Insecticidal and Anti-juvenile Hormone Activities of Precocene II against the Grasshopper Euprepocnemis plorans plorans Charp. Orthoptera: Acrididae.

Abstract

The grasshopper Euprepocnemis plorans plorans caused a considerable damage to crops of the Nile Delta, Egypt. The present study was conducted aiming to assess the insecticidal and anti-hormonal effects of Precocene II on this grasshopper. The newly moulted 2 nd or 4 th (penultimate) instar nymphs were exposed to a series of doses: 60, 40, 20 and 10 µg/cm 2. Exposure of 2 nd instar nymphs to the higher two doses resulted in complete mortality of nymphs within 24 h. At the lower two doses, PII exhibited a considerably extended low toxicity on the subsequently moulted instars and emerged adults. LD50 was calculated as 0.388 µg/cm 2. After exposure of the 4 th instar nymphs to PII, no complete mortality was observed, but various mortality percentages among the treated nymphs, 5 th instar nymphs and adults. LD50 was calculated as 17.022 µg/cm 2. PII exerted a slight inhibitory action on the nymphal growth of both 4 th and 5 th instars, after treatment of 2 nd instar nymphs, regardless the dose level, but the growth rate was remarkably regressed after treatment of 4 th instar nymphs with 40 and 20 µg/cm 2. Exposure of 2 nd instar nymphs to PII led to 3.33% precociously moulted nymphs into 4 th instar, skipping off the 3 rd instar (only at the lowest dose). After exposure of 4 th instar nymphs to PII, some treated nymphs precociously metamorphosed into adultoids, omitting the 5 th instar, only at the higher tow doses. Another noticeable feature of the deranged development was 'permanent nymphs' which induced in 2 nd instar nymphs (3.85%) after exposure only to 20 µg/cm 2. Also, similar permanent nymphs were induced during the 4 th instar. No permanent nymphs had been induced after exposure of 4 th instar nymphs to PII.

Impairment of Development and Reproductivity of the Egyptian cotton leafworm Spodoptera littoralis Boisduval (Noctuidae: Lepidoptera) by Cycloheximide.

“…In addition, toxicities of various anti-juvenile hormone (anti-JH) compounds had been reported against several insects, such as precocenes against several mosquito species (Yasyukevich and Zvantsov, 1999) and the Colorado potato beetle Leptinotarsa decemlineata (Farazmand and Chaika, 2008); precocene II (PII) against the lepidopterous pest Pericallia ricini (Khan and Kumar, 2000), the red palm weevil Rhynchophorus ferrugineus (Abdullah, 2009), the grey flesh fly Parasarcophaga dux (Nassar et al, 1999), and the Asian tiger mosquito Aedes albopictus (Liu and Liu, 2014) as well as some synthesized analogues of Fluoromevalonate (Shuto et al, 1988) against the mulberry silkworm Bombyx mori. After exposure of the newly moulted 2 nd or 4 th (penultimate) instar nymphs of the grasshopper Euprepocnemis plorans to some doses of PII, various mortalities were recorded among the treated nymphs and the emerged adults (Ghoneim and Basiouny, 2017). Results of the present study on S. littoralis were, to some extent, in agreement with those previously reported results, but all larval, pupal and adult mortalities were reversely correlated with the dose level of cycloheximide.…”

“…For examples, LC 50 values of PI and PII against A. albopictus were estimated in 41.63 and 43.55 μg/ml, respectively (Liu and Liu, 2014); LC 50 values of PII and PI against the book louse Liposcelis bostrychophila were calculated in 30.4 and 64.0 g/cm 2 , respectively (Lu et al, 2014); LC 50 of PI against the cat flea Ctenocephalides felis was estimated in 10.97 ppm (Rust and Hemsarth, 2017); LC 50 values of the anti-JH agent Pitavastatin against M. sexta and the viviparous cockroach Diploptera punctata were estimated at 5.23, and 395.2 µM, respectively (Li et al, 2017); etc. LD 50 values of PII against E. plorans were 0.388 and 17.022 µg/cm 2 after topical treatment of newly moulted 2 nd and 4 th instar nymphs, respectively (Ghoneim and Basiouny, 2017). In the current investigation, LD 50 of cycloheximide against S. littoralis was calculated in 0.013µg/larva.…”

“…stephensi by PI and PII (Yasyukevich and Zvantsov, 1999) and M. sexta by the anti-allatostatins, fluvastatin, lovastatin and pitavastatin (Li et al, 2017). After exposure of the newly moulted 2 nd or 4 th instar nymphs of E. plorans to different doses of PII, the nymphal growth had been inhibited (Ghoneim and Basiouny, 2017). Likewise, some IGRs failed to affect the growth of different insects, such as M. domestica (Ghoneim et al, 1991), the American cockroach Periplaneta americana and the milkweed bug Oncopeltus fasciatus (Darvas et al, 1992), the African armyworm Spodoptera exempta, the beet armyworm Spodoptera exigua and L. decemlineata (Smagghe and Degheele, 1994).…”

“…Some anti-JH compounds had been reported to induce permanent larvae or nymphs in some insect species, such as the grasshopper E. plorans in which exposure of the newly moulted 2 nd instar nymphs to 20 µg/cm 2 of PII induced some 'permanent nymphs' in both 2 nd and 4 th instars (Ghoneim and Basiouny, 2017). In the present study, topical treatment of S. littoralis larvae only with the lower two doses of cycloheximide (60 and 30 µg/larva) induced some 'permanent prepupae'.…”

Disruptive Impact of Precocene I (juvenile hormone-antagonist) on the Adult Performance and Reproductive Potential of the Egyptian Cotton Leafworm Spodoptera littoralis Boisduval (Lepidoptera: Noctuidae)

“…Injection of a single dose (of 50 or 150 µg) of PII into 4-day old adults of the desert locust Schistocerca gregaria led to high mortality of adults (Tawfik et al, 2014). After exposure of the newly moulted 2 nd or 4 th (penultimate) instar nymphs of the grasshopper Euprepocnemis plorans to different doses of PII, various mortality percentages were recorded among the emerged adults (Ghoneim and Basiouny, 2017).…”