Morphological effects of some insect growth regulators on Musca domestica , ( Diptera , Muscidae )

The current work was carried out to evaluate the morphological effects of insect growth regulators e.g. : applaud (buprofezin), consult (hexaflumuron) and match (lufenuron) as chitin synthesis inhibitors (CSIs), mimic (tebufenozide) as ecdysone agonist (EA) and admiral (pyripyroxyfen) as juvenile hormone analogue (JHA) against the housefly, M. domestica. Various morphological aberrations were induced in larvae, pupae and adults of M. domestica. The highest percentage of larval deformities caused by mimic, (can not molt or shrinked). Consult gave the highest percentage of malformation in the resulting pupae (C. shaped, elongated, distorted, two constricted, tapering anterior and broad posterior , cylindrical adult uncompleted). Admiral and mimic induced high percentage of abnormalities in the adult flies (small size body and curved legs, crumbled wings and curved abdomen). Larval-pupal intermediates and pupal-adult intermediates were induced as a result of these treatments.


INTRODUCTION
The house fly, Musca domestica is the most common and widely distributed mechanical vector of several pathogenic organisms of human and animals.Resistance insects have been recorded for most insecticide.The use of IGRs against the house fly are considered environmentally safer alternatives to broad-spectrum insecticides because of their low toxicity to human, little likelihood that insects would develop resistance to compounds that mimic their own hormones and specificity for their insect targets.Thus, the application of IGRs remains one of promise for the future.

MATERIALS AND METHODS
The strain of insects was obtained from Research Institute of Medical Entomology, Dokki, Giza, Egypt.The colony was maintained according to Hashem and Youssef, (1991).The eggs were collected and transferred to larval medium, which contain wheat bran (655 gm.) + Milk powder (50 gm.)+yeast powder (38 gm.)+ Tap water (600ml.).The pupae were transferred into cages until adult emergence.Different concentrations, (10, 100, 1000and 2000ppm) of insect growth regulators, buprofezin (applaud), hexaflumuron (consult), lufenuron (Match), tebufenzoide (Mimic) and pyriproxyfen (Admiral) were prepared by adding water.First instars larvae were divided into five groups, each consists of 20 larvae, put in plastic cups containing media which exposed to selected concentration.The morphological changed were recorded for larval, pupal and adult stages.All tested IGRs induced larvalpupal intermediates.Admiral gave the highest percentage of malformed larval Morphological effects of some insect growth regulators on M. domestica 31 pupal intermediates, which induced 4, 5 and 7% at 10,100 and 1000 ppm, respectively.The puparia of these forms were incomplete with retained parts of the last larval cuticle {plate ( 1 Deformed pupae failed to complete their metamorphosis properly which could not emerge completely and remain concealed in the puparia until they die.Consequently incomplete adult ecolsion dominated.In some cases the head and thorax ecolsed while in other cases, the head, thorax and part of the abdomen with the fore wings were released but the rest of the body still attached to the puparia (Plate 5).Other IGRs induced larval-pupal intermediates on M.domstica, BAY SIR (Moustafa, 1991); diflubenzuron and pyriproxyfen (Shalaby, 1994); and methoxyfenozide & pyriproxyfen (Assar and Abo-Shaeshae, 2004) All tested IGRs induced adult malformations.Admiral and mimic induced high percentage of abnormalities.Admiral elicited 6 and 8% abnormalities at 10 and 100 ppm, respectively, while mimic caused 4.2 and 7.19% abnormalities at 10 and 100 ppm, respectively.The tested IGRs induced adult with small sized body and curled legs {(plate ( 6) fig (C and D)}, some adults were with crumpled wings while others were with curved abdomen {(plate (6), Fig ( E, F)}.The same abnormalities were reported by some investigators on the same insect species using other IGRs, JHA (Cerf and Georghiou, 1974); diflubenzuron (El-Kordy, 1985); dimilin, BAY SIR and altosid (Baker, 1986); diflubenzuron (Shafi et al., 1987); IGI -DC 902, denate, dimilin and amix-500 (Youssef et al., 1990); BAY SIR (Moustafa., 1991); diflubenzuron and pyriproxyfen (Shalaby, 1994); pyriproxyfen (Osman 1998); and pyriproxyfen and methoxyfenozide (Assar and Abo-Shaeshae., 2004).Carton et al. (1998) found that treatment of S.exigua larvae with methoxyfenozide led to malformation in wings, the emerging adults often had problem in discarding the pupal exuvium.

RESULTS AND DISCUSSIONS
Application of pyriproxyfen to the German cockroach, Blattella germanica (10-100µg) induced molting of nymphs into supernumerary nymph, (Reid et al., 1994).They said that pyripoxyfen and fenoxycarb induced significant developmental delays and levels of morphogenetic wing.
Plate (1): Larvae & larval-pupal intermediate of M. domestica Normal larva (untreated) Malformed larvae: B-treated with consult and admiral .C-treated with match, mimic and applaud.D-Malformed larval-pupal intermediate treated with all tested IGRs.Plate (2): Pupae of M. domestica A-Normal pupa.Malformed pupae: B-treated with match, consult and mimic.C-treated with applaud and admiral.D-treated with applaud, consult and mimic,and E -treated with admiral and match Plate (3): Malformed pupae of M. domestica Malformed pupae: A-treated with match, admiral and applaud.B-treated with match, consult and mimic.C & D treated with consult.Plate (4): Malformed pupae of M. domestica A-treated with consult and mimic B-C-&D-treated with consult Plate (5): Pupal-adult intermediates of M. domestica, A,B, C and D: Adult which can not emerge completely when treated with all tested IGRs.Plate (6): Adult of M. domestica A, B: Normal male and female.Malformed adults: C, D: treated with match, consult and applaud.E-&F-: treated with mimic and admiral.

Table 1 :
Morphogenic effects of the tested IGRs against M. domestica as 1 st larval instar.