Milkweed bugs

It can also be made by nitrating diethyl phenyl phosphate below 0°. It is a red oil, almost insoluble in water, and Schrader found it effective against aphids, while Ball and Allen1 proved it active against the housefly, milkweed bug and cockroach. Later work showed it active against the two-spotted spider mite. 

Cardenolldes appear to be metabolized by a variety of species, possibly as a mechanism for converting these steroids into compounds that can be efficiently sequestered. The milkweed bug, Oncopeltus fasclatus, metabolizes (hydroxylates ) the nonpolar cardenollde dlgltoxln to more polar compounds that are subsequently sequestered In the dorsolateral space fluid (17. 18). Larvae of another cardenolide-adapted Insect, the monarch butterfly, Danaus plexlppus. also convert these steroids Into compounds that are readily sequestered. For example, uscharldln, which contains a carbonyl group at C-3 ( ) of the... 

In the second series, the exposed insects included several of the above, and, in addition, two species of mosquitoes, mealworms, and milkweed bugs. 

Blood and various organs of humans and other animals contain esterases capable of acetylsalicylic acid hydrolysis. A comparative study has shown that the liver is the most active tissue in all animal species studied except for the guinea pig, in which the kidney is more than twice as active as the liver. Human liver is least active the enzyme in guinea pig liver is the most active. The relatively low toxicity of some of the new synthetic pyrethroid insecticides appears to be related to the ability of mammals to hydrolyze their carboxyester linkages. Thus mouse liver microsomes catalyzing (+)-/runs-resin e 111ri n hydrolysis are more than 30-fold more active than insect microsomal preparations. The relative rates of hydrolysis of this substrate in enzyme preparations from various species are mouse > > milkweed bug > > cockroach > > cabbage looper > housefly. 

We began to extract plants with apolar solvents and tested these extracts by contact and fumigation against the cotton stainer, Dysdercus cingulatus, and the milkweed bug, Oncopeltus fasciatus. Eventually we found that the extract of the bedding plant, Ageratum houstonianum, contained two potent anti-juvenile hormones. 

By contact and fumigation the extract induced milkweed bug and cotton stainer nymphs to molt to tiny adults, skipping one or more of their immature stages. These miniature adults did not reproduce and quickly died (Figure 2). 

In additional biological work we found that virgin female American cockroaches, Periplaneta americana, stopped producing their sex attractant following treatment with Precocene II, while milkweed bug and Mexican bean beetle eggs treated with Precocene II were unable to hatch. Normal non-diapausing Colorado potato beetles treated with Precocene II promptly left their food plants, burrowed into the soil and entered diapause. 

The steroids known to play major regulatory roles in insect development and metamorphosis all fall into the class of polyhydroxylated ketosteroids called ecdysones (19-22). With the exception of Makisterone A (a C2 ecdysteroid identified from the milkweed bug Oncopeltus fasciatus) the known insect ecdysteroids constitute a group of eight or nine steroids that differ from one another... 

We also used a protocol where treatment was initiated with newly emerged adult milkweed bugs. The results of this experiment are shown in Table III. The preoviposition period (10-12 days) was not affected by canavanine but all other parameters measured showed concentration-dependent effects. Thus canavanine increased mortality, reduced the total number of eggs laid (fecundity) as well as the percent hatch (fertility). Once oviposition began, 0. fasciatus normally deposited eggs daily until death. The preoviposition period was subtracted from the total number of live days before the... 

Oncopeltus fasciatus (Dallas) large milkweed bug adult nymph T GR 77 79... 

The Milkweed bug, Oncopeltus tasciatus [168], is unable to dealkylate plant sterols into cholesterol before they are incorporated into the larval or adult tissues or into the egg, and is apparently able to utilize campesterol as a precursor for their Cjg moulting hormone, makisterone A. 

Larvae of the large milkweed bug, Oncopeltus fasciatus treated with precocene II undergo precocious metamorphosis and moult into diminutive forms with adult characters. Freshly hatched females treated with precocene II remain sterile and their corpora allata loose their ability to secrete juvenile hormone even when transplanted into an untreated body (Muller et al., 1979 Masner et al., 1979 Pener et al., 1978). 

---