced by females that had fed on and been in contact with the pyriproxyfen-treated leaves than by those in the water control (11.94 larvae per female). However, the number of progeny produced by the thrips females increased significantly (3.32-7.28 larvae per female) when the females were transferred to untreated leaves after feeding on treated leaves for 5 days; the daily larval hatching pattern was similar to those in water control, indicating that female adults were able to produce viable eggs when untreated food was offered.

Section: Discussionsupporting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Effects of a juvenile hormone analog, pyriproxyfen, on Thrips tabaci (Thysanoptera: Thripidae)

Pest Management Science

2003

“…Therefore, knowledge about the effects of pesticides on beneficials is indispensable. Pyriproxyfen 2‐[1‐methyl‐2‐(4‐phenoxyphenoxy) ethoxyl] pyridine is a potent juvenile hormone analog (JHA) that acts on a variety of pests including Diptera (I TAYA , 1987; L ANGLEY et al., 1993), Homoptera (P ELEG , 1988; I SHAAYA and H OROWITZ , 1992), Dictyoptera (K AWADA , 1988; K OEHLER and P ATTERSON , 1991), Lepidoptera (Y OKOYAMA and M ILLER , 1991), Hymeoptera (R EIMER et al., 1991), Siphonoptera (P ALMA et al., 1993), Orthoptera (V ENNARD et al., 1998).…”

Section: Introductionmentioning

confidence: 99%

Susceptibility of immature stages of Chrysoperla rufilabris (Neurop., Chrysopidae) to pyriproxyfen, a juvenile hormone analog

Chen

2002

J Applied Entomology

Effects of pyriproxyfen (Knack), a juvenile analog, at three concentrations (10, 50 and100 mg [AI]/l), on survival and development of all immature stages of Chrysoperla rufilabris (Burmeister), were determined in the laboratory. Pyriproxyfen significantly reduced the survival rates when eggs, first and third instars were treated, but not when the second instars and pupae were treated. When eggs were treated, the two higher concentrations reduced the eggs viability by 33.3–50%, and only 0.0–6.7% developed to adults. The lowest concentration of pyriproxyfen (10 mg [AI]/l) caused high mortality on third instars, not on other stages, indicating the third instar was the most vulnerable stage. Pyriproxyfen had significant effects on development for all immature C. rufilabris that successfully developed to adults with variations among the developmental stages and concentrations. The overall developmental duration from eggs to adults when eggs, first, and third instars were treated were 2.6–4.2, 2.4–4.1 respectively, and 6.0–7.1 d longer than those in water control, respectively. However, the overall developmental durations from eggs to adults were 0.5–1.2 d shorter than in water control when the second instars were treated with pyriproxyfen. The compatibility of pyriproxyfen with natural enemies in integrated pest management programs is discussed.

“…Pyriproxyfen, 2-[1-methyl-2-(4-phenoxyphenoxy) ethoxyl] pyridine, is a JHA with relatively low mammalian toxicity (Yokoyama & Miller, 1991) that was first registered in Japan in 1991 for controlling public health pests (Miyamoto et al, 1993). It also acts on a variety of insect pests including Diptera (Langley et al, 1993), Homoptera (Peleg, 1998;Liu & Stansly, 1997), Dictyoptera (Koehler & Patterson, 1991), Lepidoptera (Yokoyama & Miller, 1991), Hymenoptera (Reimer et al, 1991), Siphonoptera (Palma et al, 1993), and Orthoptera (Vennard et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

Effects of a juvenile hormone analog, pyriproxyfen, on the apterous form of Lipaphis erysimi

Entomologia Exp Applicata

Chen

2001

Effects of a juvenile hormone analog, pyriproxyfen, on various developmental stadia of the apterous form of the turnip aphid, Lipaphis erysimi (Kaltenbach), were bioassayed at three concentrations (50, 100, and 150 mg [AI]/l) in the laboratory. Supernumerary-molted nymphs with 1-3 extra molts were found when the first three nymphal instars were treated, and all these nymphs died prematurely. In contrast, all treated fourth instar nymphs molted normally to adults. The longevity of all pyriproxyfen-treated L. erysimi nymphs and adults and the fecundity of treated adults were reduced by ≈50%. Higher concentrations of pyriproxyfen (100 and 150 mg [AI]/l) caused sterility in adults from treated fourth instars; whereas the lowest concentration (50 mg [AI]/l) did not cause any adult sterility. A majority of adults from treated fourth instars and treated adults produced normal nymphs, and some adults produced dead nymphs with normal appendages or dead and deformed nymphs without any appendages. Normal nymphs produced by the adults from treated adults or treated at fourth instars developed more slowly from first instar to adult than the water-treated nymphs, and all adults in the new generation apparently reproduced normally. The potential role of pyriproxyfen in a vegetable aphid IPM program was discussed.